Study On The Water-rock Coupled Model Of The Karst Collapse In Taian Area

Karst collapse is a metamorphism that occurres because of karstification in karst area. It is a kind of geological function that the geotechnical mass which above the karst tunnel occurres ground deformation failure and lead to ground collapse pit under the natural and human effect.The karst collapse occurred more than 40 years from last century 60 ages in Taian City in Shandong Province. This paper based on the project of National Natural Science Foundation of China , "Study on the cause mode of formation and forecast, prevention and cure of the karst collapse (Batch Number:40772145)",which made the karst collapse in Taian for an example, by studying it's forming condition,historical development scale and the dangerous degree, summarized the forming mechanism; Combined with the mechanics content, established the cause model ; Basis these make an Water-Rock coupled model and verify it's feasibility. The paper provided the basis for the prediction and prevention of Karst collapse in this area.The paper proposed that under the natural condition, the collapse won't occurred. That's because the force of the soil mass are in a balance. When the force changed, the balance lost, the soil mass will be damaged . The karst water of Taian City are mainly received the recharge of fracture water from the igneous rock and the metamorphic rock on the north of mountain Tai. Then run to Dawen River and run upward "excrete" at the "skylight" where alternate with the pore water overbite. While mining the groundwater highly strengthened, formed the landing funnel at lacal area. And the karst water changed into no pressure from confined. The pore water recharged vertically downward instead of being recharged of karst water. Thus , the natural balance of the force were damaged. At this time , if the karst water level lower than the karst water's upper plate especially fluctuated around the upper plate ,the karst water will scour and impact the plate. Then damage the structure of the sock and the collapse occurred at last. At this time, if add the force from the external water filling, the occurre of the collapse will be accelerated . The paper according to the moire-coulomb criterion and the palstic balance theory to analysis the force condition . At last, obtained the Water-Rock coupled model.After the verification of the example of the karst collapse in Taian City. We know the results of the prediction from the model are coindidence with practical situation.