库水位骤降对公路边坡的稳定性研究

发布时间：2018-03-21 06:14

本文选题：库区公路　切入点：边坡　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：库区公路由于其所处地区地形地貌、水文地质条件、自然人文环境的制约,导致其工程环境往往相比一般公路建设更为复杂。库区公路的稳定性不但受到岩土性质、边坡形式的影响,还受到库区水位不断涨落的影响,处治不当极易发生失稳破坏。本文主要采用FLAC3D数值方法模拟得到了库区公路边坡在不同工况下的稳定性变化,并利用FLAC3D建立流固耦合模型,采用强度折减法,得到了库水位骤降过程中边坡的稳定系数变化及潜在的破坏形式的变化。根据边坡稳定性模拟的结果,提出了库区边坡的加固处治建议,对实际工程具有一定的指导意义。本文主要取得了以下的研究结论:(1)分析了库水位在下降时,非稳定渗流方程的建立,坡体内浸润线的确立及库水骤降缓降对边坡稳定的影响。研究表明:长期高水位后的骤降对迎水坡是最不利的,主要是饱和坡体内的孔隙水压力来不及消散而形成向坡外渗流所致,而且多发生在浸润线高、透水性差的较陡粘性土质边坡上。(2)利用FLAC3D软件建立数值模型,采用强度折减法,研究了不同工况下库水位涨落,尤其是当库区水位发生骤降时,边坡稳定性的变化。结果表明:库区公路边坡在施工期的稳定性主要受到边坡土体的自重和坡面形式的影响;库区公路边坡在正常蓄水期由于水的渗透力作用往往安全系数得到提高;在库水位发生骤降后,边坡的安全系数迅速减小。经放坡和抛石加固处治后,再次对库区公路边坡在不同工况的稳定性进行了模拟,结果表明安全系数得到了较大的提高,确保了公路的正常运行。(3)对水位骤降过程中的边坡安全系数的变化进行了分析。研究表明:在此过程中安全系数随着水位下降呈现先减后略增的趋势。在最危险水面高度处,边坡的水平位移、竖直位移、整体位移等达到了最大值。因为坡内水体来不及排出,与坡外水体形成的高水位差,使得下部坡体和坡脚有向外“剪出”的潜在破坏,此时的边坡稳定性最差。(4)利用FLAC3D软件对经放坡和抛石加固处治后的库区公路边坡,在不同工况下的稳定性进行了模拟,结果表明:经加固处治后,不同工况下其安全系数均得到了较大的提高,但上部可能出现局部失稳,应采取必要措施。对于受库水影响的高陡边坡,建议采用放坡加固,且进行上部路基的加固和蓄水位以下的坡面防护;对于受库水严重影响的浸水路基,可采用挡土墙加固,且应注意设置排水系统。
[Abstract]:Because of the constraints of topography, hydrogeology and natural and humanistic environment, the engineering environment of the highway in the reservoir area is often more complex than that of the general highway construction, and the stability of the highway in the reservoir area is not only affected by the rock and soil properties, but also by the stability of the highway in the reservoir area. The influence of slope form is also affected by the constant fluctuation of water level in the reservoir area, and the improper treatment is very easy to occur instability damage. In this paper, FLAC3D numerical method is mainly used to simulate the stability changes of the highway slope in the reservoir area under different working conditions. The fluid-solid coupling model is established by FLAC3D, and the variation of slope stability coefficient and potential failure form during sudden drop of reservoir water level are obtained by using strength reduction method. According to the results of slope stability simulation, This paper puts forward some suggestions for reinforcement and treatment of slope in the reservoir area, which is of certain guiding significance for practical engineering. The following conclusions are obtained in this paper: 1) the establishment of unsteady seepage equation when the water level of reservoir is falling is analyzed. The establishment of the infiltration line in the slope and the influence of the sudden drop of reservoir water on the slope stability. The study shows that the sudden drop after a long period of high water level is the most disadvantageous to the slope facing the water. The main reason is that the pore water pressure in the saturated slope can not be dissipated and the seepage is formed out of the slope, and mostly occurs on the steep viscous soil slope with high infiltration line and poor permeability.) the numerical model is established by using FLAC3D software, and the strength reduction method is adopted. The fluctuation of reservoir water level under different working conditions is studied, especially when the water level of reservoir area drops suddenly, the stability of highway slope in reservoir area is mainly affected by the gravity of slope soil and the form of slope surface during the construction period. During the normal storage period, the safety factor of the highway slope in the reservoir area is often improved due to the effect of water permeability, and the safety factor of the slope decreases rapidly after the sudden drop of the reservoir water level. Thirdly, the stability of highway slope in reservoir area under different working conditions is simulated, and the results show that the safety factor has been greatly improved. The variation of slope safety factor during the sudden drop of water level is analyzed. The results show that the safety factor decreases first and then increases with the decrease of water level in this process. The horizontal displacement, vertical displacement, and overall displacement of the slope have reached the maximum value. Because the water in the slope cannot be discharged without time, the difference between the high water level of the water body outside the slope and the water body outside the slope makes the lower slope body and the foot of the slope have the potential damage of "shearing out" outwards. At this time, the slope stability is the worst. The stability of the reservoir area highway slope strengthened by sloping and riprap is simulated by using FLAC3D software. The results show that: after strengthening and treating, the stability of the slope under different conditions is simulated. The safety coefficient has been greatly improved under different working conditions, but the local instability may occur in the upper part, so the necessary measures should be taken. For the high and steep slope affected by reservoir water, it is suggested to reinforce the slope by sloping. The reinforcement of the upper subgrade and the protection of the slope below the storage water level, the retaining wall can be used to reinforce the flooded roadbed which is seriously affected by the reservoir water, and the drainage system should be set up.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.14

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