Influence of Temperature Variation with Depth on Initial Stress Field and Its Redistribution during Mining in Stratified Rock Mass
V. M. Seryakov
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Rock temperature, great depths, stratified rock mass, initial stress state, thermophysical and mechanical characteristics, mathematical modeling, mined-out stope, backfill, operation sequence
Abstract
The author calculates initial stress state generated under the action of gravity and temperature which changes linearly with depth in stratified rock mass. It is shown that the dominant influence is exerted on the initial stress distribution by the parameter δ which is a ratio of products of triaxial compression moduli and linear expansion factors of rock layers. In two-layer rock mass, when δ calculated as a ratio of thermomechanical characteristics of the upper and lower layers is higher than one, the temperature effect results that the tensile vertical stresses are induced in the lower layer; when suchwise calculated δ is lower than one, the compressive vertical stresses arise in the lower layer. In case of a great divergence of δ from one, in the lower layer, the initial vertical and horizontal stresses increase jump-wise, and the stress pattern resembles a hydrostatic stress distribution. The author performed mathematical modeling of thermal stress field redistribution during advancing undercut-and-fill operations. The software used in the calculations took into account the backfill sequence. The features of stresses in enclosing rock mass and in backfill were revealed.
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