崩岸的模型试验及数值模拟分析

发布时间：2018-03-24 18:33

本文选题：崩岸　切入点：物理力学性质　出处：《合肥工业大学》2017年硕士论文

【摘要】：河流崩岸是一个跨学科的前沿研究课题,目前,对崩岸机理的研究尚未清楚,崩岸问题还没有得到较好的解决,缺乏各学科的综合交叉研究。通过对河岸崩塌机理研究成果,旨在丰富各学科的内容,具有重要的理论价值。依托和悦洲崩岸治理工程,通过对河岸崩岸的模型试验、数值模拟以及理论分析,揭示崩岸演化规律,对崩岸机理的进行初步认识和理论探讨。采用室内模型试验的方法,重点分析坡体在四种不同地下水位与坡前水位组合工况下的坡内孔隙水压力、土压力以及坡体位移的变化规律。试验结果表明:坡体从稳定到崩塌大致经历了水流冲刷、裂缝发育、整体崩塌的过程;在崩塌过程中,孔隙水压力基本保持稳定,而坡体崩塌时土压力值发生突变,且在突变前有一定的上升或波动现象;工况一与工况二试验结果比较,得出当地下水位稳定且坡前水位较高,坡体较为容易发生崩塌;工况二与工况三试验结果比较,当坡前水位一定且地下水位较高时,坡体易失稳;在工况四坡前水位下降过程中,地内水位具有滞后性,坡内形成非稳定渗流。采用数值模拟方法,结合考虑流固耦合理论及强度折减法,研究水位下降过程中的边坡稳定性问题。研究结果表明:在水位下降过程中,坡内孔隙水压力逐渐减小,坡内渗透压逐渐增大,坡体表层低应力区(130kPa区域)范围增大且逐渐向坡脚处移动,坡体稳定性下降,逐渐失稳破坏。综合研究成果,水位骤降是最危险工况之一,当水位快速下降时,平衡岸坡饱和土体的侧向静水压力迅速减小,坡内水位的滞后性导致孔隙水压力未完全消散,同时又产生指向坡外的渗透压力,不利于岸坡稳定。因此,在丰水期更需防范崩岸险情。且在实际工程中,不仅要监测坡体位移变化,其表层应力的监测分析也是必要的,这为深入研究皖江崩岸提供了新思路。
[Abstract]:River bank collapse is an interdisciplinary and frontier research subject. At present, the research on the mechanism of bank collapse is not clear, the problem of bank collapse has not been solved well, and there is a lack of comprehensive cross-study of various disciplines. In order to enrich the contents of various disciplines and have important theoretical value, relying on the Heyuezhou bank collapse control project, through the model test, numerical simulation and theoretical analysis of the bank collapse, the law of bank collapse evolution is revealed. This paper makes a preliminary understanding and theoretical discussion on the mechanism of bank collapse. By using the method of indoor model test, the pore water pressure of slope body under four different conditions of combination of groundwater level and front water level is analyzed emphatically. The experimental results show that the slope body experienced the process of flow erosion, fracture development and overall collapse from stability to collapse, and pore water pressure remained stable in the process of collapse. However, when the slope collapses, the earth pressure changes, and there is a certain rise or fluctuation before the abrupt change, the results of the first condition and the second condition show that when the groundwater level is stable and the front water level is high, the slope body is prone to collapse. Compared with the test results of the third condition, the slope body is vulnerable to instability when the water level in front of the slope is fixed and the groundwater level is high, and the water level within the ground has the hysteresis in the process of the water level falling in the four slopes under the working conditions. Unsteady seepage is formed in the slope. The slope stability in the process of water level decline is studied by using numerical simulation method, considering the fluid-solid coupling theory and strength reduction method. The results show that: in the process of water level falling, The pore water pressure in the slope decreases gradually, the osmotic pressure in the slope increases gradually, the area of low stress region of slope surface layer increases and gradually moves to the foot of the slope, the stability of the slope body decreases and the stability of the slope is destroyed gradually. The sudden drop of water level is one of the most dangerous conditions. When the water level drops rapidly, the lateral hydrostatic pressure of equilibrium bank saturated soil decreases rapidly, and the pore-water pressure does not dissipate completely due to the lag of the water level in the slope. At the same time, the seepage pressure pointing to the slope is also produced, which is not conducive to the stability of the bank slope. Therefore, in the high water season, it is more necessary to prevent the bank collapse. In the actual engineering, it is necessary not only to monitor the displacement of the slope body, but also to monitor and analyze the surface stress. This provides a new idea for the further study of the bank collapse of Anhui River.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV147

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