Modern models of soils to describe elastic-viscoplastic properties do not always lead to the desired results , especially when it is necessary to take into account the time factor. In particular, one cannot always describe the rheological model and creep and relaxation , as well as get extreme at kinematic mode loading. This is due to the fact that the deformation in the soil medium is accompanied by complex physical and physico-chemical phenomena , changes in the orientation of each mineral particles in space and time , their mutual offset seal ( hardening ) and decompression ( softening ) . Quantitative assessment of buildings and facilities associated with the calculation of the stress - strain state ( SSS ) foundation soils subject to numerous factors , including the physical feature of the power and influence ( statics, kinematics, dynamics ) and mechanical properties of soils under such effects ( creep , ductility ) .In the present paper the results of scientific studies of the rheological properties of sandy soils. The purpose of these studies - determination of viscosity sandy soils kinematic and dynamic triaxial test mode. A technique for determining the viscosity of soils results in triaxial kinematic mode (with speed control vertical movements). The paper considers the problem of estimating the impact of the dynamic loads on the viscosity of sandy soils.
A characteristic feature of high-rise buildings is the fact that they are erected, as a rule, in deep pits, have a large support area, and transmit significant loads onto the bed soils. Moreover, enormous soil masses both beneath the foundations, and also beyond the pit enclosure are implicated in interaction between the underground and above-ground portions of high-rise buildings.A complex stress-strain state (SSS), which is transformed in space and time during construction of a high-rise building, is formed during interaction of the "bed − foundation − sub-and superstructures − surrounding setting system" (hereinafter "system"). This is dictated by numerous factors, and above all, by a characteristic feature of the physico-mechanical properties of the soil mass enclosing the underground portion of the building and surrounding setting. The following are classed as such factors: physical and geometric nonlinearity, degree of anistropy, plasticity, and creep.Consideration of the soil properties and characteristics of the procedure used to erect the building (step-by-step) for a quantitative assessment of the SSS of the "system" is possible only by the numerical method recommended in standard documents [1].A reliable assessment of the SSS of the "system" is needed to determine the settlements and tilt of the foundation (slab, slab-pile), the deflection of the enclosing structures, and the additional settlements of foundations within the surrounding setting.
This article provides a solution to the problem of the stress-strain state of a soil mass adjacent to a vertical excavation when applying a uniformly distributed load on its surface. The solution of the problem was obtained by the method of trigonometric Ribere-Fileon series. The final expressions for the SSS components are provided. Contours of stresses and displacements are also shown.
We address the effect of three groups of factors on supplementary ground surface displacements during tunnel construction. The first group of factors includes the engineering and geological properties of the massif in which the tunneling is conducted; the second group includes the structural features of the designed tunnels and surrounding buildings, and the third group includes the engineering parameters of the tunneling process. The research takes advantage of the geotechnical monitoring data obtained during the construction of underground facilities and the engineering parameters of shield tunneling during construction of single- and double-track Moscow underground lines by using EPB (earth pressure balance)–TBM (tunnel boring machines) in different soils. The dependence of additional displacements, occurring above the designed tunnel, on the TBM pressure, is addressed in detail. The presence of a close interdependence is evidenced by a correlation coefficient equal to 0.77. No dependence of the settlement on the diameter or depth of the designed tunnel, the distance from the tunnel axis to the monitored object, the loading that comes from a building in the affected area, or the boring rate was identified. The consideration of this parameter can be used to predict the soil displacement around the tunnel at construction facilities having similar geological profiles and boring parameters.
The present paper states and provides an analytical solution for the problem of evaluating the settlement and load-bearing capacity of weighty soil layers of limited thickness resting upon incompressible soil bases and an excavation pit wall upon exposure of the foundation to a distributed load in the vicinity of a wall. The authors develop a method for determining the stressed state component in the reduced engineering problem based on the Ribere–Faylon trigonometric series and for accounting for the nonlinear deformation properties of soils, building on the analytical dependencies of S.S. Grigoryan and S.P. Timoshenko. In order to determine the relationship between stress and strain, the Hencky’s physical equation systems were used. They factor in the impact of average stresses σm on the shear modulus of elasticity G (σm) and volumetric modulus of elasticity K (σm). The obtained solutions make it possible to assess the deformation of soil bases and the load-bearing capacity with respect to nonlinear properties in a way that accurately corresponds to the actual performance of subsoils exposed to loading. The theoretical results are followed by numerical experiments to prove their validity.
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