The use of lime to improve the behavior of marine clays has been in practice in several parts of the world over a long period. In this paper, the beneficial changes occurred in a marine clay due to the diffusion of lime from lime column and lime injected points have been studied using XRD and SEM techniques. The new compounds formed have been identified using the XRD technique. The diffusion of lime has been established through the measurements of lime content and pH from the samples taken at different locations and at various time periods. The transformation of the soil particles due to lime attack on the clay minerals present in a marine clay has been studied and discussed.

A nonlinear, three-dimensional finite element technique for deep excavation analysis is proposed in this paper. The technique as well as the analytical procedures for modeling the excavation processes were coded into a computer program, and the accuracy of the program was assessed. In order to minimize the number of elements and nodes without sacrificing the accuracy of analysis, a series of convergence studies were performed, which makes three-dimensional analysis computationally and economically feasible. The effect of the existence of the corner on the deflection behavior of an excavation was studied in detail by analyzing a typical excavation with soft to medium clayey subsoil stratum. By performing a series of parametric studies, a tentative relationship is developed for estimating three-dimensional maximum wall deflection of an excavation based on two-dimensional finite element results. Finally, the case of an irregularly-shaped excavation with field measurements of wall deflection was studied. The results of analyses show close agreement with field measurements.

Electroosmosis techniques have been used in geotechnical and geoenvironmental engineering applications. However, due to electrochemical changes and gas generation at the electrodes as a result of prolonged application of a direct current electric field, its application in determining soil properties has been limited. A methodology, which uses a weak alternating current (AC) as the driving force is developed to minimize these adverse effects. The governing partial differential equation for one-dimensional AC electroosmosis is presented for an experimental situation in a companion paper. Three boundary conditions, which reflect the possible range for a closed boundary are identified. Transient and steady-state solutions are given for the ideal undrained boundary conditions. Analytical steady-state solutions are given for the two nominally undrained boundary conditions. These solutions indicate that both small deformations of the boundary cavity and impedance effects due to relatively low permeability of an equivalent porous stone play an important role in the pore-pressure responses. Procedures based on the steady-state solutions for backcalculating the coefficient of permeability are presented.

Alternating current (AC) electroosmosis tests, which permit rapid determination of the coefficient of permeability of saturated cohesive soils are described. The testing device was developed to minimize the adverse effects of prolonged application of direct current on observed responses. The apparatus and procedures to conduct the AC experiments are presented and results of 19 experiments are analyzed. In these tests, a weak AC is sinusoidally applied under nominally undrained boundary conditions to saturated kaolinite specimens; excess pore pressure and phase angle are measured at frequencies between 0.25 and 4 Hz. The results of the experimental program and the procedures of backcalculating the coefficient of permeability are presented. The coefficient of permeability from falling head permeability and AC electrosmosis tests on specimens of resedimented kaolinite are shown to agree within a factor of five. These data support the theoretical conclusions of the companion paper and suggest that this type of test is feasible to rapidly evaluate the coefficient of permeability of saturated cohesive soils in the laboratory.

This paper describes the results of a test program in which the setting and hardening of cement, bentonite-cement slurries, and attapulgite-cement slurries are monitored in the laboratory with mechanical-shear and electromagnetic waves. Specimens are prepared by prehydrating the clay before adding cement. The presence of clays in soil-cement slurries delays hydration and its manifestation. The complex permittivity emerges as a sensitive indicator of ongoing reactions. Permittivity reflects changes in the mobility of water, liberation and entrapment of ions, changes in specific surface, and variations in double-layer phenomena. The increase in shear-wave velocity reflects the rise in effective stress due to consolidation, the decrease in double-layer repulsion, and the higher rigidity of the mixture as a result of cementation. Early stages of hydration denoted by changes in permittivity do not contribute to the formation of a rigid, cemented network. Overall, it is shown that the simultaneous measurement of permittivity and shear-wave velocity provides complementary microlevel information on the fundamental dependency between chemical reactions, physical changes, and rigidity in cementitious materials. The application of these results to field situations will lead to the development of nonintrusive, nondestructive monitoring techniques.

Existing methods commonly used for determining drained angles of the internal friction of sands using cone penetration test (CPT) data are examined and interpreted in this paper, with emphasis on the influence of the compressibility of sands. The methods examined are based either on the bearing-capacity theory or on the cavity-expansion theory. This paper emphasizes the development of an empirical approach, based on the cavity-expansion theory, for determining the drained friction angle of sands from CPT data. To this end, a new empirical correlation for determining the volumetric strain, which is required in the Vesic method for determining the drained friction angle, is developed through calibrations with methods based on the bearing-capacity theory. Using this new empirical correlation, the volumetric strain can be obtained solely from CPT data without additional laboratory tests such as the triaxial test. Field CPT data are used to examine and demonstrate the new approach, and the results show that the drained friction angle can be consistently determined using this approach.

Dynamic properties of three compacted cohesive soils, kaolinite, sodium montmorillonite, and calcium montmorillonite, which were treated with up to 8% lime, were determined under a wide range of strains and confining pressures. The soils had plasticity indices ranging from 18 to 514. Lime treatment affected and improved the dynamic properties of the three soils. For all of the soils, the cyclic secant shear modulus decreased and the equivalent viscous damping ratio increased with increased strain levels. By increasing the lime content, the shear modulus of the sodium montmorillonite dramatically increased and the damping ratio decreased. Similar behavior was noted for the calcium montmorillonite. The difference in response between the two montmorillonite soils was attributed to the presence of calcium already in the calcium montmorillonite soil. The response of the kaolinite soil to lime treatment was moderate. Normalized plots of treated soils with respect to values of untreated soils are presented. These plots provide a useful guide for the preliminary estimation of lime requirements to improve the dynamic properties of soils.

Nonuniformity within specimens of granular materials is considered to be one of the major reasons for the dependence of the observed static/dynamic response during laboratory testing on the method of preparation. In this paper, a resin-impregnation/digital image analysis method to examine the uniformity of cohesionless specimens at microscopic, macroscopic, and global scales is described. The approach relies on the equivalence between volume fraction and the expected value of area fraction where the area fraction of voids on two-dimensional sections is obtained using a computer-based digital image analysis system. A sampling strategy which allows porosity variations in the vertical direction as well as in the radial direction of the specimen to be examined is proposed. The method is illustrated with the results of measurements performed on a typical specimen and shows that a much larger amount of nonuniformity exists when the soil is examined at a microscopic level. A statistical procedure to evaluate the accuracy of a volume-fraction measurement using areal analysis is also described. The proposed method offers much promise for examining the uniformity of specimens accurately and efficiently.

Relationships between electrical resistivity, compaction conditions, hydraulic conductivity, and index properties are reported for ten soils that have been used for constructing compacted soil liners having low field-scale hydraulic conductivity ( <1 × 10 ⁻⁹ m/s). The electrical resistivity of compacted clay is sensitive to compaction conditions, with lower electrical resistivity obtained for compaction at higher water content or greater compactive effort. A unique relationship exists between electrical resistivity and initial (as-compacted) saturation for each clay that is independent of compactive effort. A unique relationship between hydraulic conductivity and electrical resistivity exists for some, but not all soils. Electrical resistivity is also correlated with index properties. Soils with higher liquid limit or plasticity index, a greater percentage of fines or clay, or a smaller coarse fraction have lower electrical resistivity.

This note describes slide failures of the inside slope of a water reservoir, following a prolonged period of heavy rainfall. The reservoir had just been completed and was empty. Sliding took place along the plane of the smooth-surfaced geomembrane high-density polyethylene (HDPE), which had been installed 0.4 m below the face of the slope to contain stored water. Sliding cannot be explained by gravity forces only. By considering the combined effect of gravity and seepage forces acting on the surface of the membrane at the time of sliding, under wet conditions, it was calculated that the coefficient of friction between the geomembrane and the nonplastic silty sand of the soil cover is between 0.325–0.360. Under wet conditions, either of these values agree with previously published coefficients of friction between HDPE geomembrane and sand, or between smooth-surfaced concrete and steel, and plastic silt.