A theoretical study is presented on the usefulness of a row of rigid piles as an isolating barrier for elastic waves. The problem is formulated as one of multiple scattering and diffraction. A set of cylindrical coordinate systems is used in such a way that it allows solving in an exact form the problem of multiple scattering for circular cross‐sections. Some numerical results are presented. The effectiveness of this isolation system is discussed.

Using the results of eight field load tests reported in the literature, the ultimate lateral load for rigid shafts in clay is defined as the load corre sponding to a shaft rotation of 2 degrees. This definition is used to develop a new empirical correlation between lateral load and rotation. In‐addition, a new empirical correlation is developed relating the coefficient of ultimate resistance at the groundline to soil shear strength. A proposed new design procedure if formulated which utilizes the new empirical correlations. Comparison of lateral loads predicted by the proposed new design procedure shows excellent agreement with measured lateral loads obtained from field tests.

Model studies have shown that end‐bearing pile settlement in a saturated sand deposit is very sensitive to excess pore pressures induced by earthquake shaking. Settlement amounting to pile failure will be reached before liquefaction occurs, for pile safety factors in the 1.5 to 3 range Variables considered in the program were effective stress level, relative density and stress history of the sand, diameter and safety factor of the pile. Tests were carried out in an apparatus designed so that the model pile tip could be inserted into a saturated sand mass under effective stress levels of up to 40 psi,(276 kPa). Excess pore pressures were then induced by applying cyclic load to the sand in undrained conditions. Tests with piles of three diameters showed consistent behavior when corrected for apparatus boundary conditions.)These results may therefore serve as an element of judgment in predicting the behavior of fullsize piles.

Three facts can lead to permeability‐anisotropy in sedimentary soils: (1) Macro‐stratification; (2) micro‐stratification; and (3) flatness plus orientation of particles. The effect of flatness and orientation of particles is quantitatively investigated using a fabric of lenticular particles as a soil model. The investigations comprise permeability tests with alternate directions of percolation (i.e., parallel and perpendicular to the orientation of the particles) and theoretical considerations based on the hydraulic radius and pore channel model. The geo metrical parameters of the samples are measured with the help of oriented sec tions after stabilizing the model with hardening resin. The theoretical investi gations show that the factor of permeability‐anisotropy is equal to the square of the ratio of the pore‐channel‐tortuosity, and both the analytical and experi mental results reveal that, even for a high degree of particle‐flatness, the permeability‐anisotropy can hardly exceed a factor of about 2.5.