Vol 56, No 1 (2019)

We present the results of full-scale tests of barretes in the area of future building of a 56-storey residential building in Moscow. These tests were performed with an aim to determine admissible loads caused by the action of soil upon the barretes. We present the results of numerical analyses of a barrette by the finite-element method with the help of the "MIDAS GTS NX" software complex and show the principal possibility of application of this method for the analyses of barretes with an accuracy admissible for practical purposes.

The softening and degradation effects of water on soil mass, increase of pore water pressure, and reduction of matric suction are usually considered for analyzing the contributions of rainfall to the failure of shallow soil slope. However, the effect of drag force at the fluid-solid interface due to slope surface runoff also deserves to be taken into account. To quantitatively investigate this effect, a modified approach based on the limit equilibrium method is proposed by establishing a nonlinear coupled mathematical model. The calculation results show that the effect of drag force at the fluid-solid interface should not be neglected especially when the runoff on shallow soil slopes is relatively deep.

Vertical earth pressure on the geosynthetic-soil interface is the key to estimate behaviors of geosynthetic sheets and surface settlement of low geosynthetic-reinforced embankments. New calculation methods of embankment backfills and vertical earth pressures on geosynthetic sheets considering static equilibrium are proposed. According to reasonable boundary conditions, a new approach for three behaviors of geosynthetics subjected to linear localized sinkholes is derived. It considers load transfer of embankments over voids, deflection of geosynthetic sheets over voids, and horizontal displacement of geosynthetic sheets in anchorage zones. Moreover, the values predicted by this study and other studies are compared with the results of the existing tests and finite element analyses. The comparisons validate the reliability and feasibility of the new improved approach.

Traditional methods used for the enhancement of the load-carrying capacity of ice crossings are not always efficient and the physicomechanical properties of the ice cover may strongly depend on the action of external factors. We present some results of the experimental and numerical investigations of the load-carrying capacity of ice samples, strengthened by longitudinal and transverse reinforcing bars. These investigations were carried out for different schemes of reinforcement. The experimental results were compared with the results of numerical analysis of the stress-strain state by using the ANSYS software complex and revealed their good agreement. We also estimated the efficiency of application of different schemes of reinforcement for the enhancement of the load-carrying capacity of ice cover.

To account for the mutual influence of objects in finite-element geomechanical models, it is proposed to limit the deformation computation zone and adjust accordingly the settlement of the object, ground surface, and neighboring objects located in the influence zone. The boundary of the influence zone is represented by an isoline (isosurface) selected so that the additional vertical pressure from the erected structure in the deepest point of such zone does not exceed 10% of its initial value.

A behavior of various soils under exposure to seismic effects is analyzed. To optimize the seismic stability calculations for buildings and structures, a relationship developed based on processing the instrumentation records of the previously occurred earthquakes is proposed, which can be used to estimate ground vibration accelerations considering the specifics of the rock formations.

There are different techniques to stabilize and improve the properties of soils with low shear strength, bearing capacity and other swelling parameters. This study includes the chemical analysis of expansive soils using X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after the stabilization using tire rubber powder (TRP) and cement kiln dust (CKD) in order to evaluate the geotechnical properties. Test results indicate that the inclusion of CKD-TRP mixture, not only reduces the plasticity of soil but also increases its unconfined compression strength, maximum dry density, and other strength characteristics. Finally, 5% TRP and 10% CKD addition is recommended as an optimum amount from the viewpoint of plasticity and strength characteristics.

A procedure for performing experiments in the presence of different axial and volumetric stress combinations corresponding to the action of thawing base soils is proposed for triaxial testing of thawing frozen soils during thawing. Comparison of the deformation characteristics obtained for thawing sandy soils in field tests performed with a hot stamp and under triaxial compression showed that the thawing coefficient differs by no more than 5% and the compressibility coefficient by 30%.