Study On Geological Origin And Long Term Strength Of Ordovician Gypsum-bearing Breccia In North China Area

Gypsum-bearing beccia occurs at north china and northwestern region widely, which has such extremely special physical mechanics characteristics as the material ingredient's nonuniformity, structural looseness, constructional nonuniformity, low strength, strong water reaction, weak to medium degree expansibility, corrosiveness as well as solubility.Deep researching the project characteristics and proposing the countermeasure plan not only concern the success or failure of priority projects such as Shijiazhuang-Taiyuan passenger dedicated line's special long, long and big tunnels, but also have the very significant practice guiding sense to the later design and construction of railroads, highways, tunnels, bridges and roadbeds at north china and northwestern region.The author of the study based on previous, through indoor geotechnical test and field scientific study investigation, the author launched the research about gypsum-bearing beccia's the distortion characteristic and the intensity characteristic from the theory, the indoor geotechnical test two aspects, and studied with an emphasis gypsum-bearing beccia's single axle compressive strength and its changing characteristic. At the same time through gypsum-bearing breccia's fluid pressure experiment at circumstances of high temperature and high pressure and the ground temperature field ANSYS numerical simulation, the author analyses and studied gypsum-bearing breccia's geological origin. The main research contents as follows:1. Through the scene reconnaissance to find out the Shijiazhuang-Taiyuan line's terrain, the characteristics of stratum, the geologic structure, the hydrogeological conditions and so on, to investigate gypsum-bearing breccia's essential features and distributed condition in the Shijiazhuang-Taiyuan line as well as Shanxi.2. Selecting the representational rock samples to analyze its physical mechanics nature through the rock mechanics experiment, then the results that the single axle resistant to compression intensity value and the creep test can be obtained.3. Using ANSYS to imitate the ground temperature field, the paper analyzed the various strata ground temperature situation at north china region in the Yanshan time magma activity process.4. In high temperature and high pressure triaxial test system, the rising change relations of gypsum-bearing gypsum-bearing breccia's hole gas (liquid) pressure and temperature were tested, microscopic structural change characteristics of breccia were tested after high temperature high pressure fluid pressure experiment.5. According to the above research results, the paper obtained gypsum-bearing breccia's the classification of mechanical strength and the changing characteristic. Through numerical simulation and the high temperature and high pressure mechanical experiment, analysis of the geological causes of gypsum-breccia...