Том 56, № 2 (2019)

This study sought to assess the probabilistic stability of slope analysis under seismic conditions in the middle of the Mzymta River Valley in Russia's Greater Sochi. In probabilistic analysis, almost all input parameters can be assigned a probability distribution; however, the seismic coefficient probability distribution has been difficult to define in previous studies. This study aims to assign a probability distribution to the seismic coefficient based on seismogram acceleration distribution. The study showed that seismogram-based probabilistic analysis is a feasible way to assess slope stability.

Based on numerical simulation and the statistics of fine sand layers in the Wuhan area (China), the effects of uncertainty of dynamic shear modulus (due to the limited range of current instruments) ratio on design ground motion were explored. Its effects on design seismic acceleration response spectrum, platform value of response spectrum, and characteristic period of response spectrum were analyzed quantitatively. This study could provide a guideline for the analysis of seismic response as well as theoretical study of nonlinear dynamics on geotechnical earthquake engineering.

The resilience of the Daikai subway station during the Kobe earthquake is taken as a case study of tunnel endurance at various points under different soil conditions. The Mohr-Coulomb material model is used. The effect of peak ground acceleration, overburden depth, and soil-tunnel interaction is analyzed. The effect of cohesive force on stresses for various soil tunnel interface conditions (full slip, partial slip, and no slip) is studied. The model is validated by comparing axial force and displacement, and its results are consistent with those presented in the literature.

The paper contains the results of long-term monitoring during construction of the "Lakhta Center" tower in St. Petersburg. A brief description of the geotechnical monitoring system is provided, including types, quantity and location of the measurement equipment, methods of placement within structural components, and reading techniques. The comparison between the monitoring data and calculation results obtained by various methods demonstrated their qualitative and quantitative differences. A hypothesis regarding the effect of a number of factors on pile performance within the pile field is proposed. The recommendations on performing geotechnical calculations when constructing high-rise buildings are provided.

The main objective of the present study is to evaluate possible changes in the efficiency of a deep excavation anchored wall after the excavation had been recharged for about two years. Extensive instrumentation monitoring was carried out to assess ground movements, groundwater levels, and the displacement of adjacent structures during the process of construction. Because of uncontrolled water seepage in one of the critical excavation wall, shallow pressure relief drains were installed in the wall base in the approximately deepest parts of the excavation. This was done to limit the uplift pressures and control the displacement and stability of the wall. Careful monitoring of the adjacent building and ground movement, especially in soft ground, gives confidence to contractors and designers to predict the effects of groundwater drawdown required for constructing large and/or deep excavations and controlling uplift pressures during construction. The findings of this study may offer some recommendations for the selection of methods of groundwater dewatering control when there is seepage through the excavation wall.

For the extraction of piles, sheet piling, and casings from soil, we propose new decisions for the devices that make it possible to increase the machine time of using diesel hammers due to the extension of the field of their application. The efficient combination of the dynamic action by shock pulses and static extraction forces directed upward in the direction of pulling of elements from the soil makes it possible to use tubular-type diesel hammers not only to deepen but also to extract elements from soils.

This paper presents estimations of bearing capacities of precast concrete joint piles at two construction sites in the regions of Port Prorva located in Western Kazakhstan. The capacities of the piles were predicted using the static pile load test data with the conventional interpretation methods. The results were compared to those from APILE analyses, analytical calculations based on the Kazakhstani standard method, and the pile driving analyzer. It was shown that the highest pile capacities were obtained from the Chin interpretation and Decourt extrapolation methods. The results from De Beer, Davisson, and Fuller and Hoy interpretation methods were found to be similar. The result from the Butler and Hoy interpretation method was similar to the ones obtained from pile driving analyzer and APILE analyses. The pile capacity obtained by the Kazakhstani standard method was found slightly higher, though it is applicable for estimating ultimate pile capacities. The yield capacity of the piles was determined under working loads. The methods used in the paper can also serve as practical guidelines to assess the capacities of driven piles installed in the field.

A unified classification of accidental leaks of water from utility lines according to the magnitude of the effect of the permafrost in the base of buildings is developed. The classification is recommended for improving regulatory documents. A procedure is proposed for taking local effects of heat from accidental leaks into account in the calculation of the thermal and thermal stress-strain state of the permafrost in the base of buildings.

To analyze the stress and deformation law of a stope roof, the coal seam and direct roof in front of the coal wall are regarded as an elastic foundation. The deflection-differential equation of the roof rock beam is established based on the Pasternak elastic foundation model. According to the boundary conditions and continuous conditions, the expressions of deflection and bending moment during the first and the periodic fracture of the roof rock beam were established. The first and periodic fracture step were also obtained. The analysis shows that the first break distance of the Pasternak model is 15.9% less than that of the Winkler model, and the deflection is 40.2% larger than that of the Winkler model. The maximum negative bending moment is 39.5% smaller than that of the Winkler model because the Pasternak model considers the continuity of the foundation deformation by the shear modulus. The maximum bending moment during the first fracture increases with the elastic characteristic coefficient n. During periodic fracture, the fracture position is located in the coal wall, and the maximum negative moment of the rock beam increases with an increase in elastic-characteristic coefficient. The results can provide some reference value for roof pressure and stability control of the stope.