桥址区老滑坡复活机理及风险评估
发布时间：2018-07-31 08:41
【摘要】：随着高等级公路不断向地形条件复杂的西部地区延伸,在建有桥梁的斜坡地区发育着一系列不同规模的滑坡地质灾害。滑坡灾害不仅威胁到了周围的居民生命财产安全,由于斜坡的不稳定会促使桥梁产生负面的影响,给桥梁的安全运行带来了很大的威胁;另外,斜坡上的桥基在施工、运行中与土体之间存在着桩-土相互作用,反过来给斜坡的稳定性带来一定的影响。所以针对桥址区滑坡灾害,本文首先从理论上分析了在斜坡上的桥基受力特点以及斜坡上桥基-土体之间的相互作用,对比分析了斜坡地段桥基与平坦地段桥基受力状态的区别,同时对滑坡诱发因素作了具体分析;然后以棕树凼大桥滑坡工程实例为依托采用有限元方法对桥址区老滑坡启动机理、抗滑桩位置的选择进行了数值模拟;最后运用蒙特卡罗和层次分析法方法对棕树凼大桥滑坡进行了风险评估计算,确定了滑坡灾害的风险等级。通过以上步骤,本来论文得出以下几点结论:(1)斜坡上桥基的受力状态有其特殊性而不同于平坦地段:斜坡上桥基起到了承受上部结构荷载和坡后土体下滑力,具有“承载抗滑”的双重特点。(2)由于斜坡一侧临空面的存在,桥基四周土体不再是半无限空间体,所以存在“陡坡效应”现象,桥基所受的地基抗力有一定程度的弱化。(3)诱发滑坡产生的因素众多,可以分为两大类:外部因素(地形地貌、地层构造、气象水文、地震作用、人类活动),内部因素(滑坡土体结构、坡面形态),有这些因素的作用才导致了滑坡的产生。(4)通过数值模拟,确定棕树凼大桥老滑坡的启动机理为牵引式,是由于坡体前缘开挖逐渐引起的整个滑坡的失稳破坏。(5)以棕树凼大桥滑坡为例,对与牵引式滑坡在采取抗滑桩支挡的位置进行了优化,得出在桥基前部设置抗滑桩起到抗滑效果更好,限制桥基区土体的位移变形。(6)对棕树凼大桥滑坡灾害进行了危险性分析:得出其失稳概率为0.7785;同时对人口、房屋建筑、交通设施作了易损性分析。(7)在危险性分析和易损性分析的基础上,对棕树凼大桥滑坡的风险值作了计算,得出了灾害风险等级为Ⅲ级。
[Abstract]:As the highway continues to extend to the western region with complex terrain conditions, a series of landslide geological hazards of different scales are developed in the slope area with bridges under construction. The landslide disaster not only threatens the safety of the residents' lives and property, but also brings a great threat to the safe operation of the bridge because of the instability of the slope. In addition, the bridge foundation on the slope is under construction. There is pile-soil interaction between soil and operation, which in turn has a certain influence on the stability of slope. Therefore, in view of the landslide disaster in the bridge site area, this paper first theoretically analyzes the stress characteristics of the bridge foundation on the slope and the interaction between the bridge foundation and soil on the slope. The difference between the stress state of the bridge foundation in the slope section and that of the bridge foundation in the flat section is analyzed, and the induced factors of the landslide are analyzed concretely. Secondly, based on the example of Changshutang Bridge landslide project, the starting mechanism of the old landslide and the selection of the anti-slide pile are numerically simulated by using the finite element method. Finally, the risk assessment and calculation of landslide of Changshutang Bridge are carried out by using Monte Carlo and Analytic hierarchy process (AHP) method, and the risk grade of landslide disaster is determined. Through the above steps, the following conclusions are drawn: (1) the stress state of the bridge foundation on the slope has its particularity and is different from the flat section: the bridge foundation on the slope has played a role in bearing the superstructure load and the sliding force of the soil behind the slope. (2) because of the existence of one side of the slope, the soil around the bridge is no longer a semi-infinite space body, so there exists the phenomenon of "steep slope effect". The ground resistance of bridge foundation is weakened to a certain extent. (3) there are many factors that induce landslide, which can be divided into two categories: external factors (topography and geomorphology, stratigraphic structure, meteorology and hydrology, earthquake, etc.) Human activities), internal factors (landslide soil structure, slope shape), the role of these factors to cause the landslide. (4) through numerical simulation, determine the Changshutang Bridge landslide starting mechanism is traction, This is due to the instability of the whole landslide caused by the excavation of the front edge of the slope body. (5) taking the Changshutang Bridge landslide as an example, the position of the anti-slide pile supporting the landslide with the traction type is optimized. It is concluded that the anti-slide pile in the front of the bridge foundation has better anti-slide effect and limits the displacement and deformation of soil in the bridge foundation area. (6) the hazard analysis of landslide disaster of Changshutang Bridge is carried out: the probability of instability is 0.7785; at the same time, for the population and housing, The vulnerability analysis of traffic facilities is made. (7) on the basis of hazard analysis and vulnerability analysis, the risk value of Changshutang Bridge landslide is calculated, and the disaster risk grade is obtained to be grade 鈪，
本文编号：2155043
[Abstract]:As the highway continues to extend to the western region with complex terrain conditions, a series of landslide geological hazards of different scales are developed in the slope area with bridges under construction. The landslide disaster not only threatens the safety of the residents' lives and property, but also brings a great threat to the safe operation of the bridge because of the instability of the slope. In addition, the bridge foundation on the slope is under construction. There is pile-soil interaction between soil and operation, which in turn has a certain influence on the stability of slope. Therefore, in view of the landslide disaster in the bridge site area, this paper first theoretically analyzes the stress characteristics of the bridge foundation on the slope and the interaction between the bridge foundation and soil on the slope. The difference between the stress state of the bridge foundation in the slope section and that of the bridge foundation in the flat section is analyzed, and the induced factors of the landslide are analyzed concretely. Secondly, based on the example of Changshutang Bridge landslide project, the starting mechanism of the old landslide and the selection of the anti-slide pile are numerically simulated by using the finite element method. Finally, the risk assessment and calculation of landslide of Changshutang Bridge are carried out by using Monte Carlo and Analytic hierarchy process (AHP) method, and the risk grade of landslide disaster is determined. Through the above steps, the following conclusions are drawn: (1) the stress state of the bridge foundation on the slope has its particularity and is different from the flat section: the bridge foundation on the slope has played a role in bearing the superstructure load and the sliding force of the soil behind the slope. (2) because of the existence of one side of the slope, the soil around the bridge is no longer a semi-infinite space body, so there exists the phenomenon of "steep slope effect". The ground resistance of bridge foundation is weakened to a certain extent. (3) there are many factors that induce landslide, which can be divided into two categories: external factors (topography and geomorphology, stratigraphic structure, meteorology and hydrology, earthquake, etc.) Human activities), internal factors (landslide soil structure, slope shape), the role of these factors to cause the landslide. (4) through numerical simulation, determine the Changshutang Bridge landslide starting mechanism is traction, This is due to the instability of the whole landslide caused by the excavation of the front edge of the slope body. (5) taking the Changshutang Bridge landslide as an example, the position of the anti-slide pile supporting the landslide with the traction type is optimized. It is concluded that the anti-slide pile in the front of the bridge foundation has better anti-slide effect and limits the displacement and deformation of soil in the bridge foundation area. (6) the hazard analysis of landslide disaster of Changshutang Bridge is carried out: the probability of instability is 0.7785; at the same time, for the population and housing, The vulnerability analysis of traffic facilities is made. (7) on the basis of hazard analysis and vulnerability analysis, the risk value of Changshutang Bridge landslide is calculated, and the disaster risk grade is obtained to be grade 鈪，
本文编号：2155043
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