Numerical Simulation And Application For Cross-street Resistivity Tomography And Four-dimensional Monitoring Technology

The surface of the urban road is the area where vehicles and pedestrians pass through,and below the road is the area where various underground pipe networks,subways,tunnels and other hidden projects pass through.The road subgrade is prone to void deformation under the action of vehicle pressure heavily and groundwater,resulting in cavity collapse.The occurrence and development of cavity collapse have the characteristics of long-term,randomness and concealment,while the appearance of surface collapse is sudden,posing a major threat to the safety of life and property of urban residents.How to locate and predict cavity collapse quickly and accurately is a worldwide technical challenge that urgently needs to be solved in the process of urban development.Aiming at the problem of detection and monitoring of hidden dangers in urban roads,this paper evaluates and verifies the feasibility and application effect of cross-street resistivity tomography technology and four-dimensional resistivity monitoring technology through numerical simulation combined with actual measurement application.Firstly,this paper designs two lumpy underground targets,and through the numerical simulation method,the imaging effects of different arrangement settings of cross-street resistivity tomography and traditional ERT are compared,which confirms the superiority of cross-street imaging technology and the feasibility of its application to target detection under the street.Then,a simulation study is carried out for some specific geological problems in the city(dynamic process monitoring of underground tunnel excavation,detection of underground pipe network damage,etc.)to evaluate the feasibility and detection effect of cross-sectional imaging and four-dimensional monitoring.The simulation results show that the cross-street resistivity tomography technology has a good imaging effect on these complex underground targets.Finally,the RHD resistivity sensing system newly developed by Geopen Ltd.is used to carry out a comparative experiment with the traditional ERT instrument in the Zijingang Campus of Zhejiang University,both instruments have a good response to the 28 mdeep Metro Line 5,which proves that the RHD resistivity sensing system has the detection and imaging capabilities of ERT.And the RHD resistivity sensing system was used to carry out cross-street imaging and four-dimensional monitoring experiments.The field measurement verified the instrument’s four-dimensional monitoring capability and the feasibility and application prospect of cross-street resistivity tomography technology.