Mechanism of rupture of shaft linings in coal mine areas buried by thick over-soils in East China

Non-mining ruptures of shaft linings in coal mines, which have repeatedly occurred in coal mine areas of East China in recent years, are a new kind of geological disaster. In this paper the characteristics of non-mining ruptures of the shaft linings are presented. The engineering geology conditions of the ruptures are analysed. A method for testing the interaction between soil and shaft wall by high-pressure direct shear apparatus and triaxial servo test system has been presented. The shear stress– displacement curves, coefficient of unit stiffness and strength parameters of the interaction between soil and shaft wall are obtained. Combining with the test results, the deformation characteristics of the interaction between soils and shaft wall during deep soil compression due to water loss are analysed: they are elastic in the shallow and bottom parts and plastic in the deep part. An elastic perfectly plastic analysis model of the interaction between soil and shaft wall has been set up. Some analytic formulae are obtained to calculate the additional vertical displacement, strain and stress of the shaft lining. Their variation laws with depth, compression value of deep soils and so on are discussed. Finally, one example is presented to show the practicability of the theoretical researches.