Soil Mechanics and Foundation Engineering

The diffusion behavior of expanding polyurethane foam, which is widely used in soil improvement, foundation remediation, and road maintenance, was investigated. This study is the first step towards the ultimate aim of examining the feasibility of using polyurethane foam for constructing a vertical impervious curtain in soil dams or dikes. Using a hole-sealing grouting method, experimental grout injection tests were performed in situ on a type of foaming polyurethane grout, comprised of two components. The results reveal that sheet fracturing diffusion was evident in the foaming polyurethane grout, eventually forming wedge-shaped segments in the generated cracks. Moreover, the direction along which the grout fractures the soil exhibits some uncertainty due to the unevenness in the soils and the random distribution of stress inside the dam. The test results show that for the purpose of constructing a continuous cut-off wall in the dam by injecting polymer grouts, some effective measures should be taken to guarantee that the polymers fracture the soil in the required direction, or axis of the dam or dike, and that the final solidified segments overlap one other.

A method is proposed for the calculation of piles injected into predrilled holes with allowance for their flexibility and possible initial curvature of the pile's axis. The stability of the pile is assessed in the soil mass. An example is cited for the calculation of foundation strengthening by inclined piles.

The possibility of dynamic damping of vibrations is considered for massive structures on non-rock bases. The main feature of the structures under consideration is the large dissipation of vibrational energy due to its radiation into the base. The following models of the soil base are considered: normative model used in Russian norms for calculating foundations, a homogeneous, elastic, inertial half-space model, and the Il’ichev-Anik’ev inhomogeneous, inertial, half-space model. It is shown that the well-known recommendations for tuning dampers in damped systems are unsuitable for the models used for bases. The dependences of the damper tuning and damping on the deformation modulus of the base and on the structure--base interaction parameters are obtained.

A mathematical model is proposed for calculating the temperature regime of the soils of the basement of a residential building on the alluvial soils of Yakutsk in the coastal zone of the Lena River. The model takes into account the air temperature in the building, ambient air temperature, and water filtration depending on the hydrological regime of the river and calculates the change in the soil temperature at the building base to ensure its stability.

As a progression of our studies, this paper presents solutions to problems of stress and total-settlement calculation at points of a half plane, when the latter is subject to a system trapeziform inclined loads. Stress components and total settlements are determined for points of an elastic half plane when a system of three inclined trapeziform loads spaced at various distances is applied to its boundary. Graphic representations of stress and settlement isolines are presented.

Positive experience is noted for use of pile foundations in the construction of high-rise buildings and structures under complex soil conditions. V. I. Krutov’s paper, which was published in order of discussion in our journal (No. 6, 2003), is analyzed.