水流淘刷作用下土质边坡稳定性研究

发布时间：2018-05-16 04:23

本文选题：土质边坡 + 冲刷破坏　；参考：《东北农业大学》2017年硕士论文

【摘要】：天然土质河岸受到长年累月冲刷导致的崩岸问题屡见不鲜,河岸边坡冲刷破坏一直是工程界和科研工作者关心的问题之一。在黑龙江省,由于边界河众多,我国一侧河岸的冲退,无时不刻蚕食的国土,崩岸给人民财产和正常社会生活造成的影响日益凸显。本文在总结前人对极限平衡法的丰富和发展基础之上,利用有限差分强度折减法(Flac3D软件)和有限元法(Geo-studio软件)对土质岸坡稳定性进行分析,探讨了各影响因素对边坡稳定的敏感度。研究了在水流冲刷作用下,河岸展宽和冲深数学计算模型,利用松花江某水文站2008-2010年水文地质资料进行了冲刷模拟计算。利用有限元边坡稳定分析方法,借助Geo-studio软件对土质岸坡稳态渗流条件下,考虑边坡内部应力应变的变化,探讨了水位升降对岸坡稳定性的影响。主要研究成果和内容如下:(1)河岸土质条件是崩岸发生的内在因素,水流条件是破坏发生的外在因素,也是决定性因素。通过对各内在因素进行敏感性分析得出坡角的敏感度为0.785,内摩擦角为0.561,粘聚力为0.417,容重为0.409,边坡坡角对边坡稳定性影响最大,内摩擦角和粘聚力其次,相比而言土的容重最小。(2)对一概化均质边坡进行稳定性计算,发现有限元法和有限差分强度折减法计算得到安全系数要大于极限平衡法的计算结果。相比极限平衡法,有限元法和有限差分法无需对滑坡体受力情况进行假定,减少了误差,计算结果更为精确。(3)利用松花江2008-2010年相关水文地质资料计算的河流展宽和冲深结果表明,河岸在汛期冲刷较为剧烈,非汛期冲刷量较小。横向和纵向冲刷速率在2010年汛期达到了3.4 cm/d和3.1 cm/d。河道冲刷深度受河道含沙量变化影响较大,受水深和河道宽度变化影响较小。河道横向展宽受水深和河道宽度变化影响较为明显,受含沙量因素影响较小。(4)随着坡前水位上升边坡稳定性逐渐增强,随着水位下降稳定性逐渐降低,河岸易在退水期发生失稳崩岸。随着水位的下降岸坡安全系数呈指数下降。水位降低速率越快,边坡稳定性越差,越快达到临界失稳状态。边坡坡脚处不断冲退,导致坡脚处出现应力集中现象,最大变形量逐渐增大,稳定性逐渐降低。(5)雷诺护垫结构、砼铰接块结构、预制混凝土板结合保温衬砌结构等护岸措施应配合合理的护岸形式,因地制宜综合运用,充分发挥材料特性才能减轻季冻区河岸在受到水流冲刷、冻胀和冻融循环作用时的破坏。
[Abstract]:The problem of bank collapse caused by long years of erosion of natural soil riverbanks is common. Erosion and damage of riverbank slopes has always been one of the problems concerned by engineers and researchers. In Heilongjiang province, because of the numerous border rivers, the bank of one side of our country is washed away and the land is nibbled away from time to time. The impact of bank collapse on people's property and normal social life is becoming increasingly prominent. On the basis of summing up the enrichment and development of the limit equilibrium method, this paper analyzes the slope stability of soil by using the finite difference strength reduction method (Flac3D) and the finite element method (Geo-studio). The sensitivity of each factor to slope stability is discussed. In this paper, the mathematical model of river bank widening and scouring depth under the action of water flow is studied, and the hydrogeological data of a hydrologic station in Songhua River from 2008 to 2010 are used to simulate the scour calculation. By using the finite element method of slope stability analysis, the influence of water level rise and fall on slope stability is discussed under the condition of steady seepage of soil bank slope under the condition of Geo-studio software, considering the variation of internal stress and strain of slope. The main research results and contents are as follows: (1) the soil condition of the river bank is the internal factor of the bank collapse, the water flow condition is the external factor and the decisive factor of the damage. The sensitivity of slope angle is 0.785, internal friction angle is 0.561, cohesion force is 0.417, bulk density is 0.409, slope angle has the most influence on slope stability, and internal friction angle and cohesion force are the second. By comparison, the stability of the homogeneous slope is calculated by the minimum bulk density of soil. It is found that the safety factor obtained by the finite element method and the finite difference strength reduction method is greater than that by the limit equilibrium method. Compared with the limit equilibrium method, the finite element method and the finite difference method do not need to assume the stress of the landslide body, thus reducing the error. Based on the hydrogeological data of the Songhua River from 2008 to 2010, the results of river widening and scouring show that the river bank scour is more intense in flood season and less in non-flood season. The horizontal and vertical scour rates reached 3.4 cm/d and 3.1 cm / d in the flood season in 2010. The depth of the channel erosion is influenced by the sediment content of the channel greatly, but by the change of the water depth and the width of the channel to a lesser extent. The lateral widening of the channel is affected by the variation of water depth and channel width, and the influence of sediment content is less. 4) the slope stability increases gradually with the rise of the water level in front of the slope, and decreases gradually with the decrease of the water level. Banks tend to collapse during the receding period. With the decrease of water level, the slope safety factor decreases exponentially. The faster the water level is lowered, the worse the slope stability is and the faster it reaches the critical state of instability. At the foot of the slope, the stress concentration appears at the foot of the slope, the maximum deformation increases gradually, the stability decreases gradually) the Renault cushion structure and the concrete hinge structure, The bank protection measures such as precast concrete slabs combined with thermal insulation lining structure should be combined with reasonable bank protection form and be used comprehensively according to local conditions to give full play to the characteristics of materials in order to reduce the erosion of river banks in seasonal frozen areas by the flow of water. Damage caused by frost heaving and freeze-thaw cycles.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223

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