Abstract

The reliable determination of the physical and mechanical properties of the rock is one of the major issues of geomechanical modelling. It is needed to ensure exploitation safety in underground mine. This is especially relevant for the huge potassium salt deposits which uniqueness is the presence of the watered rocks that lies above the exploiting potassium seams. Particularly, a part of the rock mass that lies between potassium seams and watered rocks is called waterproof strata (WPS). The highest risk is the presence and propagation of the cracks in WPS through which the above-water can probably enter the openings that could lead to the total flooding of the mine. In order to prevent it and to provide exploitation safety the joint application of geophysical and geomechanical studies is suggested. In this paper 2D mine seismic investigations and geomechanical studies are described. And, as the conclusion, the analysis of the stress-stain state of the rock mass and its potential weak zones are presented.

Introduction

Geological uniqueness of many potassium salt deposits is the presence of the watered rocks that lies above the extracting potassium seams. Particularly, a part of the rock mass that lies between potassium salt seams and watered rocks is called waterproof strata (WPS). At Verkhnekamskoe potassium and magnesium salt deposit (VKSD), located in the Western Urals, WPS is the part of water-impermeable rock mass of 50-140 m thick. WPS lies between the exploiting potassium seams and the level where weakly mineralized water is contained. There is also active water exchange with overlying freshwater levels of 150-350 m thick [1].

WPS helps to protect the mine from water entrance. However, there can be different anomalous zones in WPS structure that have negative impact on exploitation works at the deposit.

In order to identify anomalous zones in WPS rocks through which the above-water can probably enter the openings the joint application of geophysical and geomechanical studies is suggested [2, 3].

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