Research On The Geological Environment And Engineering Stability Of LuoJia Village Tunnel

Geological environment is vital natural environment vector for tunnel engineerings, which controls geological disasters' scale, frequency and the development trend, and effects seriously the stability of region and ground surface and deep part and mountain and wall rock in the tunnel zone by means of geological structure and rock soil media environment and crustal stress and hydrogeology. Therefore, geological environment issue must be researched on systematically and in depth to ensure tunnel engineerings' stability and construction safety.Based on above ananlysis, this paper, via construction of LuoJia Village tunnel of DaLi-RuiLi railway in western YunNan mountainous area, is intended to systematically study on faults and joints distribution and engineering features by kinds of methods such as geological survey and predication and monitoring at site and theoretical analysis and numerical calculation. The numerical calculation model is established to analyze tunnel excavation's influence on mountain body stability. It is to be conferred on mountain body cracking cause of formation and special construction scheme for engineering safety. The main research work and accomplishment of the paper are generalized at follows:Statistic investigations and analysis of joints show that there are three preferred joints planes with SW and SE and NW tendency. Their distribution is equidistant and cadenced metrical. The joints planes with SW tendency is so compressed that they are worst for wall rock.The experienced maps of fault zones with different mechanical mechanism are gained by 3D seismic waves tracking technology based on lots of field test and engineerings practice. The criterions are established for different mechanical property faults and predication surrounding rock mass classification quantitatively. Overall analysis on geological environment with 3D seismic waves tracking technology and infrared waterprospecting and drilling is consistent with excavation results.Calculation model is setted up to dynamically simulate the anti-slide stable state of slope body by Strength Reduction FEM. It shows that the slope body stability changes obviously as long as the tunnel excavation between 20m to 45m based on safety coefficient variation curve. The tunnel can pass through the slope body safely without landslide failure. Mountain body cracking cause of formation includes landform and physiognomy factor and geological structure factor and rock soil media factor and tunnel excavation evoking factor. Mudstone with special engineering geology property is the material base; The complex geological structure with lots of faults is precondition; There are enough gravitational potential energy because the single anticline structure leads to enough discrepancy in elevation and inclination. There are enough space and free surfaces for mountain body cracking with latitudinal valleys deep incision. Stress in rock mass adjust once more so strongly after excavation resulted in stress relief because of deadweight and unloading that rock mass begin to subside and crack. The connection between the cracks and joints in formation rock mass of mountain body leads to mountain body cracking.Monitoring data analysis shows that construction plan are so reasonable that tunnel engineering structural is stably and secure.