Countermeasures And Application Of Non-uniform Pressure Support For Deep Intensive Pump House Chamber Group In Wanfu Coal Mine

The surrounding rock of the deep chamber group is often in a complex geological environment with a non-uniform stress field.It will produce a non-uniform pressure field when interacting with symmetrical sections and uniform and small deformation supporting materials.This is the main cause of large deformation disasters such as the collapse and roof fall of the surrounding rock of the deep shaft,the horse head gate,the main roadway at the bottom of the shaft,and the cavern group,and seriously affects the safe and efficient construction of deep mines.Based on the engineering background of-820 horizontal pump house chamber group and-950 horizontal pump house chamber group in Wanfu Coal Mine,aiming at the non-uniform pressure characteristics of pump house chamber group under non-uniform stress field,this thesis systematically studies the failure mechanism,optimal design and stability control countermeasures of traditional pump house by means of Engineering investigation,indoor test,theoretical analysis,numerical simulation and engineering application.The main conclusions are as follows:(1)Through the detailed analysis of the geological conditions and lithological characteristics of the-820 level traditional pump room group and-950 level pump room group in Wanfu Coal Mine under the non-uniform stress field,this thesis expounds the complex in-situ stress conditions faced by the-820 level and-950 level pump room group in Wanfu Coal Mine.The detailed rock structure of the roof and floor of the site is determined by rock sample collection of the site rock mass.Through field strength test and indoor experiment,the strength characteristics of roof and floor lithology of chamber group are determined.The deformation and failure causes and main influencing factors of deep chamber group are summarized,which provides a basis for the next study of the failure mechanism and stability control countermeasures of chamber group.(2)This thesis expounds the traditional design,chamber distribution characteristics and original support form of chamber group of-820 level typical pump house.Based on the geological conditions and stress characteristics of-820 level,the numerical model of-820 level pump room group is established.Based on the actual excavation process,the excavation process and monitoring section of-820 level pump room group are designed to reproduce the deformation and failure process of-820 level pump room group.The results show that the traditional design form of pump house chamber group has obvious non-uniform pressure failure characteristics,such as superposition stress and non-uniform deformation failure of chamber group.The original excavation sequence of the chamber group of the pump house,i.e.the excavation sequence of the Main pump hous-niche and suction well-water distribution roadway,has a great impact on the stress and deformation damage of the chamber group of the pump house.The excavation of water distribution roadway directly leads to the redistribution of surrounding rock stress between main pump house and suction well,and the surrounding rock of chamber group has obvious non-uniform pressure failure characteristics.The non-uniform stress field and the excavation sequence of the chamber group are the main reasons affecting the failure of the chamber group of the pump house.With the increase of the horizontal stress ratio,the deformation,stress and failure plastic zone of the chamber of the pump house also increase,and the stability of the chamber becomes worse.The excavation sequence of water distribution roadway-main pump house-niche and suction well can effectively reduce the non-uniform pressure characteristics such as deformation,stress concentration and failure of pump house chamber,which is the best excavation sequence of pump house chamber group.(3)According to the non-uniform pressure characteristics caused by deep nonuniform stress field,the intensive design and non-uniform pressure support countermeasures of pump house chamber group are put forward,and the optimal combination of suction wells of traditional pump house chamber group is carried out.Based on the stability theory of deep chamber rock column,the stability of pump house chamber group rock column is analyzed.The numerical analysis shows that the rock column of traditional pump house chamber group is disturbed by chamber group excavation,the shear fracture and tensile fracture of rock column are extremely developed,and the rock column almost loses its bearing capacity.The spacing of the pump room chambers is optimized.Finally,when the spacing is 16 m,there is a relatively stable elastic core in the rock column width,the bearing capacity of the intensive chamber group is improved,the non-uniform pressure failure is reduced,and the stability of the chamber group is improved.According to the characteristics of deep non-uniform pressure,a coupling support idea with high prestressed NPR anchor cable as the core is proposed.The static tensile test shows that the constant resistance of new NPR steel anchor cable can reach 400 k N and the elongation can reach 30%.High prestress can transform the two-dimensional stress state to three-dimensional stress state after chamber excavation,and improve the bearing capacity of surrounding rock.Based on the classical elasticplastic theory and considering the expansion and softening characteristics of surrounding rock,the interaction model between high prestressed long and short NPR anchor cable and surrounding rock is established.Based on the non-uniform pressure support theory of deep well construction,this thesis puts forward the non-uniform pressure support countermeasures of deep pump house chamber group,adjusts the stress of surrounding rock to develop towards homogenization and improves the stability of surrounding rock.(4)In order to obtain the stability characteristics of the surrounding rock of the intensive Pump House chamber group,the deformation and stress monitoring scheme of the intensive Pump House chamber group is designed,and the space-time law of threedimensional stress,deformation and failure in the excavation process of the intensive Pump House chamber group is reproduced.The key positions of failure and stress of intensive Pump House chamber group are captured,so as to provide basis for the stability support of pump house chamber group.By comparing the stress distribution and failure characteristics of intensive pump room group and traditional pump room group,the nonuniform pressure characteristics of more obvious stress disturbance and cross influence of traditional pump room group are summarized,and the advantageous characteristics of intensive design in reducing the non-uniform pressure failure of pump room group are established.According to the three-dimensional stress transfer path and the failure distribution characteristics of plastic zone during the excavation of chamber group in intensive pump house,the non-uniform pressure support countermeasures of high prestressed NPR long and short anchor cable + non-uniform support are put forward.The results show that this support strategy can improve the bearing capacity of surrounding rock,give play to the cooperative bearing effect of support and surrounding rock,reduce the uneven pressure failure of chamber group,make the stress and deformation of surrounding rock tend to be uniform,and ensure the stability of chamber group.(5)Based on the above research,the non-uniform pressure support strategy of high prestressed NPR long and short anchor cable is applied to the site,and the surface displacement of surrounding rock and the stress characteristics of anchor cable are analyzed.The results show that under the condition of non-uniform pressure support,the coordinated deformation of anchor cable and surrounding rock greatly reduces the nonuniform pressure deformation of pump house chamber group and improves the stability of pump house chamber group,It provides a reference for the stability control of similar deep chamber groups.