An investigation of high frequency, traveling wave excitation of a two‐dimensional, multiple block, rock slope was conducted with a discrete element model to quantify the effects of variable frequency blasting vibrations. The investigation involved a responding upper rigid block and multiple lower rigid blocks that were excited so as to represent a wave propagating through the rock mass. At constant particle velocity or acceleration, increasing dominant excitation frequency significantly decreases shear displacement. Other propagating wave factors such as propagation velocity, wave type, and joint stiffnesses affect calculated shear displacements to a lesser extent than the frequency.

Results of torsional shear tests on specimens of reconstituted 20‐30 Ottawa sand are presented to resolve inconsistencies in prevailing interpretations of previously published test results regarding: (1) The conditions leading to limited or steady‐state flow deformation under monotonic loading; and (2) the state conditions marking the initiation of strain softening behavior under either monotonic or cyclic undrained loading. It was found that the effective stress path in monotonic undrained shear appears to constitute a state boundary that controls the initiation of strain softening under undrained cyclic shear loading. Evidence is presented in support of a new concept of the collapse of sand fabrics. It is used to explain the sudden increase in pore‐water pressure associated with the initiation of strain softening behavior on loading, or with the development of a condition of zero effective stress after repeated cyclic unloadings beyond a critical level of mean effective normal stress. The concept also explains why steadystate conditions in drained shear are not necessarily the same as in undrained shear. The implications of the new findings on the determination of the liquefaction potential of sands are discussed.

A 300‐ft‐long anchored bulkhead at Kake, Alaska, failed following placement of fill behind the bulkhead wall. The entire wall rotated outward at the toe and moved downslope 40 to 60 ft. No on‐site over‐water borings had been made, but local geologic investigations and pile driving resistances noted during construction suggested that a 5‐ to 20‐ft‐thick zone of soft marine clay overlying relatively dense offshore sloping soils and shallow bedrock lay beneath the project site. The failure is believed to have resulted in the displacement of the soft clay down to the surface of the competent soils. After the failure, the granular fill originally placed behind the bulkhead lay immediately over competent soils along the bulkhead alignment. Observations from onshore borings, dredging, and offshore test pile driving after the failure support the conclusion that the clay was removed from the bulkhead and till area by the failure. The bulkhead was redesigned with its alignment about 24 ft inland, and with a higher dredgeline elevation. It was successfully completed using materials salvaged from the original construction. Postconstruction alignment surveys have not disclosed any movement of the reconstructed wall.

A volcaniclastic formation, known as Cangahua, found in the Andes of Ecuador and Colombia is focused on. The deposit is composed of moderately cemented fine sand and silt‐sized particles. A pronounced linear correlation is shown between strengh, in terms of both uniaxial compressive and Brazil tensile strengths, and the dry unit weight of the deposit. The tensile strength is unusually high for soil, being between 18 and 29% of the uniaxial compressive strength. Brazil tensile, uniaxial compressive, and triaxial strength characteristics depend on the initial void ratio and degree of saturation. As the saturation declines from 90 to 40%, test results show a fourfold increase in tensile strength. Moreover, increasing degrees of saturation cause a shift from brittle to ductile failure. Slope failures in Cangahua develop from fractures which initiate at zones of high tensile stress. Material properties such as tensile strength and fracture toughness play an important role in explaining and evaluating slope failures in this material. The strong dependence of tensile strength on the degree of saturation indicates that local moisture conditions and exposure to rainfall should be considered in stability assessments.

Tie‐back walls are frequently used presently for the support of deep excavations, yet soil‐structure interaction under “service” conditions is not really understood. This study is an attempt to analyze the problem using the results of experimental work by the writer. Soil and wall movements, variations in anchor prestress, as well as sand stresses on the wall were measured on a small scale physical model. Numerical parametric analyses of soil‐structure interaction based on a Winkler model were also made by varying soil stiffness, soil properties, and anchor prestress values to fit the model tests. Results were subsequently extrapolated to real size. It was shown that the soilwall‐anchor interaction was profoundly influenced by an increase in the anchor prestress, which generally led to a large reduction of the associated tie‐back displacements. This should be attributed to the force equilibrium on the wall, which was shown to differ markedly from the one used by conventional limit equilibrium design.

Due to cyclic loading, a soil sample may be either densified or loosened accompanied with cumulative shear deformations. The cumulative volume change and shear deformation behavior depend significantly on the static stress state existing prior to the application of cyclic loading. Based on the principle of energy balance, during cyclic loading, the work done on a soil sample is dissipated in rearranging particles, thus creating irrecoverable strains. Using the concept of critical‐state soil mechanics, a relationship is obtained between the dissipated energy and the cumulative strains. Based on this relationship, a simple expression is derived to relate the static stress state and the ratio of cumulative volume to cumulative shear strains (i.e., the first to the second strain invariants). The derived relationship is used to illustrate the dilative and contractive characteristics of sand under cyclic loading. This relationship is also validated by comparing the predicted results with the measured ones obtained from cyclic triaxial tests on sands.

The note describes seismic refraction tests above a water table at shallow depth. The depth of water table estimated by the refraction test is always greater than the real level of the water. An interpretation based on the effect of relative displacement between solid and fluid (Biot model) is disregarded. It is shown that this effect is probably due to a nonsaturated zone below the water table. The test is therefore considered a good technique for estimating in situ the saturation ratio below the water table.

A series of model tests on grouted pile shafts in reconstituted calcareous sand is reported, in which the effective stress state is controlled by altering the back pressure in the soil and keeping the total pressure constant. Under these conditions, it is found that the average limiting skin friction on the pile shaft is related linearly to the effective overburden pressure.

VerticalHorizontal soil force on the heel of cantilever retaining wall is a very significant part of the total horizontal soil force considered in the calculation for sliding. Practically, the force on heel can be from 0.15 of total horizontal force minimum to more than 0.5 of total horizontal force when retaining of small height or select fill is used above base level. This force can be drastically reduced or even completely eliminated by forming a sloped heel. Practically, it is enough to make a slope of 45° to achieve a horizontal soil force on the heel reduction from 73%–98% for the soil with internal angle of friction of 20°–40°. A sloped heel can be used as a very simple and efficient method to reduce horizontal soil pressure and thus increase retaining wall safety factor against sliding.

The stability of a groin in a littoral system is dependent upon the engineering properties of the embedment soil and the fluid dimension. If the sub-bed soil is an ideal cohesionless deposit, the groin rigid and impermeable, and the fluid flow steady, then the stability factors of the groin include the angle of friction and bulk weight of the deposit, the depth of embedment of the groin, and the incident angle and velocity of the flow. The higher the incident angle of the flow, the greater is the stability of the groin. For a stability condition, an increase in the angle of flow leads to a decrease in embedment depth and, consequently, to a decrease in construction cost.