The state of stress in undisturbed stratified rocks with steeply dipping strata of various thicknesses

Abstract

An important problem in mining geomechanics, especially in connection with the opening-up of deep ore and coal deposits, is to determine the state of stress of the rock before mining operations begin. Without a knowledge of the natural state of stress of the rocks, it is impossible, e.g., to determine the mechanism and nature of such dangerous phenomena as shock bumps and gas bursts. Many problems in tectonics also require analysis of the natural stress field. In research on rock mechanics, a popular approach regards the undisturbed rock as a homogeneous isotropic elastic half-space loaded by its own weight; to study its state of stress one usually assumes that the horizontal and vertical components of the stress are related by dependences corresponding to the hypotheses of hydrostatic or empirically nonhydrostatic stress distributions. Important geological factors which influence the stress distribution and which must be taken into account in investigations on the scale of the mineral deposit as a whole include the distance below the surface, the stratification of the rocks, the thickness and number of the seams, the variation in stress through the thickness of the seams, and the interactions between strata. Previously we have studied the state of stress more » of a stratified rock mass in the case of an infinite number of doubly alternating plane-parallel or curved strata. We discussed the distribution of stresses and strains (displacements) in rock consisting of any number of horizontal, homogeneous, anisotropic strata and the rocks underlying them. In this article we discuss the case of a finite or infinite number of inclined plane-parallel strata of any arbitrary thickness. « less