To investigate the behavior of reinforced clay, drained triaxial compression tests were performed on kaolin clay reinforced with horizontal discs of sintered porous plastic. The results of two series of tests are presented—on involving the use of multi‐reinforced samples and the other using unit cells of clay of various heights. In both cases it was found that decreasing the spacing between the horizontal layers of reinforcement increased both the drained shear strength and the secant deformation modulus of the reinforced sample. The results of a radiographic investigation are also presented, which indicate the mechanism of the strength enhancement to be one of radial strain control, arising from shear stresses mobilized on the soil‐reinforcement interface. The experimental results are compared with a theoretical model, the basis for which is that the radial shear stresses lead to an enhanced minor principal stress, and hence, enhanced strength. Upper and lower bounds are defined, within which the experimental results are generally found to fall.

Bearing capacity predictions for surface footings on sand based on modifications of Terzaghi's superposition method are partly empirical and partly theoretical. Based on currently available data for surface footings on sand, these predictions are compared with statistical analyses. For small uncertainty in soil properties, coefficients of variation of bearing capacity for cohesionless soil without surcharge range from 20% to 30%. As uncertainty in soil properties is introduced, uncertainty in bearing capacity rises rapidly. Quantified expressions of uncertainty are derived and illustrated by example. These analyses are used to identify sources of uncertainty.

In recent years, new seismic design methods for gravity retaining walls, based on the earthquake‐induced permanent displacement of the wall, have been proposed. These methods generally ignore the effects of ground motion amplification in the backfill on the seismic behavior of the wall. In the present paper, results obtained with a finite element model capable of taking into account the amplification of ground motion in the backfill, while computing permanent distortions, are presented. Implications of these results for design are also considered.

An empirical model to describe the unconfined compressive creep behavior of frozen sands is developed. When combined with the proposed method for parameter evaluation, this model accounts for the effect of applied axial stress, ambient temperature and level of pore ice saturation and can be used reliably for data fitting and creep prediction. Comparisons indicate that this new tertiary creep model is more accurate and reliable than primary and secondary creep models.

A finite element procedure is developed for stress, seepage and stability analysis of dams and earthbanks. The seepage analysis is based on a residual flow scheme involving saturated and unsaturated zones in which the original mesh remains invariant during transient flow and iterations. By using the same mesh for stress analysis including sequential embankment construction, it is possible to superimpose directly the effects of external and seepage forces. The soil behavior is modeled by using linear elastic, piecewise linear elastic and Drucker‐Prager models. The procedure is applied to a number of problems involving free surface seepage, stress analysis with stability, and combination of both. The predictions are compared with closed form solutions and field observations.

Stiffness constants and constants of equivalent viscous damping are presented for single, vertical piles in the form of tables and charts. The soil shear modulus is either constant or varies with depth according to a quadratic parabola. The butt is either fixed or pinned. The piles are presumed to be both end bearing and pinned. Geometric as well as material damping is considered.

A series of reinforced soil beams with varying reinforcements were tested to study the improvement in the flexural characteristics of soil beams. A small percentage of reinforcement in the form of metallic strips is observed to impart substantial improvement in the load carrying capacity and flexibility to the soil beams.

Ties or reinforcements are normally connected to the backside of a retaining wall and extend horizontally into the backfill. This horizontal, parallel array was compared with a radial tie array in which ties radiated in clusters from single points. The latter array simulates the roots of woody plants growing in the frontal interstices of retaining walls and also the action of a ``reticulated root pile'' system of criss-crossing ties or inclusions. The study was carried out using a rigid model retaining wall, dry sand backfill, and natural reed fibers as ties. Reduction in lateral forces or overturning moment against the wall was measured as a function of tie length and attachment at the wall. Test results showed that clusters of radiating ties were equally, if not more effective than horizontal, parallel tie arrays in reducing overturning moments.

Some characteristics of wave-seabed interaction are described, and stresses and displacements from an elastic, static analysis for a sinusoidal stress wave acting on a homogeneous half space are compared with results from a dynamic, nonlinear, layered continuum analysis. The elastic approach provides a good estimate of the soil shear stresses induced by bottom pressures if the strength profile can be represented by a near straight line with a constant value or positive slope. This simple approach does not usually provide a good estimate of either the magnitude or pattern of the shear stresses if the strength profile has a crustal zone. This elastic method often provides a good preliminary estimate of the lateral soil motion.

A fundamental approach, based on Gouy-Chapman theory of double layer, has been provided to micromechanistically interpret the plasticity index of soils and their relationship with liquid limit. The relationships between plasticity index and liquid limit, developed earlier, through statistical approaches and critical state concepts, have been reexamined. The statistical analysis of extensive published data has resulted in the relationship, I_P = 0.74 (w_L - 8). On comparison with other relationships in vogue the proposed equation has been found to give better agreement. From the reappraisal of critical state approaches consistent with the micromechanistic interpretation, the possible range of parameters have been computed and compared with those obtained by statistical means to enhance the credibility of the proposed relationship.

Plastic behavior of soil that is uniformly reinforced by fibers is studied. This analysis considers reinforced earth as macroscopically anisotropic and homogeneous, and it describes its gross behavior based on a knowledge of the mechanical properties and interactive contribution of each component. The rigid plastic model of reinforced earth is developed and an application of the proposed model is given. Experimental results are given.