基于桩土共同作用的集约式微型桩群加固路基边坡机理与效果研究

发布时间：2018-07-01 10:37

本文选题：微型桩群 + 弹性地基梁　；参考：《北京交通大学》2015年博士论文

【摘要】：随着人们对滑坡危害的认识及其破坏机理的深入研究,滑坡防治措施在向轻型化、小型化、机械化施工、经济性方向发展,集约式微型桩群是其中最具代表性的轻型支挡措施。微型桩群支挡体系是一个较为复杂的系统,目前工程技术人员对桩土共同作用机理尚不能准确分析,在工程设计中,桩土参数及桩群布置形式的确定都是经验性的,同时也缺乏对加固后滑坡稳定性的分析评价。因此, 本文对集约式微型桩群的内力计算理论、桩侧阻力影响效力、桩群水平承载性能、加固效果评价等方面进行了系统深入的研究,主要研究内容和创新成果归纳如下：(1)基于弹性地基梁理论,建立考虑桩侧摩阻作用的微型桩挠曲微分方程,求解出齐次微分方程通解、初参数解、均布荷载下特解及集中荷载下特解,提出了考虑桩侧摩阻作用的集约式微型桩群的内力计算理论。(2)通过衡量由微型桩桩侧阻力作用引起桩周一定范围内土压力改变量ΔP与桩周处土压力减量值P0的大小,提出高、中、低影响区域和无影响区域的概念,为方便的指导桩排间距的设置,提出与影响区域相应的高、中、低影响半径。为更好的发挥桩群间岩土体的耦合抗滑作用,建议间距设置为高影响半径与中影响半径之间。(3)通过集约式微型桩群水平承载性能的现场原型试验,揭示桩间注浆岩土体也发挥了较强的抗滑能力。在滑体介质为粉质黏土条件下,桩群承担滑坡推力的692%,桩间土体承担滑坡推力的30.8%,桩—土荷载分担比约为7：3。(4)经有限元计算及归一化分析得出,优化桩长、桩径、桩排数和排间距可显著增强集约式微型桩群的水平承载能力,降低桩顶位移。在进行集约式微型桩群的工程设计时,建议微型桩嵌固段长度设为滑面以上桩长的2/3-1,桩排数设为3-4排,最佳排间距为5倍桩径。(5)通过建立加固后边坡的数值计算模型,研究了运煤道路典型荷载作用方式——非对称行车荷载作用下路基和微型桩的受力与变形特征,具体分析了不同荷载幅值对其影响规律。(6)开展了微型桩弯曲应力、桩侧土压力和深部位移的长期原位监测,分析不同阶段滑坡的运动形态及支挡结构物的受力状态,并通过深部测斜孔不同深度处的时间—位移曲线评价集约式微型桩群加固滑坡的效果。
[Abstract]:With the deep study of landslide hazard and its damage mechanism, landslide prevention measures are developing towards light, miniaturization, mechanized construction and economy. Intensive miniature pile group is one of the most representative lightweight retaining measures. Micro-pile group retaining system is a complicated system. At present, the mechanism of pile-soil interaction can not be accurately analyzed by engineers and technicians. In engineering design, the determination of pile-soil parameters and pile group layout is empirical. At the same time, there is also a lack of analysis and evaluation of the stability of the strengthened landslide. Therefore, in this paper, the internal force calculation theory of intensive miniature pile group, the effect of pile side resistance, the horizontal bearing capacity of pile group, and the evaluation of reinforcement effect are systematically and deeply studied in this paper. The main research contents and innovative achievements are summarized as follows: (1) based on the theory of elastic foundation beam, the differential equation of deflection of micro-pile considering the friction on the side of pile is established, and the general solution of homogeneous differential equation and the solution of initial parameter are obtained. Special solution under uniform load and special solution under concentrated load, In this paper, the internal force calculation theory of intensive miniature pile group with consideration of pile side friction is put forward. (2) by measuring the magnitude of soil pressure change 螖 P and soil pressure decrement value P0 in a certain range caused by the lateral resistance action of micro pile, the paper puts forward the high value. In order to guide the arrangement of pile-row spacing, the high, middle and low influence radius corresponding to the influence area is put forward for the concept of middle, low impact area and no influence area. In order to better exert the coupling anti-sliding effect of rock and soil between piles, it is suggested that the spacing be set between the high influence radius and the middle influence radius. (3) through the field prototype test of the horizontal bearing capacity of the intensive miniature pile group, It is revealed that grouting rock and soil between piles also play a strong anti-slip ability. Under the condition that the sliding medium is silty clay, the pile group bears 692um of the landslide thrust, the soil between the piles bears the 30.8% of the landslide thrust, and the load-sharing ratio of the pile to soil is about 7: 3. (4) through the finite element calculation and the normalized analysis, the results show that the pile length and diameter are optimized. The pile row number and row spacing can significantly enhance the horizontal bearing capacity of the intensive miniature pile group and reduce the pile top displacement. In the engineering design of intensive miniature pile group, it is suggested that the length of embedded segment of miniature pile should be 2 / 3-1 of the length of pile above sliding surface, the number of piles should be 3-4 rows, and the optimum row spacing should be 5 times diameter of pile. (5) the numerical calculation model of reinforced slope is established. The stress and deformation characteristics of subgrade and micro-pile under the action of asymmetric driving load are studied, and the influence of different load amplitudes on it is analyzed. (6) bending stress of micro-pile is carried out. The long-term in-situ monitoring of the soil pressure and deep displacement of the pile side is carried out to analyze the movement pattern of the landslide and the bearing state of the retaining structure in different stages. The effect of intensive miniature pile group on landslide reinforcement was evaluated by time-displacement curves at different depths of deep inclined holes.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U416.14

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