Research Of The Gravity Anomaly Changes Caused By Mining In Mining Area

Any object on the earth's surface or near space will receive the gravity, and uneven distribution of subsurface material will cause a change in gravity. With minerals mining from the underground, forming a goaf cavity, it the ground will lead to change in the gravity field.When gravity exploration in the mining subsidence, with coal resources mined from the underground that will cause the ground to sink unceasingly,at the same time the coal mining area will develop form underground to the ground along with time, this will lead to the ground gravity value of dynamic change.The surface will sink continuously because of the underground mining,which will cause the earth gravity's changes. Therefore,the study the change law of gravity anomaly that caused by the diggings exploitation,which will have the vital significance on detecting goaf position and refining mining area geoid.The paper study the residual law of goaf residual cavity on the basis of the theory of mining subsidence, according to the characteristics of the mining subsidence, use the existing gravity anomaly theoretical model as the foundation, and use Gauss to make mathematical transform that make triple integral transform into double integral, and use the finite element to realize the numerical calculation. Meanwhile, the study use Matlab2014 a software platform to discuss the factors influencing accuracy of finite element numerical calculation and find that the accuracy is related to the unit size,calculation methods and the distance between calculation points and unit. In order to well find and summary the relationship between gravity anomaly and geological anomalous body, using Matlab to compile GUI program to show the gravity anomaly. This program has the advantages of calculation quickly and accurately.The ground subsidence caused by coal mining is calculated by the Probability-integral Method,and the gravity value simulation is used by the gravity anomaly forward program,then we use regression analysis to establish the relational model between gravity field and ground subsidence.At the same time, the additional value of gravity anomaly caused by residual cavity is calculated. In the end, Based on the gravity field additivity, we can get the gravity anomaliescaused by the working face mining and ground subsidence.In this paper, this study has improved the application of gravity anomaly calculation, and build the relational model between coal mining subsidence and gravity anomaly, which has important theoretical and practical significance.