【作者】 张瑞；

【导师】 刘奉银；

【作者基本信息】 西安理工大学 ， 岩土工程， 2010， 硕士

【摘要】 随着我国基础设施建设规模的扩大及功能的扩展,基础工程中钻孔灌注桩与防渗墙等开挖的深度越来越大,地层条件也越来越复杂。西部大开发中水利水电建设遇到的河谷深厚覆盖层的问题越来越突出。在深厚覆盖层这种复杂地层中建造防渗墙,如何才能保证钻孔成槽的工程质量及槽孔的稳定性,因此,研究造孔成槽的过程中孔、(槽)壁的稳定性关键影响因素研究十分重要。由于地下条件的复杂性以及地下施工的隐蔽性,很难对地下情况有足够详细的了解,特别是对防渗墙施工过程中泥浆护壁的机理及泥浆渗透过程缺乏详细的了解,因此,很有必要专门对泥浆护壁过程及护壁机理进行分析研究,为泥浆护壁措施及槽壁稳定分析提供理论依据。基于以上原因,本文首先对深厚覆盖层防渗墙施工过程中槽壁稳定性的影响因素进行了分析,具体从泥浆的性能、地层条件、地下水位、槽段的划分及施工工艺、施工机械及孔口地面荷载等因素进行了详细地分析与总结,然后针对上述影响因素提出了一些提高防渗墙槽壁稳定性的有效措施,并指出了今后在深厚覆盖层防渗墙槽壁稳定性方面需要开展的工作及研究内容。为了基本定量地确定各因素对槽孔稳定性影响的大小,以大渡河黄金坪水电站防渗墙槽孔为研究对象,运用大型通用有限元软件Abaqus并引入邓肯-张E-B本构模型,分步模拟了防渗墙槽孔的开挖过程,并对三种不同密度的泥浆护壁条件下槽孔的应力-变形进行了计算,分析了槽孔开挖以及不同密度的泥浆护壁条件下槽孔的变形特性,发现泥浆密度的增大与槽壁侧向位移的减小基本呈线性关系。在考虑泥浆发生沉淀的情况下,模拟计算了三种泥浆密度分层变化以及泥浆分三层沉淀过程中防渗墙槽孔的变形,运用计算得到的应力-变形结果,对比分析了不同泥浆密度分层变化以及泥浆沉淀过程对防渗墙槽孔的变形特性及应力分布的影响规律。更多还原

【Abstract】 As the expansion of China’s infrastructure construction and scale, the depth of the bored piles and cut-off wall is increasing in the infrastructure projects, as well as the formation conditions are moreand more complex. With the implementation of the western development, the problem of the thick overburdens in the valley is increasingly prominent in water conservancy and hydropower construction. How can we ensure the forming slot’s quality and slot stability when the cut-off wall is build in this complex formation condition, so it is very important to study the effect factors in the slot and trench wall stability in the process of making hole and groove. Due to the complexity and the hidden nature of underground conditions, It is difficult to have enough and detailed knowledge of ground conditions, especially the of and slurry infiltration process.Above all,it is necessary to specially research the process and mechanism of the to provide a theoretical basis for the measures of slurry protection and wall stability.Based on the above reason, effect factors to the trench wall’s stability were researched fristly in the construction process of the cut-off wall in the thick overburdens, and specifically from the factors such as the slurry performance、ormation conditions、water table、groove section division and construction technology、construction machinery and ground orifice load which were analysised and summaried detailedly, then some effective measures were given to improve the stability of cut-off wall pointuing to the above factors,as well as some need researched works were proposed in the trench wall’s stability of cut-off wall in thick overburdens.In order to determine the basic quantitative impact size of various factors on the stability of the slot.,cut-off wall slot of the HuangJin ping hydropower station in DaDu river as the research object, using the large-scale general-purpose finite element software Aabaqus and introduced of Duncan-Chang E-B constitutive model, excavation process of the cut-off wall’s slot was simulated as well as the slot stress and displacement was calculated under the conditions of three different densities of slurry protection, the slot deformation characteristics was analysised under the condition of the slot excavation and different densities, and found that slurry density increasesis and trench wall lateral displacement reduced for the linear relationship.Considering the slurry precipitation, the displacements of the three kinds of slurry density variations and the slurry precipitation process on cut-off wall’s slot was simulated. Using the calculated stress and displacement results, the impact of the slurry density variations and the slurry precipitation process on the deformation characteristics and stress distribution of cut-off wall’s slot was analysised.更多还原