Method of nonlinear in-situ stress construction with deep multi-field coupling

Deep high-energy and large-scale engineering disasters occur frequently, which are difficult to predict and effectively control.In-situ stress is an important basis for the optimization design and dynamic disaster prevention of mining engineering, geotechnical engineering and oil mining engineering.In the analysis of deep in-situ stress field, the limitation of field measurement theory and method, the difficulty of in-situ coring technology and the complexity of geological conditions all increase the difficulty of cognition and interpretation of in-situ stress field in engineering area, and affect the accuracy of in-situ stress assessment results.Shanghai Miao mining area in Ordos is one of the largest deep mining coal mines with cemented soft rock in China.The main mining coal seam is more than 1 000 m deep, and the local difference of temperature distribution is obvious.The regional strata have undergone many times of structural movement, with many faults and folds, complex hydrogeological conditions, large karst water and pore water.In view of the complex coupling effect of the above-mentioned factors on the ground stress field, and unclear mechanism, so it is necessary to analyze and study the distribution of in-situ stress field from many aspects.For this reason, firstly, several kinds of boundary load forms are introduced, which are suitable for the distribution law of the deep ground stress field, and a new nonlinear optimization algorithm is put forward for the deep in-situ stress field multiple progressive iterative optimization.This method can ensure high accuracy and fast global optimum solution, and is suitable for the inversion and reconstruction of deep complex in-stress field.Secondly, using the methods of theoretical analysis, field measurement and laboratory test, the distribution law of deep geothermal field is systematically analyzed, the analytical solution of temperature distribution in the neighborhood of deep discontinuous structure is derived.The geothermal data, thermodynamic parameters of rock mass, softening coefficient and stress data of measuring points are obtained.Finally, based on the geological conditions of the study area, a three-dimensional deep geological model is constructed.Considering the coupling characteristics of deep multiple fields, discontinuous structure and the complex stratum attributes, the distribution law of the geothermal field and the distribution state of the ground stress field in the area are reconstructed by inversion.The calculated results are consistent with the measured values and field geological data.