Disturbed Effect Of Excavation Unloading And Control Of Surrounding Rock Of Roadway In Highly Stress Rock Mass

At present,many large-scale projects in China involve the excavation of deep buried caverns,including water conservancy and Hydropower Engineering,mining engineering,railway and highway tunnel engineering,deep geological disposal of nuclear waste,national deep strategic protection engineering and construction of deep foundation physical underground laboratory.Due to the deep buried tunnel,the ground stress caused by the self weight of the rock mass is very large.In addition,the deep rock mass is affected by the mining or blasting disturbance stress field,and the two are superposed to form the high ground stress,which makes the construction of the deep underground tunnel face a serious problem of deformation control.In this paper,laboratory test,theoretical calculation,numerical simulation and engineering practice are used to study the disturbance effect of excavation unloading and surrounding rock control.First of all,through the development of the true triaxial unloading disturbed rock testing system,the surrounding rock near the excavation unloading Lane(tunnel)is tested with different loading and unloading paths,different main stress sizes and different unloading rates on one side to explore the influence factors of high stress excavation unloading;Then,the deformation and failure mechanism of the surrounding rock near the excavation unloading tunnel(tunnel)is mastered by the in-situ micro test of different rock masses,and the failure strength criterion of the surrounding rock near the tunnel(tunnel)under the condition of high stress unloading is established;Third,the propagation mechanism of the disturbance wave is deeply studied,the damage mechanism of the dynamic and static combination rock mass is analyzed,the three-dimensional excavation numerical model is constructed,the excavation unloading disturbance support scheme of the high stress rock mass is proposed,and the field industrial test is carried out;Finally,the feedback of support effect is carried out to verify the reliability of theoretical,experimental and numerical analysis results.The main contents of this paper are as follows:(1)Analysis of unloading effect of high stress rock excavation.According to the adjustment process of excavation and unloading stress of high stress rock mass,different loading and unloading paths,different unloading rates and different main stress sizes are tested.The deformation characteristics,strength characteristics,failure characteristics and energy evolution mechanism of high stress rock mass under excavation and unloading conditions are analyzed,and the mechanical characteristics of high stress excavation and unloading rock mass are studied;On this basis,the stress-strain curve and fracture characteristics of rock under the condition of single side unloading are mastered,and the laws of rebound deformation,dilatancy and brittle failure of rock in the unloading direction are considered.Based on the double reduction method of strength,the strength yield criterion of rock under the condition of single side unloading is established.(2)In-situ micro test and failure mechanism analysis of high stress rock mass excavation unloading surrounding rock deformation.The failure mode of high stress excavation unloading surrounding rock is mastered,the deformation and failure evolution mechanism of high stress excavation unloading surrounding rock is studied,the mechanism of surrounding pressure cracking caused by unloading is analyzed,and the critical condition of airfoil crack is determined;through the true triaxial unloading disturbed rock test system,the rock is micro tested,the unloading size effect of high stress in-situ rock is analyzed,and the research is carried out In this paper,the characteristics of failure strength,acoustic emission and failure evolution of high stress rock mass under excavation and unloading are studied.The mechanism of fracture development,expansion and formation of macro spallation structure and the instability mechanism of spallation structure are revealed.The deformation and failure law of high stress rock mass adjacent to roadway induced by excavation and unloading are clarified;(3)Surrounding rock control disturbed by excavation and unloading of high stress rock mass.According to the stress state,strength characteristics,energy evolution law and the sensitivity of critical failure value of unloading surface under the condition of single side unloading of high stress rock mass,the disturbance tests of different frequency,amplitude and static load are carried out;based on the deformation reinforcement theory,the mechanical model of support system considering the interaction between surrounding rock and support structure is established,and the reasonable reinforcement time and reinforcement force are determined The stability and reinforcement efficiency of the structure are studied.(4)Study on the stability of surrounding rock after excavation and unloading of high stress rock mass.According to the geological conditions of Xinhu mine,the primary fracture of rock mass before excavation and after unloading is analyzed,and the physical properties and structural evolution characteristics before and after the process of initial dynamic loading and unloading are explored.The distribution characteristics and change rules of three-dimensional spatial stress field and displacement field of Roadway after unloading are analyzed by 3DEC numerical simulation method,and the roadway enclosure is studied The progressive failure law of rock,the evolution law of excavation,failure and support balance of surrounding rock of roadway are explored,the support scheme is designed,the support effect is analyzed,and the feedback of field is tracked.Figure[102]table[15]references[187]...