Study On Curtain Grouting Test And Numerical Simulation In Karst Geology

China is a country with a vast territory and complicated geographical and geological conditions.With the needs of economy,traffic,mining and other fields,the karst hazards of different degrees and different causes cause immeasurable economic losses and personal safety threats to mining every year.Underground fissures and karst caves in karst geology often develop continuously under the action of man-made or natural environment,seriously affecting the local mining industry and the production and life of residents,and forming safety hidden dangers.The continuous development of karst fissure leads to the expansion of rock gap and the further opening of groundwater circulation channel,which makes the original groundwater flow into the open pit.In addition to its own karst cave,the rock layer loses the force of groundwater,the ground often collapses,local houses sink and crack,farmland loses water,and a series of geological disasters exist.In order to ensure the safety of mine production and the safety of nearby villages,curtain grouting will be carried out on an open-pit mine in a limestone mining area.Based on the curtain grouting project of a mining area,the main research contents and conclusions are as follows:（1）The research area in this paper is a mining area,which is covered karst area.There are limestone,tectonic faults,karst and other unfavorable geological bodies under the overburden in the northern part of the mining area.According to karst survey data,the working area is composed of north-south,northeast,and near-east-west secondary faults.The karst is concentrated at the intersection of the faults,and the bedrock surface is undulated,which is a typical erosion area,and the overall development degree of karst is relatively strong.（2）The fault in the study area is relatively complex,and the main fault is the northeast trending fault F1,and a series of subfaults derived from it,including the north and south,the northeast,and the east and west,constitute a northeast trending fracture zone.At present,the phenomenon of water inrush and mud outburst caused by karst has been found in the mining process of this mine.Water seepage can be seen in some parts of the excavated rock wall,with a large amount of water seepage.At the bottom of the mine,there is a certain amount of water inrush and water inrush,and a large number of ground subsidence has been found around the mine.（3）In the process of rainfall,the rainwater penetrates into the ground,and the karst aquifer mainly underflows along the karst pipes or channels formed by karst cracks,karst caves and karst dissolution zones,which further increases the erosion scale of karst caves and flows to the bottom of mining pits.In the dry season,large areas collapse.The study area is in form a monoclinal structure formation,formation due to the affected by the regional tectonic formed more small fold,the heart of fold structure and common have karst development turning point,under the influence of tectonic stress,folds,faults and fissures,carbonate,due to rainfall in the district,for karst development provides a favorable external conditions.（4）Based on the summarization of grouting theories at home and abroad,the mechanism of grouting is analyzed.Due to the nature of the project,the project requires fast setting time of grouting,the use of cement and water glass double grout grouting construction,high pressure rotary jet method and ordinary rotary jet method for comparison,considering the actual quantity and cost,the final use of ordinary grouting method construction.Finally,the comprehensive test of grouting is adopted to judge the effect of curtain grouting,and the emergency treatment measures under special circumstances are put forward to provide reliable experience for engineering construction.（5）FLAC^3Dsoftware was used to simulate the displacement field change,principal stress change and pore water pressure of karst geology before and after grouting.The results show that the displacement field before grouting is large,and the displacement field after grouting is small.The simulation results show that grouting reinforcement and water-stopping effect are obvious.