Study On Inrush Of Water And Mud Mechanism And Grouting Control Technology In Water-rich Fault Fracture Zone Of Tunnel

During Tunnel and underground engineering construction crossing water-rich fault fracture zone, it often happens on large scale geological hazards, such as inrush of water and mud, which seriously threatens the safety of tunnel construction and surrounding environment and restricts the development of tunnel construction. Therefore, it is of great scientific significance and engineering application value to study on mechanism and grouting control theory of gushing water and gushing mud in water-rich fault fracture zone of the tunnel. Based on project of Zhongjiashan tunnel (Yonglian tunnel), of Ji-Lian highway in Jiangxi province, the mechanism of gushing water and gushing mud in tunnel fault broken zone and its process of catastrophe evolution were studied in this paper by material collection, theoretical study, numerical simulation and field test. What is more, grouting control technical system was established, and it is applied to the engineering, gaining a certain researching achievement.(1) Upon systematical analyses on structural characteristics and hydrogeology features of fault, the reason why inrush of water and mud is prone to occur in fracture zone was revealed. Based on summarizing and analyzing universal characteristic of gushing water and gushing mud in tunnel fault, its catastrophe features, occurrence condition and influencing factors were studied.(2) On account of systematical analyses on the effect of groundwater to fault zone rock mass, including physical action, chemical interaction and mechanical functions, filler migration, structural deformation, porosity and permeability in broken rock because of variable-mass fluid-solid coupling effect were studied, and its the temporal variation in porosity and permeability of fault zone rock mass were given. What is more, disaster mechanism of catastrophic destabilizing was investigated.(3) Against the background of backing project, the variation law of stress, displacement and seepage in process of tunnel fault excavation was simulated through COMSOL Multiphysics, which reveals its mechanism of gushing water and gushing mud in the view of surrounding rock stability. In addition, the influence of geological factors on inrush of clay and water in tunnel fault, including surrounding rock grade, groundwater level and surrounding rock permeability, were simulated by means of single factor analysis.(4) Based upon the analysis and summary on cases of gushing water and gushing mud in tunnel fault at home and abroad, its formation conditions were systematically researched closely combined with gushing water and gushing mud situation of backing project. Moreover, with development of gushing water and gushing mud deeply analyzed, its characteristics and mechanisms of evolution process (including inoculation, latency and occurrence) was studied.(5) Based on research results above and summary of successful grouting harnessing cases in gushing water and gushing mud in tunnel fault at home and abroad, grouting harnessing technical system was established, which mainly includes comprehensive survey, grouting design, grouting implementation, process control technology and effect evaluation. Furthermore, this system is applied successfully in project of Zhongjiashan tunnel with high effectiveness.