Study On Earthquake Responses And Shock Absorption Measures For Water-Conveyance Tunnel In Soft Soil

As the society and economy develop rapidly, the problem of safety attracts more and more attention worldwide. As it is known to us, water is necessary for human's survival, life and development. However, the distribution of water resource in our country is not homogeneous. The reality of suffering from water-logging in the north and drought in the south has already severely influenced the development of economy and improvement of people's living standard. Extracting groundwater excessively leads to drop of water height and the subsidence of ground surface in many central cities. In order to solve this problem completely, the Project for South-North Water Transfer of world interest has been already going on. Our country is an earthquake region and the geological condition is complicated. Thus, a lot of water-conveyance tunnels will pass through rivers and bays unavoidably, around which usually is soft soil consists of gravel layer, glue soil layer and deposit layer. For example, the central line of the Project for South-North Water Transfer in our country passes through northwest loess. The water-conveyance tunnel may settle non-homogeneously. So, it is necessary to study the characteristics of the water-conveyance project under the earthquake. Moreover, the water-conveyance tunnel is different to general underground structures. Not only the interaction of surrounding rock and structure but also the interaction of the structure and water are considered in the water-conveyance tunnel. So its characteristic of vibration is much more complicated than underground structure or ground structure. Thus, fluid-structure coupling analytical method is used in this paper. The dynamic response of water-conveyance tunnel is analyzed by solving the fluid-structure coupling dynamic equation based on the potential fluid. The main content is as follows.Firstly, the basic equations of solid and fluid also several fluid simplified models are discussed, which are the base of after work.Secondly, according to models chosen for surrounding rock, lining and water, the fluid-structure coupling equation based on potential fluid is established. The seismic response of a water-conveying tunnel through river bed is analyzed, which considers the influence of additional water mass and free surface. As an important accessory structure of water-conveyance tunnel, the shaft is specially studied.Thirdly, the seismic response and failure mechanism of lining, circular seam join, vertical shaft, and are studied aiming at several main parameters which affect the water-conveyance tunnel under the earthquake: embedment depth, surrounding rock property, structure characteristic and inputting of earthquake motion, etc. Particularly, according to fluid-structure-solid coupling equation for uniform earthquake excitation, fluid-structure-solid coupling equation for multi-support seismic excitations is derived. Meanwhile, effect of wave velocity on seismic response of water-conveyance tunnel is analyzed.Subsequently, the simplified model of inner water is applied to the aseismic design of water-conveyance tunnel in the soft soil, which is in contrast with the fluid-structure method based on potential fluid. According to geological conditions and earthquake characteristics, corresponding shock isolation and absorption of vibration methods are presented for different positions of water-conveyance tunnel.Finally, a dynamic numerical model experiment of the water-conveyance tunnel in soft soil is present. Firstly, the similarity criterions of model experiment for identical materials and different materials are certified. Subsequently, a similarity technique for different materials is presented.