Vol 53, No 1 (2016)

The results of numerical studies examining the interaction between a foundation slab and a uniform bed are examined. A comparison is presented of foundation settling according to the way in which the bed and foundation are modeled.

A spatial model of dilatating soil under triaxial load conditions with different regimes are described on the basis of a hypothesis that the Coulomb dry friction force acts in the plane of tangential particle shear. Spatial soil deformation over time is described in accordance with the theory of inherited creep in the form of the sum of deformations due to changes in volume and shape, with due regard for their interrelation.

In past applications of electrical resistivity survey, users commonly focussed on the Earth's subsurface to locate water table, bedrock, etc. Nowadays, this electrical resistivity method is used by engineers for shallow subsurface investigations. This paper presents the integration of soil mechanics properties with electrical resistivity tomography methods and recommends the proper selection of resistivity array (survey planning) and appropriate inversion constraint parameters (data processing) that are able to deliver optimum resistivity tomography model results. This study identifies the empirical correlations of the soil's properties such as shear strength parameters, moisture content, void ratio, porosity, saturation degree, and Atterberg's limits with the electrical resistivity values (resistivity tomography models). A total of 11 undisturbed clayey sand soil samples was collected at different distances, depths, and times and were tested under both infield and laboratory conditions during the slope monitoring period. The soil mechanics properties of the soil samples were obtained right after the electrical resistivity survey was made. It is shown that the electrical resistivity values are greatly influenced by the soil mechanics properties. Thus, the electrical resistivity (4-D) survey using the optimized Wenner-Schlumberger array (high data density) is capable of reliably enhancing the conventional outcome of the Earth's subsurface investigation.

The magnitude and the application point of the resultant active earth pressure are two key problems in the design of a variety of civil engineering structures. Experimental results indicate that these parameters are affected by the wall movements. In this paper, series of two- dimensional finite difference analyses have been carried out using the code FLAC (Fast Lagrangian Analyses of Continua) to study the active earth pressure distribution behind a retaining wall under horizontal translation, rotation about the bottom, and rotation about the top modes of wall displacements. The computation results show remarkable similarity to experimental results available in the literature indicating that the active earth pressure distribution is nonlinear due to the arching effect. It is found that, for a wall under translational and base rotation modes, the active earth pressure is substantially hydrostatic except at the wall base where curvature was observed. These two wall modes are in good agreement with classical solutions. However, the earth pressure distribution due to rotation about the top is found far from the hydrostatic distribution and is highly affected by the arching effect.

A method for analyzing the viscosity coefficient using spherical press test data is proposed, based on the use of rheological curves. Viscosity is determined for different types of soil in the frozen and thawed states. A significant reduction (by two orders of magnitude) is achieved for the viscosity coefficient after thawing and compaction.

Requirements stated in regulatory documents are discussed with respect to determining deformations in beds of vertical steel cylindrical tanks used to store oil and oil products. A procedure is proposed for determining tilt in the foundation and the tank proper, based on the aggregate settlement of deformation markings on the foundation and points along the bottom edge. A computer program was developed to calculate tilt. An example is presented of determining settlement and tilt for a pile foundation of a vertical steel tank after 5 years of operation.

The causes of and a prediction of slump displacement along the section between the straightened Karamyshev and Khoroshev sections of the Moscow River are examined. It is shown that the cause of the slump slide in 2006 was the above-norm settlement and erosion due to rainwater drainage in the lower part of the slope. The slump continues to move and predicted displacements will attain significant values, which may result in the formation of a new slump.

The dynamic characteristics are examined of buildings constructed on soft soil in Ashkhabad. The frequency spectrum and damping are evaluated with respect to soil conditions. It is determined that for buildings up to 5 stories high, damping is strongly nonuniform. Modal first-mode damping is 3-4 times greater than for the rest. For high-rise buildings, modal damping values were close, which was the result of pivoting foundation vibrations and exposure to Rayleigh surface waves. Calculation programs that do not consider nonuniform damping are proposed to be used to assess damping in the first approximation.