A constitutive model based on the theory of plasticity is proposed and used to characterize stress‐deformation behavior of rocks. It allows for factors such as hardening, volume changes, stress paths, cohesive and tensile strengths, and variation of yield behavior with mean pressure. It is applied to characterize behavior of three hard rocks: Sandstone, Westerly Granite, and Dunham Dolomite. The constants for the model are determined from series of available laboratory tests conducted under different initial confinements and stress paths obtained by using multiaxial and cylindrical triaxial testing devices. The model is verified with respect to observed laboratory responses. Overall, the proposed model is found suitable to characterize the behavior of the rocks and involves less or equal number of constants compared to available models of similar capabilities and is easier to implement in (numerical) solution procedures.

Open caissons are a very efficient method of deep foundation, provided the ground conditions are favorable. Design and construction of a 60‐m deep shaft, 27.0‐m ID for a pumped storage hydroelectric power station is described. The soil consists of about 8 m of soft fluvial deposits on a 200‐m thick layer of homogeneous over consolidated stiff marly clay. The upper 8 m of soft soil were excavated and replaced by 5 m of compacted soil on which the leading ring of the shaft was concreted. Above the leading ring a 20‐cm wide slit filled with stabilized bentonite slurry was provided in order to eliminate skin friction during sinking. The shaft was concreted using slip form work. The method of excavation and verticality control of the shaft axis during excavation and concreting and the construction procedure of the shaft bottom are described in some detail. The shaft was successfully completed within 120 working days. Two examples of open caisson foundation that had to be changed due to unfavorable soil conditions are discussed. It is emphasized that careful soil exploration is prerequisite to success in open caisson foundations.

Using a boundary element formulation, a systematic parametric study is performed on the static and dynamic horizontal stiffness of arbitrarily shaped rigid foundations embedded in a reasonably deep and homogeneous soil deposit. Results are presented for rectangular base shapes of aspect ratios up to 10, a wide range of embedment depths, three values of the Poisson ratio, and an ample range of frequencies. The height of the foundation sidewalls is varied parametrically between the two extremes of no sidewall and complete sidewall with height equal to embedment depth and in perfect contact with the surrounding soil. Results have been obtained for circular and triangular plan shapes as well, including cases of non‐uniform contact along the foundation perimeter. The results are presented in the form of simple and versatile analytical expressions and dimensionless graphs. Two examples illustrate their direct practical applicability.

Using numerical results obtained by the boundary element method, the paper develops a simple method involving algebraic formulas and dimensionless parametric charts for estimating the lateral radiation damping coefficients of arbitrarily shaped rigid foundations embedded in an elastic halfspace. Complete as well as partial, symmetric and nonsymmetric types of contact are considered between the vertical sidewalls and the surrounding soil. Valuable insight is gained into the mechanics of radiation damping and conclusions of practical significance are drawn regarding the effects of potential separation/slippage between the walls and the soil near the ground surface. Two examples illustrate the direct applicability of the method while its versatility is shown through an extension to treat a more realistic inhomogeneous soil profile.

The paper presents the results of a series of monotonic and cyclic triaxial tests carried out to study the influence of the rate of strain and load cycles on the undrained shear strength of three undisturbed sensitive clays from eastern Canada. For structured clays (naturally overconsolidated), pore pressures generated at a given deviator are essentially independent of the strain rate, while the peak strength envelope is lowered as the strain rate is decreased. For destructured clay (normally consolidated), a lower strain rate results in an increase in pore pressure generation during shearing, due to the tendency of the clay skeleton to creep, while the peak strength envelope remains the same. Nevertheless, from a quantitative standpoint, the increase in shear strength caused by an increase in strain rate is similar for both structured and normally consolidated clay, and it is linear for at least five log cycles of strain rate.

Driven piles in calcareous sands may have only a small fraction of the capacity of driven piles in noncarbonate sands. This has become a particular problem in the offshore and coastal areas of Australia, India, Saudi Arabia, and the Caribbean. The great expense of load tests and/or remedial measures has caused many offshore operators to turn to drilled and grouted piles when these materials are encountered. The latter tend to have higher capacities but are also very expensive. This paper summarizes a review of the published literature pertaining to driven and drilled and grouted piles in calcareous sands. The summary includes a discussion of the relevant characteristics and behavior of calcareous sands, proposed soil classification schemes, and published pile load test results. It is concluded that pile capacities for driven piles are not only low but have a high variability. Generalized principles for classifying the soil, identifying controlling characteristics, and predicting pile behavior are badly needed. Drilled and grouted piles, on the other hand, appear to have capacities at least as great as driven piles in noncarbonate sands. Additional data are needed, however, to confirm these preliminary conclusions. Furthermore, alternative economical techniques for installation or postinstallation treatment to enhance pile capacity would be welcome.

Equations relating collapse footing pressure with soil strength property and void conditions for strip footings centered above continuous circular voids are developed using the upper bound theorem of limit analysis. Results of the analysis compare fairly well with available data.

The dilatometer was first introduced by Marchetti in 1975. This new in situ device has a very large potential in evaluating some important soil properties. The knowledge of drainage conditions during penetration is an important part of the test results. Unfortunately, the dilatometer by itself cannot measure the pore pressure generated during penetration. Therefore, in order to determine what the drainage conditions were, a piezoblade was designed. This new piezometer has the same shape as a dilatometer. Many dilatometer and piezoblade tests were performed and the dilatometer's first pressure readings were compared to the generated excess pore pressures. From the test results, it appears that the maximum effect of generated excess pore pressure in very overconsolidated soil is about 40% of the dilatometer's first pressure reading.

The static horizontal stiffness of pile foundations, for which there is continuous contact between the bottom of the pile cap and the underlying soil, is studied. Finite element results for a single pile with a circular pile cap on a uniform soil layer over bedrock are presented. An approximate procedure that uses analytical relations for the horizontal stiffness of the cap in conjunction with a modified beam-on-elastic foundation model for the piles is shown to yield reasonably accurate results.

Surface strip footings subjected to central load inclined in the direction of footing length are investigated. Model tests are carried out on saturated clay of medium plasticity using 25.4-mm wide strip footing under load inclindations of 0°, 10°, 15°, 30°, and 45° with the vertical. The computed inclincation factors are found to be larger than the conventional inclincation factors obtained for load inclinations in the direction of footing width. A similar trend is also observed in the case of strip footings in sand on analyzing the available test results.

A statistical model is proposed here to estimate the in situ anistropic cyclic shear strength of a saturated sand deposit. Triaxial test results are used to develop the basic model; it is then modified for in situ conditions considering all the factors affecting laboratory testing conditions as well as in situ conditions, i.e., mean grain size, overconsolidation ratio, multidirectional shaking, uniform cyclic loads, and secondary factors. A comparison is made between the anistropic and isotropic shear strengths. Using these strengths, the risks of liquefaction are estimated. It is observed that neglecting the presence of structures will always give a higher probability of liquefaction. The difference between the two cases is significant for shallower depths. The difference increases as the anistropic stress ratio, K_c, increases. A considerable amount of uncertainty is expected in the estimation of the in situ anistropic cyclic shear strength. The uncertainty associated with the in situ relative density contributes significantly to the overall uncertainty. The effect of the anistropic stress ratio as well as the uncertainty associated with this estimation need to be considered in any rational method for evaluating the susceptibility of a saturated sand deposit subjected to earthquake loadings.