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2021 | Buch

Advances in Geotechnical Engineering & Geoenvironmental Engineering

Proceedings of the 6th GeoChina International Conference on Civil & Transportation Infrastructures: From Engineering to Smart & Green Life Cycle Solutions -- Nanchang, China, 2021

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Über dieses Buch

This book includes a collection of researches that contains research data, discussions and conclusions focusing on several related geotechnical aspects of infrastructure. Topics include issues related to civil infrastructure such as temperature-induced lateral earth pressure on bridge abutment, subsidence of high speed rail and expressway, application of recycled rubber mats, railway ballast evaluation, hurricane protection floodwall, tunnel portal stability, deep excavation case study and properties of contaminated soils. Various types of research were used in the various studies, including field measurements, numerical analyses and laboratory measurements. This findings and results should lead to more resilient infrastructure design, maintenance and management, which will provide benefits to both civil engineering practitioners, researchers and students

Inhaltsverzeichnis

Frontmatter
Response of Approach to Integral Abutment Bridge Under Cyclic Thermal Movement
Abstract
Integral abutment bridges (IABs) are increasingly preferred over expansion joint bridges due to their ease of construction, and lower maintenance and repair cost. However, no consistent design guidelines exist for IABs due to the complexities associated with soil-structure interactions and nonlinear behaviour of the backfill soil used for the abutments. The temperature-induced cyclic movement of a bridge abutment causes an increase in lateral earth pressure on the abutment wall, which could lead to stress ratcheting. After a number of thermal cyclic movements, permanent soil densification and settlement at the bridge approach will result. In order to study abutment-soil interactions at a different magnitude of cyclic loading, model scale experiments have been conducted, and soil deformations were observed and measured using particle image velocimetry (PIV) technique. Test results show that the number of loading cycles has an important effect on the escalation of lateral earth pressure and soil deformation of the retained soil. Furthermore, the formation of soil settlement and heaving was notably increased with an increase in the amplitude of cyclic movement. Findings of the research presented here assist to define the important parameters to consider in the design of the IABs, besides the possible effects on bridge approach at different magnitudes of cyclic movement.
L. Sigdel, A. AI-Qarawi, C. Leo, S. Liyanapathirana, P. Hu, V. Doan
Numerical Assessment on the Influence of Various Factors for Subsidence at the Intersection of Expwy 78 and High Speed Rail of Taiwan
Abstract
Choshui River alluvial fan-delta (CRAFD) has been and still is the single-largest subsiding area in Taiwan. Some key infrastructures, including Taiwan High Speed Rail (THSR) and Expressway 78 (Expwy78) that come across this area, are suffering serious problems by the subsidence. Due to complexity of the issue, causes of the subsidence and their influences are not easily identified and quantified. This paper tends to disclose the above puzzles through a numerical approach that would allow separate applications of various factors and examination on their individual effects. The intersection of THSR and Expwy 78 is our primary concern since the subsidence at this location has become most serious along the entire route of THSR and the induced differential settlements are threatening the safety of the transportation artery. An 8-year subsidence monitoring data at the study site is used for calibration of material data adopted in the subsequent analyses. Results indicate the computed subsidence is 147.0 cm, or a rate of 10.53 cm/year, for a period approximately starting with the Expwy78 construction (01/1998–12/2011) and covering complete ranges of construction of Expwy78 and THSR of the site. Contributions due to various factors would be the greatest by previous overpumping (55.2%), followed by soil creeping (14.1%), groundwater fluctuations (11.8%), Expwy78 loading (11.6%), and the least by THSR loading (7.3%). Assessments also indicate around 1/5 and 4/5 of the total subsidence, respectively, occurred as the compression in soils with depths <70 m and >70 m, where 70 m is the average installation depth of THSR piles. Compression at shallower depths would be the greatest by Expwy 78 loading, and thus may trigger a major part of negative skin frictions and discount bearing capacity of the piles. Compression of deeper soils would be caused primarily by the previous overpumping, and would hence lead to significant settlements and distortions of vertical alignment of THSR structures.
Muhsiung Chang, Ren-Chung Huang, Chih-Ming Liao, Togani C. Upomo, Rini Kusumawardani
Application of Recycled Rubber Mats for Improved Performance of Ballasted Tracks
Abstract
This paper summaries the results of a study on the use of recycled rubber mats for improved performance of ballasted tracks. One solution used to minimise ballast degradation (breakage) is to use an innovative recycled rubber mat, known as rubber-energy-absorbing drainage mat (READ), manufactured from end-of-life tires to provide a cost-effective solution to conventional tracks. When placed underneath the ballast, the energy-absorbing nature of the rubber mats decreases the load that is transferred to the ballast, so the ballast experiences less deformation and breakage. In this study, a series of large-scale triaxial tests are conducted to investigate the performance of the READS in the attenuation of cyclic and dynamic loads and subsequent reducing of ballast degradation. Numerical modelling using the Discrete Element Method (DEM) is conducted to investigate the improved performance of ballast in a micromechanical perspective. Evolutions of contact forces and contour stress distributions during cyclic tests are investigated through coupled DEM-FEM model.
Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Appraisal of Railway Ballast Degradation Through Los Angeles Abrasion, Cyclic Loading Tests, and Image Technics
Abstract
Ballast degrades through wear and breakage due to the cumulative actions of traffic. This study evaluated ballast degradation using the Los Angeles abrasion (LAA) and cyclic loading tests, changes in the ballast aggregates shape indexes (form, angularity, surface texture and volume) were also evaluated using image analysis techniques. A typical freight train with an average speed of 120 km/h and 30 tonnes capacity was simulated for the cyclic loading test. Series of LAA and cyclic loading tests were conducted on separate samples of the same gradations, and the changes in the aggregates shape indexes were determined using the Aggregate image measuring system (AIMS) package and a 3D laser scanner before and after each of the tests. The image-based assessment revealed that ballast degradation is related to the particle edge breakage and surface wear. The overall experimental results showed that ballast degradation is more profound in the ballast early stage of service, and the degradation index has a good correlation with the changes in aggregate shape indexes. The results also revealed that the two tests gave different degradation indexes, hence a relationship between the ballast degradation index and the number of load cycles with the number of LAA drum turns is proposed to reflect the effect of the number of train’s axle load cycles on ballast degradation.
Zhihong Nie, Mohammed Ashiru, Xingchen Chen, Said Hussein Mohamud
Design and Analyses of the Hurricane Protection Floodwall in South Louisiana
Abstract
This paper presents a comprehensive review on the finite element analyses for the performance-based design of the Floodwall, an important component of hurricane storm surge barrier for New Orleans, Louisiana. The finite element models are calibrated and verified with a lateral pile load test, and they are used to derive the design hurricane storm surging loads on the Floodwall. Such storm surging loads are used to determine the seepage cut-off depth of the wall based on design seepage criteria. The settlement of the Floodwall during its design life is estimated by the finite element consolidation analysis with considering soil-pile-interaction. Finally, a brief discussion is given to the finite element stability analysis for an effective remediation design of the submerged rock dike of the Floodwall using a soil cut-off structures at the dike toe.
Wenjun Dong, Robert Bittner
Study on Stability of Tunnel Portal Section Based on Strength Reduction Shortest Path Method
Abstract
It is very significant to maintain the stability of surrounding rock during the entire lifetime of the tunnel. Generally speaking, the stability of the surrounding rock in the portal section of the tunnel is the worst. Therefore, it is meaningful to study the instability mechanism and factors affecting the instability of the surrounding rock in the tunnel portal section. In this paper, we studied the stability of tunnel surrounding rock based on a novel double strength reduction method (the strength reduction shortest path method). The double strength reduction method was used to reduce the cohesion and internal friction angle with different reduction factors in the stability analysis of surrounding rock. We used the overall safety factor to evaluate the stability of the tunnel. The smaller the overall safety factor, the more likely the tunnel is to lose stability. The influence of strength parameters of surrounding rock on the stability of the portal section was discussed emphatically. The results show that: As the reduction ratio \(\lambda \) increases, the length of the strength reduction path first decreases and then increases, which indicates that there is a shortest strength reduction path; It is reasonable to take the drastic change of the vault displacement as the instability criterion; As the initial internal friction angle and the initial cohesion increase, the length of the strength reduction shortest path and the overall safety factor increase, in which the effect of the internal friction angle is more significant.
This paper can provide a new method for studying the stability of the tunnel portal section and provide a useful reference for future tunnel construction.
Wei Wang, Guiqiang Gao, Mingjun Hu, Yanfei Zhang, Haojie Tao
Lessons and Mitigation Measures Learned from One Deep Excavation Failure Case
Abstract
Deep excavations, most of those are temporary retaining structures, have not attracted enough attention from all parties involved in projects. Nowadays there have been numerous failures of deep excavations, and mostly have significant impacts on the safety of the excavation and the surrounding environment, especially in congested urban areas with poor hydrogeology and geology conditions. However, many failure cases remained unpublished and poorly explored due to complex reasons. The reported failure cases were too scarce to provide enough lessons to improve corresponding guidelines. Therefore the database needs more supplement cases. This paper briefly presents the failed case of a deep excavation in soft soil area in downtown city of Shanghai, China, which had an excavation area of about 25,000 m2 and two-story basements. According to the field investigation, forensic studies and preliminary analysis, the main reasons for the failure was pointed out. Furthermore the re-checking calculations and mitigation measures were described briefly. The direct cost of repairing and rebuilding the failed excavation was more than 20 million RMB (about 2.8 million dollars), much more expensive than savings. Preserving some redundancy in design and construction is essential. This failed case report is expected to help deep excavations attract more attention and avoid similar failures.
Wei Xiang, Yu-shan Luo, Zhi-rong Liang
Analysis of Dielectric Properties and Influencing Factors of Zn Contaminated Soil
Abstract
Studying on the influence of heavy mental contents and moisture contents on dielectric properties of soil and its internal mechanism, which is the basis of quantitative detection of soil pollution by ground penetrating radar (GPR). Taking zinc contaminated soils as an example, soil cakes are made by adding zinc salt solution of different mass concentration into silty clay. Then, the complex permittivity of soils in different wet densities, different moisture contents were measured by vector network analyzer. The laws of variation of complex permittivity were summarized and grey relational analysis was carried out. Finally, the mechanism of influence of various factors on dielectric properties of zinc contaminated soil was explained by dielectric theory. The results show that the real part of complex permittivity of zinc contaminated soil is most affected by moisture content, which increased with the increase of moisture content, the correlation between real part and moisture content was 0.93. The imaginary part of complex permittivity is most affected by zinc salt content, which increased with the increase of zinc salt content, the correlation between imaginary part and zinc salt content was 0.77.
Jiaqi Li, Xianggui Xiao, Jipeng Wang, Zonghui Liu, Kang Lin
Backmatter
Metadaten
Titel
Advances in Geotechnical Engineering & Geoenvironmental Engineering
herausgegeben von
Ph.D. Shanzhi Shu
Dr. Jinfeng Wang
Dr. Mena Souliman
Copyright-Jahr
2021
Electronic ISBN
978-3-030-80142-7
Print ISBN
978-3-030-80141-0
DOI
https://doi.org/10.1007/978-3-030-80142-7