Study On Anti-explosion Stability Of Fissure Rock Chamber

With the rapid development of social economy,it has become a consensus to vigorously develop underground space on the premise of making full use of aboveground resources.The natural underground environment is complicated,and there are often heterogeneous structural planes such as joints,bedding and weak interlayers in rock mass,which seriously affect the dynamic properties of rock mass,and then affect the stability of the chamber in fractured rock mass.In the mining sector,with shallow coal drying up,coal mining depth are also increasing year by year,in the coal mining gas explosion risks,and antiknock stability of underground cavern is closely related to workers’ life safety,so the fracture rock cavern under explosion load the influence factors of deformation and failure,and improve the antiknock performance of underground space and the carrying capacity,It has become an urgent problem to prevent its destruction under the action of explosion load.In this paper,by means of theoretical analysis,model test and numerical simulation,the deformation characteristics,failure mechanism and stability influencing factors of the chamber of fractured rock mass under the action of explosion load are studied.The main work and conclusions are as follows:(1)Based on the basic theory of stress wave,the propagation law of explosion wave in joint layer and free surface is analyzed.Explosion loading effect on underground geotechnical engineering structure is the essence of the explosive stress wave,after the formation of a certain depth of rock mass media transmission and energy loss,acting on the underground engineering structure,resulting in structural vibration,produce the process of deformation and failure,and the explosion wave energy loss and heterogeneous structure distribution have larger link below.(2)Using explosion experiment Froude similarity theory to carry out the model of the cavern,to study the different gap across the antiknock than rock cavern stability,different cavern surrounding rock under the action of the explosion load stress and the relative displacement of vault,arch ring wall compared to the changing law of strain,on the theoretical analysis and the failure pattern,the study found that: The gap span ratio has a great influence on the anti-explosion stability of the chamber.Under the same blast load,the chamber with the gap span ratio of 1/10 and 1/20 has no obvious damage,and the overall stability is good,while the chamber with the gap span ratio of 1/30 has a more serious failure phenomenon,and the bearing capacity is obviously insufficient.(3)Use Froude similarity theory of different reinforcement schemes cavern explosion experiment,by comparing the multiple arch under explosion loading different reinforcement cavern relative displacement and the arch wall ring to the strain monitoring data,the following conclusions: anchor rod and anchor rope combined support for cavern deformation with larger constraints,and supporting effect has relationship with arch,joint thickness above;The control effect of short dense bolt and cable combined support is better than that of long loose bolt and cable combined support,in which the latter has better restraint effect on the formation of compressive strain of side wall,arch foot and part of arch waist,but the control effect on the tensile strain of vault position is inferior to the former.(4)By comparing the failure modes of the test models under the action of explosion load,it is found that compressive shear failure and slip failure mainly occur in the joint layer above the arch of the chamber,while the annular tensile failure,layer crack failure and punching shear collapse failure mainly occur in the surface of the arch of the chamber.Through theoretical deduction,it can be concluded that: The failure of jointed strata is mainly related to the reflection phenomenon of stress wave at the structural plane,while the failure of chamber surface is closely related to the tensile stress generated by explosion wave at the free plane.(5)LS-DYNA and 3DEC software were used to simulate the change of vault displacement in chambers with different gap to span ratios under the action of explosion load,and the calculation results were compared with the model test to analyze the reasonable feasibility of numerical simulation research methods and results.The results show that: There is a high coincidence between the numerical simulation and the model test,which can reflect the deformation law of the fissure rock chamber under the action of explosion load.The method can be used to analyze other factors affecting the anti-explosion stability.(6)In the gap across than working condition of numerical simulation on the basis of development,further analysis,the critical point location and scope of joint,joint Angle joint antiknock dynamic mechanical properties of cavern stability,the influence of different working conditions,by comparing the same under explosion load cavern arch parts moving situation,analysis the influence extent of different factors on the stability of cavern of anti-explosion The reasons for the displacement and deformation of the chamber arch are also discussed.