Prediction And Exploration Of Engineering Geological Anomalies In The 8th Section Of The East Ring Of Chongqing Metro

With the increasing demand of railway tunnel construction in China,the problem of engineering geological disaster is becoming more and more prominent,which seriously affects the construction safety.Therefore,it is an urgent task to accurately and effectively forecast the geological disaster of tunnel construction.Chongqing,this article selects the subway loop line kite east rock tunnel project as an example,study the tunnel adverse geological conditions,based on the results of TSP advanced detection for rock mechanics parameters,analysis of screening in forecast physical parameters,surrounding rock classification prediction model is established,at the same time using a variety of methods to verify this model prediction results,the excavation show that better prediction accuracy,provide reference for tunnel construction.The main research results are as follows:(1)Based on data collection and geological survey for geological analysis,physical parameters of tunnel surrounding rock detected by TSP are extracted.Cluster analysis shows that longitudinal wave velocity,volume modulus,Poisson’s ratio and wave velocity ratio are highly correlated in the four kinds of tunnel surrounding rock,which can better explain the lithologic changes of fault and coal-bearing strata.The shear wave velocity,density,Young’s modulus and shear modulus are highly correlated,which better reflect the water-rich degree of karst and water-rich strata and the self-stabilizing ability of rock mass.Factor analysis reflectively plastid parameters in karst and karst cave,fault fracture zone,water content,coal-bearing strata,four kinds of bad geological condition of surrounding rock contribution degree of surrounding rock,compressional wave velocity,density,young’s modulus,bulk modulus is the highest physical parameters in the contribution rate,better reflect the lithological change and hydrogeological conditions of surrounding rock.(2)The physical parameters participating in the classification were dynamically selected according to the contribution of parameters.By calculating the factor scores and individual scores,the prediction model of tunnel surrounding rock classification under different geological conditions was established,and the geological characteristics of rock mass corresponding to each classification and the variation rule of parameter data were analyzed.The selected tunnel surrounding rock is divided into five grades.As the grade increases,the rock hardness stiffness decreases,the density of joints and fissures increases,the degree of rock fragmentation increases,the degree of groundwater development increases,and the self-stability ability becomes worse.With the increase of the number of cases,the lithologic change interface increases,and the integrity of surrounding rock is poor.(3)Based on the TSP detection and prediction model,segmentation interpretation and classification are carried out,and the effect of surrounding rock classification and prediction is verified through the comparative analysis of excavation exposure.In the surrounding rock of karst and karst cave,the surrounding rock of fault broken zone and the surrounding rock of rich water,the classification effect of the surrounding rock of coal-bearing stratum is not good,and the prediction model established is reasonable on the whole.(4)Advanced horizontal drilling,geological radar,transient electromagnetic and other means are used to verify and explore the high-risk section of abnormal response in TSP detection.The comprehensive advanced geological prediction combined with multiple detection methods greatly reduces the multi-solution brought by a single method of TSP,and improves the accuracy and reliability of prediction.It can reveal the hydrogeological and engineering geological conditions of surrounding rock and predict the possible geological disasters.