Study On The Genetic Mechanism And Numerical Simulation Of The Evolution Process Of Karst Collapse In Taoyuan Town,Datian City

This article carried out the survey and analysis on the engineering case of karst collapse in Taoyuan Town,Datian City,Sanming City,and analyzes the formation mechanism of karst collapse.After that,the ground surface collapse hazard and harmfulness were partitioned and preliminary measures were put forward.Finally,the numerical simulation method was applied to study the evolution and development process of the karst collapse,so that the karst collapse disaster occurrence and development can be presented.The main research contents and conclusions are as follows:(1)The engineering case of karst collapse in Taoyuan Town,Datian City,Sanming City is surveyed and analyzed,the meteorology,hydrology,topography,lithology,geological structure and its activities as well as hydrogeological conditions are explored.Preliminary analysis shows that the internal cause of the karst ground collapse is that the site belongs to the development area of karst limestone,which has been eroded by groundwater for a long time,while the external cause is that the overburden layers lose the support due to the permeation of the nearby ore chamber.The basic situation of the subsidence area was understood so as to provide some guidance for the development of the follow-up work.(2)By laying six lines of detection on the test site,the karst ground collapse was further studied by means of the geophysical detection method of high-density electrical method.The results show that a number of obvious underground cavity distributions are found in the range of L1 and L4 survey lines,and the distribution of karst underground cavities in the study area is obtained intuitively.A total of five potential karst caves have been identified,in which the size of the largest one is about 50 m in length long and 10 m in height.This is an very important cause of the collapse.(3)Based on the basic data obtained,the large deformation finite element program ANSYS/LS-DYNA was adopted to simulate andanalyze the whole process of the ground collapse before and after the development of karst underground cavity at different stages.The results turn out that due to the expansion of the underground cavity,the thickness of the cave roof decreases to certain extent and then the collapse finally occurs suddenly.Through the reveal of the causes of the collapse,some references for the study of the future treatment countermeasures can be provided.(4)Based on the results of field investigation and high-density electrical geophysical prospecting,the risk and hazard zones of ground collapse are preliminarily determined,and a series of reasonable emergency measures are proposed to ensure the safety of people and property in the site.