| The development of landslide disaster is closely related to the regional geological background and geological structure process.The unique geological structure,landform,dynamic response and man-made disturbance are the main control factors of landslide disaster evolution.Regional structure is the basis of landslide development,especially for complex slope systems such as open-pit mines,which are strongly artificially transformed.The effects of high stress unloading effect driven by high-intensity mining and advanced drainage and precipitation engineering will induce the activation of geological structures such as the interruption layer of the original geological body,thus affecting the mining operation and slope safety.Taking the third mining area of Yimin open pit mine as the engineering background,this paper studies the fault activation mechanism,groundwater seepage evolution law,landslide disaster pregnancy mode and disaster causing mechanism under the conditions of high-intensity mining and advanced drainage and precipitation by using the comprehensive research methods of field investigation,geological survey,theoretical analysis,experimental research and numerical simulation,so as to provide the basis for mine safety production and dynamic evaluation of slope stability,It is conducive to the further study of major issues such as prediction,prediction,evaluation and governance.The main research work and results are as follows:(1)The engineering geological survey and two-dimensional seismic geophysical survey were carried out in the study area,and the geological structure,fault occurrence and groundwater occurrence in the study area were proved;Hydrogeological observation holes are established,single hole and multi hole pumping tests are carried out,the distribution state of confined water is studied,and the seepage parameters are calculated and analyzed.The measured permeability coefficients of each layer and fault area are 47.03m/d and 0.47m/d respectively.The difference of permeability coefficients is caused by the existence of faults.(2)Based on the theory of geological body structure and the mechanical mechanism of fault formation,the influencing factors of fault activation are analyzed;Combined with engineering practice,the concept of relative water resisting fault is put forward,and its internal and external characteristics are expounded;Based on the fault tectonic stress analysis formula and Mohr Coulomb criterion,the influence relationship between fault activation and mining disturbance horizontal stress is determined,and the formula of water level difference between the upper and lower walls of the fault and the formula of critical value of hydraulic gradient are deduced.(3)The fault deformation and failure mode of mining slope under mining disturbance and seepage is analyzed.(1)Under the condition of single open-pit mining,the slope deformation area is mainly on the left side of the fault,and the "V" shaped deformation area is an active sliding area,and the deformation increases obviously under the influence of seepage;(2)The horizontal displacement forms the sliding deformation along the bedding plane in the exposed area of the fault;(3)The fault zone is an active deformation area,which is the main shear stress accumulation area;(4)After the completion of the fourth mining,the horizontal displacement and deformation of the slope top and bottom area show an obvious decreasing trend.(4)The hydraulic variation characteristics of the fault are studied,and the water control scheme to improve the slope stability is put forward.After the third mining,the hydraulic gradient difference on both sides of the fault does not change,indicating that the fault changes from the relative water isolation state to the water diversion state at this time;When it drops to 590 m,the hydraulic gradient on both sides of F1 and F5 faults is 2,which is the critical state of fault hydraulic gradient;By optimizing the number and location of control wells,the slope stability coefficient is increased to 1.2,which can meet the actual needs of the project. |
