【作者】 仝元通；

【导师】 宋建学；

【作者基本信息】 郑州大学 ， 岩土工程， 2013， 硕士

【摘要】 伴随着我国经济的迅猛发展,人们也对基坑支护结构提出了越来越高的要求,传统的支护结构己不能很好的满足这种要求。上部土钉墙下部桩锚(撑)复合支护结构兼顾了桩锚支护结构和桩撑支护结构各自的优点,取得了扬长避短的效果。然而针对这种复合支护结构的相关研究明显落后于工程需求。结合郑州市兰德国际中心深基坑工程,在基坑开挖过程中,对基坑周边及支护结构主要部位的位移进行现场监测并分析监测数据,概述上部土钉墙下部桩锚(撑)复合支护结构支护下深基坑位移的发展规律；采用ABAQUS软件对整个基坑开挖过程进行模拟分析,并与实测数据进行对比,验证模型及参数的合理性和适用性；通过变化设计参数进行虚拟设计,总结各设计参数对基坑及支护结构位移变化的影响。主要得到了以下结论：(1)上部土钉墙下部桩锚(撑)复合支护结构应用于郑州地区该类土层时,土钉墙部分的高度以3.6m为宜,且不宜超过6m。(2)支护结构选型时需要确保排桩冠梁的标高高于附近需要保护建筑物的基础底面。(3)下部桩锚(撑)支护体系对上部土体的支护效应不明显,上部土钉墙的设计应立足于自身的强度和稳定性设计。(4)上部土钉墙下部桩锚(撑)复合支护结构中排桩的深层水平位移曲线大体呈现“P”字形状,且最大位移出现在钢筋混凝土内支撑位置附近。(5)在当场地条件对基坑变形控制要求比较严格时,有必要在支护桩高度(基底以上)上部的1/3区间内设置内支撑；当基坑深度较大时,深部支护结构承受的主动土压力较大,应在该范围内增设内支撑。更多还原

【Abstract】 With the rapid development of economy in our country, people also put forward higher requirements for foundation pit supporting structures, the traditional supporting structures cannot meet this requirement very well. The upper soil nailing wall and lower anchor pile (bracing) composite supporting structure takes account of the advantages both of the pile anchor supporting structure and inside supporting structures. Not only can it enhance advantages but also circumvent weaknesses. Yet the related researches on this composite retaining structure obviously lag behind the demand of the engineering.This paper bases on the deep foundation pit engineering of the rand international center in Zhengzhou. The displacement of the surrounding foundation pit and main parts of the supporting structures has been monitored in site during the process of excavation of foundation pit; the monitoring data has been analyzed. The law of displacement of the foundation pit with supporting of the upper soil nailing wall and lower anchor pile (bracing) composite supporting structure has been summarized. ABAQUS has been used to simulate the whole process of excavation, the model and parameters shows rational and applicable according to the comparison between simulation result and monitoring data. The influence from design parameters on displacement of foundation pit and supporting has been summarized by changing design parameters for the virtual design. The paper mainly got the following conclusions:(1) It will be better if the height of the soil nailing wall is between three to six meters when the composite supporting structure is used in this type of soil in Zhengzhou, and it should not more than6meters.(2) Should ensure that the beam elevation is higher than the bottom of the surrounding foundations where the upper buildings need to be protected during the process of choosing supporting structures.(3) The under supporting system of pile anchor (bracing) do little to the stability of the upper soil, and the design of the upper soil nail wall should be done based on its own strength and stability.(4) The deep horizontal displacement curve of piles in the composite supporting structure of upper soil nailing wall and lower anchor pile (bracing) is generally presents the "P" shape, at the same time, the maximal displacement appears near the reinforced concrete brace position.(5) It is necessary to set up interior bracings in the interval of upper one-third of the piles if the restriction of deformation is strict. For the deep excavation, inner bracing should be added where the active earth pressure of the under supporting structure is large.更多还原