Research On High-precision Gravitational Terrain Correction Of Tunnels

With the mining depth becoming deeper and deeper,it is difficult to obtain obvious anomalies in surface geophysical prospecting.Therefore,geophysical prospecting for tunnels has emerged as the times require.Geophysical prospecting methods include gravity,magnetic and electrical production,due to mine strong electromagnetic interference,so that the electric and magnetic method,it is difficult to carry out,and the tunnel of gravity from electromagnetic interference is small,it is a valuable method for research application.There are many factors influence the development of tunnel work by gravity,the greatest impact is the terrain effects produced by the related literature and the domestic research on the influence of the outer tunnel terrain can be found very few,so it is necessary to study the terrain correction of the tunnel.This article from the tunnel gravity terrain correction principle,influence factors,terrain factors and practical application in Huize mine tunnel of gravity terrain correction of the several aspects of the study,the purpose is to provide a fast and high precision terrain correction method for gravity tunnel work.The main research work of this paper is as follows:(1)summarized the basic principle of gravity and topographic correction in tunnel.(2)through the forward method of the model,the topographic influence of the first body,the two degree body and the three degree body on the gravity of the tunnel is studied.(3)summarized three methods used by former people for tunnel ground modification.This paper extends the scope of application of the method of topographic correction to the tunnel modification,and deduces a sector formula suitable for tunnel ground modification.(4)the influence of the curvature of the earth on the topographic correction of the tunnel is different from that of the surface topography,not 20 km beyond the standard requirement,but with the depth of the tunnel.(5)to change the effect of tunnel radius on the terrain,to achieve large scale gravity standard absolute error of terrain correction,correction radius to be big,but far from the zone to change the error close to constant,by eliminating base correction.(6)the influence of elevation accuracy on topographic correction of near tunnel is studied.The research shows that the requirement of height accuracy can be relaxed when the tunnel is deep buried.(7)the influence of the change of formation density on topographic correction of tunnel is studied,and the error of terrain correction by means of mean density instead of stratified density can produce great error.(8)through the practical application study of the topographic correction of gravity data in the middle 1571 and the 1031 middle section of Huize mining area,good results have been achieved.