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2023 | Buch

5th International Conference on New Developments in Soil Mechanics and Geotechnical Engineering

Proceedings of ZM 2022


Über dieses Buch

This volume highlights the latest advances and innovations in the field of soil mechanics and geotechnical engineering, as presented by leading international researchers and engineers at the 5th International Conference on New Developments in Soil Mechanics and Geotechnical Engineering (ZM), held in Nicosia, Northern Cyprus on June 30-July 2, 2022. It covers a diverse range of topics such as soil properties and characterization; shallow and deep foundations; soil improvement; excavations, support systems, earth-retaining structures and underground systems; earthquake geotechnical engineering; stability of slopes and landslides; fills and embankments; environmental preservation, water and energy; modelling and analyses in geotechnical engineering. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.



Keynote Lectures

Bearing Capacity of Shallow Strip Foundation on Granular Soil Under Eccentric, Inclined and Eccentrically Inclined Loading—A Review

Bearing capacity of shallow foundations is one of the most important areas of study in geotechnical engineering. Since the founding work of Karl Terzaghi in 1943, results of several theoretical and experimental investigations have been published. Most of these studies relate to the case where the foundation is subjected to centric vertical load. In the present paper, an attempt has been made to summarize the important developments related to the estimation of the ultimate bearing capacity of shallow foundations on granular soil subjected to eccentric vertical loading, inclined centric loading, and eccentrically inclined loading. Reduction factors to estimate the ultimate bearing capacity of foundations under eccentric, inclined, and eccentrically inclined loading from that subjected to vertical centric loading have been discussed.

B. M. Das, C. R. Patra, R. N. Behera, K. Sobhan, C. Atalar
Static and Dynamic Behavior of Shallow Foundation Reinforced by Honey Cell Modular Block

The construction of residential building and industrial complex in the soft ground is rather difficult to meet the requirement by the design code in terms of settlement as well as bearing capacity. There are a number of methods to improve the soft ground for shallow foundation with utilizing geosynthetics and chemical stabilizer as well as mechanical compaction. This paper presents the soft ground reinforcement method for shallow foundation by utilizing concrete hollow modular block (250× 250× 150 mm). The space of hollow in the modular block is 150× 150× 150 mm. The theoretical formula for estimation of bearing capacity is developed with the modification of Based on the laboratory model tests results, the best combination of soil reinforcement method is proposed for practical use in the field.

Eun Chul Shin, Chul Hee Lee, Jeong Ku Kang
The “Site Recognition Challenge” in Data-Driven Site Characterization

One distinctive feature of geotechnical engineering is site uniqueness or site-specificity. However, there is no data-driven method to quantify site uniqueness. The corollary is that it is not possible to identify “similar” sites from big indirect data (BID) automatically and no method to combine sparse site-specific data with big indirect data to produce a quasi-site-specific model that is less biased compared to a generic model and less imprecise compared to a site-specific model. This “site recognition” challenge is difficult because site-specific data is MUSIC-X (Multivariate, Uncertain and Unique, Sparse, Incomplete, and potentially Corrupted with “X” denoting the spatial/temporal variability). This paper presents the application of 4 methods (hybridization, hierarchical Bayesian model, record similarity method, site similarity method) to construct a quasi-site-specific transformation model between the undrained shear strength and normalized cone tip resistance. The similarity methods are “explainable”, because a list of “similar” sites can be generated explicitly for inspection.

Kok-Kwang Phoon, Jianye Ching
New Tool for the Measurement of Soils’ Shear Strength

Disturbance encountered when testing soft soils both in laboratory and in-situ conditions makes the determination of undrained shear strength, Su, very challenging. This paper introduces a new tool called “Cylindrical Shear Tool” (CST) to measure the undrained shear strength, Su, of soft soils. Description of this tool is given and the related shear test procedure is detailed. The proposed tool offers the advantage to avoid the disturbance of soft soils prior to the measurement of shear strength. From recorded measurements, and based on considerations of the existing shear tests, a specific method of determination of Su is proposed. Recorded results by the CST on a reconstituted Tunis soft clay revealed in fair agreement with those obtained from direct shear tests and from a triaxial test. Using the CST a series of tests was also performed from which the friction angle of the interface between the CST and a compacted sand is determined. First, characterization of the chosen quarry sand comprised identification tests, Proctor tests and the direct shear test (DST). Then follows the preparation of sand samples compacted, in Proctor molds, at the optimum modified and normal Proctor water contents. Those remolded sand specimens were subject to the CST tests for which the failure shear strength is captured. Then the method of determination of the sand specimens’ friction angle is detailed.

Mounir Bouassida, Dalel Azaiez

Soil Properties and Characterization Final

Apparatus Design and Measuring of Apparent Swelling Pressure of Compacted Bentonite

Apparent swelling pressure of compacted bentonite (ps) is a basic parameter for structure design for the geological disposal projects of high-level radioactive waste (HLW). The equilibrium apparent swelling pressure (peq) observed by wetting compacted bentonite have been reported extensively in past studies, however, peq variation, i.e. difference between peq measurements under similar conditions, may significantly large equilibrium swelling pressure. This variation was sometimes attributed to swelling deformation of specimens during testing, however, few studies discussed this issue in detail. In this study, a swelling pressure apparatus was newly developed with aim of obtaining good repeatable peq measurements. Efforts are made on apparatus design to achieve simple configuration, low cost and low system compliance. A series of tests were conducted to find a proper way of obtaining peq with less variation for identical specimens. It was found that slight deformation of might not be the fundamental reason for peq variation, however, slight deformation may introduce difficulties of dry density measurement, which may result in apparent peq variation. With the new apparatus, good repeatability of ps measured on identical specimens was obtained. The apparatus may provide an inexpensive tool for further understanding the behaviours of compacted bentonite.

Hailong Wang, Takumi Shirakawabe, Daichi Ito
Volume Change Behavior of Natural Sands with the Addition of Mica Particles

The volume change behavior of sands is affected by the grain size, shape, mineralogical origin, initial void ratio, effective stress level, and the existence of pore water inside the soil medium. The presence of mica minerals changes the inter-particle force chain and causes the re-arrangement of sand particles under varying stress conditions. The intergranular void ratio concept is a useful approach to evaluate the grain size range that is in control of the soil behavior. Two different natural sand samples were mixed with varying mica contents to perform oedometer tests. The volume change behavior was evaluated with the intergranular void ratio concept. The triaxial test results were used to support the findings of the oedometer test results. The test results indicated that the volume change behavior depending on the mica content differed with the effective stress level and the mineralogical origin of the sand. There was a certain range of mica content, a transition zone, that changed the soil behavior. The behavior was controlled by the fine particles when the soil contained approximately 20% or more mica.

Furkan Egemen Kahya, Tugba Eskisar
Estimation of Compression Index of Lightly Overconsolidated Soils from In-Situ Time-Settlement Plots

Compression index is an important parameter in the determination of settlement response of soft soils under preloading with PVDs. Compression index typically estimated using oedometer tests on samples with the assumption that the result represents the entire deposit in the field. Most of the soils in in-situ condition are lightly overconsolidated, with Over Consolidation Ratio (OCR) ranging from 1.0 to 2.0 due to glaciation, ground water level fluctuation, aging, isostatic uplift, cyclic loading, creep, erosion, cementation, etc. The effect of overconsolidation ratio on the estimation of compression index is analyzed in this study. The in-situ time-settlement plots at different depths for sites, Suvarnabhumi International Airport [2] and Mukasa Express Way [4], are analysed to estimate compression index of in-situ ground, which truly represents the deposit's overall behavior unlike the values obtained from ‘so called’ extremely small undisturbed samples tested in the laboratory. The variation of compression index with depth of the deposit are also presented for different OCR values considered.

T. Lenin, M. R. Madhav, V. Padmavathi
Granular Soil Relationship Between Angle of Internal Friction and Uniformity Coefficient

The strength characteristics of the sand and gravel are influenced by the size of the grains, their distribution and packaging. The theoretical approach states that the sand angle of internal friction decreases if the uniformity coefficient increases. There are insufficient data for gravel correlation between the uniformity coefficient and the angle of internal friction. Consolidated drained triaxial compression tests (CD) were conducted to determine the strength parameters of remolded sand and gravel samples. These samples were classified as sands and gravels. The optimal water content and density were determined by standard Proctor compaction test and used for these samples. Consolidated drained triaxial compression test gives more reliable data that idealize the soil behavior in the real situation. Three different confining pressures of 20, 50 and 70 kPa were applied to restore horizontal stresses for the soil specimens imitating embankment behavior affected with traffic load. The results indicate that the sand angle of internal friction decreases if the uniformity coefficient is increased. The gravel angle of internal friction does not correlate with the uniformity coefficient.

Mindaugas Zakarka, Šarūnas Skuodis
Mechanical Strength Tests of Building Blocks of the Historical British Government Building in Famagusta, North Cyprus

Damage assessments and strength tests of building blocks of the British Government Building in Famagusta have been carried out. A total of 40 core samples, three or four-inches in diameter, were drilled from different spots, and mechanical strength tests were performed applying standard laboratory procedures. The building in question is made of Pliocene–Pleistocene age calcarenite (granular limestone) blocks whose trade name is Saritas, which means yellow stone. As a result of a fire, ceilings and roofs of the building collapsed, steel beams bent, wooden beams and other wooden elements burned, interior plasters fell. The compressive strengths of overall core samples varied between 1.01 and 21.85 MPa. The mean value for the formation is 6.86 MPa. The porosity of the samples varies between 16.74 and 50.44%. Porosity versus compressive strength revealed an inverse correlation between the two parameters. Collected samples were grouped into three facies based on their petrographic analysis. These are 1. Fine-grained calcarenite, 2. Coarse-grained calcarenite, and 3. Vuggy calcarenite. Compressional strength dependency on lithology type has been studied and the coarser the rock texture the weaker the rock strength is concluded.

Salih Saner, Hasan Okaygun
Using Compression and Swelling Indices to Characterize Expansive Soils

Expansive soils are a worldwide problem. The volume variation of this soil is depended on its moisture content. A new approach to characterize this kind of soil is based on the oedometer test results, performed on compressible soils, either expansive or non-expansive. The Cc/Cs ratio is determined, where Cc is the compression index and Cs is the swelling index. Zones delimited by a Cc/Cs value and a swelling pressure (σs) value are identified to differentiate expansive soils from non-expansive soils. When Cc/Cs ratio is higher or equal to 15, the swelling pressure is practically equal to zero.

Sergio Andrew Manigniavy, Yosra Bouassida, Dalel Azaiez, Mounir Bouassida
Probabilistic Interpretation of CPTu-DMT Data for Soil Profiling

Cone Penetration Test (CPTu) and flat Dilatometer Test (DMT) are widely employed in-situ tests for ground unit profiling in terms of Soil Behavior Type Index IC and Material Index ID. CPTu provides a nearly continuous data profile with respect to DMT, making it more appealing for soil unit identification, leaving DMT data for qualitative comparison. This work proposes a first attempt of integrating CPTu-DMT data within soil profiling task, aiming to probabilistic assess congruence and discrepancy between the two sets of data. A semi-automated CPTu-DMT bivariate data interpretation tool is here presented aiming to facilitate communication of layer delimitation while eliciting the heuristics that designers apply in this process. Conventional classification class boundaries –here taken from (Robertson, 2009) and Marchetti, (2001) chart– are applied with user-specified refinements. The proposed algorithm is applied to CPTu and DMT sounding records performed at Barcelona harbor (Spain).

Stefano Collico, Marcos Arroyo, Amadeu Deu
Clay Soil Stabilization Using Xanthan Gum and Sodium Alginate as Biopolymers

This study deals with the effect of xanthan gum and sodium alginate biopolymers on the consistency, compaction, and strength properties of clay. Atterberg limits tests, standard proctor compaction tests, and unconfined compression tests were performed. The curing time of the specimens varied from 7 to 56 days. Xanthan gum ratios were %0.5, %1, %1.5, %2, %3 and sodium alginate ratios were %1, %2, %3, %4. As a result, a noticeable increase in liquid limit was observed in both biopolymers. Plastic limit and plasticity index of the specimens showed minor changes compared to the liquid limit of the soil specimens. Optimum water content of the clay specimens with additives was %2 higher compared to that of the untreated clay. Maximum dry density slightly decreased compared that of the untreated clay. The results of unconfined compressive tests showed that using xanthan gum and sodium alginate biopolymers had the beneficial effect of increasing the strength of the soils.

Ayberk Temurayak, Tugba Eskisar
Estimation of OCR and Compression Index by Different Methods

Preconsolidation stress ( $${\sigma }_{c}^{\mathrm{^{\prime}}}$$ ) is an important parameter to understand the stress history of the soil and in calculating settlements. Accurate determination of settlement depends largely on the accuracy of $${\sigma }_{c}^{\mathrm{^{\prime}}}$$ . Several researchers have proposed different methods to obtain $${\sigma }_{c}^{\mathrm{^{\prime}}}$$ from e-log $${\sigma }^{\mathrm{^{\prime}}}$$ plot. Determination of preconsolidation stress relies on the graphical approach of Casagrande method. This method depends on identification of the point of maximum curvature on the e-log $${\sigma }^{\mathrm{^{\prime}}}$$ curve which is highly subjective and leaves room for errors. Several methods have been proposed in the literature for interpretation of preconsolidation stress based on curve fitting rather than subjective judgment. These approaches are based on graphical interpretation of void ratio (e) versus effective stress ( $${\sigma }^{\mathrm{^{\prime}}}$$ ), log e versus log $${\sigma }^{\mathrm{^{\prime}}}$$ , log (1 + e) versus log $${\sigma }^{\mathrm{^{\prime}}}$$ plots. The methods used in this study are semi-logarithmic [1, 2, 3, 4], bi-logarithmic [5, 6, 7] and based on variation of constrained modulus with effective stress [8]. In this study, test data taken from the three (Egypt, California and India) different locations around the world is analysed. Compression index (Cc) and over consolidation ratio (OCR) are determined using the above methods and the variation is studied.

Zeeshan Firdous, V. Padmavathi, M. R. Madhav

Shallow and Deep Foundations

Limit Load Exemplary Analyses of Foundations Accidentally Placed on Sand Underlain by Peat Using Their Various Parameters

The interaction of underlying organic soils with buildings and infrastructure is an important aspect of environmental engineering. Especially since these soils have a particularly important role in the ecosystem, as well as because of the great variety of their mechanical and permeability characteristics. This limit load study concerns the hypothetical situation of accidental direct foundation of a building on a layer of sands under which are peats (and the unconfined groundwater table). The analyzed case is a common situation in the vicinity of rivers and lakes, especially in areas with high urban pressure. In the calculations, the finite element method (FEM) was used to model the strip foundation of a residential building in a plane strain approach. The peat parameters were derived from various literature analyses of different locations (specifically from Poland, Nederland, and Turkey,) to provide a range of possible soil failure load scenarios. This type of analysis identifies the most undesirable variant and gives an idea of the scale of the issue.

Łukasz Kaczmarek, Maria Grodzka-Łukaszewska, Grzegorz Sinicyn
Interaction of Laterally Loaded Free Head Barrette Pile in Elastic Soils

Barrette piles are usually preferred over circular piles where larger bearing capacity, stiffness, and structural capacity are needed. Currently, design work with such piles is usually made assuming an equivalent circular pile diameter. Previous research did not cover pile-soil-pile interaction among piles with rectangular sections. In this study, the soil is assumed as elastic and the three-dimensional nature of the problem necessitated the establishment of 3D numerical analysis models. Piles are modeled as volume elements so that shape effects are properly studied. In this respect, the effects of cross-section and orientation of piles, spacing between piles, stiffness of the soil, and the magnitude of the loading were investigated on the behavior of group barrette piles. Considering these effects, interaction factors were calculated for different pile orientations in a group. Since barrette piles have rectangular cross-sections, the most important factor in their interaction with each other is the resistance of pile on the direction along which the load is acting on the pile. Circular and barrette group piles have been analyzed under horizontal loads. Analyses results showed that unlike circular piles, which have an equal moment of inertia in all directions the barrette piles were highly affected by loading direction and their orientation inside the group. This study emphasized that it is critical to determine the disposition of the piles considering the loading direction if less interaction among piles is desired.

Yasar Taner, Gurkan Ozden

Environmental Preservation, Water, and Energy

Influence of Thermal Cycles on the Volume Change of Ulexite Added Sand-Bentonite Mixtures

Bentonite and sand-bentonite mixtures are recommended as engineered barriers. In waste disposal facilities, especially radioactive waste, a significant temperature increase occurs. The engineering properties of sand-bentonite mixtures change depending on temperature. Sand-bentonite mixtures used as buffer material should be able to maintain their properties unchanged at high temperatures and under thermal cycles. In the present study, the volumetric deformation behavior of sand-bentonite mixtures containing 10% bentonite was investigated under room temperature and thermal cycles. In addition, ulexite, one of the boron minerals known for its high resistance to high temperature and low thermal expansion coefficient, was added to these mixtures at rates of 10 and 20% by dry weight. The compression-swelling behavior of ulexite added sand-bentonite mixtures under room temperature and thermal cycles was investigated. According to the results of the present study, when ulexite was added to the sand-bentonite mixture, the compression amount increased at room temperature, while the swelling amount decreased. However, the total compression amounts were reduced by half when thermal cycles were applied compared to the tests performed at room temperature.

Sukran Gizem Alpaydin, Yeliz Yukselen-Aksoy
Assessment of Climate Impact and Costs Comparing Two Railway Embankment Fill Methods

Emissions from infrastructure projects and construction projects have a large impact on the environment. Construction activities and materials, including geotechnical engineering works, account for a great share of that impact and the monetary costs of the projects. In railway projects, crushed bedrock is often used as fill material in the embankments, and less suitable soil is excavated and transported to a landfill causing emissions. Despite that, sustainability assessments are rarely made when comparing the crushed bedrock fill method with other alternative methods, when the geotechnical engineer is designing an embankment. This paper, therefore, shows how climate impact and monetary costs can be compared for two fill methods in a railway embankment in Sweden, namely crushed rock fill and fill made of cement-stabilized sandy till. A comparing life cycle assessment (LCA) of climate impact and a life cycle cost analysis (LCCA) of monetary costs were made for the two methods. Activities and materials used in the production and construction stages were assessed. The results show that the stabilized sandy till method had both a smaller climate impact and lower life cycle cost (LCC) than the crushed bedrock fill method.

Ida Samuelsson, Johan Spross, Stefan Larsson


Field Trial to Rapidly Classify Soil Using Computer Vision with Electric Resistivity and Soil Strength

In Singapore, large volumes of excavated soils from the construction industry are sustainably re-purposed in land reclamation projects as fill material. The excavated soils are trucked to Staging Ground (SGs), where they are received and categorized into two broad groups (“Good Earth” and “Soft Clay”). The soil type categorization is traditionally done using properties such as particle size distribution (PSD) and water content (w). However, due to the heterogeneity of soils and non-uniform mixing during the excavation and truck loading process, the actual excavated soils in each truckload received at the SGs may vary. As such, visual checks of each truck are presently implemented at the SGs, which is labour-intensive and can be subjective. Therefore, an objective rapid classification method is required at the SGs. This can be achieved through an innovative system using computer vision complemented by in-situ probe measurement to perform non-destructive and instantaneous soil classification on-site. An accurate classification of excavated soils is critical in maximizing the recovery and reuse of natural resources in land reclamation projects for long-term sustainability. This paper presents the assessment of rapid soil testing methods that are suitable for integration with a recently developed novel rapid soil classification using computer vision. The objective of this complementary soil parameter measurement is to enhance the soil type prediction accuracy, as well as the capability to detect soil type with depth. The methods that are deemed suitable are the four-probe soil electrical resistivity measurement, cone penetration test (CPT) and moisture content test using time-domain reflectometer (TDR).

Y. J. Eugene Aw, Soon-Hoe Chew, Yeow-Chong Tan, Pei-Ling Goh, Cheng-Soon Teo, Danette S. E. Tan, Mei-Lin Leong
Influence of Excess Pore Pressure Development on Inertial Pile Response

The behavior of piles in submerged and liquefiable sandy soils under earthquake loads attracted attention of researchers since 1980s. In this study, behavior of soil surrounding piles in such soils was investigated. In the study, response of the piles under inertial loads was considered, and it was assumed that the soil was in passive terms of during the earthquake. In other words, kinematic and inertial interactions are separated in soil-pile interaction. In the three-dimensional finite element analysis, harmonic loading was applied to the pile head. As a liquefiable soil layer, sandy soil whose liquefaction model parameters were determined at the California Wildlife Test Site was considered. In the analyzes made under different horizontal loads and frequencies, it was determined that the stresses transferred from the pile to the soil can force the soil up to liquefaction by causing excess pore water pressure to change in the soil, and its reflection on the horizontal load–displacement curves (p–y curves) is discussed. The results of the analysis revealed that the loading frequency had some effect on soil behavior and development of excess pore water pressure significantly affected the horizontal load- displacement curves.

Hande Yumuk, Gurkan Ozden
Numerical Study of Uplift Induced Levee Failure for the Design of a Centrifuge Test

In geotechnical engineering, physical and numerical models seek to shed light on multiphase phenomena that threaten earth structure stability. This is the case of river levees: when subjected to non-ordinary hydraulic loads, local and global failures with consequent floods could occur. If, on one hand, centrifuge models can replicate the real phenomena, exploiting the enhanced gravity, while scaling geometrical features and time, on the other, numerical models extend the possible case studies by capturing key elements, governing the hydro-mechanical behaviour of the earthworks. However, the two techniques could complement and benefit each other. In this research, a potential failure mechanism, induced by the development of uplift pressures beneath the toe of a levee characterized by a peculiar stratigraphic profile, is investigated. The foundation consists of a shallow weak low-permeability layer, overlying a coarser and more permeable one, this latter acting as a hydraulic preferential flow path between riverside and landside. Results of a preliminary numerical study carried out with different methods are presented and discussed. The study aims to improve understanding of complex failure mechanisms and to encourage the development of more robust forecasting methods. Indeed the results have provided fundamental guidance for a centrifuge experimental set up.

Veronica Girardi, Elena Dodaro, Roberta Ventini, Marianna Pirone, Carmine Gerardo Gragnano, Daniela Giretti, Francesco Zarattini, Fabio Gabrieli

Emerging Subjects in Geotechnical Engineering

Prediction of Load Capacities of Closed-Ended Piles Using Boosting Machine Learning Methods

In this study, a novel data-driven model is developed using boosting-type machine learning algorithms with the aim of predicting the ultimate load-bearing capacities of closed-ended piles. A comprehensive database is gathered using the full-scale load test data with four features. Special boosting type machine learning methods are trained and tested with the database. Once predictions are made, a newly developed machine learning algorithm called Shapley method is utilized to decide the effectiveness of the selected features in predicting pile capacities. Results indicate that the pile cross-section area and length features are sufficient to achieve accurate predictions covering the parameters on the pile side and the CPT-based tip resistance is the only parameter needed on the soil side. While different boosting methods result in different levels of accuracy in predicting the load bearing capacities of closed-ended piles, it is generally possible to determine the minimum number of features necessary to satisfy a high goodness of fit. In the end, optimum number of features are determined in the prediction process using the Shapley method through the boosting algorithms giving us a valuable prediction tool for estimating the bearing capacity of closed-ended piles.

S. Karakaş, M. B. C. Ülker, G. Taşkın
Shear Strength Behavior of Perlite Added Sand-Bentonite Mixtures Under Room Temperature and Thermal Cycles

The present study investigates the shear strength behavior of perlite added sand-bentonite mixtures under room temperature and thermal cycling. The increase in the number of energy structures causes interaction of soils with high temperature. Thermally durable soil material is needed around energy geo-structures. In this study, it was aimed to obtain a new buffer material to be used around energy structures by adding 10 and 20% perlite additive to 20% bentonite-80% sand mixtures (20B-80S). The direct shear tests were conducted under temperature cycling (8 hrs heating-16 hrs cooling). As a results of the compaction tests, it was seen that the perlite additive decreased the maximum dry unit weight (γdry-max) and increased the optimum water content (wopt). The test results showed that perlite additive reduced the shear strength of the mixture under thermal cycles but with 20% perlite additive reached higher strength than 10% perlite additive.

Esra Güneri, Yeliz Yukselen-Aksoy
Role of BIM for Different Phases of Geotechnical Investigation of the Transport Infrastructure

The paper deals with application of BIM—Building Information Modelling and is focused on different phases of the Geotechnical Investigation, preferably for Transport Infrastructure. The result is combined 3D model of the Ground and Geotechnical structure—embankment of the motorway which enables to the construction partners not only discussed technica problems but also construction time schedule, financial flow.

Ivan Vaníček, Martin Vaníček
Use of Neural Networks to Predict Correlations Between CPT and PMT Tests for Clay and Marl Soils

The Menard pressuremeter (PMT) and the cone penetrometer (CPT) are the most widely used in situ tests for geotechnical investigations of sites in Algeria. Due to the quick and accurate results, they allow for field surveys, geotechnical design parameters and quality control assessments. Numerous correlations of geotechnical parameters measured from these two tests have been established in the literature. In this work, it is proposed to establish correlations between the gotechnical parameters deduced from the pressuremeter and the cone penetrometer tests for the clays and marls of the Algiers region in Algeria using the artificial neural networks approach (ANN). The parameters taken into account are the cone resistance of the CPT, the deformation modulus and the limit pressure deduced from the PMT. The results obtained will be discussed and compared to empirical relationships in the literature. The obtained correlations are relatively low compared to those from the literature.

Mohamed Khiatine, Ramdane Bahar

Stability of Slopes and Landslides

Numerical Analysis of Slope Instability Due to Water Pipe Leakage

Buried pipe leakage can initiate landslides in road slopes. This study deals with stability analysis of a clayey slope subjected to water pipe leakage. A case study of landslides is considered for slope in Chatham Village of south Trinidad. Numerical analyses were conducted in two ways: (1) unsaturated seepage analysis using SEEP/W software to obtain the porewater pressure distribution and (2) slope stability analysis using SLOPE/W to calculate the factor of safety during water leakage. The results demonstrate that most important observations in water flow and stability responses of unsaturated clayey soil slope under water pipe leaking condition can be reasonably well simulated using the proposed numerical procedure.

K. H. Park, G. Ramnauth
GIS Susceptibility Maps for Shallow Landslides: A Case Study in Shawinigan, Quebec, Canada

Landslides on various scales represent an important category of morphological processes in Quebec, playing an important role in the evolution of slopes, as well as causing instability problems for infrastructures and occasionally, loss of life. In this paper, we present the potential for shallow landslides, within the La Bissonnière amphitheatre, near Shawinigan, itself created progressively over the last 10,000 years, by a combination of episodic quick clay flows and fluvial downcutting of the St Maurice River and its tributaries. An infinite slope model, using the so-called factor of safety was used to produce GIS shallow landslide susceptibility maps for the area and the validity of the model was confirmed through field observations and comparisons with orthophotos.

Michael Barbosu, James Gray
Determination of Critical Height of Unsupported Vertical Cuts Using Experimental and Numerical Methods

Stability of unsupported cuts are commonly analyzed numerically as a 2-dimensional problem using commercial geotechnical software such as SLOPE/W. This is also true for the unsupported cuts excavated into unsaturated soils. However, limited experimental studies have been undertaken to validate the numerical approaches in estimating the critical heights of unsupported cuts in unsaturated soils. To bridge this gap, laboratory test was conducted using a large-scale soil tank (W × L × H = 1.5 × 2.2 × 2.4 m) to determine the critical height of an unsupported vertical cut in sand with water table at 0.7 m from the surface. Excavation was simulated by removing 0.1 m height retaining panels until general failure took place. The matric suction profile in sand above the water table was established based on the suction values measured from various depths with high capacity tensiometers (i.e., T5X). The critical height determined in the laboratory test was compared with the one estimated using PLAXIS (3D).

Z. Nil Kutlu, Gregory Brennan, Won Taek Oh
Slope Stability Analysis of Open-Pit Mines Using Statistical Methods

A non-traditional method of slope stability calculation is presented, which often occurs during geotechnical design. The possible occurrence of slope failure is not illustrated by a safety factor but by the probability of failure. The result is the percentage of failure or, the safety of the stability that can be expected for a given slope. Unlike the deterministic calculation, not a constant value is given for each input parameter but statistical variables according to the distribution belonging to the sample data set, such as mean, standard deviation, relative minimum, and relative maximum. An approach is taken to how slope resistance calculations can be performed on a probabilistic basis through a case study. The subject of this case study is Hungary’s largest open-pit lignite mine in Visonta, eastern Hungary. On the optimised sections using the deterministic method, the slope resistance test was performed on a probabilistic basis. The analysis of statistical parameters is also presented as the most important step of the investigation. To determine the input parameters for the probabilistic analysis, the first step is collecting the shear strength values (in this case, friction angle and cohesion) and then deriving a statistical distribution, carrying out the goodness of fit test finally determining the parameters.

Petra Olah, Péter Gorog
Investigation of Ground Stability of the Surroundings of the “Statue of Peace and Freedom”, Alsancak-North Cyprus

The Peace and Freedom Monument is about seven kilometers to the west of Girne on the main road to Güzelyurt. It was built in 1977 by the Ministry of Public Works and Transport of the State of North Cyprus, in memory of the 1974 Peace Operation on the beach where Turkish soldiers first set foot on the island of Cyprus. Due to some adverse ground conditions and repair deficiencies to date, some foundation-related damages and structure depreciations occurred. This study includes foundation damages observed and assessment of the mass movements that might occur in the ground allocated for construction of the Beach Project in the nearby area. Geomorphological, geological, and groundwater aspects affecting the ground durability have been brought to the attention of engineers.

Salih Saner
Dynamic Response Analysis of Highway Embankments

As the severity and the occurrence rate of natural disasters, such as earthquakes, increases; highway embankments become more susceptible to related hazards. However, highway embankments are considered to be an important lifeline which must be in continuous operation under any circumstances. In light of the recent advances and latest research, geosynthetics can successfully and effectively be used to reinforce highway embankments against the primary and secondary effects of earthquake induced damages. It is important to estimate the approximate dynamic behaviour of engineering structures via numerical simulations before the experimental studies. This study covers numerical modelling of the dynamic response of full-scale highway embankments using the Mobile Seismic Shaker (MSS) in the field as a dynamic source. This numerical simulation phase has been used to ensure the true structural design and true instrumentation. The numerical simulations have been performed implementing the FEM technique using PLAXIS 2D software and includes the dynamic response analysis of dimensionally identical unreinforced and geogrid reinforced highway embankment models. Revealed numerical results clearly show that, geogrid reinforcement can successfully reduce the total displacements and transmitted accelerations at crest level which are key structural performance indicators.

Yasin S. Toksoy, Ayşe Edinçliler
Motion Analysis of Ground Failure Considering Rainfall and Ground Water Migration in Sandy Slopes

Failure of sandy slopes during heavy rainfall is often attributed to the rise of the groundwater table, which causes the slope to gradually transition from an unsaturated to a saturated state. Conventional methods for evaluating the stability of slopes under the influence of rainfall neglected the migration of groundwater and the dynamic motion of particles. In the current study, a model test is conducted to evaluate the trend of the groundwater table migration. In addition, a framework for partially saturated and unsaturated slopes is proposed for the dynamic process based on the analytical method. The results of the study show that based on the data analysis of the model tests, the upward trend of the groundwater table can be determined. Furthermore, the factor of safety (Fs) calculated from the analytical method shows that, Fs decreases sharply due to the upward migration of the groundwater table. The motion analysis provides the soil displacement and particle trajectory. This study provides an effective and practical method for evaluating the stability of unsaturated slopes under rainfall conditions, which can also be used for preliminary analysis in the early warning process.

Yan Liu, Hemanta Hazarika, Divyesh Rohit, Sahibbi Ali, Yasuhide Fukumoto, Masanori Murai, Nguyen Thi Hoai Linh, Yurika Taguchi

Excavations, Support Systems, Earth-Retaining Structures and Underground Systems

Experimental Investigation and Visualization of Failure Surfaces in Pipe-Soil Interaction Problems Using PIV Technique

In this study, the effect of relative density on bearing capacity was investigated for cases in which a pipe is buried within the zone of influence. As a novelty, failure mechanisms are experimentally determined using Particle Image Velocimetry (PIV). Within the scope of the study, six different physical model experiments were carried out for this purpose. In these experiments, the load imposed on the neighboring surficial foundation model and the resulting displacements relationship were also determined. The results suggest density dependency of the distribution of deformations.

Selçuk Bildik, Peter Rogenbuke, Gizil Tak, Baran Tulan, Özer Çinicioğlu

Earthquake Geotechnical Engineering and Associated Problems

P-Y Curves for Piles in Sand Based on the SPT Test–Parametric Study and Practical Recommendations

ULS and SLS limit state design of pile foundations under lateral loads is often undertaken on the basis of the P-Y curves concept. Since more than half a century, the methods of P-Y curves have been subject of an extensive research work worldwide. Nowadays, the P-Y curves parameters, namely the reaction modulus and the soil lateral resistance, are derived by correlation with geotechnical parameters measured by laboratory test or in-situ tests like the cone penetration test. The contribution of the standard penetration test SPT to the direct construction of P-Y curves is however not demonstrated in the literature. The paper aims at presenting an original semi-empirical method of construction of the P-Y curves along the pile directly based on the N-value measured by the SPT. On the basis of a detailed parametric study it was highlighted some key factors affecting the pile load–deflection behavior.

Abdesselem Laouedj, Ali Bouafia
Behaviour of Embedded Beam Formulations Under Dynamic Loading

Fully-coupled dynamic finite element analyses (FEA) of pile foundation structures are computationally demanding; hence, they are rarely performed in practice. Due to their exceptional ability to circumvent this obstacle, dimensionally reduced beam-type-elements (BTE), such as embedded beam formulations (EBF), have gained popularity in dynamic FEA of related problems. The current engineering approach assumes a high level of compliance in the predicted dynamic response across different pile modelling techniques. However, static FEA have shown that this assumption is not generally warranted, primarily due to limitations of the line-to-volume coupling scheme employed in classical BTE. This raises an obvious questions about their general applicability to dynamic FEA of pile foundation structures, which generally require a realistic representation of dynamic soil-structure interaction. Subsequently, comparative dynamic FEA are carried out considering different embedded beam formulations. The credibility of results is numerically validated based on direct comparisons with the well-accepted standard FE approach. In this regard, EBF capture the free vibration behaviour with high accuracy. Special care must be taken when using EBF for the prediction of kinematic amplification ratios close to resonance.

Andreas-Nizar Granitzer, Franz Tschuchnigg
Estimation of Ground Motion at One of the Damaged Building Sites Following the October 30, 2020, Samos Earthquake

On October 30, 2020, an earthquake with a moment magnitude of 7.0 occurred on the Kaystrious fault in the north of Samos Island. Although the effects of the earthquake in İzmir were widespread in several districts, the majority of the damage was concentrated in alluvial sites, the Bayraklı-Manavkuyu region, which is approximately 70 km away from the epicenter being the most heavily affected area. The fact that none of the buildings as high as four storeys did not experience considerable damage in contrast with the heavily damaged or collapsed structures with a number of storeys varying between 8 and 12 demonstrated that longer period harmonics that were close to the natural periods of these taller buildings were amplified by deep and soft saturated alluvial soils. Strong ground motion stations available at the time of the earthquake in the Manavkuyu region were established on soft grounds where the engineering bedrock with a shear wave velocity of 760 m/s is seated at about 200–350 m. Therefore, it was necessary to conduct deconvolution analyses to come up with engineering bedrock motions that would further be used in convolution runs to come up with realistic ground motions at the sites of the collapsed buildings. Shear wave velocity data captured in seismic surveys, capable of providing reliable data from deeper soil layers, were utilized along with deep borehole logs while establishing the one-dimensional soil response models. A sequential series of deconvolution analyses were then made in order to come up with the engineering bedrock motions. Site response analyses were made on accordingly established 1D model at the site of one of the collapsed buildings yielding acceleration response spectra which were later modified to reflect kinematic soil-structure interaction that would take place underneath the considerably large foundation of the damaged building. It was found that significant soil amplification took place at the building site, and the base shear force obtained based on the kinematic SSI analysis was close to the one found with respect to the 1975 Turkish Seismic Design Code with which the building was designed for.

Doga Altunevlek, Gurkan Ozden
Analysis of the Pile Foundation Calculation Results Given the Action of an Earthquake and Soaking of the Loess Base

Purpose and task: On the territory of Mongolia, loess type subsiding soils are widespread and where seismic activity is 6–9 points according to the modified scale of Giuseppe Mercalli (Charles Richter) system. During the calculation of piles, the goal was to analyze the reduction in the bearing capacity of the pile foundation, depending on the activity of the earthquake and the water saturation of the soil of the building base in the operational stage. Brief description of the methodology: Based on the results of the analytical calculation, a comparative analysis of the reasons for the decrease in the bearing capacity of the pile foundation under action 6 was carried out; 7; 8 and 9 points and in the condition Wsat. A method was used to predict the probability of a risk from unacceptable and uneven settlement of buildings and structures. Results and conclusions: A quantitative assessment of the reduction in the bearing capacity of the pile foundation was obtained and the inequalities of the boundary conditions were revealed based on the results of comparative analyzes of numerical values, relevant factors of influence, such as an earthquake and wetting of the subsiding soil of the base. Conclusions are drawn on the basis of a quantitative assessment and comparative analyzes that when designing pile foundations in a mandatory laying, consider the problem of reducing and increasing uneven settlements, and make a design decision taking into account the coefficient of reduction in the bearing capacity of the foundation.

Nyamdorj Setev, Dashjamts Dalai
Proposal of a Model Setup for Verification of the Origin of High Frequency Motion in Soil

High frequency components of motion are typically measured in laboratory tests on shaking tables when investigating the dynamic response of soil subjected to harmonic excitation. The source of these high frequency components is often thought to be related to uncertainties of experimental setups. In contrast, a group of numerical and theoretical research works suggested potential physical explanations to high frequency components of motion as related to soil mechanical behavior including soil fluidization, cyclic mobility, pounding or unloading elastic waves. This paper presents a finite element numerical study of an example model setup designed to verify the origin of high frequency motion in soil as potentially related to the presence of soil elastic waves in the steady state response of nonlinear hysteretic soil. The soil is modelled with an advanced soil constitutive model within the general framework of hypoplasticity to account in a reliable manner for soil cyclic behavior. The results show that high frequency motion can be observed in the computations in free field and on a simple structure even though a simple harmonic sinusoidal input motion is introduced at the base of the model setup. It is shown that apparently this high frequency motion can be representative of soil elastic waves released in nonlinear hysteretic soil in the steady state response.

Piotr Kowalczyk
A Comparison Study Between 1D and 2D Site Response Analyses Based on Observed Earthquake Acceleration Records

The objective of the present work is to evaluate the necessity of 2D site response analysis based on the comparison among the peak ground and spectral accelerations recorded by Istanbul Rapid Response Network and Istanbul vertical array stations during the Mw = 6.5 24/5/2014 Gökçeada and Mw = 5.9 19/5/2011 Kütahya earthquakes with the calculated accelerations by 1D and 2D site response analyses. The shear wave velocity profiles determined based on in-situ geophysical and geotechnical measurements and laboratory tests within the Istanbul Microzonation Project are revaluated adopting a revision scheme to obtain the best fits between the recorded and calculated spectral accelerations by 1D site response analysis. These modified shear wave velocity profiles are later used for 1D and 2D site response analyses performed in North–South and East–West directions to model peak ground and spectral accelerations on the ground surface. Finally, by modelling different distances around boreholes the influence of variation of the soil profile in horizontal direction is investigated by 2D analyses.

Shima Shamekhi, Atilla Ansal, Aslı Kurtuluş
Subsurface Study of Flowslide Liquefaction in Petobo, Palu, Indonesia

A huge flowslide due to liquefaction occurred at Petobo on September 28, 2018. Many building structures were collapsed, tilted, buried, or moved away up to a distance of 800 m or more. Flowslide occurred at slopes of around 3° and the affected area was approximately 1.64 km2. Magnitude and intensity of earthquake shaking, soil and groundwater conditions etc., would have contributed to the phenomena of the flowslide. Drilling, SPT with hammer energy measurements, laboratory testing on grain-size distributions and groundwater monitoring were performed after the incident. This paper discusses subsurface conditions and the assessment of liquefaction susceptibility. The geometry of ground surface was developed based on topographic survey and DTM data. Results show the materials at Petobo site consist primarily of loose silty sands and sandy silts in the middle and the debris flood areas. At the crown, the soils are mostly gravelly sands or sandy gravels. The groundwater is generally very close to the surface in the middle and the toe areas. The liquefaction susceptibility was assessed by Seed/NCEER method. At BH-1, located near the crown, liquefaction would be more susceptible in layers with depth generally more than 10 m. In the middle areas, BH-2 would likely be liquefied due to the earthquake at depth of less than 10 m. At BH-3, situated near the toe, the liquefaction susceptibility appears low, where only few separated depths are computed with low factors of safety.

Togani Cahyadi Upomo, Muhsiung Chang, Rini Kusumawardani, Galih Ady Prayitno, Ren-Chung Huang, Muhammad Hamzah Fansuri
Deformation of Earthquake Resistant Gravel-Tire Chips Mixture as Drains

Gravel-tire chips mixture (GTCM) as an alternative geomaterial has been introduced in recent years. In addition to its low-carbon-released characteristics, other advantageous material characteristics include lightweight, excellent vibration absorption capability, and high permeability. A newly designed earthquake-induced liquefaction mitigation countermeasure has been proposed. This so-called GTCM drains technique utilized GTCM as the material for precast drains installed around existing infrastructures located on the liquefiable ground. During the earthquake, the excess pore water could be dissipated through the drains, therefore, mitigating the potential of liquefaction. However, the deformation characteristics which has a significant influence on foundation settling post-earthquake, are not clearly researched on such improved ground. In this research, based on modelling experiment on 1-g shaking table, Particle Image Velocimetry (PIV) has been used to track and analyse the deformation of the ground foundation during dynamic loadings. The results indicate that with GTCM drains installed, the movement and acceleration of the foundation beneath the on-surface structure were limited. Meanwhile, the excess pore water pressure increased much slower due to the combined effect of drainage and less ground deforming. This study on the deformation characteristics proves the effectiveness of such liquefaction mitigation technique from another perspective.

Yutao Hu, Hemanta Hazarika

Special Subjects in Geotechnical Engineering

Evaluation of Relationships Between Strength Properties of Rock Samples and Drilling Rate Index

A comprehensive subsurface investigation program was conducted to delineate the soil, rock and groundwater conditions in subject area of the project site located in Gulf Region consisted mainly of land-based geotechnical drilling. In the scope of this study, the onshore site characterization is based on an integrated approach that combines the site specific data collected from borings, field and laboratory tests. Within the scope of laboratory studies, relationships between strength properties of rock samples and drilling rate index were examined. For this purpose, uniaxial compression test, Schmidt hammer rebound test and drillability test were conducted for the rock samples which were collected from different rotary drilling boreholes. The experimental studies have shown that the drilling rate index (DRI) decreases with the increasing uniaxial compressive strength (UCS) and Schmidt Hammer Rebound Hardness (SHRH).

Efe Aslan, Hakan Köpüklü, H. Turan Durgunoğlu
Unsaturated Geomechanical and Physicochemical Characterisation of Soils Used for Adobe Blocks

A mechanical and physicochemical characterisation of soil used for adobe block production is presented in this paper, considering a geomechanical framework. The main research objectives were to apply the partially saturated soil mechanics theory and obtain some of the soil's physicochemical characteristics. The soil used in this research was extracted from Putaendo, Chile, as it is representative of the vernacular building of that region. The soil was classified as silty sand, of low plasticity. Further inspection showed a 7% content of organic matter. The unsaturated shear strength of the soil was obtained using a conventional shear box test, coupled with the soil–water characteristic curve (which was obtained using the filter paper technique) to estimate suction values. The soil–water characteristic curve had a similar shape as for other sands previously reported in the literature, but with a higher air entry and residual values. Results show that shear strength increases for drier soil samples, reaching an asymptotic value after the air entry suction of the soil. It is concluded that shear box tests without suction control can be used to estimate the unsaturated strength of soils and that the organic matter in soils can influence its cohesive strength, although further research on this aspect is required.

Jose Concha-Riedel, Susana Lopez-Querol

Soil Improvement

The Evaluation of Stone Column and Jet Grouting Soil Improvement by Conducting a Comprehensive Experimental Program

Ground improvement is an important requirement in today`s construction industry as land reclamation is becoming increasingly popular. Many different ground improvement techniques have been developed over the past few decades to treat weak soil deposits. Two of commonly used techniques are jet grouting and vibro-stone column. The goal of this study is to investigate the advantages and disadvantages of both techniques using in-situ tests such as cone penetration testing, standard penetration testing, seismic wave velocity measurements and laboratory tests including direct shear tests, density and void ratio measurements on undisturbed samples obtained from the soil between produced columns. A test area including 25 jet grout columns with 1.8 m spacing and diameter of 60 cm was prepared to investigate the effectiveness of jet grouting method. A test area with same dimensions as it was for jet grout columns was prepared for stone columns. 25 stone columns with diameter of 1 m and spacing of 1.8 m were produced in the test area. Vibroflotation technique was used to produce stone column with top feeding method. In-situ and laboratory tests were carried out for these test areas to investigate the advantages and disadvantages of both techniques. The most important result obtained from in-situ tests was the better improvement of soil mass between stone columns than that of jet grout columns which plays a key role in reducing seismic risks and liquefaction hazards. Laboratory tests on undisturbed samples obtained from the soil between produced stone columns and jet grout columns also approved the findings from in-situ tests.

Arshiya Abadkon, Erol Güler
Feasibility Study of Transforming Excavated Clayey Soil into ‘Sand-Like’ Material

In order to upcycle clayey soil, which generally has poor strength properties, it was proposed to transform them into a more useable ‘sand-like’ material using sintering technology in this feasibility study. A muffle furnace was adopted to heat the clayey soil at different sintering schedules. The results showed that the well sintered ‘sand-like’ pallets had a friction angle (about 34–37°) in the same range as a typical medium dense sand. The sintered product’s permeability was found to be in the order of 1 × 10−3 m/s, which is similar to the gravel-sand mixtures category. The maximum dry unit weight and optimum moisture content in compaction behaviour were slightly lower than a typical silty sand-gravel. Mineralogy check and soil fabric check using X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the kaolinite (weak mineral) had been transformed into metakaolinite (stronger mineral) in the ‘sand-like’ material. The sintered product was almost irreversible through the acid and saltwater dissolvability test. All the findings confirmed that it is feasible to produce “sand-like” material from excavated clayey soil through sintering technology.

Juan-Wei Koh, Sathyamoorthy Subramanian, Soon-Hoe Chew, Yeow-Chong Tan, Cheng-Soon Teo, Meng-Yang Charmaine Koh, Hui-Bin Grace Foo, Ting-Hong Hadley Cheung, Tamilselvan Thangayah, Czhia-Yheaw Tan
Estimation of Modular Ratio and Modulus of Deformation of Granular Piles from in Situ Compression Tests Under Direct Loading

Granular piles have been and continues to be used extensively for improving the ground in terms of increased load carrying capacity, reduced settlements, for rapid dissipation of pore pressures, to mitigate liquefaction effects etc. The effective application of granular piles in soft ground necessitates the knowledge of deformation parameters of the ground and of the granular piles, for determining the behavior of granular piles in different soil conditions. This paper presents a method to estimate the modular ratio of granular piles and modulus of deformation of surrounding in situ soil from the load—settlement response obtained from the compression tests. The direct loading test cases in which the applied load is totally transferred onto the granular pile have been considered in this study.

M. Najamuddin, M. R. Madhav, V. Padmavathi
Resilient Modulus as a Technical Parameter for Evaluating the Cement-Stabilized Soil

The design and construction of road pavement substructures involves compacting aggregate in conditions close to optimum moisture content. The recommendation introduced by AASHTO, obliges designers to use mechanistic-empirical design methods by using the resilient modulus. The value of cyclic resilient modulus is determined based on cyclic triaxial tests, in which elastic axial strain and cyclic deviator stress are measured. Laboratory tests were performed on natural (gravelly sand) and chemically stabilised (CEM I 42.5 R) soil. The study compared the effect of different cement additives (1.5, 3.0, 4.5, 6.0%) on the resilient modulus tested on samples which were compacted using the Standard Proctor method. The addition of cement increased the stiffness of the soil and the resilient modulus, while the elastic axial strain has decreased. The samples were tested after 7 and 28 days of care. A longer period of treatment increased the resilient modulus. The gravelly sand stabilised with cement obtained high values of resilient modulus.

Patryk Dobrzycki, Katarzyna Zabielska-Adamska, Mariola Wasil
Effect of Freeze–Thaw Cycles on the Strength of a Nanosilica and Lime Treated Clay

In this study, the unconfined compressive strength of a clay treated with nanosilica and lime was investigated under freeze–thaw conditions. The specimens were prepared at their corresponding optimum water contents and compacted under a standard Proctor compactive effort. The pure clay and the clay treated with 5% lime were subjected to freeze–thaw cycles to determine the strength changes of specimens. The maximum number of cycles applied to the specimens was 10. The cycles were applied in 12 h intervals and the temperature range was ±18 °C. Subsequently, the clay was treated with 0.3, 0.5, 0.7 and 1% nanosilica and 5% lime. The clay specimens showed a tendency to decrease in strength as a result of freeze–thaw cycles. The maximum strength loss observed was around 41%. It was concluded that, it was not possible to achieve sufficient amount of improvement by using solely nanosilica in the clay specimens. The unconfined compressive strength of nanosilica and lime treated clay accelerated with curing time. Besides, the strength loss of specimens due to freeze–thaw cycles could be partially prevented with the addition of nanosilica and lime. Consequently, usage of nanosilica together with lime, resulted in a better improvement, even if the soil was subjected to freeze–thaw cycles.

İsmail Taş, Tugba Eskisar
Improvement of Shear Strength of Fine-Grained Soils by Waste Glass

Due to clay having little or no impressive engineering properties causes a need to develop its properties prior to construction taking place as foundation play a very essential and important role hence the need for soil stabilization techniques. This study focuses on the utilization of waste glass in stabilizing and improving the soil shear strength parameters. Waste glass passing 0.075 µm sieve and 0.300 µm sieve was sequentially added in soil with 0, 6, 8, 10 and 12%. According to unified soil classification system the soil is low plasticity clay, CL. Direct shear strength tests were performed on un-stabilized soil and waste glass added sample to see the effect of waste glass addition on cohesion and angle of internal friction. From the results obtained 10% was found to be optimum addition value for waste glass for this since it improves cohesion values from 4 to 12 kPa for 0.300 µm sieve passing added waste glass and 4–17 kPa for 0.075 µm sieve passing added waste glass while angle of internal friction showed a continual decrease for each waste glass added which may be attributed to the characteristics of the waste glass and chemical compositions. Results showed 8% to be the optimum value as internal angle of friction and cohesion values peaked but showed decrease as the percent increased afterwards. Waste glass increases the cohesion amongst the soil particles thereby changing the shear strength parameter for the soil. Waste glass is a suitable stabilizer for clay soil.

Victor Ojotisa, Ayse P. Balkis
5th International Conference on New Developments in Soil Mechanics and Geotechnical Engineering
herausgegeben von
Cavit Atalar
Feyza Çinicioğlu
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