Papers by Keyword: Geostress Field

Abstract: In this paper ,the geostress field of a large area complicated in geological structures was inverted with the stress data of a few measured points by using FLAC^3D numerical stimulation and regression analysis. Two types of models were built. One type is a big model without geological structures, which considered the influence of layer thickness, lithology, stratigraphic dip and ground surface fluctuation first, and then corrected the simulation results according to the measured data, and finally got the geostress field without regional structures by regression analysis. The other type is small regional structure models, which paid attention to the influence of depth, fault type and fault throw, or fold type and fold amplitude, and gained the influence range and coefficients of each geological structure to the geostress field. At last, the results of two types were integrated together, and the large area geostress field under complex geological condition was got. According to this method in allusion to a specific example, the principal stress isoline and vector horizontal projection of coal seam roof including three faults and one fold were obtained, which could analyze the stress magnitude and direction. The method above can solve the problem of how to use the stress data of a few measured points to gain a wide range geostress field under complex geological condition, which could also promote the study of geostress field inversion and have certain engineering application value.

Abstract: Focus on the topography features of V-shaped deep river valley in Ada dam area, the influence of intensively, moderately and slightly weathered stratum as well as the action of river valley erosion on geostress field was considered. Then, the 3-D initial geostress unloading model was established based on the measured geostress data and geological conditions. Combining the finite element numerical method and inversion theory, multiple regression analysis was established between the measured and corresponding calculated results of geostress. Then, the optimal regression coefficient could be derived. In addition, for convenience of comparison, another method was adopted by ignoring the action of river valley erosion. Through the comparison between the computed values by two methods and the measured geostress values respectively, it is found that the computed values by the former method are more close to the measured ones. Therefore, the distribution rule of initial geostress field can be obtained accurately, which provides important reference for design and construction of Ada dam and its diversion tunnel layout.