Foundation Engineering Handbook

Frontmatter

1. Subsurface Explorations and Sampling

Abstract

The proper design of civil engineering structures requires adequate knowledge of subsurface conditions at the sites of the structures and, when structures are to consist of earth or rockfill materials, of subsurface conditions at possible sources of construction materials. The structures may be divided into three categories.

1

Structures for which the basic problem is the interaction of the structure and the surrounding ground. Such structures include foundations, retaining walls, bulkheads, tunnel linings, and buried pipes. The main point of interest is the load-deflection characteristics of the interface.

 

2

Structures constructed of earth such as highway fills, earth and rockfill dams, bases and subbases for pavements, and backfill behind retaining walls. Besides the interaction of the earth structure with the adjacent ground, properties of the construction materials are required for determining the action of the earth structure itself.

 

3

Structures of natural earth and rock as natural slopes and cut slopes. In this case, knowledge of the properties of the natural materials is required.

 

John Lowe III, Philip F. Zaccheo

2. Sampling and Preparation of Marine Sediments

Abstract

The recent development in the exploitation of the resources of the ocean floors of the world for petroleum, natural gas, and other minerals, along with waste disposal has resulted in an increased interest in the application of geotechnical sciences to the marine environment (Anderson, 1981; Chaney, 1984; Chaney and Fang, 1985, 1986; Chaney et al., 1986; Fang and Chaney, 1985, 1986; Fang and Owen, 1977; Lee, 1985; Richards and Chaney, 1981, 1982; Winterkorn and Fang, 1971). The selection of an offshore site is essential for most seafloor engineering projects. It is a process strongly influenced by engineering judgment that is often constrained by economic, political, environmental, and societal considerations. Fletcher (1969) considers that the purpose of an offshore site investigation is to “secure such information by procedures appropriate to the project and to report the findings in sufficient technical detail to provide a basis for economic studies and design decisions.” The process of site evaluation from the recognition of a siting problem to the development of a problem solution involves a number of discrete steps as shown in Figure 2.1 (Chaney et al., 1985). These steps are: (1) determination of environmental loading, (2) site reconnaissance, (3) development of a stratigraphic model based on both a combination of sampling and in-situ testing, and (4) interpretation of data.

Ronald C. Chaney

3. Soil Technology and Engineering Properties of Soils

Abstract

Soil, in the engineering sense, comprises all materials found in the surface layer of the earth’s crust that are loose enough to be moved by spade or shovel. Such materials are natural systems that are normally composed of solid, liquid, and gaseous phases. The solid phases are contributed by particulate matter of inorganic or organic character. The liquid phase is usually an aqueous electrolyte solution. The gaseous phase in contact and exchange with the atmosphere may have a different composition from the latter, depending on location and biologic activity within the soil. Since water and air content vary with variation in environmental conditions, soils are normally characterized by their particulate components, while the air and water contents are considered together as porosity. However, in assaying the actual physical properties of a soil system, due consideration must be given to the volume percentages of the component phases as well as to the distribution of the different phases throughout the system.

Hans F. Winterkorn, Hsai-Yang Fang

4. Bearing Capacity of Shallow Foundations

Abstract

Foundations, like the structures or equipment they support, are usually designed to meet certain serviceability and strength criteria. Serviceability conditions dictate that the foundation should perform such that under normal operating loads the structure or equipment it supports may fulfill its design purpose. These serviceability limitations are typically described by settlement or other motion limitations. The strength criteria have the purpose of insuring that the foundation has sufficient reserve strength to resist the occasionally large load that may be experienced due to extreme environmental forces or other sources. In most, but not all cases, the serviceability or settlement criteria and the strength criteria may be treated as unrelated design tasks. Serviceability is typically a long-term consideration for the foundation that may depend on time-dependent consolidation characteristics. Foundation strength, or bearing capacity, may be a short-term problem such as an embankment construction on an undrained clay foundation or a long-term problem in which the maximum foundation load may appear at some unknown time.

Wai-Fah Chen, William O. McCarron

5. Stress Distribution and Settlement of Shallow Foundations

Abstract

The basic requirements for a good foundation are that (1) it is safe against complete collapse or failure of the soils upon which it is founded; (2) it experiences no excessive or damaging settlements or movements; (3) environmental and other factors (see below) are properly considered; and (4) the foundation is economically feasible in relation to the function and cost of the overall structure.

Robert D. Holtz

6. Earth Pressures

Abstract

Design of earth-retaining structures requires knowledge of the earth and water loads that will be exerted on them. The first methods for determination of earth loads acting on retaining structures were developed in the eighteenth and nineteenth centuries by Coulomb and Rankine. These were based on idealized concepts where the retaining structure is rigid and moves as a unit. Also, the soil that loads the wall is assumed to be “wished in place,” and to undergo systematic, prescribed failure patterns as the wall displaces. These assumptions ignore the true effects of soil-structure interaction, and the processes of construction of the system. Nonetheless, the Coulomb and Rankine methods provide simple and reasonably accurate means for estimating earth loads, and remain useful tools today.

G. W. Clough, J. M. Duncan

7. Dewatering and Groundwater Control

Abstract

Whenever excavation must take place below the water table, groundwater affects the project. It affects the function and design of the facility, and the cost of its construction. Groundwater is a frequent cause of disputes between the owner and the contractor. Dewatering by unsuitable methods can under some conditions cause damage to adjacent properties, and result in third party litigation. Under some conditions dewatering may be harmful to the environment. Activities involving groundwater are closely regulated in many areas. The process of obtaining permits is often tedious, and sometimes authorities require special procedures that can be expensive.

J. Patrick Powers

8. Compacted Fill

Abstract

As a construction material, soil has been used since antiquity with both success and failure. The widespread availability and relative economy of earth material continue to make it attractive for use in foundations, embankments, and as backfill. It has long been recognized, first empirically and then scientifically, that compaction changes the physical properties of soils-in some cases tremendously. For example, a properly compacted, well-graded gravel may be 15 times as resistant to deformation under a bearing load as the same material in the loose state.

Jack W. Hilf

9. Soil Stabilization and Grouting

Abstract

Soil stabilization and grouting are methods of soil improvement. Soil improvement is a combination of physical and chemical methods for regional or mass densification, reinforcement, cementation, and control of drainage and volume stability of soil when it is used as a construction material.

Hans F. Winterkorn, Sibel Pamukcu

10. Stability of Earth Slopes

Abstract

The failure of a mass of soil in a downward and outward movement of a slope is called a slide or slope failure. Slides occur in.almost every conceivable manner, slowly or suddenly, and with or without any apparent provocation. They are usually caused by excavation, by undercutting the foot of an existing slope, by a gradual disintegration of the structure of the soil, by an increase of the pore water pressure in a few exceptionally permeable layers, or by a shock that liquefies the soil.

Hsai-Yang Fang, George K. Mikroudis

11. Landslides

Abstract

In many parts of the world, especially in mountainous countries like Chile, Czechoslovakia, Iran, Italy, Japan, Mexico, Norway, Switzerland, and Yugoslavia, landslides are very common and have serious consequences for almost all construction activities in these countries. For example, over 9000 landslides were registered in Czechoslovakia during 1961-1962 (Zaruba and Mend, 1969). In Japan over 2000 embankment failures occur on the average each year along the lines of the Japanese National Railways alone (Saito and Uezawa, 1969).

Bengt B. Broms, Kai S. Wong

12. Retaining Structures and Excavations

Abstract

Structures that retain lateral forces from soil and/or water are composed of various materials, constructed by numerous procedures and methods, and are used for many purposes. In this chapter the manner of support is used to classify the different types of structures. Reinforced earth structures are not included, as that type of structure is covered in Chapter 21. The three means of support consist of restrained, gravity, and cantilever systems. Each support system has variations—the restrained system having the greatest number and cantilever the least. Gravity structures are far more numerous than the other two since they are used for the construction of many small structures such as soil-retaining walls. The largest retaining structures are of the gravity type. Restrained structures are prominent in the construction of waterfront facilities and excavations. Cantilever structures are the least used because they allow large deflections to occur. Combinations of support types are sometimes used.

Thomas D. Dismuke

13. Pile Foundations

Abstract

Piles are vertical or slightly inclined, relatively slender structural foundation members. They transmit loads from the superstructure to competent soil layers. Length, method of installation, and way of transferring the load to the soil can vary greatly.

Bengt H. Fellenius

14. Drilled Shaft Foundations

Abstract

A drilled shaft, also known as drilled pier, drilled caisson, caisson, bored pile, etc., is a versatile foundation system that is used extensively on a worldwide basis. In its simplest form, a drilled shaft is constructed by making a cylindrical excavation, placing a reinforcing cage (when necessary), and then concreting the excavation. With available drilling equipment, shaft diameters up to 20 ft (6 m) and depths exceeding 250 ft (76 m) are possible. However, for most normal applications, diameters in the range of 3 to 10 ft (1 to 3 m) are typical. This size versatility allows a single drilled shaft to be used in place of a driven pile group and eliminates the need for a pile cap. In addition, normal construction practices for drilled shafts effectively eliminate the noise and strong ground vibrations that develop during pile driving operations. For these and other secondary reasons, drilled shafts have become both the technical and economic foundation of choice for many design applications. In fact, they have become the dominant foundation type in many geologic settings around the world.

Fred H. Kulhawy

15. Foundation Vibrations

Abstract

When subjected to dynamic loads, foundations oscillate in a way that depends on the nature and deformability of the supporting ground, the geometry and inertia of the foundation and superstructure, and the nature of the dynamic excitation. Such an excitation may be in the form of support motion due to waves arriving through the ground during an earthquake, an adjacent explosion, or the passage of a train; or it may result from the dynamic forces imposed directly or indirectly on the foundation from operating machines, ocean waves, and vehicles moving on the top of the structure.

George Gazetas

16. Earthquake Effects on Soil-Foundation Systems

Abstract

The damage resulting from earthquakes may be influenced in a number of ways by the characteristics of the soils in the affected area. Where the damage is related to a gross instability of the soil, resulting in large permanent movements of the ground surface, association of the damage with the local soil conditions is readily apparent. Thus, for example, deposits of loose granular soils may be compacted by the ground vibrations induced by the earthquake, resulting in large settlements and differential settlements of the ground surface. Typical examples of damage due to this cause are shown in Figures Figure 16.1 and Figure 16.2 Figure Figure 16.1 shows an island near Valdivia, Chile, which was partially submerged as a result of the combined effects of tectonic land movements and ground settlement due to compaction in the Chilean earthquake of 1960. Figure Figure 16.2 shows differential settlement of the backfill of a bridge in the Niigata earthquake of 1964.

H. Bolton Seed, Ronald C. Chaney, Sibel Pamukcu

17. Foundation Problems in Earthquake Regions

Abstract

A major earthquake produces a strong ground motion in the subsoil; consequently, underground and surface structures supported on the soil mass will be induced to move and take dynamic forces. The magnitude of the inertia forces are proportional to the acceleration at the depth at which the foundation structure is placed. Their action in the foundation structure may be estimated knowing the subsoil behavior. For this purpose, the maximum displacements, stresses, and accelerations should be determined in the soil mass.

Leonardo Zeevaert

18. Offshore Structure Foundations

Abstract

Marine foundations are used to transmit structural design loadings to the subsoil. The type of foundation element to be employed will depend on (1) the nature of loading, (2) the stiffness and strength of the surface sediments, and (3) the desires of the builder. A summary of the common platform types is shown in Figure 18.1. The two major foundation types are those that employ a surface loading mechanism (shallow foundations) and those that extend down through the surface sediments to a lower layer (deep foundations). An example of a foundation system for surface loading is the mat used on a gravity platform. The deep pile that is used on a jacket platform is an example of a deep foundation system. Examples of various marine foundation types are presented in Figures 18.2a and 18.2b

Ronald C. Chaney, Kenneth R. Demars

19. Foundations in Cold Regions

Abstract

The design of foundations in cold regions differs significantly from that in temperate regions. Cold regions include both those areas with seasonal frost and perennially frozen ground (permafrost). On the basis of air temperature, snow depth, ice covers and permafrost, Bates and Bilello (1966) reported that about 48 percent of the northern hemisphere’s land mass is categorized as cold regions and the southern most reaches of discontinuous permafrost over land masses approximately follow the 40°N latitude line, as illustrated in Figure 19.1. In cold regions, the upper soil layer, or active layer, experiences cycles of winter freezing and summer thawing.

Arvind Phukan

20. Geotechnics of Hazardous Waste Control Systems

Abstract

Contamination of the subsurface environment with hazardous and toxic wastes has become the number one environmental problem. In the United States, a national cleanup effort has begun under C.E.R.C.L.A., the Comprehensive Environmental Response, Compensation and Liability Act (42 USC 9601 et seq., 1980), commonly known as Superfund, and its subsequent reauthorization under S.A.R.A., the Superfund Amendments Reauthorization Act (P.L. 99-499, October 17, 1986). Over 30000 sites have been identified, each having the potential for the introduction of contaminants into the subsurface environment. Over 1000 sites have been specifically identified under the Superfund Program as requiring cleanup or remediation; these constitute the National Priorities List (N.P.L.). The geotechnical engineer will continue to play a key role in the assessment and cleanup of hazardous waste sites. More often than not, hazardous waste site conditions include contamination of groundwater and soil, necessitating control and remediation systems interacting with the subsurface environment.

Jeffrey C. Evans

21. Reinforced Earth

Abstract

Reinforced Earth was invented in 1963, by the French architect-engineer Henri Vidal. It is a construction material made of a frictional backfill material reinforced by linear flexible strips generally placed horizontally (Fig. 21.1). Since its invention, Reinforced Earth has found a wide use in many different areas of civil engineering, notably in retaining walls, seawalls, dams, bridge abutments, and foundation slabs. This technique has been adopted worldwide and the total number of Reinforced Earth structures built each year has been continuously increasing as indicated in Figure 21.2.

F. Schlosser, M. Bastick

22. Geosynthetics in Geotechnical Engineering

Abstract

Geosynthetics are a rapidly emerging family of materials used in geotechnical engineering in a wide variety of applications. They are almost exclusively polymeric and consist of the following major types (Koerner, 1990):

• Geotextiles
• Geogrids
• Geonets
• Geomembranes
• Geocomposites

Robert M. Koerner

23. Deep Compaction of Granular Soils

Abstract

Several new or improved methods for deep compaction of granular soils have been developed during the last few years:

• to control settlements
• to increase the bearing capacity
• to prevent or to reduce the risk of liquefaction

Bengt B. Broms

24. Stabilization of Soil with Lime Columns

Abstract

The behavior of very soft clay or silt can be improved with lime or cement columns. In this soil stabilization method, the soft soil is mixed in situ either with unslaked lime (CaO) or with cement using a tool shaped like a giant dough mixer, as illustrated in Figure 24.1. Other materials can be used, such as gypsum (Holm et al., 1983a), fly-ash and furnace slag (Nieminen,1978), hydroxyaluminum (Bryhn et al., 1983), and potassium chloride (Eggestad and Sem, 1976).

Bengt B. Broms

25. Durability and Protection of Foundations

Abstract

Failure of structures due to deterioration of the foundations occurs infrequently in some applications and far too frequently in others. Waterfront facilities (particularly in marine and tidal exposures) have a much higher incidence of material deterioration than land-based facilities. Protection of materials in aggressive environments and operations (or use) has long been recognized as a necessity. Satisfactory protection systems are available, but are, in many instances, misapplied or ignored. Foundation deterioration is. usually thought of in terms of electrochemical and chemical phenomena; however, causes of deterioration also include heat, abrasion, and inadequate time-dependent strength properties. Deterioration due to low-temperature environments and temperature cycling occurs rarely and is usually related, in the case of concrete, to severe exposure while curing. Foundations are not subjected to the temperature extremes that the supported structures are. This is a decided benefit.

Thomas D. Dismuke

26. Ground Anchors and Soil Nails in Retaining Structures

Abstract

Ground anchor and soil nail retaining systems are designed to stabilize and support natural and engineered structures and to restrain their movement using tension-resisting elements. The basic design concept consists of transferring the resisting tensile forces generated in the inclusions into the ground through the friction (or adhesion) mobilized at the interfaces. These systems allow the engineer to efficiently use the in-situ ground in providing vertical or lateral structural support. They present significant technical advantages over conventional rigid gravity retaining walls or external bracing systems that result in substantial cost savings and reduced construction period. Therefore, during the past few decades, ground anchors, and more recently soil nails, have been increasingly used in civil engineering projects.

Ilan Juran, Victor Elias

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