四川省荥经县杨底下滑坡组合支挡结构失效机理研究

发布时间：2018-04-02 20:16

本文选题：抗滑桩　切入点：土拱效应　出处：《西南交通大学》2017年硕士论文

【摘要】：四川荥经县杨底下滑坡原属老滑坡,因2013年4.20芦山地震居民集中安置,在老滑坡体前缘进行开挖,开挖前已完成了抗滑桩工程,但桩间未挂板,在2015年汛期首先桩间土体发生坍滑,严重时导致部分抗滑桩发生倾倒变形而失效(抗滑桩A6～A9以上土体垮塌至原放坡坡顶,A12～A24桩以上格构全部垮塌损毁,A19～A24桩发生倾斜)。显然系统研究针对复杂施工条件下滑坡体前缘桩间板组合结构变形乃至失效机理,不仅对本工程具有重要意义,而且对类似地质条件下的抗滑桩板墙结构设计及施工也具有示范借鉴意义。杨底下滑坡整体平面上呈"长弓状"分布,长约225m,宽约440m,面积约0.082km2,体积约176×104m3,主滑方向120°。据钻孔和抗滑桩开挖揭露,老滑坡体下部仍保留原岩结构的似层状结构特点,滑体主要由含粉质粘土夹泥岩碎块和原有基岩滑体滑动破碎后形成的似层状巨块石层组成。滑带土主要为含粘粒的碎石土,滑床为白垩系上统灌口组(K2g)泥岩。本文在现场勘查、取样室内试验等基础上,对滑坡前缘局部抗滑桩倾倒失稳原因进行了探讨,通过正交试验、采用FLAC3D数值模拟方法,对滑坡推力、桩间距、桩边长、弹性模量和泊松比影响桩间土拱效应的程度进行定量分析。在桩间成拱基础上,先用理论和模拟方法分析土拱拱高,再根据拱高分析拱前土体产生的土压力和剩余下滑力,并根据其较大值来判断桩间板(墙)所受到的荷载和组合支挡结构的失效机理。最后根据上述研究成果,对已倾倒抗滑桩提出相应的修复加固治理措施建议。主要研究内容和成果如下:1、通过野外调查,描述说明了杨底下滑坡的工程地质条件和变形破坏特征,并据此提出其变形失稳和形成机制;2、利用极限平衡法、传递系数法分别对老滑坡和推测表层滑坡进行了稳定性分析,并描述因烈太产业新城开建而采用的治理措施;3、研究了抗滑桩与土体之间相互作用的受力模型,并利用正交试验和FLAC3D数值模拟分析了滑坡推力、桩间距、桩边长、弹性模量和泊松比对土拱效应的影响程度;4、分析了土拱效应对桩板墙结构中各个结构物受力分配产生的影响;5、利用FLAC3D和土拱理论分析了抗滑桩组合支挡结构的失效机理;6、根据上述滑坡体的整体研究和失效部位工程的失效机理,对此失效工程提出了"砂袋堆砌+钢管桩基础+竹夹板临时防护+坡面平整"的综合治理措施。
[Abstract]:The landslide in Yangxia, Xingjing County, Sichuan, originally belonged to the old landslide. Due to the concentrated settlement of the residents of the Lushan earthquake on 20 April 2013, excavation was carried out on the front edge of the old landslide body. Before the excavation, anti-slide piles were completed, but no plates were hung between the piles.In the flood season of 2015, the soil between piles collapses and collapses, which results in the toppling deformation of some anti-slide piles. (the soil above A6~A9 of anti-slide pile collapses to the top of the original slope slope, and all the overlying structures of A12 and A24 piles collapse and damage the slope of A19 and A24 piles.It is obvious that systematic study on deformation and failure mechanism of composite structure with pile and plate at the front edge of landslide body under complex construction conditions is not only of great significance to this project,It is also of great significance for the design and construction of anti-slide pile-slab wall under similar geological conditions.The whole plane of Yangxia landslide has a "long bow" distribution, which is about 225 m long, 440 m wide, 0.082 km ~ 2 area, 176 脳 10 ~ 4 m ~ 3 volume and 120 掳main slide direction.It is revealed by drilling and anti-slide pile excavation that the lower part of the old landslide still retains the characteristics of the stratiform structure of the original rock structure. The slip body is mainly composed of silty clay mudstone fragments and the similar layered megaclones formed after sliding and breaking of the original skid rock.The slip zone soil is mainly clay grained gravel, and the sliding bed is K2g mudstone of upper Cretaceous Guankou formation.On the basis of site investigation and sampling laboratory test, this paper discusses the causes of the toppling instability of local anti-slide piles at the leading edge of the landslide. Through orthogonal test and FLAC3D numerical simulation method, the thrust of landslide, the spacing of piles, the length of pile side, and so on, are studied.The influence of elastic modulus and Poisson ratio on the soil arch effect between piles was analyzed quantitatively.Based on the arch foundation between piles, the soil arch height is analyzed by theory and simulation method, and then the earth pressure and residual sliding force produced by soil in front of arch are analyzed according to the arch height.The failure mechanism of the composite retaining structure and the load on the pile plate (wall) are judged according to its larger value.Finally, according to the above research results, the paper puts forward the corresponding measures for repairing and strengthening the toppled anti-slide pile.The main research contents and results are as follows: 1. Through field investigation, the engineering geological conditions and deformation-failure characteristics of Yangxia landslide are described, and the deformation instability and formation mechanism of the landslide are put forward, and the limit equilibrium method is used.The transfer coefficient method is used to analyze the stability of the old landslide and the surficial landslide respectively, and to describe the treatment measures adopted for the construction of the new city of Liedai industry. The interaction between the anti-slide pile and the soil is studied.By using orthogonal test and FLAC3D numerical simulation, the thrust of landslide, the distance between piles, the length of pile side are analyzed.The influence degree of elastic modulus and Poisson ratio on soil arch effect is analyzed. The influence of soil arch effect on the distribution of various structures in pile-slab wall structure is analyzed. Using FLAC3D and soil arch theory, the loss of anti-slide pile composite retaining structure is analyzed.According to the overall study of the landslide and the failure mechanism of the failure site engineering,In view of this failure engineering, the comprehensive control measures of "temporary protection of bamboo splint on sand bag pile foundation for slope leveling" are put forward.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.22

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