Back Analysis of In-Situ Stress under Complicated Geological Conditions Based On Function Superposition of Multiple Regressions

Abstract

A phosphate mine area is identified in steep terrain to the mountain and deep river valley with broken rock zone and accompanied by large fracture; the in-situ stress field is very complex. In order to prevent the underground goaf instability, surface mountain collapse and riverbed fracture caused by mining activities, how to accurate analysis the in-situ stress distribution is great significance. In allusion to the back analysis of in-situ stress under complicated geological conditions, we put forward the multiple regression analysis of functions superposition that superposed many typical functions by using multiple linear regression method, it could achieve a better fit between the inversion value and the measured value, and avoided the problem of poor fitting and deviation of the single type function regression, the regression data is high relevance with the measured value and closer to the engineering practice. Based on 3Dmine-MIDAS-FLAC3D software, we established the numerical calculation model of whole mine under complex geological conditions, and performed the nonlinearly boundary stress changed with depth through stress loading procedure with the multiple function regression equation by use the fish language. Through analysis of the results of numerical simulation, the results show that the method used for calculating the initial stress field is reasonable and reliable. Besides, the methods have an important significance in engineering application and can provide a new train of thought for other regression analysis.