Study On High-pressure Seepage Simulation System And Key Technology For Deep Buried Diversion Tunnel

With the advances of new concepts, theories and methods in underground engineering, and the needs of energy development, environmental conditioning, ecological protection and sustainable development, more and more underground projects appear in our daily production and life. The numerical analysis is insufficient to the problems of underground chamber excavation in complex geology conditions, so geo-mechanical model test is developed with the improvement of test technology. The excavation of Jinping second-cascade hydropower station underground diversion tunnel in the condition of high geostress and high external water pressure is simulated in this test based on the informed research of model test. During this test, the stress field, displacement field and seepage field are monitored to study the mechanics effect and the deformation mechanism, and provide an academic reference prove for the construction of diversion tunnel. And the results of this research will be helpful to the evaluation of tunnel safety and long-term stabilization. The main outcomes of this paper are exhibited as follows:1) The Froude similarity criterion is primarily chosen in the similarity condition. A normal model test is taken with 1:100 geometric scale in this test based on the conditions of both practical engineering and model test, and the density scale is 1:1.2) The seepage field is calculated by finite element program. And the water supply is checked with the result to ensure the supply. Comparing the seepage field from calculating with that from test, we can know more about the special display of seepage field in the condition of high geostress and high external water pressure.3) The stability and deformation of both structures and seepage simulation system are designed and checked by SAP2000 to ensure the test requirement of stress and deformation.4) A discrete multi-planes loading system with waterproof function is brought forward to load the stress field without any change of the seepage field for leaking.5) The placements of different kinds of monitoring instruments are synthetically designed to get enough data for study with no placement conflict. 6) A sealing arrangement is invented to solve the leaking problem with displacement monitor, which is helpful to the stability and authenticity of seepage simulation system. And it is being applied for patent protection.7) A new method which is called inverse control method construction based on the multiple-acting function of the compression energy is used in the construction of physical model to ensure the uniformity of the molding material.