Driven piles in clay - the effects of installation and subsequent consolidation
TL;DR: In this article, the effects of installing a driven pile on the strength of the soil were investigated using a work-hardening elasto-plastic soil model, which has the unique feature of allowing the strength to change as the water content changes, thus it is possible to calculate the new intrinsic soil strength at any stage during consolidation.
Abstract: This paper describes the results of numerical analysis of the effects of installing a driven pile. The geometry of the problem has been simplified by the assumption of plane strain conditions in addition to axial symmetry. Pile installation has been modelled as the undrained expansion of a cylindrical cavity. The excess pore pressures generated in this process have subsequently been assumed to dissipate by means of outward radial flow of pore water. The consolidation of the soil has been studied using a work-hardening elasto–plastic soil model which has the unique feature of allowing the strength of the soil to change as the water content changes. Thus it is possible to calculate the new intrinsic soil strength at any stage during consolidation. In particular the long-term shaft capacity of a driven pile may be estimated from the final effective stress state and intrinsic strength of the soil adjacent to the pile. A parametric study has been made of the effect of the past consolidation history of the soil...
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26 Apr 1991TL;DR: In this article, the basic ingredients of a family of simple elastic-plastic models of soil behaviour are described and used in numerical analyses. But the models on which this book concentrates are simple, understanding of these will indicate the ways in which more sophisticated models will perform.
Abstract: Soils can rarely be described as ideally elastic or perfectly plastic and yet simple elastic and plastic models form the basis for the most traditional geotechnical engineering calculations. With the advent of cheap powerful computers the possibility of performing analyses based on more realistic models has become widely available. One of the aims of this book is to describe the basic ingredients of a family of simple elastic-plastic models of soil behaviour and to demonstrate how such models can be used in numerical analyses. Such numerical analyses are often regarded as mysterious black boxes but a proper appreciation of their worth requires an understanding of the numerical models on which they are based. Though the models on which this book concentrates are simple, understanding of these will indicate the ways in which more sophisticated models will perform.
1,671 citations
Book•
12 Jan 2000
TL;DR: Soil Mechanics and Foundations as mentioned in this paper is a collection of articles about soil mechanics and foundations, including: 1. Physical Characteristics of Soils and Soil Investigations; 2. Stability of Earth Retaining Structures.
Abstract: Introduction to Soil Mechanics and Foundations. Physical Characteristics of Soils and Soil Investigations. Stresses, Strains and Elastic Deformations of Soils. One--Dimensional Consolidation Settlement of Fine--Grained Soils. Shear Strength of Soils. A Critical State Model to Interpret Soil Behavior. Bearing of Capacity of Soils and Settlement of Shallow Foundations. Pile Foundations. Two--Dimensional Flow of Water Through Soils. Stability of Earth Retaining Structures. Slope Stability. Appendices. Answers to Selected Problems. References. Index.
655 citations
Cites background from "Driven piles in clay - the effects ..."
...Randolph et al. (1979) recommended that G should be related to the historically maximum value of K9, such that...
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TL;DR: In this article, the authors address the degree of confidence we can now place on the conceptual and analytical frameworks for estimating pile capacity, and on the quantitative parameters required to achieve a design, restricted to driven piles in clays and siliceous sands.
Abstract: Scientific approaches to pile design have advanced enormously in recent decades and yet, still, the most fundamental aspect of pile design—that of estimating the axial capacity—relies heavily upon empirical correlations. Improvements have been made in identifying the processes that occur within the critical zone of soil immediately surrounding the pile, but quantification of the changes in stress and fabric is not straightforward. This paper addresses the degree of confidence we can now place (a) on the conceptual and analytical frameworks for estimating pile capacity, and (b) on the quantitative parameters required to achieve a design. The discussion is restricted to driven piles in clays and siliceous sands, with particular attention given to extrapolating from design approaches derived for closed-ended piles of relatively small diameter to the large-diameter open-ended piles that are used routinely in the offshore industry. From a practical viewpoint, we need design approaches that minimise sensitivity...
437 citations
TL;DR: An analysis of the quasi-static expansion of a cylindrical or spherical cavity in an infinite dilatant elastic-plastic soil is presented in this article, where closed form solutions for the stress and displacement fields in the soil during the expansion of the cavity are given.
Abstract: An analysis of the quasi-static expansion of a cylindrical or spherical cavity in an infinite dilatant elastic-plastic soil is presented Closed form solutions for the stress and displacement fields in the soil during the expansion of the cavity are given The soil is modelled as linear elastic-perfectly plastic, using a non-associated Mohr-Coulomb yield criterion An explicit solution for the pressure-expansion relationship is obtained with no restriction on the magnitude of the deformation It is found, in particular, that the radius of the cavity increases indefinitely as the cavity pressure approaches a finite limiting value This limiting pressure can be determined analytically with the help of a single expansion of an infinite series The novelty of the new solution lies in the introduction of dilation to the analysis of large strain expansion Examples of the implications of the new analysis in geotechnical engineering are discussed L'article presente une analyse de l'expansion quasistatique d'une
377 citations
TL;DR: In this article, closed form solutions for the expansion of cylindrical and spherical cavities in an ideal, cohesive frictional soil are presented for infinitesimal (small strain) deformations.
Abstract: Closed form solutions are presented for the expansion of cylindrical and spherical cavities in an ideal, cohesive frictional soil. An explicit solution for the pressure-expansion relationship can be obtained for infinitesimal (small strain) deformations. For finite deformations it is necessary to adopt a numerical approach to obtain the complete pressure-expansion relationship and it is found that the cavity pressure approaches a limiting value for infinite deformation. It is, perhaps surprisingly, possible to determine the precise value of this limiting pressure analytically. It is suggested that the small strain solution for a cylindrical cavity is applicable to the interpretation of pressuremeter tests in sand, and that the solutions for limit pressures have application to the problem of pile installation and the end bearing pressure of deep foundations. L'article presente des solutions de forme fermee pour l'expansion de cavites cylindriques et spheriques dans un sol ideal coherent a frottement. On pe...
345 citations
References
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15 Jan 1943
6,612 citations
"Driven piles in clay - the effects ..." refers background or methods in this paper
...Under these conditions, the governing equations reduce to the same form as Terzaghi’s one-dimensional consolidation equation (Terzaghi, 1943) gqQJ~]}=c”v2u . . . . . ....
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...Under these conditions, the governing equations reduce to the same form as Terzaghi’s one-dimensional consolidation equation (Terzaghi, 1943)...
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01 Jan 1968
TL;DR: The theory of the three-dimensional stress-strain behavior of WET CLAYs was introduced by BURLAND as discussed by the authors, who showed that WETCLAYs are subject to three dimensions of stress and strain.
Abstract: THE BASIC CAMBRIDGE THEORY OF THE STRESS-STRAIN BEHAVIOUR OF WET CLAYS, AS DEVELOPED FOR 'TRIAXIAL' (AXI-SYMMETRIC) COMPRESSION TEST CONDITIONS, IS EXTENDED TO INCLUDE GENERALIZED THREE-DIMENSIONAL STRESS AND STRAIN CONDITIONS. THE THEORY IS DEVELOPED IN THE LIGHT OF A NEW WORK EQUATION PROPOSED BY BURLAND. TWO OTHER NEW CONCEPTS ARE INTRODUCED. FIRST, A NEW YIELD LOCUS TO TAKE ACCOUNT OF THE SHEAR DISTORTION THAT OCCURS, WITHOUT PLASTIC VOLUME CHANGE, FOR STATE PATHS BENEATH THE STATE BOUNDARY SURFACE. SECONDLY, THE MOHR-COULOMB CRITERION IS INCORPORATED IN THE THEORY TO PREDICT RUPTURE WHEN WET CLAYS ARE SUBJECTED TO STRESS PATHS IN THREE-DIMENSIONAL STRESS SPACE. THE MECHANICAL BEHAVIOUR OF A GIVEN WET CLAY UNDER SUCH A GENERAL SYSTEM IS PREDICTED FROM THE THREE SOIL CONSTANTS, M, LAMBDA AND KAPPA OBTAINED FROM TRIAXIAL COMPRESSION TESTS. AFTER SHOWING THAT TRIAXIAL EXTENSION TEST RESULTS CAN BE SATISFACTORILY PREDICTED FROM TRIAXIAL COMPRESSION DATA, PARTICULAR ATTENTION IS PAID TO PLANE STRAIN WHICH IS SO FREQUENTLY RELEVANT IN PRACTICAL PROBLEMS. THE PLANE-STRAIN BEHAVIOUR AS PREDICTED FROM TRIAXIAL DATA IS COMPARED WITH OBSERVATIONS IN A PLANE-STRAIN APPARATUS, AND A SIMPLE-SHEAR APPARATUS. EXCELLENT AGREEMENT IS OBTAINED, AND CONFIRMS THE PREDICTION THAT FOR WET CLAYS THE ANGLE OF INTERNAL FRICTION IN DIRECT SHEAR TESTS IS LESS THAN THE TRIAXIAL VALUE. TO ILLUSTRATE THE POWER AND PRACTICAL SIGNIFICANCE OF THE THEORY, IT IS USED TO PREDICT THE STRAINS THAT ARE REQUIRED TO DEVELOP THE ACTIVE AND PASSIVE RANKINE STATES IN A MASS OF WET CLAY. THESE PREDICITIONS ARE IN AGREEMENT WITH EXPERIENCE. /RRL/A/
1,761 citations
"Driven piles in clay - the effects ..." refers methods or result in this paper
...The model is based on the critical state concepts (Schofield and Wroth, 1968) and is similar to the model suggested by Roscoe and Burland (1968)....
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...The former paper also gave preliminary results for the case of a soil modelled as a workhardening elasto-plastic material, based on modified Cam-clay (Roscoe and Burland, 1968)....
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TL;DR: In this article, the authors used several hundred experiments to determine the magnitude of skin friction, in which the following variables were considered: (1) Various construction materials: steel, wood, concrete; (2) For each material two surface conditions were used: smooth and rough; which are described in such a way that they may be reproduced by anyone with a reasonable degree of accuracy.
Abstract: Synopsis Until recently the values of skin friction used for design purposes were the average values obtained by field tests, with only qualitative reference to such factors influencing their magnitude as type of soil, type of construction material, and surface finish, moisture content of the soil, etc. The modern trend is to establish skin friction coefficients through laboratory experiments in which the factors influencing the results may be controlled quantitatively. Several hundred experiments were carried out by the Author to determine the magnitude of skin friction, in which the following variables were considered:— (1) Various construction materials: steel, wood, concrete. (2) For each material two surface conditions were used: smooth and rough; which are described in such a way that they may be reproduced by anyone with a reasonable degree ofaccuracy. (3) Various types of soil. (4) Strictly controlled moisture content. (5) Variation of the normal load between the friction surfaces. The test result...
645 citations
"Driven piles in clay - the effects ..." refers background in this paper
...Also, it is necessary to study the changes in effective stress around a pile when it is loaded, and the ratio of the adhesion between pile and soil to the strength of the intact soil for different pile materials (see, for example, Potyondy, 1961)....
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TL;DR: The sensitivity of clays is defined as the ratio of their undisturbed and remoulded strengths, and varies from about 1·O for heavily overconsolidated clays to values of over 100 for the so-called extrasensitive or quick clays.
Abstract: Synopsis The sensitivity of clays is defined as the ratio of their undisturbed and remoulded strengths, and varies from about 1·O for heavily over-consolidated clays to values of over 100 for the so-called extrasensitive or “quick” clays. As a result of experimental work it is shown that thixotropy can account for low or medium sensitivity but not for high sensitivity. Both laboratory and field evidence, however, show that a reduction in the salt concentration in the pore water, caused by leaching clays of marine or estuarine origin, can result in high sensitivities. Moreover, of the small number of clays so far investigated, those which have not been leached are found to exhibit only low or medium sensitivities of the order of magnitude explicable in terms of thixotropy. But it is, nevertheless, not suggested that leaching is the sole cause of high sensitivity and other possibilities are briefly discussed. Reasons are given, supported by experimental work, for the insensitivity of heavily overconsolidate...
439 citations
"Driven piles in clay - the effects ..." refers background in this paper
...Skempton and Northey (1953) discuss some of the reasons for sensitivity in clay....
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Journal Article•
TL;DR: In this paper, the authors point out further aspects of limit point bearing capacity of piles in sand as well as the overlayered stratum and critical depth, and propose a relationship between the critical depth D sub c and p sub c, or 1 sub 1.
Abstract: The discussers point out further aspects of limit point bearing capacity of piles in sand as well as the overlayered stratum and critical depth. It is noted that if phi (angle of friction) is the parameter that can describe the part in p sub o N sub q, it cannot alone explain the part in q sub 1, which essentially depends upon the compressibility phenomena. Experiments on various sands have shown that the relationship between q sub 1 and phi is valid only for sands, the physical and mechanical properties of which are not very different. For homogeneous medium, A relationship is proposed between the critical depth D sub c and p sub c, or 1 sub 1. For overlayered stratum, experimental results have shown that the value of D sub c decreases rapidly with the value of the overload applied to the bearing stratum. It is shown that for long poles, the current rule of 3-5 diameters of penetration in the bearing stratum allows a mobilization of the full point resistance of the pile.
377 citations
"Driven piles in clay - the effects ..." refers background in this paper
...In the past few years, several workers have endeavoured to interpret the maximum shaft friction on the pile, in terms of the effective stresses acting in the soil around the pile (Chandler, 1968; Burland, 1973; Meyerhof, 1976; Parry and Swain, 1977a and 1977b)....
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