In an attempt to develop an acoustic emission (AE) field procedure to directly determine preconsolidation pressures, laboratory feasibility tests on granular soils (published earlier as a companion paper; Ref. 7) and on cohesive soils (this study) have been conducted. Consolidation test specimens were prepared, stressed to known values and then unloaded. Upon restressing, acoustic emission and deformation data were taken for use in estimating the previously applied stress level, i.e., the preconsolidation pressure. Six soils, each at three different water contents were tested, and all 18 were evaluated at four different stress levels, i.e., 72 tests were performed. It was found that the average error between the known and estimated values of preconsolidation pressures Varied from $+2.5\%--4.4\%$ for direct deformation (dial gage) monitoring, and from $+5.5\%--7.0\%$ for AE monitoring. This variation was very similar to the results found in the prior study on granular soils. While not quite as accurate as direct deformation monitoring, the data suggests that AE monitoring is within engineering accuracy for such determination. Its strength, however, lies in the fact that the AE method can be readily used in field measurements, e.g., by adapting a pressuremeter into an “acoustic pressuremeter.” This should enable one to augment (possibly in a very significant manner) the downhole deformation, or volume, measurements necessary in the field during standard pressuremeter testing.

The problem of torsional harmonic vibration of circular surface and embedded foundations on cross‐anisotropic elastic half space is considered. Solution is achieved by proper transformations involving geometric and material parameters, similar to that used in studying seepage through hydraulically anisotropic soils. Parametric results for dynamic stiffness and damping coefficients are presented in the form of formulas and graphs which may be readily used in practical applications.

Much evidence is now available that freshly deposited or densified saturated clean sand may exhibit substantial stiffening and strength increase with times up to several months. Sand deposits may undergo a significant loss in strength as a result of disturbance, thus behaving in some respects in a manner similar to sensitive clay. These phenomena appear to be related to solution and precipitation reactions involving quartz, amorphous silica, and other compounds and the formation of cementing bonds at interparticle contacts. The effects of these phenomena must be considered when evaluating the results of laboratory tests on reconstituted samples, in the assessment of ground improvement using deep densification, in the evaluation and interpretation of relative density measurements, and in the estimation of liquefaction potential.

A brief treatise of the mechanics of stability aspects of slurry trenches excavated in short panels is presented. Three case histories of slurry trench excavation including two failures are described and back‐analyzed by arching theory. Some existing analytical methods for trench stability are shown to be conservative in predicting earth pressures. Special emphasis is made on the subject of stability of slurry trenches subjected to heavy surcharge load, such as from adjoining and adjacent foundations. A design procedure is proposed for such loading conditions without undue conservatism by taking into consideration the redistribution of surcharge load to soil adjacent to the excavation and the redistribution of stresses in the building structure.

The stability of spread footing situated above a continuous void was investigated. The study involved a theoretical analysis and a model footing testing. The theoretical analysis was made using the finite element method in which the foundation soil was idealized as an elastic perfectly plastic material. The model footing testing was performed on a commercially available kaolinite, which was compacted to 95% compaction based on the standard Proctor compactive effort. The model footing test results were compared with those obtained from the finite element analysis. As a result of this study, a three‐dimensional finite element computer program was developed. Using this computer program, the stability of spread footing was analyzed for different conditions. The results of the analysis indicate that there is a critical region under the footing. Only when the void is located within this region will the footing performance be significantly affected by the presence of the void. The size of the critical region depends on several factors such as footing shape, soil property, void size and void shape. When the void is lócated within the critical region, the bearing capacity of the footing varies considerably with the void location.

This paper presents a numerical model for calculating permanent strains and stresses in sand caused by cyclic loading. The model is fitted to the results of drained static and cyclic triaxial tests. The model can predict permanent stresses and strains resulting from drained or undrained cyclic loading under various boundary conditions. Predictions of the model are compared with experimental results from cyclic odometer tests and cyclic undrained triaxial tests. Good correlation exists between the predicted and measured response.

An unfavorable groundwater condition is a frequent cause of slope sliding. Pore pressure decreases the effective stress level and consequently the shear existance of the soil on the slip surface is decreased. Thus the slope safety against sliding is reduced. A change in the groundwater condition is achieved by drainage systems. The drains introduce a lower potential to the pore water which reduces the pore pressures in the sliding mass. Drainage trenches are suitable for stabilizing shallow translational slides. This paper examines the determination of the necessary spacing of trenches for a required increase in factor of safety. The factor of safety obtained represents the long‐term value for the steady state condition.

A series of ten field pullout tests was performed on vertical cementgrouted rock anchors. The rock was an unweathered moderately horizontally jointed granite. In five of the tests the anchor bars were instrumented with strain gages. These testing results, together with rock surface vertical deflection measurements and visual inspection of a 2‐dimensional model of an anchor grouted in similar rock, indicate that as the pullout load increases, the rock bulges upward to a distance roughly equal to the anchor depth, with simultaneous formation of tensional cracks along the joints and separation of the blocks along horizontal joints. Based on these observations and other testing results, this design method is proposed for rocks with horizontal and vertical joints based on the idealization of the discontinuous rock mass in an advantageous way, so that the pullout capacities can be predicted from empirical values of certain variables. More specifically, the pullout capacity of a certain anchor in a certain discontinuous rock can be estimated based on empirical values from past experience of the probable total anchor deflection at failure.

Advective fluid flow, which depends directly on hydraulic conductivity, controls contaminant migration through soils in many cases. The state of practice in laboratory measurements of hydraulic conductivity of soils was reviewed and found to be extremely variable, with the result that measurements on a given soil material often give variations of several orders of magnitude. An experimental program was completed using compacted clay soils to study several facets of laboratory testing practice, and a suitable test procedure for consistent results was developed. Recommendations on several important aspects of procedure are presented. The procedure was also evaluated with a synthetic lead‐zinc tailings leachate, and alteration of the test soils' hydraulic conductivity was evaluated and correlated with probable chemical interactions of the test permeants and soils.

A method is presented for the analysis of load distribution of piles driven in sand and subjected to static vertical loads. This method is unique in that it considers the existence of residual stresses due to driving. It uses the results of standard penetration tests to obtain the load transfer curves for friction and point resistance. These curves are modeled by hyperbolas which start at the residual friction and residual point pressure for zero displacement. The design method is based on a simple theory and a 33‐pile data base. Since each pile had sufficient instrumentation and a sufficiently complete load test program, the residual stresses and transfer curves could be determined with reasonable accuracy from the data base.