An experimental study using resonant column tests determined the effects of drained shearing creep on the low‐amplitude shear modulus, $G_O\text{,}$ of three cohesive soils. The soils tested were a remolded kaolinite clay, a slurry consolidated clay and a natural “undisturbed” silty clay. It was found that in normally consolidated clays during the first stages of creep, characterized by fast rates of deformation, the value of $G_O$ is reduced significantly. The reduction was more pronounced for the higher stress levels. For the low rates of deformation characterizing the later stages of creep $G_O$ not only regains the initial loss but eventually exceeds the pre‐creep value. In over consolidated clays the initial drop of $G_O$ is not recovered although the value of $G_O$ is increasing slowly with time. It was also found that a temporary release of the confining pressure from a clay specimen may enhance the effects of previous creep on this specimen.

An experimental study using resonant column tests determined the effect of a temporary release of confining pressure (under conditions of no drainage) on the low‐amplitude shear modulus, $G_o\text{,}$ of two cohesive soils. The soils tested were a remolded kaolinite clay and a natural “undisturbed” silty clay. It was found that a temporary release of confining pressure induces disturbances which are manifested by a drop in the value of $G_o\text{.}$ After reapplication of the original confining pressure the cohesive soil regains the lost amount of $G_o\text{,}$ with the logarithm of “regain‐time” increasing linearly with the logarithm of the duration of the confinement prior to its release (i.e. the “age” of the cohesive soil). It is suggested that the findings be used for estimation of the secondary time that must be taken into account in a resonant column test on “undisturbed” samples, to establish $G_o$ representative of the in‐situ value.

AS part of a project to demonstrate the feasibility of retorting oil shale by the Paraho vertical retort process, laboratory and field tests were per formed to determine the physical and chemical properties of retorted oil shale for use as criteria for the design of full scale disposal systems. The material which exits from the retort is classified as a non‐plastic silty gravel. The material can be compacted to about 90 to over 100 pcf (1,440 to $1\text{,}600\mathrm{kg}/m^3)$ depending upon the degree of compactive effort applied. The addition of moisture from the dry state does not improve densification appreciably. When moistened to about optimum moisture and highly compacted, the material is classed as impervious and the material gains strength with time from cementing action. The retorted shale, so treated, can be used to construct stable, impervious retaining structures and impervious linings in valleys for holding the main disposal de posit and provide ground water protection.

Driven and drilled piles transfer comparable unit loads to over consolidated clays, yet the stresses to which they subject the soil are different. Fullscale load tests of piles of both types in the overconsolidated Beaumont clay of Houston, Texas are reviewed, and the measured load transfer relationships are compared. The drilled piles transfer more load to the soil at shallow depths, while the driven piles transfer more load at depths exceeding about 20 ft (6 m). The differences are explained by considering the different stress paths followed by the soil adjacent to the piles.

Dynamic lateral pile‐group effects are studied parametrically for a linearly elastic soil‐pile‐structure system. The soil layer is assumed homogeneous, and all piles are identical and vertical. Pile‐group responses for the soil‐pile systems used in this study are affected primarily by the spacing ratio, the dimensionless frequency, and the directional angle between two piles. Spring and damping coefficients of a pile group are strongly frequency dependent. Spring coefficients of a pile group can be negative for a clustered group, and they can be larger than a simple summation of single pile stiffnesses. Damping of a pile group also is frequency dependent, and it can be either larger or smaller than that of a surface footing with identical plan dimensions. Distribution pat terns of shear and moment among piles are affected largely by frequency. The study demonstrates potential importance of dynamic pile‐group effects. Also, it provided a procedure to generate theoretical pile‐group effects for dynamic analyses of complex soil‐pile‐structure systems.

Various physical mechanisms controlling the strength of frozen sand are proposed, evaluated and quantified by drawing upon an extensive literature survey, unconfined creep data on frozen sand and frozen saturated wetting and nonwetting glass beads. The principal mechanisms are: Ice strength and strengthening, soil strength, and ice matrix‐soil skeleton interaction through dilatancy effects and structural hindrance.

A general nonlinear differential equation for the one‐dimensional consolidation of saturated plastic soils, taking into account the variations of compressibility and permeability of the soil, is integrated by numerical methods and the corresponding consolidation curves are presented. If $\lambda =1-\gamma \kappa$ where γ and κ are the nonlinear coefficient of compressibility and the coefficient of permeachange, respectively, the consolidation curves depend only on the ratio of the final to the initial thicknesses $H_2/H_1$ and on the ratio of the parameters $\lambda /\gamma \text{.}$ Taking as reference the consolidation curves for which the coefficient of consolidation is constant, for which case $\lambda =0\text{,}$ then it is found that the displacement of the consolidation curves increases with values of λ/γ compared to zero and with values of $H_2/H_1$ compared to unity. The Terzaghi's linear solution is found to be a very good solution for the special case $\lambda /\gamma =1\text{.}$

The three‐dimensional, drained stress‐strain and strength behavior of Cambria Sand prepared in cubical specimens with cross‐anisotropic fabric was studied using triaxial compression, plane strain, and cubical triaxial tests with independent control of the three principal stresses. All specimens were loaded under conditions of principal stress directions fixed and aligned with the directions of the material axes. For comparable test conditions, the major principal strain was smallest and the rate of dilation was highest when the major principal stress acted perpendicular to the long axes of the sand grains. The opposite extremes were obtained when the major principal stress acted parallel to the long grain axes. The effects of initial cross‐anisotropic fabric were mainly observed in the prefailure stress‐strain behavior, whereas sufficient changes in the fabric had occurred at large strains to produce failure conditions which resembled those observed for isotropic sands. The three‐dimensional failure surface could for practical purposes be modeled by an isotropic failure criterion.

Since centrifuge time is expensive it is necessary to keep testing times to a minimum. Where clay forms an important part of the soil model, reasonable drainage periods can only be achieved by using a high permeability clay. This leads to serious problems if clay strengths and deformations, to be used in analyzing the test, are measured after the centrifuge is stopped. Any excess water available, such as drainage ducts or surcharge layers, can quickly enter the soil and cause softening. The critical state theory is used to estimate undrained shear strength and the results compared with values measured by vane in-flight. Measured shear strengths during flight and after stopping the centrifuge are compared.

A direct method of proportioning a rectangular footing area subjected to biaxial bending is proposed as an alternative to the trial and error method of solution. Formulas for the dimensions of the footing area are derived using the ordinary flexure formula and the limiting conditions that the maximum and minimum pressures are developed at the critical corners which are diagonally opposite each other. In addition, the maximum pressure is equated to the allowable bearing capacity of the soil while the minimum pressure is equated to zero. This condition assures the validity of the application of the flexure formula since the footing area is in full compression. Th analysis yielded the basic relationship of the footing area dimensions as 12 times the eccentricities of the total vertical load about the centroidal axes while the minimum area is controlled by the allowable soil bearing capacity. Once the area of the footing has been determined, adjustments can be made in the magnitude of the total vertical load to satisfy the above relationships.

The development of an analytical model for describing ground behavior during dynamic compaction requires that the magnitude of impact stresses be known. Although several theoretical methods for calculating dynamic stresses have been proposed, very few field measurements from full-scale operations have been made available for checking their validity. This technical note presents measured peak dynamic stresses at the ground surface obtained from an accelerometer mounted on the falling weight. The field testing program investigated a range of drop heights up to 19 meters using a constant weight of 20.9 tonnes. A simple analytical model derived from the conservation of momentum is shown to provide reasonable estimates of the magnitude and duration of impact stresses during dynamic compaction.