【作者】 王洪发；

【导师】 白顺果；

【作者基本信息】 河北农业大学 ， 岩土工程， 2010， 硕士

【摘要】 桩-网复合地基适用于软土地基和路基的处理,其特点是“桩-网-土”三者的协同工作,在网、桩和土变形协同作用下,桩土荷载分担比发生变化。桩-网复合地基具有沉降变形小、施工快、工后沉降易于控制、稳定性高、不需预压期、工期短、施工方便等优点。在天然地基上,通过科学合理的设计桩-网复合地基可以较多的减少用桩的数量进而降低工程造价实现良好的经济效益。因此对桩-网复合地基的工作机理进行研究是十分必要的。论文首先在总结前人研究成果的基础上分析了桩-网复合地基的工作机理,以及土工合成材料的加固机理。然后,本文叙述了土拱理论和薄板变形理论。在桩-网复合地基中,基于土拱理论、薄板变形理论和Winkler弹性地基理论,提出了桩-网复合地基工后沉降计算方法和桩土应力比计算方法,由于该计算模型考虑了桩-网复合地基各组成部分之间的相互作用,能够更准确地反映出桩-网复合地基的工作机理,同时克服了传统算法中“两者不能同时未知”的缺陷,并通过工程算例验证了本文方法的正确性,对于实际工程的应用提供一定的理论依据。利用有限元软件对桩-网复合地基进行了模拟。分析了桩体、土体、桩间距、桩径等参数变化对桩-网复合地基沉降的影响,进一步分析了桩-网复合地基的工作性状。论文所得主要结论如下:(1)土工格栅的设置能有效地减小竖向沉降,土工格栅的设置更有效地限制路堤的侧向变形。(2)桩-网复合地基最大沉降量发生在两桩中心顶部。最大沉降量随着荷载的增加而增加。(3)最大沉降量随土模量的增大而减小,减小幅度较大。(4)沉降值相同时,桩-网复合地基比普通复合地基桩间距明显要大。验证了疏桩理论的设计思想。更多还原

【Abstract】 Pile-net composite foundation is especially suited for soft foundation treatment, its characteristics is that pile and soil share the loads with the cooperation of piles, soil and net. It has many advantages, such as small settlement, ease controlled post-construction, high stability, no precompression, shorten construction, and so on. We can cut down the number of piles and construct cost, on the natural foundation, by scientific and rational design, which can accomplish projects with thetremendous economy benefit.At the beginning of the thesis, some conclusions on pile-net composite foundation are provided. Working mechanism of pile-net composite foundation and reinforcement mechanism of geotechnical synthetic materials are analysised.There are also a short introduction on the soil arch theory and deformation plate theory .Based on the Soil arch theory, Deformation plate theory and Winkler model, the method is proposed for calculating residual settlement and pile-soil stress ratio of pile - net composite foundation. Because of considering the interaction of the various components of the pile - net composite foundation, the theoretical model shows the working mechanism of the pile - net composite foundation more accurately and overcame the shortcomings of traditional methods. At last, the model was verified by an engineering example and provided the basis for the practical engineering.And then pile - net composite foundation are simulated using finite element software. From the results of simulation, we get to know some rules about the pile - net composite foundation. Here are some results :(1) The vertical settlement and lateral deformation are decreased effectively by setting the geotechnical grille.(2) The maximum settlement of pile - net composite foundation appears at the top of center between two piles. The maximum settlement of pile - net composite foundation increases when the load increases.(3) The maximum settlement of pile - net composite reduces substantially when the soil modularincreases.(4) With the same settlement , the pile distance of pile - net composite foundation is longer than normal composite foundation’s .更多还原