Pile-supported dolphins are designed for significant amounts of lateral loads. In this paper, the results obtained from tests carried out on model groups of piles to support dolphin-type structures are presented and discussed. Load tests have been conducted on instrumented model pile groups embedded in a marine clayey bed (liquid limit = 82% and plastic limit = 32%). The spacing between piles, number of piles in a group, and arrangement of pile group with respect to the direction of lateral loading have been varied. The results indicated that the capacity of pile group not only depends on the spacing between the piles, but also on the arrangement of piles in the group. The experimental program was further substantiated by a simplified analysis using a three-dimensional finite-element technique. The lateral group efficiencies obtained from the present investigation are compared with the published literature and found to be in good agreement.

The 1994 Northridge Earthquake affected two geotechnical structures of the Van Norman Complex, the Los Angeles Reservoir (LAR) and the Power Plant Tailrace, in different ways. Both the Los Angeles Dam and North Dike of the LAR slightly moved and settled, and sustained small superficial cracks. The North Dike underwent a noticeable increase in seepage, without significantly impeding normal reservoir operations. The Northridge Earthquake uplifted and shifted the foundation of the LAR by 30 cm, and provided us with a unique example of tectonic effects on embankments. In contrast to the LAR, which performed well, the nearby rolled fill dike of the Power Plant Tailrace slowly failed by piping due to transverse cracks and differential lateral spreading induced by liquefaction. Both case studies yield valuable information about the response of embankments subjected to near-source ground motion.

This paper presents an interpretation method for determining sand properties from the cone tip resistance and the pressuremeter limit pressure measured with the cone pressuremeter. The method developed here can be used to deduce the angle of internal soil friction and in-situ sand state from the ratio of measured cone tip resistance and pressuremeter limit pressure. In developing the theoretical correlations between soil strength parameters and the cone pressuremeter test results, the limit pressures of both spherical and cylindrical cavity expansions in sand are used to estimate the cone tip resistance and the pressuremeter limit pressure, respectively. The relevance of this simple interpretation method has been confirmed by the results of a large number of cone and pressuremeter tests carried out in both calibration chambers and the field.

By measuring electrical conductivity in two perpendicular directions, the variation of fabric anisotropy of kaolinite is determined during one-dimensional ( K₀ ), anisotropic (σ₁/σ₃= constant), and isotropic (σ₁/σ₃= 1) consolidation tests. To verify the validity of test results, the fabric anisotropy is determined at selected stages of loading by analyzing electron micrograph images of vertical and horizontal sections of parent specimens. The results from the two independent techniques are in agreement with each other. The results reveal aspects that can aid in the process of constitutive modeling of clays. In general, it is found that an isotropic consolidation loading or an anisotropic consolidation loading in extension, which causes rotation of principal strain directions, decreases the fabric anisotropy developed during prior K₀ consolidation. The initial fabric anisotropy, however, cannot easily be erased or reversed by such a loading.

A triaxial apparatus to measure small strains in the range between 10 ⁻⁶ and 10 ⁻² has been set up to investigate the reversible behavior of various types of soils (sands, gravels, clays). Reversible behavior, along compression and extension triaxial paths, was demonstrated for strain amplitudes lower than 10 ⁻⁵ . Elasticity was found to be nonlinear, since the Young's modulus depended on the mean effective stress. We also studied the influence of such parameters as deviatoric stresses, void ratio, stress and strain history, and soil structure on the elastic coefficients of these soils. A general equation was proposed for determining the Young's modulus E in initially isotropic soils, which was modified by further loading. In granular materials, strain hardening increased the value of E , while in structured materials, a decrease of E was observed due to internal structure damage.

This paper is concerned with optimum design and sensitivity of retaining structures. The optimum design formulation in terms of a constrained nonlinear programming problem, is given for reinforced concrete-cantilever retaining walls. The objective function may be chosen as the cost or weight of the wall. The solution is carried out by a specially prepared computer program (RETOPT). Illustrative problems are solved, and their results are presented and discussed. The formulation allows for a detailed sensitivity analysis to be made for selected design parameters, also depicted with numerical examples.

Downhole ground motions recorded at the Lotung Large-Scale Seismic Test (LSST) site were used in this paper to infer in-situ dynamic soil properties. The purposes were (1) to provide field evidence of nonlinear soil behavior during earthquake excitation; and (2) to evaluate the accuracy of dynamic properties obtained from geophysical measurements and laboratory tests. For each horizontal component and event analyzed, representative shear-wave velocity and effective shear strain (defined as 65 of peak strain) between consecutive recording stations were estimated. The representative shear-wave velocities were estimated from fundamental resonant frequencies identifiable from the Fourier spectral ratios. The effective shear strains were estimated by linear ground response deconvolution analyses based on the inferred shear-wave velocity profiles. The inferred reduction in shear modulus with increasing effective shear strain was compared with laboratory test data. The degree of agreement between the inferred shear modulus reduction curves and the laboratory test data varied with different testing programs. The inferred low-strain shear-wave velocity profile agreed with geophysical measurements. These observations not only provide field evidence of nonlinear dynamic soil behavior during earthquakes, but also confirm the reasonableness of data provided by geophysical measurements and laboratory tests.

Electrokinetic extraction has been demonstrated to be effective in removing lead from pure Georgia kaolinite characterized by a low acid/base buffer capacity and cation exchange capacity. The relatively high removal efficiency is dependent on the low soil pH generated by the electrokinetic process. However, when impurities such as iron oxides are present, electrokinetics alone may not be effective in the extraction of lead due to the higher acid/base buffer capacity and cation exchange capacity of the soil. In this study, the effects of ethylenediaminetetraacetate (EDTA) on enhancing electrokinetic extraction of lead from a natural kaolinite containing approximately 4.3 iron oxides as Fe ₂ O ₃ were examined. Interactions between lead and soil at different pH values were evaluated by batch tests. Results of the study show that approximately 90 of the lead spiked uniformly into the soil can be migrated toward the anode and accumulated within about 15 of soil for easier removal.

Lineaments, linear features visible on remotely sensed imagery, can be used to predict ground control problems in underground structures. Lineaments were used to backpredict hazardous ground conditions in an underground constructed facility, a coal mine in Alabama. The mine property was mapped above and below the surface for fractures and other geologic structural features. Both parametric and nonparametric statistics were employed in correlating field data with information derived from lineament maps. Results showed that fractures observed on the surface dipped vertically and extended to the mine level. Direct correlation of fracture trends with lineament trends was not apparent. However, lineaments were correlated with a change in the local fracture trend from the regional geologic structural trend. This deviation between lineament trend and fracture trend was consistent and statistically significant. Forty-two percent of all roof failures could be directly correlated with lineaments. It was found that the number of roof failures decreased exponentially with distance from a lineament. However, no relationships were found between roof fall occurrences and lineament intersections or lengths.

This paper deals with geosynthetic tubes that are made of several geosynthetic sheets sewn together to form a shell capable of confining pressurized slurry. The slurry is sufficiently fluid so that it is possible to hydraulically fill the tube. After pumping the slurry in, the geosynthetic shell acts as a “cheese cloth,” allowing seepage of liquid out and retaining the solid particles. The availability of a wide selection of geosynthetics in terms of strength, durability, and permeability enables the use of hydraulically filled tubes in many applications, some of which may be considered critical (e.g., encapsulate contaminated soil). This paper presents an overview of an analysis to calculate both stresses in the geosynthetic and geometry of the tube. It also verifies the correctness and validity of the results obtained from a computer program developed to solve the problem. An instructive parametric study implies that the most critical factor needed to assure successful construction is the pumping pressure; a slight accidental increase in this pressure may result in a very significant stress increase in the encapsulating geosynthetic. Pressure increase beyond a certain level, however, has little influence on the storage capacity of the tube. Guidance in selecting an adequate geosynthetic, including partial safety factors and filtration properties, is also presented. Design aspects associated with required spacing of inlets and head loss of the slurry as it flows through the tube are considered outside the scope of this paper.

The contact stress distribution underneath foundations under operating loads is important for a realistic estimation of settlements. Theoretical and numerical models are difficult to apply due to the nonlinear properties of the subsoil. Previously conducted modeland full-scale tests on real sand gave varying and contradictory stress distributions. A series of model tests using a photoelastic model of a rigid foundation resting on sand were conducted at Queen's University Belfast, Northern Ireland, to determine contact stresses underneath a rigid foundation. Models were tested for centrally and eccentrically applied loads at different load levels. It was found that the stress distribution for central loading was bell shaped, with zero corner stresses for small and nonzero contact stresses for higher loads. For eccentrically loaded foundations, the stress distribution was again bell shaped, whereby the effective width of the foundation was reduced. The photoelastic method was found a valuable tool for analyzing this nonlinear contact problem.