【作者】 胡荣华；

【导师】 刘国楠；

【作者基本信息】 中国铁道科学研究院 ， 岩土工程， 2011， 博士

【摘要】 衡重式桩板挡墙是一种新型支挡结构,由桩板墙和衡重台等组成,该挡墙利用衡重台的卸荷作用,使衡重台下部结构的受力减小,同时为桩柱提供一个反向弯矩(相对于土压力作用引起的弯矩),使整体结构的内力分布相比悬臂式桩板挡墙更为合理,相比锚索桩板挡墙施工方便、耐久性好、造价低。但其受力特性和破坏机理较复杂,设计理论不完善。因此,对衡重式桩板挡墙的受力特性及破坏机理进行深入、系统的研究,将有助于设计方法的完善和施工工法的改进,具有重要的理论和工程实际意义。本文以已建造的深圳市某工程衡重式桩板挡墙为原型,设计建造了1:7缩尺模型,开展了衡重式桩板挡墙的模型试验。试验研究了衡重式桩板挡墙结构在无外荷载作用下和有外荷载作用下的受力、变形特性。具体研究了: 1)上下墙土压力的分布模式; 2)衡重台(卸荷板)的尺寸和布置位置对土压力分布模式的影响; 3)衡重式桩板挡墙在受力和破坏时的变形性状等问题。在此基础上,提出了土压力分布模式、卸荷扩散角以及嵌固段反力分布模式。采用FLAC软件对衡重式桩板挡墙模型试验进行了多组数值模拟,具体分析了挡墙土压力、挡墙位移以及结构内力等随板宽与埋深的变化规律,并与模型试验结果进行了对比,对比分析表明本文采用的数值研究方法能够用于模拟模型试验。基于此,选择板宽为0.40倍的墙高与板埋深为0.45倍的墙高,深入研究了桩长对衡重式桩板挡墙整体稳定性的影响。数值分析结果表明,衡重式桩板挡墙以倾覆破坏为主。对衡重式桩板挡墙进行了四组1:50的土工离心模型试验,每组试验通过不同的离心加速度,模拟正常使用荷载和破坏荷载,对衡重式桩板挡墙的倾覆破坏以及整体滑移破坏过程进行了研究。离心试验结果表明:1)衡重式桩板挡墙的破坏模式有倾覆破坏和整体滑移破坏;2)以倾覆破坏为主,地基土强度很低时出现过桩底的圆弧滑移破坏。根据对衡重式桩板挡墙缩尺模型试验、数值模拟及离心试验结果的综合分析,提出了整体滑移的模式,并基于条分法推导了相应的整体滑移计算公式;提出了倾覆稳定性计算的模式并推导了抗倾覆稳定系数的计算公式;并以模型试验为例对整体滑移稳定性及抗倾覆稳定性基于matlab编程进行了计算。最后对衡重式桩板挡墙的板宽、埋深以及桩长的优化计算进行了探讨,并编制程序进行了计算。更多还原

【Abstract】 The sheet pile wall with relieving platform is a new type of retaining structure, which is composed of sheet pile wall and relieving platform. Because of the unloading effect of the relieving platform, the stress of the structure below reduced the relieving platform, and the relieving platform provides a reverse moment to the pile (relative to the moment caused by earth pressure), which brings about the internal force distribution of the integral structure more reasonable compared with the cantilever sheet pile wall. The sheet pile wall with the relieving platform is more convenient in construction, lower cost and higher durability than the anchored soldier pile and lagging wall, its mechanical behavior and failure mechanism are very complicated, great gap existed in current theoretical research, and its design theory isn’t perfect. Therefore, carrying out the mechanical behavior and failure mechanism of in-depth, systematic study will help to improve the design method and construction method, which has important theoretical and practical significance.Based on a project of the sheet pile wall with relieving platform in Shenzhen, a 1:7 scale model was designed and build, and the model test was taken on. In two cases of with and without external load on top of the wall, the stress and deformation characteristics of the sheet pile wall with the relieving platform were researched by the laboratory scale model test of this structure. Experimental focused on the following aspects: 1) the distribution pattern of earth pressure along the upper and lower wall; 2) the effect of the change of the releiving platform depth and width on the earth pressure distribution pattern; 3) the stress and deformation behavior of the structure during loading and destroying. On this basis, the earth pressure distribution patterns, the relieving diffusion angle, and the counter-force distribution pattern of embedded body were proposed.Multiple sets of numerical simulation analysis were carried out in accordance with the model tests of the sheet pile wall with releiving platform with FLAC. The change rule of earth pressure,the displacement of the retaining wall and the internal force of structure along with the width and depth of the relieving platform were analysed in detail.And results were compared with those of model tests, which showed that numerical methods in the paper can be used to simulate model test. Then, choosing 0.4 times the high wall as the width of relieving platform and 0.45 times the high wall as the depth of relieving platform. A intensive research on effect of the pile length on the whole stability of the sheet pile wall with relieving platform was performanced.The numerical simulation results demonstrated that the failure mode of this structure was mainly overthrow damage. Four groups of 1:50 geotechnical centrifuge model test was carried out for the sheet pile wall with releiving platform. Each group test with the different centrifugal acceleration simulated the normal load and destruction load. The overthrow damage and the overall sliding failure process of the sheet pile wall with releiving platform was studied. The results of centrifuge model test showed that: 1) the failure patterns of the sheet pile wall with releiving platform were overthrown damage and whole sliding failur; 2) the overthrown damage was prevailing, It occurred as circular sliding damage through the pile bottom when foundation soil strength was very low.According to results from comprehensive analysis of the scale model tests,numerical simulation and geotechnical centrifuge test for the sheet pile wall with releiving platform, the overall slip mode was proposed and the corresponding formula was derived based on‘Slice method’, and anti-overthrow mode was forwarded and safety stability formula was deduced. And taken the model test as an example, based on MATLAB programming, the whole sliding stability and anti-overturning stability were calculated. At last, the optimization of the width and depth of the relieving platform and the length of pile were discussed, and the programming was developed for the optimization calculation.更多还原