【作者】 李焕强；

【导师】 尚岳全；

【作者基本信息】 浙江大学 ， 防灾减灾工程及防护工程， 2008， 博士

【摘要】 我国是世界上遭受台风危害最严重的国家。我国东南部地区经常受台风暴雨影响。每次台风带来的暴雨都会对公路工程带来巨大损失。近年来由于经济的快速发展和公路交通设施的大力建设,台风暴雨对公路造成的经济损失随时间呈快速上升的趋势。通过对200多个公路水毁路段的现场调查和相关水毁资料的收集,对公路水毁类型进行了系统的分类,分析公路水毁的特征和各种破坏形式之间的相互影响关系。并通过构建多个实验模型,展开了降雨对均质边坡、含隔水层边坡坡体含水量、坡体应变、坡体前端推力、坡面变形影响的全面研究。人工降雨模型实验采用了水份传感器实时监测坡体含水量、采用布里渊光时域反射技术(BOTDR)监测坡体应变量、采用压力盒监测坡前推力变化、采用光纤光栅(FBG)位移传感技术监测坡面位移,得到了降雨作用下和地下水作用下边坡各性状随时间及深度的变化规律。并在前人研究的基础上,改进了有限元离心加载计算边坡稳定性的方法。得到了以下的成果和结论:(1)系统地按不同的标准对水毁进行了分类,为深入研究水毁提供了基础支持。对水毁的类型、特点和产生原因有全面分析,提出了各水毁类型之间存在相互影响关系的观点,应该将各种水毁防护措施作为一个整体系统进行水毁的防治工作。(2)在降雨作用下,入渗是从坡面到坡体自上而下逐步发展的。降雨入渗过程中,坡体中部深度附近会存在一个含水量相对较小的区域。降雨过程不仅对土体含水量的数值有影响,而且对含水量等值线的形态也有影响。(3)在降雨作用下坡体前端推力、坡体变形、坡面变形这三个特性指标随时间变化规律相似:在降雨作用下,边坡特性指标的监测数值会产生一个峰值,在降雨作用消退以后,监测数值逐渐回落,最终趋于一个稳定值。不同的是坡体前端推力在降雨之后就开始产生变化,而坡体变形和坡面的位移在降雨过程初期没有明显反映,持续较长时间降雨后,监测数值才会发生明显反应。(4)降雨入渗对边坡不同深度上的坡体含水量、坡体变形和坡前推力影响规律相似:边坡顶层、上层土体变化幅度较大,速度较快;边坡底层、下层土体变化幅度较小,速度较慢。(5)降雨对不同坡角边坡的坡体含水量、坡体前端推力、坡体变形的影响规律也具有相似性:降雨过程中较大坡角边坡的反映较为强烈,其峰值要远大于小坡角边坡,但是大坡角边坡需要降雨的时间比较长。(6)通过对新老边坡分别实施人工降雨模拟实验,结果表明与雨前相比新边坡抗滑支撑结构受力增大;而老边坡在接受相同降雨作用时,坡体的应力状态变化较不明显。说明了新边坡在降雨作用下比较容易失稳,而老边坡则相对比较稳定。(7)地下水的作用对边坡性状的影响与降雨对边坡性状的变化规律相似,不同点主要存在两个方面:①降雨作用和地下水作用对坡体含水量的影响过程不同,在降雨作用下,边坡的坡面附近土体含水量最先发生变化,含水量自上而下逐渐发生变化,边坡底层土体的含水量受影响最晚。而在地下水的作用下,边坡后缘以及底层土体的含水量最先受到影响,含水量是自下而上逐渐发生变化的。②在降雨作用下,边坡受影响产生变化需要一定的积累时间,而在地下水作用下,发展几乎不需要积累时间,地下水作用之后边坡就受影响产生变化。(8)降雨对含不透水层边坡的影响与均质边坡类似,但是边坡的性状反映主要在不透水层的上部,即降雨可以影响的部分。地下水作用在不透水层下部坡体时,实验表明不透水层上部坡体会受到影响。上部坡体的坡前推力、坡体变形、坡面变形都会产生较大的变化,其中靠近坡面的部分产生的变化最大。(9)重新构建有限元离心加载法的实现过程,克服原方法的缺陷,使其达到了与有限元强度折减法有相同应用价值的水平。更多还原

【Abstract】 China is a country suffered typhoons most seriously of the world, and southeast region is usually influenced by typhoon rainstorm. Every time typhoon rainstorm would cause extensive damage to roads. In recent years, considering economy and highway traffic facilities have a rapid development, the damage submit zooming trend with time. Based on the field investigation of more than 200 road disease spots and the collected information, the water damage forms are classified systematically, and the interaction relation of destructions is analyzed. On this basis, multi-experimental model were constructed to study the effect of rainfall on slope characters of homogeneous and slope with confining stratum. The slope characters including water content, body strain, thrust at front end, surface deformation of slope. In this experiment, water sensors were adopted to detect the water content in slope body on real time; BOTDR for strain in slope body; pressure cell for thrust at front end; FBG for the surface deformation. The characters change laws with time and depth of slope were obtained under rainfall and groundwater. On the basis of previous study, the FEM centrifuge loading method was improved. The results and conclusions were got as following:(1) The water damage forms are classified systematically, which provide basic support to the further study. After comprehensively analyzing on the water damage forms, characters and cause, the point is proposed that the different water damage forms affect each other. So the protective work of water damage should take all the protective measures as a whole system.(2) Under rainfall, the infiltration develops gradually from slope surface to the bottom. In the rainfall infiltration cause, there is a region with a relatively less water content temporarily. Not only rainfall can affect the water content value in slope, but also can affect the morphology of the water content isoline.(3) Under rainfall, the change laws with time of the slope characteristic indexes, including body strain, thrust at front end, surface deformation of slope, are similar. The slope characteristic indexes bring a peak value during rainfall course, when the rainfall effect is extinct, the characteristic indexes value will fall back, and approach a stable value finally. But the difference of the change laws is that, thrust at front end starts changing after the rainfall begins. While the body strain and surface deformation of slope had obvious change after a relatively long rainfall time.(4) Under rainfall, the change laws with depth of the slope characteristic indexes, including water content, body strain, thrust at front end of slope, are similar. The changing of characteristic indexes in the top and upper part of slope is with great range and speed; the bottom and lower part of slope with less range and speed.(5) Under rainfall, the change laws of the slope characteristic indexes in different angle slope, including water content, body strain, thrust at front end of slope, are similar. Compared with less angle slope, the changing of characteristic indexes in larger angle slope is more strong and with a peak value much higher than that in less angle slope; but the rainfall time needed in larger angle slope is more than the less one(6) After the rainfall effect, comparing with the state before rainfall, the force of anti-slide structure in new slope has a great growth, but the force in old slope hasn’t obvious differentia. This phenomenon explains that the new slope is easier to fail than the old one under rainfall.(7) The change laws of the slope characteristic indexes with the groundwater effect are similar to that with the rainfall effect, but differentia as following.①The water content change processes are different. Under the rainfall, the water content in the top part of slope changes at the earliest, and the bottom part changes at latest, that is the water content changes from the top to bottom. Under the groundwater, the water content in the rear and bottom part of slope changes at the earliest; the water content changes from the bottom to top.②Under rainfall, the change in slope occurs after a certain rainfall time, but the change in slope occurs when the groundwater affect the slope, and there is no accumulating time.(8) The effect of the rainfall on the slope with impermeable layer is similar to which on the homogeneous slope, but the rainfall can only affect the part above the impermeable layer.When the groundwater affect the part under the impermeable layer, the part above the impermeable layer can also be affected. As the experiment results show, the thrust at front end, body strain and surface deformation of slope have a great change in the upper part of slope, especially in the top part.(9) By reconstructing the finite element centrifuge loading method realization process, the method is improved. The improved method remedied the defect of the original method, which has the same application value as the finite element strength reduction method.更多还原