Numerical and physical modeling of the stability of the workings developing the slope

Abstract

Enhancement of modern urban infrastructure, expansion of transport networks, creation of innovative engineering communications as well as plenty more factors stimulate the development of underground construction both in our country and throughout the world. Like any structure, an underground construction must be capable to perceive external loads without collapsing. For the successful operation of such structures throughout all term of their service, it is necessary to evaluate regularly the impact degree of all factors that one way or the other affect the construction durability. It was therefore decided to study by means of a model experiment, how the geometric parameters of the slope and underground workings’ system affect the stability of the latter. We’ll assume the cross-sectional shape of the workings and their position relative to the basis of a model from homogeneous ground massif as the geometric parameters. In this paper we examine the stability of the models of horizontal underground workings with round and semi-elliptical shape worked in an isotropic soil slope, at various distances from the point of transition of the sole into a slope. As a measure of long-term stability we chose the criterion (Bogomolov A.N., Bogomolova O.A., 2010) where a qualitative feature is the absence of zones of inelastic (plastic) deformations on the contours of the workings as well as zones manifesting the processes of loosening or breed fragmentation. The value of the reduced pressure of coherency σc is used as a quantitative indicator. The paper presents the results of numerical processing of model experiments studying the fracture processes both of the ground slope weakened by the workings and the workings themselves. In the course of the model experiments, we defined the distances L, measured from the base of the slope to the center of the workings with circular and semi-elliptical cross-sectional shape, under which the contour of the workings was stable. It is established that the stability of the round and semi-elliptical shaped workings can be provided practically at the same values of L on condition that the physical and mechanical properties of the equivalent material of the model, its geometric parameters and the transverse dimensions of the imitation workings are practically identical. The coincidence of the results of model experiments and calculations performed with the help of a computer program makes it possible to speak about their reliability.