| In recent years, deep underground engineering are developing, Which contains carbon dioxide geological disposal project, hot dry rock project and oil and gas exploration project. Such deep underground engineering are involved in deep underground rock thermal- hydro- mechanical(THM) multi-physical coupling problems. More and more scholars to carry out the research on deep underground rock multi-field coupling problems. In the study of many problems, Scholars in various countries have neglected the changes of temperature and effective stress in the deep underground rock, Which caused by deep underground engineering construction. These changes can cause the change of inherent parameters of rock mass. To solve this kind of problem, the paper carried out the experimental analysis of Rock Biot coefficient and research on multi field(THM) coupling model.Firstly, the Songliao Basin and the Ordos Basin rock experimental samples are selected. Determination of Biot coefficient, density, porosity, velocity and mineral composition of the rock. Study on the relationship between Biot coefficient and these factors. Secondly, Study on the the effect of cracks of rock, rock temperature and effective stress on four types of rocks(granodiorite, rhyolite, coarse sandstone, finegrained sandstone) to the Biot coefficient, and the Biot coefficient of the four kinds rocks varies with the changes of crack, temperature and effective stress. The empirical formula of Biot coefficient with temperature and effective stress is obtained by fitting the experimental results. Thirdly, According to empirical formula to correct the THM multi field coupling simulation software, Which is written by the author’s own research group. And the accuracy of the modified model was verified by the measured values of the InSalah site. Finally, Numerical simulation of the carbon dioxide geological disposal project of the Ordos Basin by using the modified simulation software. Researching the mechanical characteristic change and plastic zone distribution characteristics after carbon dioxide injection, and prediction of injection pressure and ground deformation.In the experimental analysis of the Biot coefficient. Determination of Biot coefficient, density, porosity, velocity and mineral composition of the rock. Study on the relationship between Biot coefficient and these factors: The Biot coefficient of rock decreases with the increasing of density; Increased with the increasing of porosity; Decreased with the increasing of the wave velocity; For the same kind of rock, the lower rock Biot coefficient is basically corroding to the greater dense the rock. The Biot coefficient of rock between different kinds of rocks is also affected by the rock structure. The Biot coefficient is lower in the structurally stable rock.Biot coefficient is not only related to the internal structure of the rock, but also related to the state of the rock and the external environment: Firstly, The experimental results show that the temperature has influence on the Biot coefficient of rock. There are different rules in the different stress regime, at low stress regime where the Biot coefficient increased with increasing temperature, and a high stress regime where the Biot coefficient decreased with increasing temperature. The effective stress has a great influence on the Biot coefficient of the rock, and the Biot coefficient of the rock decreased with the increasing of effective stress. Secondly, Through the experiments study of the change trend of Biot coefficient with the change of temperature and effective stress in the rock with fracture in different directions. The study found that the fractured rock and the intact rock affected by temperature and effective stress have the same trend. And by comparing the Biot coefficients of the intact rock and the fractured rock with different directions under the same temperature and effective stress.The Biot coefficient of the rock with fracture is larger than that of the intact rock; The Biot coefficient of the rock with vertical cracks is larger than the Biot coefficient of the rock with transverse crack.It can be concluded that the number of cracks and the location and direction of the crack in the rock have an effect on the Biot coefficient of the rock.Research on THM multi field coupling model, according to empirical formula to correct the THM multi field coupling simulation software,Which is written by the author’s own research group. And the accuracy of the modified model was verified by the measured values of the InSalah site. The results show that the modified simulation program is more close to the real monitoring results. It is show that the modified simulation program is more accurate.Numerical simulation of the carbon dioxide geological disposal project of the Ordos Basin by using the modified simulation software. According to the actual situation of the site to establish a two-dimensional model, the calculation found: With the increasing of carbon dioxide injection, the pore pressure of rock mass increases gradually, Influence scope of the effective pressure was significantly larger than that of carbon dioxide migration. With the increasing of pore pressure in rock mass, the effective stress of rock mass decreasing, and ultimate plastic damage zone appeared. According to the plastic zone and the failure mode, the calculation of the ground carbon dioxide injection pressure is not easy to exceed 22MPa; With the increasing of pore pressure lead to deformation of strata, The rock shape variable near the injection point increases with the increasing of the injection rate. The maximum shape variable from the 1.36 cm of the first year increased to 4.65 cm of the tenth years, but the deformation rate decreases year by year. |
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