有孔管桩静压沉桩挤土效应理论分析

发布时间：2018-06-27 08:03

本文选题：有孔管桩 + 挤土效应　；参考：《南昌航空大学》2017年硕士论文

【摘要】：静压管桩因其质量可靠,施工无噪声、无振动、应力小等诸多优点而被广泛用于工程中。但静压管桩属于部分挤土桩,在沉桩过程中,桩周土体不仅会产生较大位移,而且会在短时间内形成较高的水压力。有孔管桩能使土中自由水流入管腔,从而减小局部土体位移,加速超孔隙水压力的消散并降低其最大值。本文基于圆孔扩张理论,针对有孔管桩沉桩过程产生的挤土效应开展研究工作,推导了平面状态和空间状态下,无孔管桩及有孔管桩沉桩过程中土体产生的应力增量和径向位移解,并对其解析式进行对比分析。利用有孔管桩的应力增量解,对有孔管桩沉桩产生的超孔隙水压力进行了分析,推导了沉桩过程中超孔隙水压力与径向距离、沉桩速率、深度、开孔孔径以及时间之间的解析式。运用数值模拟手段,对桩体的贯入过程进行模拟,得到超孔隙水压力与各因素之间的关系,从而验证了理论分析的合理性。具体研究内容结果如下:(1)对无孔管桩沉桩时桩周土体应力增量和径向位移的一般解析解进行回顾,考虑到桩身开孔处应力的变化,推导了有孔管桩的应力增量及径向位移解。对比分析可得:有孔管桩桩周土体的应力增量及径向位移小于无孔管桩。(2)考虑到深度对沉桩的影响,推导了有孔管桩沉桩过程中的应力及位移空间解析解。对比分析有孔管桩和无孔管桩可得:空间状态下,有孔管桩的应力增量及土体径向位移比无孔管桩的应力增量及位移要大。并以此推导了基于土塞效应的有孔管桩塑性阶段土体径向位移解。(3)推导了桩周土体超孔隙水压力与径向距离、沉桩速率、深度、开孔孔径及时间之间的解析式。结合工程实例可得:超孔隙水压力随径向距离的增大呈对数衰减;随沉桩速率的加快不断增大;随深度的加深呈递增趋势;随开孔孔径的加大逐渐减小。(4)运用有限元分析软件ABAQUS,对有孔管桩贯入土体的过程进行了数值模拟,得到超孔隙水压力随径向距离的增大而衰减;相同径向距离处,超孔隙水压力随深度的加深不断增大;同一深度、同一径向距离处,超孔隙水压力随沉桩速率的加快逐渐增大。
[Abstract]:Static pressure pipe pile is widely used in engineering because of its reliable quality, no noise, no vibration, low stress and so on. But the static pressure pipe pile belongs to the partial compaction pile. In the process of piling, the soil around the pile will not only produce a large displacement, but also form a higher water pressure in a short time. The perforated pipe pile can make the free water in the soil flow into the pipe cavity, thus reducing the displacement of local soil, accelerating the dissipation of the excess pore water pressure and reducing the maximum value of the excess pore water pressure. Based on the theory of circular hole expansion, this paper studies the squeezing effect of bored pipe pile in the process of piling, and deduces the plane state and space state. The stress increment and radial displacement of soil in the process of piling without holes and pipe piles with holes are solved, and the analytical formulas are compared and analyzed. By using the stress increment solution of the pipe pile with holes, the excess pore water pressure caused by the piling of the pipe pile with holes is analyzed, and the excess pore water pressure and radial distance, the velocity and depth of the piling are deduced. The analytic formula between aperture and time. By means of numerical simulation, the penetration process of pile body is simulated, and the relationship between excess pore water pressure and various factors is obtained, which verifies the rationality of theoretical analysis. The results are as follows: (1) the general analytical solutions of stress increment and radial displacement of soil around the pile are reviewed, and the stress increment and radial displacement of the pipe pile with holes are deduced considering the change of stress at the open hole of the pile. The results show that the stress increment and radial displacement of the soil around the pile are smaller than those of the pile without hole. (2) considering the influence of depth on piling, the analytical solution of stress and displacement in the piling process is derived. It is found that the stress increment and the radial displacement of the pipe pile with holes are larger than those of the pile without holes in space. Based on the soil plug effect, the radial displacement solution of soil in plastic stage is derived. (3) the analytical formulas between soil excess pore water pressure and radial distance, piling speed, depth, aperture and time around the pile are derived. Combined with engineering examples, it can be found that the excess pore water pressure decreases logarithmically with the increase of radial distance, increases with the acceleration of piling speed, and increases with the deepening of depth. (4) by using finite element analysis software Abaqus, the process of perforated pipe pile penetrating into soil is numerically simulated. The results show that the excess pore water pressure attenuates with the increase of radial distance, and at the same radial distance, the pore water pressure decreases with the increase of radial distance. The excess pore water pressure increases with the deepening of the depth, and increases gradually with the acceleration of the piling rate at the same depth and the same radial distance.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

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