| Western development is an important national policy of our country. In order to promote Western development, we must vigorously develop the western road network construction. When the roads, railways across the mountains, we must built a large number of etsurei tunnels, and then we may encounter a high pressure water-rich region inevitably. Such as:Qi Yue mountain tunnel of Yichang-wanzhou railway, Huarong tunnel of Guang-Yu highway, Zhongliang mountain tunnel of Chengdu-Chongqing highway and so on. In twenty-first century, the harmonious development between man and nature is the theme of social development, scientific concept of development put forward specific requirements for the protection of the natural environment (especially water resources).So when we construct the mountain tunnels in high-level areas, should change the past "Row" mentality. If we take the full closure program of Mass Transit railway, not only increases costs but also make lining under tremendous water pressure and greatly increased the difficulty of the design of the tunnel structure. As a result, when construct mountain tunnels,we should be based on the requirements of the surrounding environment and change "Row" to "blocking", namely to achieve the "row-based, combination of anti-handling" to "to block the main, limited emissions" changes. In that way, how to calculate the external water pressure that tunnel lining support? How does the effect of external water pressure on the tunnel lining? And what measures can effectively reduce the lining suffered external water pressure in order to ensure the safety of lining? Slove these problems, create value of outstanding engineering practice for tunnel design and construction on the high-water rock water area. In this paper, use Yu-huai-line Yuanliang tunnel which has been built as engineering background, discuss the impact of high-pressure structural stability of the tunnel.The main research contents:(1). Access to relevant literature, a large number of practices shows that:only by changing "row-based, combination of anti-handling" which in the past as "to block the main, limited emissions" can effectively protect the groundwater resources. Elaborates the present five commonly used methods of calculate external water pressure of our country.(2). Analysis of the distribution and the burial condition of groundwater in bedrock, discuss the main types of bedrock ground water.(3). Under the condition of water shutoff and emission limit, derived the formula of the lining external water pressure in mountain tunnel about homogeneous rock. On this basis, analysis of relationship between tunnel external water pressure reduction factor and tunnel discharge, grounting parameters(thickniss and gronting level). (4). Discuss the adverse effects of the existence of groundwater to tunnel, numerical analysis the mechanical properties of lining about five sections of Yuan-liang mountain tunnel on the high water-pressure. By comparison, proposed that cross-section shape of tunnel under high water pressure should be round and egg suitable. Use a circular cross section as example, combined with the project example of Yuan-liang tunnel, numerical analysis the external water pressure of tunnel under differences grouting ring thickness and grouting level. |
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