This paper describes a procedure for predicting the residual strains developed in calcareous sand under irregular cyclic triaxial loading conditions. The rates of accumulation of volumetric and shear strains are treated separately, with the volumetric strain response being used as the basis for characterizing the effects of cyclic loading. The residual volumetric strain developed as a result of repeated loading is related to the mean and the amplitude of the cyclic deviator stress. Thus, by using empirical correlations between the applied deviator stresses, the number of cycles, and the measured residual strains, the effect of cyclic loading under one set of cyclic loading conditions can be expressed in terms of an equivalent number of cycles under a different set of cyclic loading conditions. By using this equivalent number of cycles for the cyclic loading stresses, the residual strains developed as a result of further loading are then determined, so that the residual strains developed at any stage during irregular cyclic loading can be evaluated.

Excessive settlement of bridge‐approach pavements creates problems for both road users and transportation agencies responsible for road maintenance. An important contributing factor to this settlement is the consolidation of foundation soil. A procedure based on the nonlinear finite‐element method (FEM), including infinite elements, is developed to analyze the consolidation settlement of embankment foundation at the bridge approach. Biot's theory of three‐dimensional consolidation, as proposed by Sandhu and Wilson, is used in the development. Nonlinear behavior of the soil skeleton is represented by the modified Cam‐clay model. A plane‐strain infinite‐element algorithm is developed. The semi‐infinite domain is divided into two regions. The near field is discretized by using the eight‐noded isoparametric elements, while the far field is discretized by using the infinite elements developed. The interpolation functions for the infinite element are chosen based on the far‐field behavior of a homogeneous porous elastic half plane. The analysis procedure is applied to study the time‐settlement history and pore‐pressure dissipation characteristics of a bridge‐approach site in Oklahoma.

Electro‐osmosis tests are conducted on saturated kaolinite specimens loaded with Pb(II) to investigate the efficiency and energy requirements of the process in removing this heavy metal. Kaolinite specimens were loaded with 118 μg to 145 μg of Pb(II) per gram of dry soil, below the cation‐exchange capacity of the mineral. The test results pertaining to the flow and the associated electrochemistry (voltage, current, resistance, pH gradients, and conductivity) are presented. The flow in electro‐osmosis with open electrodes is time‐dependent, and it is strongly influenced by electrochemistry resulting from the pH gradients. The absorbed Pb(II) was removed 75‐95% by the process. The extent of removal is directly related to the pH gradients developed in the process. The total charge passed to remove Pb(II) varied between 1,400 and 2,000 amp‐hr per cubic meter of soil. The energy requirement for the removal of Pb(II) in these tests was less than 29 kWh‐60 kWh per cubic meter of soil processed.

This paper summarizes the parameters that influence the axial capacity of pipe piles driven into sands. The parameters that affect pile behavior are for convenience divided into four categories: (1) Soil characteristics; (2) pile characteristics; (3) method of pile installation; and (4) type of loading. When possible, the influence that these parameters have on the capacity is quantified. In addition, the paper describes supporting evidence from pile load test data, small‐scale laboratory tests, and in situ cone probings that has been used to justify limiting values for unit shaft and toe resistances. The use of limiting values has significant economic impact on long piles, especially those used for offshore applications. This information is, therefore, evaluated and critiqued to place the use of limiting values in proper perspective. The results of this paper are based on a synthesis of literature on (1) pile load test data on piles in sand, (2) data from cone penetrometer tests in sands, and (3) information on the stress‐strain and strength behavior of sand.

The Leaning Tower of Pisa has intrigued soil mechanicians for many years as to why it tilted in the first place. The more urgent question is, however, whether it is safe today against complete collapse. Methods available in the literature concern the stability of initially vertical towers, not tilted towers, and even for the former there exist very little physical data in verification. The centrifuge is used here to make model tests on towers having small initial tilt and to determine the critical height of tower that causes instability. Two new approaches are presented that give close correlation with experimental results. These approaches are based upon: (1) The experimental determination of rotational stiffness of the soil foundation system; and (2) a method analogous to that proposed by Southwell (1932) for predicting the stability of imperfect columns.

The electromagnetic theory of Maxwell‐Fricke for the electrical conduction through heterogeneous media is extended to develop a theoretical relationship for fluid‐saturated porous media, accounting for the orientation of particles, the porosity and the dielectric constants of the pore fluid, the solid phase and the mixture. Based on this relationship, it is shown that a knowledge of the dielectric constants of saturated soils in the horizontal and vertical directions at high frequencies around 50 MHz provides the necessary data for the evaluation of the porosity for most soils when the dielectric constants of the particle and the solution are known. The method provides a rapid means for laboratory evaluation of the porosity of any saturated soil. It may also be adopted to in situ evaluations of the porosity of any saturated soil.

Auger‐cast piles are formed by drilling a continuous flight auger into the ground and, on reaching the required depth, pumping grout or concrete down the hollow stem as the auger is steadily withdrawn. The sides of the hole are supported by the soil‐filled auger, eliminating the need for temporary casing or bentonite slurry. This paper outlines important features of auger‐cast pile installation that influence the structural integrity and geotechnical capacity of completed piles. These include soil decompression, correlation between the rotational and vertical speeds of the auger, and precise coordination of auger extraction and grout supply. The results of 66 loading tests on auger‐cast piles in sand are presented. Shaft resistance is found to be independent of the relative density of the sand, while point resistance can be directly correlated with results of standard penetration and cone penetrometer tests. Empirical design methods for bored piles were found to underestimate the failure loads of auger‐cast piles. New correlations, based on pile length and standard penetration resistance, are proposed.

The method-of-characteristics approach is used in general to find the ultimate bearing capacity of footings on soils whose cohesion is homogeneous and isotropic. In this technical note, the method is further developed and equations along the characteristics are derived for the soils, whose cohesion varies linearly with depth under ϕ = 0 condition. Using these characteristic equations, the ultimate bearing capacity of strip and circular footings placed at a depth have been obtained. The numerical results are presented in the form of bearing capacity factor $N_c$ versus nondimensional depth of footing. The results show that $N_c$ varies linearly with nondimensional depth of footing for a given constant linear increase in cohesion with depth. The bearing capacity factor $N_q$ is found to be constant and equal to 1.0.

Undrained repeated load triaxial tests are carried out on anisotropically (K_o) normally consolidated specimens of a silty clay. Each specimen is subjected to five periods of loading at 0.1 Hz. The loading periods have a maximum duration of approximately 2,000 cycles, and are separated by drainage periods. A variety of cyclic loading magnitudes are applied. The experiments show that large permanent shear strains and pore pressures develop during the first few loading periods, particularly during the application of high cyclic deviator stress amplitudes, leading to failure. This is defined as an accumulated shear strain of 0.6% during a particular loading period. Drainage periods have a significant strengthening effect, even though the changes in water content are small, and it is observed that during the later loading periods very little permanent strain or pore pressure development occurs. The number of drainage periods required to produce this condition increases as the magnitude of the cyclic loading amplitude increases.