微型桩受力机理及应用分析

发布时间：2018-07-13 18:45

【摘要】：我国滑坡地质灾害频发，在滑坡治理时抗滑桩是常见的工程措施。一般，它是通过增大桩身横截面来增加桩的刚度和强度，从而抵抗滑坡推力。大截面抗滑桩在实际施工中存在很多问题，，如：滑坡施工场地坡度较大不便于大型施工机械设备进场，只好更多地采用人工挖孔的方式施工；工程土方量大，施工干扰大，对临滑状态的滑坡抢险有很大影响；施工效率低、成本高、安全性差等等。微型桩作为一种新型的抗滑支挡结构物，在治理滑坡中的优良抗滑效果已经得到了国外研究学者的一致认可，并大规模的投入到实际工程应用中，但是国内对于微型桩的研究特别是微型桩受力机理的研究还远远不足。本文通过理论计算和有限元数值模拟两种方法结合的手段对微型桩受力机理进行分析，在与他人物理模型试验结果对比的基础上得到了以下结论： ①根据微型桩应用的历史资料、工程实例分析，微型桩与大型抗滑桩相比较具有自重小、施工空间要求小，易于机械化施工，对地基承载力要求低，工期短等特点，适于路基灾害抢险和滑坡工程的应急抢险工程。 ②布设微型桩时，桩体锚固段的合理长度由微型桩截面、锚固段岩体粘结系数、滑体或变形体的粘结系数、经验共同决定，推荐值为3-5m。 ③通过数值模拟分析、理论计算与他人的物理模型试验成果比较，得出微型桩设置为3排较为合理，前排装承受更大的推力，后排依次递减12%，因此应考虑通过增加微型桩内钢筋来加强或者加密前排桩。 ④单桩微型桩受土抗力的极值出现土体高度距离地面2/3处。 ⑤运用PLAXIS有限元软件对文天路滑坡治理全过程进行模拟，从全程来看，微型桩作为应急抢险措施是有效的，但是若将其作为永久治理工程，其适用性有待考证；抢险中的微型桩的变形和失稳表现为弯剪变形。永久工程实施后，它的作用主要是辅助锚杆和抗滑桩保持滑坡的稳定。
[Abstract]:Landslide geological hazards occur frequently in China, and anti-slide pile is a common engineering measure in landslide control. In general, it increases the stiffness and strength of the pile by increasing the cross-section of the pile body to resist the landslide thrust. There are many problems in the actual construction of large section anti-slide pile, such as: the large slope of landslide construction site is not convenient for large construction machinery and equipment to enter the field, so it has to be constructed more by manual digging, and the engineering earthwork is large and the construction interference is great. It has a great influence on landslide emergency, low construction efficiency, high cost, poor safety and so on. As a new type of anti-slide retaining structure, the fine anti-slide effect of micro-pile in landslide control has been unanimously recognized by foreign researchers, and has been put into practical application on a large scale. However, the study of micro pile, especially the mechanism of micro pile, is far from enough. In this paper, the mechanical mechanism of micro-pile is analyzed by means of theoretical calculation and finite element numerical simulation. On the basis of comparison with other physical model test results, the following conclusions are obtained: (1) according to the historical data of the application of micro-pile and the analysis of engineering examples, the self-weight of micro-pile is smaller than that of large-scale anti-slide pile. The construction space is small, the construction space is easy to mechanize construction, the requirement to the foundation bearing capacity is low, the time limit is short, and so on, so it is suitable for the emergency rescue engineering of subgrade disaster and landslide engineering. The reasonable length of the anchoring section of the pile body is determined by the micro pile section, the rock mass bond coefficient of the anchoring section, the bond coefficient of sliding body or deformable body, and the experience. The recommended value is 3-5 m. 3 through numerical simulation analysis. Compared with others' physical model test results, the theoretical calculation shows that it is more reasonable to set the micro-pile to three rows, and the front row bears more thrust. The back row decreases 12% in turn, so we should consider strengthening or infilling the front row pile by adding reinforcing bar in the micro pile. 4 the extreme value of the soil resistance of single pile micro pile is 2 / 3 from the ground surface. 5. PLAXIS finite element software is used to simulate the whole process of controlling Wentianlu landslide. From the whole process, the miniature pile is effective as an emergency rescue measure, but if it is regarded as a permanent treatment project, its applicability needs to be verified, and the deformation and instability of the micro-pile are shown as bending and shear deformation. After the implementation of the permanent project, its main role is to assist the anchor and anti-slide pile to maintain the stability of the landslide.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U418.55;U416.1

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