南沙某软土深基坑支护事故分析及优化设计

发布时间：2018-02-05 22:45

本文关键词： 软土深基坑工程优化设计重力式水泥土墙双排桩　出处：《暨南大学》2013年硕士论文　论文类型：学位论文

【摘要】：南沙地区位于穗港澳的几何中心，是广州未来发展的核心地区。该地区多为海陆交互相的软弱黏性土，，工程地质和水文地质条件都较为复杂。深厚淤泥或淤泥质软土层已成为南沙地区基础工程和基坑工程中尤为突出的难题。本文主要针对南沙地区软土特性，紧密结合该地区工程实例，就基坑支护选型、基坑支护加固以及基坑支护优化方面展开分析，并提出合理的软土深基坑工程方案，为南沙地区同类工程提供参考，主要研究内容与成果如下： 1.采用理正软件计算分析了南沙某基坑顶部边坡塌方原因，结果表明：（1）施工运土车辆产生的边坡顶部超载大大降低了边坡稳定安全系数；（2）地面积水渗入边坡表层土后，土体发生软化，粘聚力降低，边坡趋于不安全甚至失稳状态；（3）基坑土体超挖使支护结构整体稳定安全系数降低，不满足规范要求。 2.对基坑原重力式水泥土墙支护方案进行了优化设计，结果表明：（1）增设两排水泥土搅拌桩使水泥土墙宽度达4.15m时，支护结构整体稳定安全系数达最大值为1.329；（2）提高水泥土墙嵌固深度至11.0m时，基坑各稳定性安全系数更为均衡；（3）当被动区加固体厚度增大时，支护结构最大水平位移明显减小，并在加固体厚度超过4m后趋于稳定；（4）顶部边坡放缓，卸除冗余土体可有效增强基坑支护稳定性。 3.引入了双排桩支护方案，并与重力式水泥土墙支护方案进行了对比，结果表明：（1）考虑被动区加固土影响时，双排桩支护方案各稳定性安全系数与重力式水泥土支护方案差别不大；（2）不考虑被动区加固土影响时，双排桩支护方案的抗倾覆稳定性、整体稳定性均明显优于重力式水泥土墙支护方案，桩身水平位移、弯矩以及所产生的地表沉降量均远小于重力式水泥土墙。
[Abstract]:Nansha is located in the geometric center of Guangzhou, Hong Kong and Macao, and is the core of Guangzhou's future development. The engineering geology and hydrogeological conditions are complicated. The deep silt or silt soft soil has become the most prominent problem in the foundation engineering and foundation pit engineering in Nansha area. This paper mainly focuses on the characteristics of soft soil in Nansha area. Based on the engineering examples in this area, the selection of foundation pit support, the reinforcement of foundation pit and the optimization of foundation pit support are analyzed, and a reasonable project of soft soil deep foundation pit is put forward, which provides a reference for similar projects in Nansha area. The main research contents and results are as follows:. 1. The causes of slope collapse at the top of a foundation pit in Nansha are calculated and analyzed with the help of leveling software. The results show that the overloading on the top of the slope produced by the construction vehicles greatly reduces the slope stability safety factor and the surface water seeps into the surface soil of the slope. The soil softens, the cohesive force decreases, the slope tends to be unsafe or even unstable. The soil overexcavation of the foundation pit reduces the overall stability safety factor of the supporting structure and does not meet the requirements of the code. 2. The optimization design of the original gravity cement-soil wall supporting scheme of foundation pit is carried out. The results show that when two drainage soil mixing piles are added, the width of the cement-soil wall reaches 4.15m. When the stability safety factor of the supporting structure reaches the maximum value of 1.329m) when the cement-soil wall depth is increased to 11.0m, the stability safety factor of the foundation pit is more balanced. (3) when the passive zone and the solid thickness increase, the maximum horizontal displacement of the supporting structure decreases obviously. When the thickness of solid is more than 4 m, the slope at the top of the slope tends to be stabilized, and the stability of foundation pit support can be effectively enhanced by removing the redundant soil. 3. The double row pile support scheme is introduced and compared with the gravity cement-soil wall support scheme. The results show that when considering the influence of the reinforced soil in the passive zone, When the stability safety factor of double-row pile support scheme is not different from gravity cement-soil support scheme, the overturning stability of double-row pile support scheme is not considered when the influence of passive zone reinforcement is not considered. The overall stability is obviously superior to that of gravity cement-soil wall, and the horizontal displacement, bending moment and surface settlement of the pile are much smaller than those of gravity cement soil wall.
【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU753;TU714

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