| Tunnel engineering is the most typical engineerintg in road traffic construction,especi ally in karst area.In the process of its construction,water gushing has been accompanied by long time,which has caused huge property losses and casualties.Xianchang tunnel,located in majang,guizhou province,is one of the important contr ol projects of the new north-south extension of wengan-machangping railway from machan gping to duyun.Carbonate rocks are widely distributed in the area where the tunnel throu ghs.Underground rivers,karst pipelines and joint cracks are widely distributed and are loc ally concentrated,the development of karst is very complex.During tunnel construction in this area,the prediction of water inflow is a key issue.To counter the problems above,this paper takes xianchang tunnel as the research objec t and makes a field geological survey for the proposed tunnel.We obtained the data by g eophysical prospecting,drilling,pumping test and field test,and expounded the geomorph ic type,lithological characteristics,tectonic types and the karst hydrogeological conditions in the study area in detail.In addition,the characteristics of karst development in tunnel area are systematically analyzed.At the same time,the maximum water inflow is predicte d in the pr-ocess of tunnel construction by precipitation infiltration method,goodman form ula method method and groundwater numerical simulation method.The main achievements are as follows:(1)Based on the field geological survey of the area where the tunnel line is locate d,expounded the geomorphic type,lithological characteristics and tectonic type of the stu dy area in detail,and systematically analyzed the development types,influencing factors a nd development rules of karst tunnel area.(2)By methods of field hydrogeological tests,obtained relevant hydrogeological para meters,and the maximum water inflow during tunnel construction was predicted by means of precipitation infiltration method and goodman empirical formula method.And predicte d the maximum water inflow by precipitationinfiltration method and goodman formula met hod during tunnel construction.The maximum water inflow predicted by the precipitation infiltration method was 87900m~3/d,and the maximum water inflow predicted by the good man formula method was 86100m~3/d.(3)Based on the structural combination,geomorphic type and hydrogeological condi tions,the tunnel arer is divided into three hydrogeological units.Then,three hydrogeological units were divided into six hydrogeological subregions accordi ng to the characteristics of groundwater flow field and water-bearing rock group.(4)The 3D groundwater numerical model was established by Visual MODFLOW and predicted the maximum water inflow during tunnel construction.Themaxi mum water inflow is 88000m~3/d.(5)By analyzing the predicted results of traditional method and numerical simulatio n method and considering the safety and stability of the project and the safety of personn el,the maximum water inflow of the tunnel was finally determined to be 88000m~3/d. |
PDF Full Text Request