Study on impermeability of different sites for the same fault based on in-situ water injection test
In order to study the impermeability of the same fault exposed by two working faces in No.10 Mining Area of Yangcun Coal Mine,which is in different sites of the pre-mined seam floor fault zones,the in-situ water injection tests of fault zone A and B were carried out successively.The chan-ging curves of water injection pressure,monitoring water pressure and flow rate in test area A for 4 times and test area B for 3 times were plotted in the process of water injection.The initial permeability and steady seepage characteristics were obtained,the differences of the two sites were analyzed for ini-tial permeability and steady seepage conditions.It is found that the fault fracture zone at site B has more larger connectivity reaction than the original micro-fracture zone at site A under the action of high pressure seepage tests.On this basis,calculation formula of permeability coefficient was used in the process of water injection tests,the permeability of both site fault zones was very weak.However,by comparing the average permeability coefficient of test site A and site B,the permeability coefficient of in-situ test in the area of site A after repeated pressure seepage tests increased nearly 2.4 times,site B permeability increased about only 20％.It shows that the fault,as a kind of fractured rock mass,has obvious anisotropy and heterogeneity in two sites.Through the characteristics of P-Q change curve fitted by the scatter plot between the piezometric water pressure P and flow rate Q at the two sites,and comparing with the relevant regulations and studies,the fault zone types should belong to the erosion and expanding types at two sites,respectively.Fault fracture is not developed,but the fractures are filled with impermeable fillings with different degrees of densification,once the water injection pressure exceeds the critical value,the part fillings are eroded,the micro-fissures should expand to a certain extent.However,due to the different filling compaction degree,the permeability of different sites for the same fault has differential changes.
in-situ water injection testthe same faultimpermeability of difference for the same faultpermeability coefficientP-Q correlation characteristics
万方数据
维普
