Study On The Mechanical Property Of Yielding Anchor Cable In Underground Cavern

Anchorage cable technology as a member of the rock anchoring technology, after years of development research, has been widely adopted in various anchoring engineering. However, with the construction of a continuous increase, large deformation of rock and soil caused by high and steep slope, deep excavation, large span underground chambers and other projects became more frequently. Since the traditional cable can not adapt to the rock deformation, cable pulled off often appeared. In order to adapt to the rock large deformation of the underground cavern, we can take appropriate pressure to the supporting structure. So, the article research on the new yielding anchor cable supporting system especially in the underground cavern integrated use of literature research, theoretical analysis, laboratory tests and numerical simulation, the main work is as follows:(1) According to the powerhouse downstream wall anchor construction practice of Jinping two cascade hydropower station, by use of theoretical analysis, numerical simulation and field survey methods, found that the traditional prestressed anchor in response to large deformation rock and soil, especially in underground caverns are obviously insufficient. We must explore and develop feasible supporting methods to ensure the safety and stability of surrounding rock of underground structures.(2) Put forward the cable technology to give full play to the pressure concept, the yielding anchor can adapt to large deformation of rock and soil; According to the force state of different between yielding part and the cable, put forward four yielding anchor cable system and three coupled models between yielding part and cable. Through the indoor yielding anchor cable tension test, get the mechanical characteristic curve, the yielding anchor cable can provide considerable yielding displacement than traditional cable and it can reduce the cable stress and the rapid increase, so it can make sure of cable’s normal work.(3) By means of numerical simulation respectively on the cavern without support, by general cable supporting and yielding anchor cable, reveals the yielding anchor which makes deformation can effectively improve the mechanical properties of surrounding rock. The pressure deformation of surrounding rock stress release is good for the stability of surrounding rock; at the same time, release the pressure can greatly release energy, reduce the cable force, can avoid anchor soon reach or exceed the the ultimate strength and causing adverse consequences of the failure, the mechanical properties of yielding anchor cable is better than ordinary cable.(4) The strength of yielding part and other parameters will affect performance and supporting effect to a great extent. When the length of yielding part remain unchanged, the anchor force increases with the increase of the elastic modulus; when the elastic modulus remain unchanged, the cable force decreases with the increase of length. Therefore, in the precondition of ensuring the stability of the surrounding rock, the yielding part’s elastic modulus can be reduced and increase the length of yielding part, to ensure that the cable on the surrounding rock supporting effect and ensure the safety of cable structure.