Том 54, № 4 (2017)

A static solution is offered for the problem of the stability of a smooth freestanding sheet pile wall. The limiting stress state of the soil surrounding the sheet pile wall is determined by way of statics-based theory of limit equilibrium of soil. On the basis of this method, a practical technique is proposed for calculating the depth to which a dowel is lowered into a trench.

A method is proposed for calculating the average rheological characteristics of inhomogeneous soils consisting of layers of elastic-creeping materials. The "cores" of the creep equations describing the stress-strain behavior of "equal" quasi-homogeneous soil media with averaged parameters are suggested. The calculation of these parameters is reduced to determining the roots of the polynomials of degree equal to the total number of exponential functions that enter the creep cores obtained for soil layers. The proposed technique can be used to calculate slow creep displacements and the stress-strain state of layered rocks, as well as to statistically assess the characteristics of composite materials. An example is presented for calculating the effective coefficients of an elastic-creeping mountain massif consisting of two parallel layers alternating in pairs.

This paper presents the influence of boundary conditions in numerical simulation of soilstructure interaction problems. It discusses aspects related to a seismic load influencing a soil medium and a frame structure resting on the soil. The soil conditions are represented by 30 m soft, medium, and dense soil deposits with four layers resting on bedrock. The side boundaries of the finite element model are simulated as fixed, viscous boundaries and newly developed infinite elements. The results from the performed analysis show that, in addition to the structural properties and soil characteristics, the choice of side boundaries also plays an important role in seismic response of RC frame structures.

Methods are proposed for evaluating the ‘pump-up’ of the lateral soil pressure by the surcharge of supported soil mass and taking account of this ‘pump-up’ in calculations of bulwarks with stabilization of the filling soil.

The dynamic response of a coupled gravity dam-reservoir water-intake tower-footing-rock foundation systems is investigated using frequency response functions of the concrete dam and the intake tower structures under horizontal and vertical ground motions. The effects of reservoir water level, reservoir bottom absorption, and presence of the dam on the tower response are studied for two tower and dam types: a squat tower adjacent to a low-height dam; a slender tower adjacent to a high dam. Using three-dimensional finite element method, it is shown that the presence of the low-height dam partially influences the response of the squat tower just for the full reservoir condition. But the high dam causes significant resonances in the response functions of the slender tower even for half reservoir. The reservoir bottom absorption strongly affects these resonances generated by the dam-water-tower interaction. It also drastically reduces the fundamental resonance amplitudes under vertical excitations. The degree of interaction between the dam and the tower is dependent on the flexibility of the foundation rock, the reservoir water level, the reservoir bottom absorption, and the slenderness ratio of the tower.

The effect of different percentages of crude oil pollution on soil geotechnical properties is shown. The results show that the moisture content required to achieve maximum dry density had decreased when the oil content increased in the contaminated soil, as well as the liquidity and specific gravity for both sandy and gypseous soils. The crude oil has a significant effect on the internal friction of the sandy soil with respect to increasing the crude oil percentages, while it increases the cohesion of the sand. The consolidation, compression, and swelling indices were increased when the soil is soaked in oil, while the void ratio and hydraulic conductivity were reduced.

The statures of legislative, normative, and scientific sources on the monitoring of objects and their base soils were analyzed. It was found that monitoring is provided during the periods from surveys to operation of objects, but because the character of the indications is different it is impossible to substantiate unequivocally the need and composition of monitoring. It was shown that on territories with developed dangerous engineering- geologic processes geotechnical monitoring as a unified system must incorporate not only observations but also calculations, modeling, recommendations, designs, and implementation of additional measures guaranteeing the reliability of structures. The need of geotechnical monitoring before the development of design-survey documentation on engineering protection for areas with active development of slipping processes is substantiated for an example of an actual highway section.