Abstract

Mechanical characteristics of soils under dynamic and static loads are determined in laboratory conditions on special devices. Dynamic loads in the devices are initiated by an impact on a soil sample. Under the impact the waves are initiated in soil; they significantly affect the stress-strain state of soil samples placed in the device. Depending on the parameters of the impact load in the device, in different sections of soil sample there arise the stress-strain states, different in quality and quantity. Mechanical characteristics of soil, determined by this stress-strain state, also differ. The effect of stress-strain state of soil on its mechanical characteristics can be estimated theoretically. The initiation of the wave process and dynamic stress-strain state in soil sample placed in the device can be theoretically examined in detail. In this regard, the wave problem is set, which corresponds to the statement of experiments on the device of dynamic loading of soil. The law of soil strain is taken as an elastic-viscoplastic one. Numerical solution of wave equations is obtained by the finite difference method. Based on the analysis of stress-strain state of soil in various sections, obtained by numerical calculations, the condition is derived under which the effect of wave processes on mechanical characteristics of soils is eliminated. This condition (formula) establishes the relationship between the wavelength, the velocity of wave propagation in soil, the thickness of the soil sample in the device and the duration of dynamic load.

Highlights

  • The reliability of buildings and structures is directly related to the strength of soil on/in which they are located

  • On the upper plane of the soil sample there is a piston, through which the dynamic load created by the impact of a weight free falling along the rod guides, is transferred [3]

  • The considered problem of the interaction of a plane continuous compression wave with a rigidly fixed obstacle in an elastic-viscoplastic medium — soil - is being investigated here on the device for dynamic loading (DDL) to substantiate a reliable determination of mechanical characteristics of soils

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Summary

Introduction

The reliability of buildings and structures is directly related to the strength of soil on/in which they are located. The soil strength depends on mechanical characteristics of soil. A reliable determination of mechanical characteristics of soils is an important problem of the reliability and seismic resistance of buildings and structures. Mechanical characteristics of soil are related to the laws of soil strain. These characteristics include the modulus of elasticity, Poisson’s ratio, unloading modulus, soil viscosity coefficient, etc. Mechanical characteristics of soil are mainly determined by experiments. Mechanical characteristics of soils based on specific elastic-viscoplastic models of soils are defined in [1 - 5] under static and dynamic loads in laboratory and field conditions

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