土工格室加筋土加固机理的研究

发布时间：2018-04-28 20:08

本文选题：土工格室 + 土工格栅　；参考：《东北林业大学》2013年博士论文

【摘要】：本研究以土工格室为研究对象,通过土工格室加筋土的抗弯承载特性和筋土界面特性的试验研究,探讨土上格室加筋土的加固机理。本研究通过承载力室内模型试验,得到PIV画像解析图片,利用PIV画像解析方法和数字图像处理技术,对地基内部砂的运动,细观结构的图像进行定量和定性分析,得出地基砂土在条形均布荷载作用下,加筋前后各项参数和各种应力、应变场的变化规律。在模型试验中将变形量测系统用于分析加筋地基加载变形破坏的位移、地基内部局部剪应变场的图像,用以研究加筋地基的破坏模式和破坏面发展机理。采用有限元模拟分析地基砂内部的局部应力状态,解析地基砂内外部的应力场、应力路径及内力变化。本研究将基础模型按照实际基础同比例缩小进行加筋土界面特性的试验研究实验,利用拉拔试验装置和位移计测土体内部位移连续变化进程,得到土工格室拉拔抵抗力产生的原理模式图像和土工格栅位移与拉拔抵抗力的分布状况图像,比较分析土工格室和土工格栅的拉拔特性,研究土工格室和土工格栅的位移传递机制。通过静承载力试验和纸状的压力传感器测定应力分布,对补强机理、应力分散效果进行探讨。利用应力测定系统,研究加筋土的网兜效应和抗弯刚性及应力分散效果。最后通过现场简易承载力试验比较不同种类补强材料的补强效果,复核土工格室模型与原型的系统相似定理。本研究利用以上方法,追踪加筋土地基的渐进性变形与破坏过程,捕捉加筋土地基的变形模式、滑动剪切面位置形状和剪切带特征。为研究砂土在拉拔水平荷载下的全场位移和局部位移的产生、发展和演化特点进行了量测和定量分析。 PIV画像解析表明无土工格室补强地基内速度向量分布是在载荷板正下方往正中心方向运动显著,速度大,表明载荷板正下方应力集中,土工格室补强地基内速度向量分布是在载荷板正下方出现横方向的运动,速度小且均匀,表明应力集中现象被冲散。变形量测系统分析表明纯砂或无补强时地基内部砂在剪切过程中,最大剪应变的方向均在约10°的破裂线上,而土工格栅加筋土剪应变等值线,即最大剪应变几乎发生在水平方向上,且该水平面与筋材的布置十分一致。有限元模拟分析表明加筋砂土地基内部的高补强效果在局部应力状态已接近破坏状态,且破坏区域扩散后才表现出来。加筋土界面特性研究表明土工格栅应变软化来得快,应变软化开始直接进入到相当小的残留强度状态；而土工格室是应变软化来得迟,先显示出稍高的最大抵抗力,以后应变软化较短,最后表现出相当大的残留强度。土工格室的内部位移是从墙壁近旁开始向后方进行传播,其进展性土工格栅比土工格室更显著。应力扩散试验表明土工格栅、土工格室加筋土地基的应力曲线在中心附近的尖顶分布,而土工格栅配合土工格室加筋土地基的应力曲线在中心附近较宽阔范围内缓慢分布,即后者比前者应力扩散效果好。土工格栅配合土工格室加筋土地基承载力较大,而碎石作为填料使用时,土工格室碎石加筋土地基承载力比土工格栅配合土工格室加筋土地基承载力还大。土工格室与土工格栅主要区别在于,前者因具有一定的厚度,固具有一定的抗弯能力,能有效扩散从上部结构传来的竖向应力；同时发挥类似于“深基础”的作用,大大提高地基的承载能力。实验结果表明,有限元数值模拟的细观力学特性与土体的宏观力学现象密切相关,有限元法数值模拟技术分析研究加筋地基的承载力和变形特性是可行的。物理模型试验PIV图像的细观结构的变化特征,反应了土体的宏观力学响应特性,说明了通过对土体的PIV细观结构变化来反应土体破坏前后的强度和变形的可行性。通过对这两种细观观测结果进行关联性分析,同时与宏观试验结果进行对比分析,结果表明PIV图像的细观结构的变化特征与宏观力学响应特性具有很好的一致性。土工格室作为一种新型建筑材料具有良好适应性(适应多种填料)、良好的经济性(工程项目上应用土工格室最多节约达30%的投资)及良好的稳定性,土工格室工法能有效利用现场土质,减少土石方量,有效削减环境负荷,加快工程进度。对土工格室加筋结构的作用机理的研究还有待深化,提出一种实用的工程设计计算方法是当务之急。
[Abstract]:In this study, the geotextile chamber was taken as the research object. Through the experimental study on the flexural bearing characteristics of the geotextile reinforced soil and the interface characteristics of the reinforced soil, the reinforcement mechanism of the reinforced soil on the soil lattice was discussed.
In this study, through the test of the bearing capacity indoor model, the PIV picture analytic picture is obtained. Using the PIV image analysis method and the digital image processing technology, the quantitative and qualitative analysis of the movement of sand in the foundation and the image of the meso structure is carried out, and the parameters and various stresses and strains before and after the reinforcement are obtained. In the model test, the deformation measurement system is used to analyze the displacement of the reinforced foundation loading deformation and failure, the local shear strain field image in the foundation, in order to study the failure mode of the reinforced foundation and the mechanism of the development of the failure surface. The stress field, stress path and internal force change of the section. The experimental research experiments are made to reduce the interface characteristics of reinforced earth with the basic model according to the actual basis. The principle pattern images and geotextiles of the pull out resistance of the geotextile room are obtained by using the drawing test device and the displacement meter to measure the continuous change process of the internal displacement of the soil. The distribution of the grid displacement and the drawing resistance is compared and analyzed. The transfer mechanism of the geomers and geogrids is studied. The displacement transmission mechanism of the geomers and geogrids is studied. The stress distribution is measured by the static bearing test and the paper pressure sensor. The reinforcement mechanism and the stress dispersion effect are discussed. The stress measurement system is used. The effect of net pocket and flexural rigidity and stress dispersion of reinforced soil are studied. Finally, the reinforcement effect of different kinds of reinforcement materials is compared through the field simple bearing capacity test, and the system similarity theorem of the geotextile room model and the prototype is reviewed.
In this study, the above method is used to track the progressive deformation and failure process of reinforced soil foundation, to capture the deformation mode of the reinforced soil foundation, the shape of the sliding shear surface and the characteristics of the shear band, and to study the development and evolution of the full field displacement and local displacement of the sand under the horizontal loading.
The analysis of PIV picture shows that the velocity vector distribution in the subsoil of the subsoil reinforcement is significant in the positive center direction under the load plate, and the velocity is large, which indicates the stress concentration under the load plate. The velocity vector distribution in the reinforcing foundation of the geotextile chamber is the horizontal movement under the load plate, which is small and uniform, indicating the stress set. The analysis of the deformation measurement system shows that the maximum shear strain is in the fracture line about 10 degrees during the shear process of the sand in pure sand or without reinforcement, and the shear strain equivalent line of the geogrid reinforced earth shear strain, that is, the maximum shear strain almost occurs in the horizontal direction, and the horizontal plane is in good agreement with the arrangement of the steel. The finite element simulation analysis shows that the high reinforcement effect in the reinforced sand soil foundation is close to the failure state in the local stress state, and only after the destruction of the regional diffusion. The study of the reinforced soil interface characteristics shows that the geogrid strain softening is faster and the strain softening begins to enter a fairly small residual strength state; and the geotextile chamber is in the geotextile chamber. It is the delay of strain softening, which shows a slightly higher maximum resistance first, the strain softening is shorter, and a considerable residual strength is shown at the end. The internal displacement of the geotextile chamber begins to propagate back from the wall near the wall, and its progressive geogrid is more obvious than the geotextile room. The stress diffusion test indicates that the geogrid and geotextile room are shown by the stress diffusion test. The stress curve of the reinforced soil foundation is distributed near the center, while the stress curve of the geogrid and the reinforced earth base of the geomer chamber is slowly distributed in the wider range near the center. That is, the latter is more effective than the former. The geogrid and the geogrid reinforced soil foundation have greater bearing capacity, and the gravel is used as a filler. The bearing capacity of geocell reinforced earth foundation is larger than that of geogrid reinforced geocell reinforced earth foundation.
The main difference between geotextile room and geogrid is that the former is able to effectively diffuse the vertical stress from the superstructure because of a certain thickness, and can effectively diffuse the vertical stress from the superstructure, and also plays a role similar to the "deep foundation", which greatly improves the bearing capacity of the foundation.
The experimental results show that the meso mechanical properties of the finite element numerical simulation are closely related to the macroscopic mechanical phenomena of the soil. It is feasible to analyze the bearing capacity and deformation characteristics of the reinforced foundation by the finite element method numerical simulation technique. The physical model test of the microstructure of the PIV images reflects the macroscopic mechanical response characteristics of the soil. The feasibility of reacting the strength and deformation of the soil before and after the soil failure is explained by the change of the PIV meso structure of the soil. The results of these two observations are analyzed and compared with the macroscopic test results. The results show that the variation characteristics of the mesoscopic structure of the PIV image and the macroscopic mechanical response characteristics are very good. Good consistency.
Geomer room, as a new type of building material, has good adaptability (suitable for many kinds of packing), good economy (up to 30% of the investment in geomer room on engineering projects) and good stability. Geotextile room method can effectively use the site soil, reduce soil Shi Fangliang, effectively reduce environmental load and speed up the project progress. The research on the mechanism of geocell reinforced structure needs to be deepened. It is imperative to propose a practical engineering design and calculation method.

【学位授予单位】：东北林业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU470

【参考文献】