三峡库区侏罗系地层推移式滑坡—抗滑桩相互作用研究

发布时间：2018-05-31 08:34

本文选题：推移式滑坡 + 演化过程　；参考：《中国地质大学》2014年博士论文

【摘要】：滑坡是斜坡破坏类型中分布最广、危害最大的一种地质灾害,其演化过程包含了从孕育、发展直至消亡的整个周期活动。随着我国经济建设的蓬勃发展,大批重大基础设施建设实施过程将受到滑坡灾害的严重威胁。因此,亟需对滑坡治理方法进行系统研究,并据此为工程实践提供科学依据。抗滑桩是滑坡治理的主要措施之一,具有抗滑能力强、适用条件广、施工安全简便、能核实地质条件等突出优点,得到了极为广泛的应用。但目前抗滑桩设计的理论方法还不成熟,抗滑桩承载特性、桩-土相互作用机理以及荷载传递规律等尚未十分明确。为此,深入开展抗滑桩与滑坡相互作用研究是当前迫切需要解决的应用课题之一。在建立滑坡地质力学分析模型并阐明滑坡基本演化特征的基础上,结合三峡库区侏罗系地层岩层结构特征,重点开展了基于推移式滑坡-抗滑桩体系演化过程的桩土相互作用研究,据此延伸出了相关抗滑桩优化设计方法并运用于工程案例。取得的主要研究成果如下： (1)基于“三段式”滑动模式的力学模型,对推移式滑坡与牵引式滑坡的力学成因机制进行了对比研究,讨论了两者的差异性。从地形地貌、地层岩性、地质构造、水文地质等方面分析了推移式滑坡的基本形成条件。总结了三峡库区典型推移式滑坡—新滩滑坡的变形破坏过程和裂缝配套体系的发展规律。从滑坡形态特征、物质组成、结构组成、动力因素四个方面,建立了推移式滑坡概化地质力学模型。提出了模拟渐进推移式滑坡演化过程的推力控制法以及适用于模拟突变推移式滑坡的位移控制法。总结了三峡库区侏罗系地层岩性特征和分布规律,对比分析了软、硬岩层物理力学性质的差异性,提出了软硬相间岩层概化分析模型。 (2)采用室内物理模型试验方法模拟了推移式滑坡的演化过程。利用三维激光扫描技术监测滑坡不同演化阶段模型表面点云数据,揭示了滑坡演化规律和裂缝体系的分期配套特征。根据坡表代表性监测点位移时程曲线,采用广义关联维方法,分析了滑坡演化过程中多重分形维数变化规律,并以此为依据,将推移式滑坡演化过程划分为后缘压缩阶段、匀速变形阶段、加速变形阶段。其中,后缘压缩阶段对应的位移多重分维数呈降维特征,匀速变形阶段时多重分维数整体呈先减后增的变化趋势,加速变形阶段多重分维数表现出增维趋势。运用数值模拟方法再现了推移式滑坡的演化过程,计算结果与模型试验结果基本吻合,验证了推移式滑坡演化过程的阶段性,揭示了滑坡演化过程中稳定性系数的非线性衰减规律。 (3)提出了兼顾滑坡自身特征和桩土相互作用的“半模型”试验方法,重点阐述了桩前滑体概化步骤；研发了一种多工况框架式滑坡地质力学模型轻便试验装置,利用该装置可模拟多工况条件下滑坡变形破坏特征与滑坡-抗滑桩相互作用过程；配套研发了一种模拟库水位升降过程的试验设备,可实现水位波动的自动化模拟；提供了一种滑坡物理模型试验多场信息监测方法,能实现滑坡演化过程中位移场、应力场、温度场多场变化特征的精确测量；考虑到干扰信号对试验监测数据的影响,采用LabVIEW程序开发平台,编程实现了基于Butterworth低通滤波器的可视化试验数据滤波软件。 (4)通过物理模型试验方法研究了抗滑桩悬臂段与推移式滑坡相互作用过程。①抗滑桩改变了滑坡的演化过程,导致滑坡主要变形阶段占整个演化过程的比例增大,初始阶段比例减小,主要变形阶段的增长量与初始变形阶段的缩短量相当,而破坏变形阶段所占比例基本保持不变；主要变形阶段,抗滑桩发挥了加固效果,将加载作用通过抗滑桩和桩后滑体变形吸收,无桩条件下则通过大范围滑体变形来吸收推力作用；进入破坏变形阶段后,桩后滑体达到了极限承载能力,从桩顶附近剪出破坏,无法继续通过抗滑桩支挡吸收更大荷载,而未植入抗滑桩的滑坡沿着鼓胀变形前缘轮廓线发生剪切破坏。②采用三维激光扫描与计算机辅助检测技术,获取了坡体表面位移场信息,捕捉到了滑坡演化过程中产生的土拱效应现象。③通过桩后与桩间不同埋深处的土压力监测数据的分析,得到了应力土拱的演化规律：随着滑坡后部推力的增大,应力土拱的影响范围扩大,在水平方向表现出土拱拱高的增大,在竖直方向上表现出土拱效应影响范围的扩展；当滑坡由初始变形阶段过渡至主要变形阶段时,应力土拱空间形态变化明显；当滑坡由主要变形阶段过渡至破坏变形阶段时,应力土拱效应变化趋势不明显;滑体达到承载极限后,滑坡模型发生破坏,土压力迅速降低,应力土拱现象消失。④推移式滑坡演化过程中,桩后滑坡推力作用点位置是不断变化的；滑坡推力作用点变化规律与滑坡的演化阶段一一对应；推移式滑坡-抗滑桩体系处于初始变形阶段时,滑坡推力大小缓慢上升,滑坡推力作用点逐渐上升,相同埋深处抗滑桩受到的水平应力值彼此接近；主要变形阶段时,滑坡推力呈线性增长趋势,滑坡推力作用点逐渐下降;破坏变形阶段时,破坏前滑坡推力呈线性增长趋势,但增长速率小于主要变形阶段,滑坡推力作用点缓慢下降并趋于恒定。 (5)通过物理模型试验方法研究了抗滑桩嵌固段与推移式滑坡相互作用过程。①抗滑桩桩侧土压力、嵌固段弯矩演化特征呈先增大、后逐渐趋于恒定的变化趋势。嵌固段弯矩、桩侧土压力对加载响应的敏感性随着距离滑带埋深的增大而减小。②抗滑桩嵌固段桩前土压力呈上大下小倒三角形分布规律；抗滑桩嵌固段桩后土压力总体较小,桩底附近土压力较大；抗滑桩悬臂段土压力分布规律呈抛物线型分布。相同加载条件下,嵌固段不同埋深处土压力值变化幅度与滑床岩性有关,以硬岩为主的滑床结构受到的最大土压力值大于以软岩为主的滑床结构,嵌固段发生弯曲变形的中心位置也较高。③抗滑桩嵌固段弯矩值总体满足随距离滑面埋深增加而减小的变化规律；相同岩性条件下,嵌固段最大弯矩值随着岩层倾角的增大而增大；不同岩性条件下,滑带附近以硬岩为主的滑床结构所对应的嵌固段弯矩值大于以软岩为主的滑床结构。 (6)桩后滑坡推力分布规律不仅与滑体介质有关,还应该由滑坡演化阶段、地质结构特征、几何形态、岩土体性质以及抗滑结构的受力变形特征等诸多因素综合确定。滑坡推力分布形态总体满足抛物线型分布规律。随着滑体抗剪强度参数的增大,滑坡推力逐渐减小,作用点逐渐上升；滑体内摩擦角对滑坡推力分布的影响比粘聚力敏感；悬臂段中上部,桩身受到的水平应力与坡角、滑带厚度呈负相关关系,而与滑面坡度呈正相关关系；悬臂段中下部,抗滑桩桩身受到的水平应力与坡角、滑带厚度呈正相关关系,而与滑面坡度呈负相关关系；抗滑桩嵌固长度对滑坡推力分布规律的影响较小。滑床岩体结构特征对抗滑桩嵌固段受力与变形影响显著：①滑床岩层倾向为顺倾向时,岩层倾角对抗滑桩受力和变形影响显著,滑床岩层为逆倾向时,影响较小；顺倾向条件下,随着倾角的增大,抗滑桩悬臂段和嵌固段受到的内力绝对值呈增大趋势,桩顶水平位移呈增大趋势,最大弯矩值点、最大剪力值出现的位置呈下降趋势,抗滑桩变形范围逐步扩大。②当层厚比较大时,抗滑桩受力与变形特征由硬岩控制,软岩起辅助作用；当层厚比较小时,受力特征主要取决于软岩,硬岩起辅助作用；随着层厚比的增大,抗滑桩嵌固段承受的最大弯矩绝对值、最大剪力绝对值呈增长趋势,桩顶位移呈减小趋势,抗滑桩发生明显变形的长度减小。③岩层厚度相似比越小,抗滑桩嵌固段单位长度穿越的软弱层位越多,对桩身受力和变形影响越大；岩层厚度相似比达到一定大小后,抗滑桩穿越的硬岩达到一定层厚,桩身受力与变形特征由硬岩控制。④抗滑桩冗余嵌固长度随顺倾向岩层倾角的增大而减小,逆倾向岩层的影响不显著；抗滑桩冗余嵌固长度随层厚比w、岩层厚度相似比v的增大而增大,有效嵌固深度则随之减小；当层厚比w、岩层厚度相似比v分别增大到一定值后,抗滑桩冗余嵌固长度趋近均质硬岩滑床所对应的冗余嵌固长度,有效嵌固长度趋于恒定。 (7)基于弹性力学理论,建立了桩后滑体应力分析模型,得到了不同时间(演化阶段)、不同空间位置、任意桩数条件下的桩后滑体应力分布函数,并由此开展了不同桩数、桩间距、桩截面尺寸下桩后滑体的土拱效应研究。探讨了该应力分布函数在抗滑桩设计中确定最大桩间距的运用,以及在物理模型试验中估测滑体空间应力的方法。以滑坡推力及其作用点位置函数关系为基础,提出了基于模型试验结果求解滑坡推力作用位置的方法,据此计算得到了更符合抗滑桩真实受力条件的弯矩值。针对滑床岩体结构特征,对传统线弹性地基系数法“K”法进行了修正,提出了一种软硬相间滑床岩体结构条件下抗滑桩嵌固段内力与位移的计算方法。该方法中引入了岩层倾角α、层厚比w、岩层厚度相似比v0岩层结构特征参数,属于抗滑桩嵌固段内力、位移计算的矩阵分析方法。基于极限平衡理论,给出了一种适用于评价三峡库区侏罗系复合层状岩质斜坡稳定性的方法及实现的技术路线图。该方法综合考虑了岩层几何特征、岩体强度参数的空间变异性,能求解复合层状岩体稳定性系数和搜索最危险滑动面位置。 (8)选择三峡库区秭归县马家沟滑坡为研究对象,结合区域地质环境背景,在系统总结研究区工程地质条件的基础上,进行了滑坡稳定性评价和稳定性影响因素分析。以滑坡物理模型试验成果为依据,确定了滑坡推力作用点的区间范围。通过岩层厚度相似比、层厚比、倾角等岩体结构参数,细化了抗滑桩嵌固段与滑床岩层的接触关系。通过与假设滑坡推力呈矩形分布、未考虑滑床岩体结构特征的常规设计方法比较,认为基于滑坡推力作用点位置和考虑滑床岩层结构特征的优化设计方法,更能真实反映抗滑桩悬臂段与嵌固段的受力特征,得到的弯矩和剪力更加合理。对马家沟滑坡防治工程而言,抗滑桩常规设计方法与优化设计方法相比,设计方案偏于危险。本文的主要创新点是： (1)从滑坡力学成因机制出发,建立了推移式滑坡概化地质力学模型,采用室内物理模型试验方法模拟了推移式滑坡的演化过程,揭示了滑坡演化规律和裂缝体系的分期配套特征,根据位移多重分形维数变化规律,将推移式滑坡演化过程划分为后缘压缩阶段、匀速变形阶段、加速变形阶段。 (2)通过物理模型试验方法研究了抗滑桩与推移式滑坡相互作用过程,基于试验多场信息对比分析了抗滑桩对滑坡演化过程的影响。探讨了滑坡演化过程对抗滑桩受力、变形的影响,揭示了推移式滑坡演化过程中桩后滑坡推力变化规律,分析了滑坡推力作用点变化规律与滑坡演化阶段的对应关系。从理论上详细推导了不同演化阶段、不同空间位置、任意桩数条件下桩后滑体应力分布函数。 (3)结合三峡库区侏罗系软硬相间岩层特点,提出了复合层状岩质斜坡稳定性评价方法。从岩层倾角、层厚比、岩层厚度相似比方面系统研究了滑床岩体结构特征对抗滑桩受力、变形和有效嵌固深度的影响。基于滑坡推力作用点和滑床软硬相间岩层结构特征,提出的优化设计方法为抗滑桩设计提供了参考依据。
[Abstract]:Landslide is one of the most widely distributed and most harmful geological hazards in the type of slope failure. Its evolution process includes the whole cycle activity from inoculation, development to extinction. With the vigorous development of China's economic construction, a large number of major infrastructure construction implementation process will be seriously threatened by the landslide disaster. Therefore, it is urgent to control the landslide. Methods a systematic study was carried out to provide scientific basis for engineering practice.
Anti slide pile is one of the main measures for landslide treatment. It has the advantages of strong anti slip ability, wide application conditions, simple construction safety, and can verify geological conditions and so on. It has been widely used. However, the theory method of anti slide pile design is not mature, the bearing specificity of anti slide pile, the interaction mechanism of pile soil and the law of load transfer, and so on. For this reason, it is one of the urgent subjects to study the interaction between anti slide piles and landslides.
On the basis of establishing the landslide geomechanics analysis model and clarifying the basic evolution characteristics of the landslide, combined with the characteristics of the Jurassic strata structure in the Three Gorges Reservoir area, the research on the interaction of pile and soil based on the process of the evolution of the sliding anti slide pile system is carried out, and the optimum design method of the relevant anti slide pile is extended and applied to the engineering. The main research results are as follows:
(1) based on the mechanical model of the "three section" sliding mode, the mechanical mechanism of the lapse landslides and the traction landslides is compared and studied, and the difference between the two is discussed. The basic formation conditions of the lapse landslides are analyzed from the topography, lithology, geological structure and hydrogeology, and the typical push of the Three Gorges Reservoir area is summarized. The deformation and failure process of the moving landslide and the new beach landslide and the law of the development of the supporting system are established. From the four aspects of the characteristics of the landslides, the composition of the material, the composition of the structure and the dynamic factors, the mechanic model of the lapse landslide is established, and the thrust control method is put forward to simulate the evolution process of the progressive slide and the simulation process is suitable for the process of the landslide. The lithologic characteristics and distribution laws of the Jurassic strata in the Three Gorges Reservoir area are summarized, and the differences in physical and mechanical properties of soft and hard rock strata are compared and analyzed. The model of soft and hard interphase rock generalizability analysis is put forward.
(2) the evolution process of the lapse landslide is simulated by the indoor physical model test method. Using the three-dimensional laser scanning technology to monitor the surface point cloud data of the model of the different evolution stages of the landslide, the evolution law of the landslide and the phased matching characteristics of the fracture system are revealed. The generalized correlation dimension is adopted according to the displacement time history curve of the representative monitoring point of the slope surface. The variation of multifractal dimension in the evolution process of the landslide is analyzed. Based on this, the evolution process of the bed load landslide is divided into the post compression stage, the uniform deformation stage and the accelerated deformation stage, in which the multiple fractal dimension of the back edge compression stage is characterized by reducing the dimension of the displacement, and the multifractal dimension is presented as a whole at the uniform deformation stage. The trend of the multifractal dimension in the accelerated deformation stage shows the trend of increasing dimension. The numerical simulation method is used to reproduce the evolution process of the bed load landslide. The calculation results are basically consistent with the model test results, which verifies the stage of the evolution process of the bed load type landslides and uncovers the nonlinear stability coefficient in the process of landslide evolution. Attenuation law.
(3) the "semi model" test method, which takes both the characteristics of landslide itself and the interaction of pile and soil, is put forward, and the general step of the pile front slide is elaborated, and a lightweight test device for the multi working frame type landslide geomechanics model is developed, which can be used to simulate the deformation and failure characteristics of the landslide and the landslide anti slide pile under the condition of multi condition. An experimental equipment is developed to simulate the fluctuation of the water level of the reservoir, and the automatic simulation of the fluctuation of the water level can be realized. A multi field information monitoring method for the landslide physical model test is provided to realize the accurate measurement of the displacement field, the stress field and the temperature field in the landslide evolution process, and the interference letter is taken into consideration. On the influence of the test data, the LabVIEW program development platform is used to realize the visual test data filtering software based on Butterworth low-pass filter.
(4) the interaction process between the cantilever section of the anti slide pile and the sliding landslide is studied by the physical model test. (1) the anti slide pile changes the evolution process of the landslide, which leads to the increase in the proportion of the main deformation stage in the whole evolution process, the decrease in the initial stage ratio, the increase of the main deformation stage and the reduction of the initial deformation phase. In the main deformation stage, the anti slide pile exerts the reinforcement effect and absorbs the load through the deformation of the anti slide pile and the post slide body, and the large range slip body deformation is used to absorb the thrust effect under the condition of no pile, and the post slide body reaches the ultimate bearing energy after the failure stage. Force, cut from the pile top near the top of the pile, can not continue to absorb more load through the anti slide pile support, while the landslide without the anti slide pile is cut along the contour line of the bulging deformation front. Secondly, the three-dimensional laser scanning and computer aided detection technology are used to obtain the information of the displacement field of the slope surface and capture the middle class of the landslide evolution process. Through the analysis of soil pressure monitoring data of different buried depths between post pile and pile, the evolution law of stress soil arch is obtained. With the increase of the thrust of the landslide, the influence range of the stress soil arch is enlarged, the height of the arch arch is increased in the horizontal direction, and the effect of the unearthed arch effect in the vertical direction is influenced by the model. When the landslide is transitioned from the initial deformation stage to the main deformation stage, the spatial shape of the stress soil arch changes obviously. When the landslide is transferred from the main deformation stage to the deformation stage, the change trend of the stress soil arch effect is not obvious; after the sliding body reaches the bearing limit, the sliding slope model breaks down, the soil pressure is rapidly reduced and the stress is stressed. The position of the thrust action point of the landslide is constantly changing in the process of the evolution of the landslide. The change law of the thrust action point of the landslide corresponds to the evolution stage of the landslide, and the thrust size of the landslide is slowly rising and the thrust action point of the landslide gradually rises. The horizontal stress value of the anti slide pile in the same buried depth is close to each other. In the main deformation stage, the landslide thrust shows a linear growth trend, and the thrust action point of the landslide gradually decreases. When the deformation stage is destroyed, the thrust of the landslide is linearly increasing before the failure, but the growth rate is less than the main deformation stage, and the thrust action point of the landslide is slowly decreased. It tends to be constant.
(5) through the physical model test, the interaction process of the sliding pile and the bed load landslide is studied. (1) the lateral earth pressure of the anti slide pile is increased first and then gradually tends to constant. The bending moment of the embedded section, the sensitivity of the soil pressure on the pile side to the loading response is reduced with the increase of the depth of the distance sliding zone. The pressure of soil pressure in the pile foundation of anti slide pile is large and small down triangle distribution law, the soil pressure in the pile bottom is relatively small and the soil pressure near the pile bottom is larger. The distribution law of soil pressure distribution in the cantilever section of anti slide pile is parabolic distribution. Under the same loading condition, the change amplitude of soil pressure value at the different buried depth of the embedded section and the sliding bed The maximum earth pressure of a sliding bed with hard rock mainly is larger than that of a soft rock, and the central position of the bending deformation is higher. Thirdly, the bending moment value of the embedded section of the anti slide pile satisfies the variation rule that decreases with the increase of the buried depth of the sliding surface; the maximum bending moment of the embedded section under the same lithology condition. The value increases with the increase of the rock dip angle. Under different lithologic conditions, the bending moment of the embedded section corresponding to the hard rock in the vicinity of the sliding zone is larger than that of the soft rock.
(6) the distribution law of the landslide thrust is not only related to the sliding medium, but also should be determined by many factors, such as the evolution stage of the landslide, the characteristics of the geological structure, the geometry, the properties of rock and soil, and the deformation characteristics of the anti sliding structure. The distribution pattern of the landslide thrust is generally satisfied with the distribution of the parabolic type. In the middle and upper part of the cantilever section, there is a negative correlation between the horizontal stress of the pile and the thickness of the slope and the slide zone, but the slope of the slide is positively related to the slope of the sliding surface, and the anti slide pile body is subjected to the middle and lower part of the cantilever section. The horizontal stress has a positive correlation with the slope angle and the thickness of the sliding zone, but has a negative correlation with the sliding surface; the impact of the anti slide pile on the distribution of the landslide thrust is smaller. And the influence of deformation is remarkable, and the effect of sliding bed rock is reverse, the absolute value of internal force of the cantilever section and embedded section of anti slide pile is increasing, the horizontal displacement of pile top is increasing, the maximum bending moment value points, the position of the maximum shear value appears downward trend, and the deformation range of anti slide pile will be reduced. When the thickness of the layer is large, the stress and deformation characteristics of the anti slide pile are controlled by hard rock, and the soft rock plays an auxiliary role. When the thickness of the layer is relatively small, the stress characteristics mainly depend on the soft rock and the hard rock plays an auxiliary role. With the increase of the thickness ratio, the absolute value of the maximum bending moment of the anchorage pile is increased, the absolute value of the maximum shear force is on the increase trend. The top displacement is decreasing, and the length of the obvious deformation of the anti slide pile decreases. The smaller the thickness of the rock thickness is, the more weak layers of the block length of the anti slide pile, the greater the influence on the pile force and deformation; after the rock thickness similarity ratio reaches a certain size, the hard rock traversing the anti slide pile reaches a certain thickness and the pile bearing capacity and the bearing capacity. The deformation characteristics are controlled by hard rock. (4) the redundant embedded length of anti slide pile decreases as the inclination of the rock layer tends to increase, and the influence of the reverse inclined rock is not significant. The redundant embedded length of the anti slide pile increases with the thickness ratio of W, the thickness of the rock layer is larger than the V, and the effective embedding depth decreases. When the thickness ratio is w, the thickness of the rock layer is similar to that of V, respectively. After increasing to a certain value, the redundant embedment length of the anti slide pile approaches the redundant embedment length corresponding to the homogeneous hard rock sliding bed, and the effective embedment length tends to be constant.
(7) based on the theory of elastic mechanics, the stress analysis model of pile rear slide is established, and the stress distribution function of post slip body of pile under different time (evolution stage), different space position and arbitrary number of piles is obtained, and the soil arch effect of different pile number, pile spacing and pile cross section post slip body is carried out. The stress distribution function is discussed. The application of the maximum pile spacing in the design of anti slide pile and the method of estimating the spatial stress of the sliding body in the physical model test are given. Based on the relationship between the landslide thrust and the position function of the action point, a method based on the result of the model test is put forward to solve the position of the landslide thrust. The calculation is more in line with the actual resistance of the anti slide pile. In accordance with the structural characteristics of the rock mass, the "K" method of the traditional linear elastic foundation coefficient method is modified. A calculation method for internal force and displacement of the embedded section of the anti slide pile under the condition of the soft and hard interphase sliding bed rock mass is proposed. This method introduces the rock dip angle alpha, the thickness ratio of the layer to W, and the similarity of the rock layer thickness to the V0 rock structure. The characteristic parameter, which belongs to the matrix analysis method of the internal force and displacement calculation of the anti slide pile, is based on the limit equilibrium theory, and gives a method for evaluating the stability of the compound stratified rock slope in the Jurassic of the Three Gorges Reservoir area and its technical roadmap. The method takes into account the geometric characteristics of the rock strata and the spatial variation of the strength parameters of the rock mass. Anisotropy can be used to solve the stability factor and search of composite layered rock mass.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV221.2;P642.22

【参考文献】