膨胀土边坡浅层失稳机理及土工格栅加固处理研究
发布时间：2018-11-07 16:35
【摘要】：膨胀土作为世界范围内广泛分布的特殊土,对相关地区的工程建设造成了极大破坏和影响,一直是岩土工程领域研究的难题之一。浅层失稳破坏是发生在铁路、公路、水利等工程中最普遍最频繁的膨胀土边坡破坏现象,但目前对浅层失稳破坏机理缺乏足够的认识,传统的极限平衡稳定性分析方法不能如实反映和解释膨胀土边坡此类破坏的真实性状,也制约了工程建设中如何采取合理有效的处理措施以解决由于其特殊性质带来的工程问题。因此,深入研究膨胀土边坡的浅层失稳破坏机理,并在此基础上探讨相应的工程措施是保障工程设计安全和经济性的关键。 本文结合南水北调中线工程的膨胀土边坡稳定问题,针对膨胀土最本质的工程特性——膨胀性开展深入研究,通过大型静力物理模型试验,研究压实膨胀土边坡在没有裂隙、超固结性、干湿循环等因素的影响下,由于水分入渗引起的边坡膨胀变形和滑动的发生发展破坏全过程。在“湿度应力场”理论基础上,提出一种非饱和渗流场-膨胀变形场-应力场的多场耦合数值分析方法,结合模型试验和数值分析成果,阐述了膨胀土边坡浅层失稳的破坏机理。在此基础上,从加筋土的筋—土作用机理出发,研究土工格栅对膨胀土膨胀变形的约束效果,及其对边坡浅层稳定的改善作用,为确定合理的膨胀土工程处理措施提供理论依据。通过本文的研究,得到的主要结论如下： (1)针对膨胀土边坡极为普遍的浅层失稳破坏形式,采用大型物理模型试验(6m×2m×2.8m),并结合湿度场-膨胀变形场-应力场的耦合数值模拟分析,揭示出膨胀土边坡浅层失稳的本质在于膨胀土的膨胀性。由膨胀变形控制的膨胀土边坡浅层渐进性失稳破坏机理可阐述如下：膨胀土边坡在受到外部水力边界作用时,首先导致边坡内含水量场发生时空不均匀分布,继而引起土体的不均匀膨胀变形,应力应变场发生重分布,在非饱和-饱和浸润交界区域形成剪应力集中区,产生局部剪切破坏,并逐渐向边坡深部扩展,最终形成多重剪切面,边坡发生渐进性失稳破坏。 (2)针对膨胀土边坡稳定性分析,在“湿度应力场”理论基础上,提出一种结合非饱和-饱和渗流场、膨胀变形场、应力场多场耦合作用的有限元数值分析方法,通过对模型试验的仿真模拟,证明这种多场耦合分析模型和方法可以真实反映膨胀土边坡的浅层渐进性失稳过程,为深入理解边坡浅层稳定性的破坏机理提供了有用的分析手段。 (3)基于温度膨胀和湿度膨胀的相似性,采用热—固耦合有限元数值分析方法,根据室内膨胀土无荷及有荷膨胀试验成果,反演得到不同含水率、干密度和荷载作用下的膨胀系数变化规律。结果表明：膨胀系数受含水率、干密度、荷载等因素的综合影响,在低荷载条件下含水率和膨胀系数近似符合线性关系。因此,在多场耦合数值计算中采用低荷载条件下对应的含水率—膨胀系数(饱和度—膨胀系数)关系来反映边坡不同部位湿度变化引起的膨胀系数的变化规律。 (4)采用大尺寸膨胀模型试验,系统研究了铺设土工格栅后膨胀土的吸湿膨胀变形发展规律,获得了不同格栅参数(强度、类型、铺设层数和方式等)对膨胀变形的影响规律,对土工格栅抑制膨胀变形的可行性进行了评价。 (5)通过大型物理模型试验,对土工格栅处理膨胀土边坡浅层稳定的效果进行了研究,为膨胀土工程处理措施提供了基本的试验依据。
[Abstract]:As a kind of special soil widely distributed in the world, expansive soil has caused great damage and influence to the engineering construction in the relevant area, and has been one of the difficult problems in the field of geotechnical engineering. The failure of the shallow-layer instability is the most common and most frequent expansive soil slope failure in the railway, highway, water conservancy, etc., but it is not enough to know the mechanism of the failure of the shallow layer. The traditional limit equilibrium stability analysis method can not faithfully reflect and explain the authenticity of such failure of the expansive soil slope, and also restrict the reasonable and effective treatment measures in the project construction to solve the engineering problems caused by the special properties. Therefore, the mechanism of shallow failure and failure of expansive soil slope is studied deeply, and the key to the safety and economy of engineering design is discussed. In this paper, the stability of expansive soil slope in the middle-line project of the South-to-North Water Transfer Project is discussed, and the most essential engineering property _ expansion of expansive soil is studied. Through the large-scale static physical model test, the slope of the compacted expansive soil is studied in the absence of cracks and supersolid. Under the influence of the factors such as the junction property, the dry-wet cycle and the like, the expansion and deformation of the side slope caused by the infiltration of water and the development of the sliding are destroyed. On the basis of the 鈥渉umidity stress field鈥，
本文编号：2316932
[Abstract]:As a kind of special soil widely distributed in the world, expansive soil has caused great damage and influence to the engineering construction in the relevant area, and has been one of the difficult problems in the field of geotechnical engineering. The failure of the shallow-layer instability is the most common and most frequent expansive soil slope failure in the railway, highway, water conservancy, etc., but it is not enough to know the mechanism of the failure of the shallow layer. The traditional limit equilibrium stability analysis method can not faithfully reflect and explain the authenticity of such failure of the expansive soil slope, and also restrict the reasonable and effective treatment measures in the project construction to solve the engineering problems caused by the special properties. Therefore, the mechanism of shallow failure and failure of expansive soil slope is studied deeply, and the key to the safety and economy of engineering design is discussed. In this paper, the stability of expansive soil slope in the middle-line project of the South-to-North Water Transfer Project is discussed, and the most essential engineering property _ expansion of expansive soil is studied. Through the large-scale static physical model test, the slope of the compacted expansive soil is studied in the absence of cracks and supersolid. Under the influence of the factors such as the junction property, the dry-wet cycle and the like, the expansion and deformation of the side slope caused by the infiltration of water and the development of the sliding are destroyed. On the basis of the 鈥渉umidity stress field鈥，
本文编号：2316932
本文链接：https://www.wllwen.com/guanlilunwen/chengjian/2316932.html
