A series of tests was conducted in a plane-strain hollow cylindrical testing device. The reinforced sand samples developed wider shear zones than the unreinforced samples and had wider shear zones than similarly reinforced samples tested in direct-shear devices. Shear-zone width increased with increasing reinforcement concentration, reinforcement stiffness, and soil-reinforcement bond strength. Reduction of displacement data to a strain basis reveals that shear, elongational, compressional, and volumetric strains differ in unreinforced and reinforced samples. Dense, dilatant unreinforced sand samples formed narrow shear zones with large strains, whereas the reinforced samples had smaller but more uniform strains distributed throughout the samples. Reorientation of zero-extension shear planes in the reinforced samples limited the range of orientations over which the reinforcements contributed to strength. Overall, the results indicate that reinforced soils deforming in uniform stress fields do not develop narrow shear zones, and, therefore, reinforcement contribution to strength through reorientation and mobilization of bending moments is unlikely under field conditions. To insure that reinforcements are loaded in tension, they should be oriented well within 45° of the minor principal stress.

A concept for evaluation of building damage resulting from differential ground movement is presented in this paper. The concept is intended as a first-order method for damage assessment and relies on ground movement profile geometry, structure geometry and design, strain superposition, and critical strains of building materials. Means for estimating the degree of damage are presented in this paper so that the ground movement effects on third-party properties resulting from adjacent construction can be quickly and rationally prioritized. Prioritizing structure evaluations according to this first-order damage assessment method allows detailed evaluations to be focused on those structures that appear to be most susceptible to moderate or severe damage. Using the methods described in this paper, 20 case histories are examined, producing 43 separate evaluations, and the results compare favorably with actual damage observations.

A finite-element approach is presented to predict the behavior of dense sand surrounding the pile tip in a fairly large stress range, from low stress levels to very high ones, where particle breakage occurs. The approach is based on a constitutive model for sand, which is characterized by critical-state–type yield surfaces and by a nonlinear Mohr-Coulomb failure criterion, the latter being defined on the basis of constant-volume shear strength and of dilatancy. In addition, the concept of constant relative breakage surfaces, which represent families of curves characterized by constant amounts of particle crushing, is introduced. It is shown that the model, applied to the analysis of the behavior of the tip of nondisplacement piles in sand, can be used to visualize and to predict the distribution of strength, dilatancy, and grain breakage in the soil surrounding the pile base.

This paper demonstrates the application of two-dimensional random networks to quantitatively represent the minifabric of compacted clays. The structure of compacted clays is idealized using aggregations of spherical clusters that in turn are simulated as circles in a two-dimensional plane. Flow is considered to take place in intercluster pores only, and the random network of pores in the minifabric is constructed using constant-diameter pore segments. The maximum diameter of the clusters is shown to govern the important network parameters, viz. the diameter, length distribution, and areal density of pore segments; and connectivity of the network. It is shown that with small clusters, the permeability is low due to the low transmissivities of individual pore segments, in spite of the well-connected nature of the networks. Conversely, for the same intercluster porosity, the permeability corresponding to large clusters is high in spite of the poorly connected nature of the networks, because of the high transmissivities of the individual pore segments. The network representation is applied to prior investigations where necessary data are available, and good agreement is observed between experimental observations of hydraulic conductivity and predictions made by the random networks.

A predictive model for drain-enhanced soil flushing is developed and presented. Results from a parametric study indicate that, as the depth of the contaminated zone ( H ) increases, the time needed to attain 50% clean up level ( t₅₀ ) increases. Results also indicated the sensitivity of the predicted contaminant concentrations to variations in the partition coefficient ( K _d ) and radial and vertical dispersivity (α_r and α_Z). For the case of α_Z= 1 m, t₅₀ is evaluated equal to 42 h, while a t₅₀ of 55 h is predicted for α_Z= 0.1 m. The estimated t₅₀ increases from 37 h for α_r= 10 m to 61 h for α_r= 0.1 m. Analyses and results presented in this paper indicate the feasibility of using the proposed model to predict soil flushing rate using PVD-enhanced system.

Construction and maintenance of buildings and roads, and normal traffic activities, all generate vibrations in nearby structures. Multiple investigations showed that in most cases the levels of vibration were too low to produce direct structural damage based on the vibration limits in existing codes. In current practice, recommended vibration criteria limits seldom take into account settlement of foundation soils due to repetitive vibrations, particularly the cumulative effects of long-term repeated exposure. Many different parameters play an important role in the evaluation of vibrational densification of granular soils. They include vibration characteristics (amplitude, frequency, number of cycles), source of vibration, distance to that source, soil parameters (attenuation characteristics, grain size distribution, density, moisture content), and state of stresses in soil layers vulnerable to vibration. This paper describes a method to predict in-situ settlement of sands caused by pile driving or vehicular traffic with a laboratory developed polynomial model. Extrapolation from laboratory to in-situ conditions are derived. Attenuation characteristics of soils are accounted for. Several case histories were investigated in detail to show practical applications of the proposed method.

Energy concepts are applied to the conditions that are likely to have existed at distant liquefaction sites in past earthquakes. From this, magnitude scaling factors are derived that reflect field cyclic strength conditions. It is shown in the paper that the factors are independent of the field acceleration assumed to have existed at the sites, and are only dependent on the magnitude-equivalent number of cycles relationship. These factors are compared with others based on laboratory cyclic strengths from Seed and Idriss and on statistical regression of data from field case histories of liquefaction. The factors derived based on energy concepts are similar to those derived by Ambraseys based on a statistical analyses of extensive liquefaction data. It is concluded that the factors derived in the paper based on energy concepts, or by Ambraseys, appropriately represent field conditions and avoid the limitations and extrapolations of the laboratory-based derivation by Seed and Idriss, and they are recommended for use in the analysis of liquefaction potential.

In this paper, the behavior of helical piles under lateral loads in clayey soils is examined through an experimental investigation on model piles. Tests were conducted on rigid helical piles with different numbers of plates. Model anchors were made of 13.8 mm diameter mild steel shafts to which mild steel plates of 33 mm diameter were welded. For comparison, a single straight shaft with a diameter of 13.8 mm was also tested. Test results revealed that the lateral capacity of helical piles is greater than that of straight shaft piles. A simple theoretical model is suggested to estimate the lateral capacity of rigid helical piles. The theoretical model suggested incorporates lateral resistance of the soil on the shaft, bearing resistance on the bottom of the helical plate, uplift resistance on the top of the helical plate, and frictional resistance on the surface of the helical plate. The validity of this model is examined.