The depth effect of geological mechanics and hydraulic behaviors of rock mass

Significant changes of geological and hydraulic behaviors of rock mass with depth was studied. The general regulation and the critical depth of qualitative change of rock mass geological and hydraulic changes with depth were studied. Preliminary research show that the mechanical properties of rock mass gradually change from solid to plastic with the increasing of its buried depth. The critical depth of this tendency was controlled by geological properties of rock mass and its overlying rock. The critical depths are different in different regions because of its different geological condition. The general change depth of rock mass from rigid property to plastic property in coal mine regions of North China is about 1 800-2 300 m. The hydraulic permeability of rock mass will change significantly with depth because of the geological and hydraulic mechanics changes from solid to plastic and the groundwater circulation condition in karst and fractured aquifer will also change. The results reflact that the stability, deformation, failure, permeability and groundwater hazardous condition of rock mass during deep mining process are quite different from that of shallow mining＇s.

Study on engineering-hydrogeological problems of hydroelectric project

Engineering-hydrogeological problems arise from the interaction between engineering activities and geological environment, in which rock-soil mass and groundwater are especially important constituents. However, up-to-date research on them is relatively dispersive and simple due to their complexity and lack of comprehensive and systematic study methods. Starting from geological analysis of mechanism to geological model based on geological regularities, the paper predicts the tendency of geological evolvement and puts forward proper measures to solve problems. In this paper, elevated water-sensitive structure in rock-soil mass, which mainly causes engineering hydrogeological problems, and problems in hydropower is discussed based on unique construction in Chinese Western hydropower projects. Engineering hydrogeological problems are reservoir induced earthquakes leakage from reservoir bottom in karst, stability of high slope at reservoir banks, sliding of dam foundation and dam abutment, and confined water at key positions which are introduced and determined by using water-sensitive factors(or structure) according to special hydrogeological conditions.

Model test of the overburden deformation and failure law in close distance multi-seam mining

Based on characteristic of the associated mining of multi-coal seam and the engineering geological characteristics of overburden,the mining impact pattern of multi- seam mining and the dynamic fracture mechanism of overburden were characterized by applying the engineering geological mechanical model test.The related strata movement parameters and influence area of multi-seam mining were obtained,the strike boundary angle is 61°,the full extraction coefficient is 0.93,the greatest subsidence angle is 81°,the horizontal movement factor is 0.38,the deviation of inflection point/mining deep is 0.11. The development height of caving zone and water flowing fractured zone of multi-seam mining were calculated,is 32 m and 81.5 m separatly.The assess of influence degree of coal layer safety mining is that,there exists the possibility of water and sand inflow when mining,some messures for mine water prevention and control should be used,and the mining thickness should be local strictly limit.