四川宣汉桐子园滑坡变形破坏机制及稳定性研究

发布时间：2018-10-04 21:00

【摘要】：桐子园滑坡形成于缓倾角(10°-20°)的砂泥岩互层的红层地层。通常认为缓倾角红层滑坡由重力提供的下滑力很小,仅靠重力作用很难形成滑坡,其形成原因与红层的特殊性质和强降雨是密不可分的。红层滑坡广泛的分布在四川盆地,对人民生命财产安全构成极大威胁。因此,对桐子园滑坡的研究进一步揭示了红层滑坡的成因机制,对防灾减灾具有重要意义。本文以四川宣汉桐子园滑坡为研究对象,根据实地调查、现场试验、室内试验,通过地质理论分析、数值模拟计算对桐子园滑坡进行了全方位的研究。本文主要研究成果如下:(1)详尽描述了滑坡的规模、边界、滑坡物质组成、变形破坏特征。根据滑坡的边界、变形破坏特征、破坏程度、裂缝分布特点,将滑坡划分为四个区域:拉陷变形区、强变形区、弱变形区、超覆区。(2)从地质条件影响因素和降雨影响因素分析了桐子园滑坡的成因机制,认为降雨是诱发桐子园滑坡的最主要因素,滑坡形成过程可分为四个阶段:降雨入渗裂隙发展软弱带抗剪强度降低,扬压力产生孔隙水压力、扬压力上升失稳滑动。通过恢复桐子园滑坡的原地貌,用离散元软件UDEC模拟了桐子园滑坡在不同工况下的变形特征。结果表明,桐子园滑坡只有在后缘高孔隙水压力、沿软弱带扬压力、软弱带抗剪强度降低的共同作用下才会发生滑动。(3)用极限平衡法计算了桐子园滑坡在天然、暴雨、地震、暴雨+地震工况下的稳定性。结果表明:天然工况下滑坡是稳定的;地震工况下滑坡稳定性有所降低,滑坡处于基本稳定~稳定状态;暴雨对滑坡稳定性影响较大,滑坡处于基本稳定状态;地震+暴雨的极限工况下滑坡失稳。(4)用单因素分析法分析了粘聚力c、内摩擦角?、地震加速度a对桐子园滑坡稳定性的影响,分析结果表明内摩擦角?对桐子园滑坡稳定性影响最大。(5)运用有限差分法数值模拟软件FLAC3D对桐子园滑坡在天然、暴雨、地震、暴雨+地震四种工况下的稳定性进行了分析。分析结果表明:天然工况下的各项特征均表明滑坡没有变形破坏迹象,滑坡处于稳定状态;滑坡在暴雨工况下的最大位移为5.2cm,局部形成了贯通的塑性变形区,未形成剪应变增量贯通带,说明滑坡整体是稳定的,局部可能发生变形破坏。滑坡在地震工况下,最大位移为3.6cm,未形成贯通的塑性变形区,未形成剪应变增量贯通带,说明滑坡是稳定的。地震+暴雨工况下滑坡出现明显变形破坏特征,最大位移量为59cm,坡体发生大规模塑性变形破坏,形成了贯通的塑性变形区,中前部形成了剪应变增量贯通带。(6)根据桐子园滑坡的变形特征、影响因素、成因机制、稳定性状况提出了“削方减载+拉陷槽回填+裂缝封闭+地表排水工程”的治理措施。
[Abstract]:Tongziyuan landslide is formed in the red stratum of sand and mudstone interbedded with gentle dip angle (10 掳-20 掳). It is generally considered that the sliding force provided by gravity is very small, and it is difficult to form landslide by gravity alone, which is closely related to the special properties of red beds and heavy rainfall. Red-bed landslide is widely distributed in Sichuan Basin, which poses a great threat to the safety of people's life and property. Therefore, the study of Tongziyuan landslide further reveals the formation mechanism of red bed landslide, which is of great significance for disaster prevention and mitigation. In this paper, Tongziyuan landslide in Xuanghan County, Sichuan Province is taken as the research object. According to field investigation, field test, laboratory test, geological theory analysis and numerical simulation calculation, Tongziyuan landslide is studied in all directions. The main results of this paper are as follows: (1) the scale, boundary, material composition, deformation and failure characteristics of landslide are described in detail. According to the boundary of the landslide, the characteristics of deformation and failure, the degree of failure and the distribution of cracks, the landslide is divided into four regions: drawing deformation area, strong deformation area, weak deformation area, and so on. (2) the cause mechanism of Tongziyuan landslide is analyzed from the factors of geological condition and rainfall, and it is considered that rainfall is the main factor that induces Tongziyuan landslide. The forming process of landslide can be divided into four stages: the shear strength of the weak zone developed by rainfall infiltration fissures decreases, the uplift pressure produces pore water pressure, and the uplift pressure rises and loses stability and slips. By restoring the original landform of Tongziyuan landslide, the deformation characteristics of Tongziyuan landslide under different working conditions were simulated by discrete element software UDEC. The results show that the Tongziyuan landslide will slip only under the combined action of high pore water pressure in the rear edge, uplifting pressure along the weak zone and decreasing shear strength of the weak zone. (3) the Tongziyuan landslide in natural, torrential rain and earthquake is calculated by using the limit equilibrium method. Stability of torrential rain under earthquake conditions. The results show that the landslide is stable under natural working conditions, the landslide stability is reduced under earthquake condition, the landslide is in the basic stable state, the rainstorm has a great influence on the landslide stability, and the landslide is in the basic stable state. The landslide is unstable under the limit condition of earthquake rainstorm. (4) the cohesive force c and the angle of internal friction are analyzed by single factor analysis. , the effect of seismic acceleration a on the stability of Tongziyuan landslide. The results show that the internal friction angle? The stability of Tongziyuan landslide is the most important. (5) the stability of Tongziyuan landslide under natural, rainstorm, earthquake and rainstorm conditions is analyzed by using finite difference numerical simulation software FLAC3D. The results show that the landslide has no signs of deformation and failure and is in a stable state, and the maximum displacement of landslide is 5.2 cm under the condition of heavy rain, and a through plastic deformation zone is formed locally. The failure of shear strain increment through zone indicates that the whole landslide is stable and local deformation and failure may occur. Under seismic conditions, the maximum displacement of landslide is 3.6 cm, the plastic deformation zone is not formed and the shear strain increment through zone is not formed, which indicates that the landslide is stable. Under the condition of earthquake rainstorm, the landslide appears obvious deformation and failure characteristics, the maximum displacement is 59 cm, and the slope body has large-scale plastic deformation and failure, forming a through plastic deformation zone. According to the deformation characteristics of Tongziyuan landslide, influencing factors, forming mechanism and stability condition, the paper puts forward the treatment measures of "sealing surface drainage project with backfill crack of reducing load and draining trough of cutting square". (6) according to the deformation characteristics of Tongziyuan landslide, the influence factors, the cause mechanism and the stability condition are put forward.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22

【引证文献】