Vol 53, No 3 (2016)

Aspects are examined of dispersive soils that are conditioned by the mechanism and magnitude of their shear resistance. From a general physicochemical perspective, we study factors not considered in the Mohr-Coulomb theory that explain its departure from experimental data-mineral and granulometric composition, morphology of structural elements, the degree of lithification, the adsorption films and hard "liners" on the surface of minerals, the effect of the disjoining pressure on the real effective stresses, the mechanism of friction, and structural changes during deformation.

Shear behavior of interfaces between steel and soil composed of crushed sandstone and mudstone greatly influences the side resistance of RSCFST pile, a new kind of pile widely used in deep water wharf in western China. This paper presents the results of experimental studies on the shearing behavior of the soil-steel interfaces. Strain-controlled shearing tests are carried out with a direct shear apparatus under constant normal load condition. The influence of water content on the response of the interfaces is investigated. The test results reveal nonlinear relations between the shear strain and the shear stress. It indicates that the shear strength of the interfaces obey the Mohr-Coulomb criterion. The strength parameters, including cohesive force and friction angle are influenced greatly by the soil properties as well.

A way is examined of creating a specified stress-strain state in a pile foundation soil bed by pre-stressing the soil mass. Dependencies are presented for soil bed deformability and settlement on process parameters of bed pre-stressing by a combined foundation and the degree of its loading. The efficiency of pre-stressing to regulate foundation settlement is determined.

Results are presented of systematizing materials on foundations and bed soil of the part of the Moscow Kremlin from the Troitskaya tower to the Spasskaya tower, based on a study of historical and modern test pits, as well as boreholes drilled through the Kremlin walls, and historical and modern geological engineering and geophysical surveys. The current state is examined of Kremlin walls and towers, their foundations, and bed soil. Recommendations are presented for restoration work and operation of structures of the Kremlin citadel.

The dependence of the coefficient of interaction between a polymer pipe and soil on soil moisture is determined experimentally. Variable coefficients corresponding to certain cases of moisture distribution are approximated. Based on variable coefficients, the longitudinal oscillations of underground polymer piping is studied in response to seismic loads. An algorithm and program were developed for calculating seismic stability.

Freezing-thawing cycles in soils reduce considerably the foundation capacity of buildings and infrastructure. In recent years, development of nontraditional stabilizers has created hundreds of new products for soil stabilization. Fiber portions of biomass (such as lignin) can be considered as byproducts of the conversion process, and these byproducts are generally used to produce octane booster fuels, bio-based products, and other chemical products. The use of lignin-based biofuel co-products (BCPs) to stabilize pavement subgrade soil is an innovative idea and satisfies the needs of sustainable development in construction. A series of laboratory tests, including unconsolidated undrained direct shear test, freeze-thaw durability test, and scanning electron microscope tests, was conducted to evaluate the effect of BCP addition on shear strength performance for four different soils encountered in Iowa. The results of this study indicate that BCPs are beneficial in the soil stabilization of low-quality materials for use in road construction.

Questions regarding the impact of soil stabilization and changes in soil stress-strain state on soil mass reinforcement in response to grout injections are discussed.