水泥土桩加固边坡变形破坏机理与稳定性研究

发布时间：2018-06-05 05:52

本文选题：边坡加固 + 水泥土桩　；参考：《广西大学》2016年博士论文

【摘要】：在航道开发建设的同时,不可避免产生大量的人工开挖高边坡,边坡土质多存在淤泥质粘土,粘土,填土等软弱及不稳定岩土层,边坡稳定性不足,必须对边坡进行治理。因边坡高度大,坡线长,范围广,采用传统的钢筋混凝土抗滑桩方案存在建设工期长,工程造价高等问题。目前,通过深层搅拌法或高压喷射注浆法形成水泥土桩来加固软土地基在工程建设中得到了广泛的应用。但水泥土桩用于基坑、边坡和路堤等工程加固时,稳定性分析尚无统一的规范遵循,水泥土桩加固边坡的变形破坏特性、抗滑机理、合理布桩结构形式以及设计计算理论等都缺少相关研究资料,理论研究滞后于工程实践。基于此,本文在国内外相关研究的基础上,通过室内试验、模型试验、数值模拟、理论分析等方法,对水泥土桩加固边坡的抗滑特性、工作机理以及设计计算理论等进行了系统研究,主要的研究工作与结论如下：(1)完成了178个试样的室内试验,内容包括单轴抗压、径向劈裂和三轴压缩,分析了水泥土的强度特性和变形破坏特性。根据水泥土剪胀过程所受到的影响因素,建立了水泥土剪胀角模型方程。同时根据论文研究目的,选取了适合描述水泥土材料力学性质的本构模型和强度准则。(2)详细介绍极限平衡法和有限元强度折减法应用于边坡稳定性分析的原理、方法及其各自的适用性。分析了D-P强度准则与M-C强度准则的等效性,并对相关参数进行探讨,结果表明D-P准则参数a有效范围为0≤a≤(?)/6。对D-P系列准则的在边坡稳定计算上的精度进行了分析,扩展了强度折减法所采用的屈服准则范围。(3)运用Abaqus结合强度折减技术对水泥土桩加固边坡的变形破坏特性和抗滑机理进行数值模拟分析。结果表明：采用离散水泥土桩加固边坡,当边坡失稳时,刚度和强度都较大的水泥土桩呈S型挠曲变形而发生弯折破坏。传统极限平衡法假设桩体只发生剪切破坏,计算结果将会高估加固边坡的稳定性。提出了水泥土剪力墙的概念,通过数值模拟发现,采用水泥土剪力墙加固边坡,因墙土界面摩擦力的作用,下滑力在剪力墙和滑体间得到调整,最终促使加固边坡产生整体剪切破坏,从而有效发挥剪力墙的抗滑能力。(4)以20：1的几何相似常数建立水泥土桩复合地基水平剪切模型试验,试验结果显示离散水泥土桩和水泥土剪力墙的变形破坏特性、抗滑机理与数值模拟的结果相似,模型试验得出的规律证明了数值模拟结果的合理性。(5)基于数值模拟和模型试验研究,提出了几个离散水泥土桩加固边坡的整体稳定性分析简化计算方法,通过对8个算例的分析证明等效抗剪强度法精度较高,宜在设计中优先采用。进一步地,将支持向量机(SVM)、粒子群算法(PSO)和强度折减法(SRM)相结合,建立了水泥土剪力墙加固边坡的SRM-SVM-PSO设计优化技术,利用Matlab编制了相关程序,算例分析表明,通过优化剪力墙的设计变量,加固边坡的安全性和经济性都得到了满足。(6)以长洲水利枢纽三线四线船闸引航道边坡加固工程为例,进一步阐明了高压旋喷桩加固引航道软土边坡的变形破坏特性及合理加固结构形式。采用饱和-非饱和土渗流固结理论,分析了航道水位变化对饱和-非饱和加固边坡渗流场和稳定性的影响,根据分析结果,为高压旋喷桩加固引航道边坡的设计施工提供了相关建议。
[Abstract]:In the course of the development and construction of the channel, there will inevitably be a large number of high slope of artificial excavation. There are many soft and unstable rock soil, such as clay, clay, fill, etc., the slope stability is insufficient, and the slope must be treated. Because the height of the slope is large, the slope line is long and the range is wide, the traditional anti slide pile scheme of reinforced concrete is used. At present, the construction cost is long and the construction cost is high. At present, the cement soil pile is formed by deep mixing method or high pressure jet grouting to reinforce the soft soil foundation in the engineering construction. But the cement soil pile is used for the foundation pit, the slope and the embankment and so on, the stability analysis has not yet unified standard compliance, the cement soil pile is added. The deformation and failure characteristics of the solid slope, the anti sliding mechanism, the reasonable structure of the pile and the design calculation theory are all lack of relevant research materials, and the theoretical research lags behind the engineering practice. Based on this, this paper, on the basis of the relevant research at home and abroad, through the indoor test, model test, numerical simulation, theoretical analysis and other methods, the cement soil pile is strengthened. The anti sliding characteristics of the slope, the working mechanism and the design calculation theory have been systematically studied. The main research work and conclusion are as follows: (1) the indoor test of 178 specimens has been completed, including the uniaxial compression, radial splitting and the three axis compression, and the strength and deformation behavior of the cement soil are analyzed. The shear expansion process of the cement soil is analyzed. In addition, the constitutive model and strength criterion suitable for describing the mechanical properties of cement soil materials are selected. (2) the principle, method and application of the limit equilibrium method and the finite element strength reduction method applied to the slope stability analysis are introduced in detail. The equivalence between the D-P strength criterion and the M-C strength criterion is analyzed and the related parameters are discussed. The results show that the effective range of the D-P criterion parameter a is 0 < < a < < < (?) /6.. The accuracy of the slope stability calculation is analyzed, and the yield criterion range adopted by the strength reduction method is extended. (3) the use of Abaqus bonding strength. The deformation and failure characteristics and the anti sliding mechanism of the cement soil pile reinforced slope are numerically simulated and analyzed. The results show that the cement soil pile is reinforced by the discrete cement soil pile, and when the slope is unstable, the cement soil pile with large stiffness and strength is flexural and damaged by the S flexure deformation. The traditional limit equilibrium method assumes that the pile is only shearing. The calculation results will overestimate the stability of the reinforced slope. The concept of the cement soil shear wall is put forward. Through numerical simulation, it is found that the cement soil shear wall is used to reinforce the slope, and the sliding force is adjusted between the shear wall and the slide body because of the friction force of the wall soil interface. The anti slip ability of the shear wall. (4) a horizontal shear model test of cement soil pile composite foundation is established by the geometric similarity constant of 20:1. The experimental results show the deformation and failure characteristics of the discrete cement soil pile and the cement soil shear wall, and the anti sliding mechanism is similar to the numerical simulation results. The model test results prove the combination of numerical simulation results. (5) based on the numerical simulation and model test research, the simplified calculation method of the overall stability analysis of several discrete cement soil piles is proposed. Through the analysis of 8 examples, it is proved that the equivalent shear strength method has higher precision and should be adopted in the design. Further, the support vector machine (SVM), particle swarm optimization (PSO) and the strength are strengthened. In combination with the degree reduction method (SRM), a SRM-SVM-PSO design optimization technique for cement soil shear wall strengthening slope is established, and the related program is compiled with Matlab. The calculation example shows that the safety and economy of the slope are full full by optimizing the design variables of the shear wall. (6) the side of the navigation channel edge of the three line and four line of Changzhou water control hub is on the edge of the ship lock. As an example, the deformation and failure characteristics of the soft soil slope reinforced by high pressure rotary jet grouting pile and the form of rational reinforcement structure are further clarified. The influence of the water level variation on the seepage field and stability of the saturated unsaturated soil slope is analyzed by the saturated unsaturated soil seepage consolidation theory. Some suggestions are put forward for design and construction of piles to reinforce the approach slopes.
【学位授予单位】：广西大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU43

【参考文献】