摘 要 :地下连续墙不仅刚度大、强度高、整体性强、抗渗性好,能适用于多种地质条件, 还具有施工简便、材料省、投资节约等优点。地下连续墙在岸壁码头中的应用是一个 值得考虑的方向,但目前其在码头工程中的应用案例少、应用方式单一,多用作小型 板桩码头的无锚碇或多锚碇单壁板岸壁结构,其原因是对复合断面的地下连续墙挡土 结构的受力变形特点缺少深刻认识。因此,开展复合断面地下连续墙的研究,分析总 结不同结构形式的地下连续墙的受力变形特点,对于在岸壁码头中的推广应用地下连 续墙结构具有实际的工程意义。
本文以 ABAQUS 有限元软件为平台,分别采用基于 Mohr-Coulomb 准则的理想 弹塑性模型和弹性模型模拟土体和地下连续墙钢筋混凝土板,建立了均质土上地下连 续墙挡土结构的有限元分析模型。基于所建立的模型,首先模拟了刚性挡土墙土压力 的分布,并与经典挡土墙土压力计算结果进行了对比,验证了计算方法的可靠性。继 而对于悬臂式单壁板地下连续墙,根据单变量原则,通过改变土体粘聚力、摩擦角、 剪胀角以及连续墙墙厚的变参数有限元计算,分析总结了不同因素对地下连续墙工作 性状的影响。在此基础上,开展了双壁板式地下连续墙、T 型地下连续墙和格构式地 下连续墙的模拟计算,分析了壁板间距、肋板长度及间距、土体参数的选取对于地下 连续墙受力变形的影响。研究表明,复合断面的地下连续墙能够有效地减少墙体水平 位移,但刚度由小到大改变,地下连续墙表现出截然相反的位移趋势;在相同条件下, 对墙体水平位移的控制能力由大到小的顺序为双排格构式结构、T 型结构、双排壁板 式结构、单壁板式结构,但在同等体积材料的情况下 T 型结构在减小墙顶水平位移上 具有优势;土体强度参数及土侧压力系数对地下连续墙的工作性状有较大影响,但土 体剪胀角对墙体位移无任何影响。
关键词:地下连续墙;有限元分析;ABAQUS
Abstract:Underground diaphragm wall has the advantages of having higher stiffness, higher strength, better structural integrity, higher seepage resistance, being applicable to a variety of geological conditions. With the improvement of construction equipment and the improvement of construction technology, underground diaphragm wall also has the advantage of having a simple construction machinery, a fast construction speed, less influenced by limitation of terrain, less material, low investment. The application of the underground diaphragm wall structure in the quay is a worthwhile consideration. However, there are few cases of underground diaphragm wall used in quay and the application mode of underground diaphragm wall is monotonous. Most the underground diaphragm walls are used as quay walls of small sheet pile piers with or without anchor. The reason is that there is a lack of deep understanding of deformation characteristics of the diaphragm wall retaining structure of the composite section. Therefore, to analyze and summarize the characteristics of the deformation of the underground diaphragm wall with different structural forms is of practical significance of promoting the application of the underground diaphragm wall structure in the quay engineering.
In this paper, ABAQUS finite element software is used as the platform to establish the numerical model of retaining wall structure of the underground diaphragm wall on homogeneous soil, with the ideal elastic-plastic model based on Mohr-Coulomb criterion is used to simulate the soil and the elastic model is used to simulate the reinforced concrete slab of underground diaphragm wall. Based on the established model, the distribution of the earth pressure of the rigid retaining wall is calculated and compared with the traditional theoretical results, so the reliability of the calculation method is verified. Further, a series of variable parameter analyses were carried out for the cantilever single-wall diaphragm wall, according to the principle of univariate, by changing the soil cohesion, friction angle, dilatancy angle and diaphragm wall thickness in turn. The effects of each variable on the working performance of single-wall diaphragm wall were summarized. Then calculations of the double-walled underground diaphragm wall, T-shaped underground diaphragm wall and lattice-type underground diaphragm wall were executed separately. The influences of the spacing of the wall, the length and spacing of the slab and the soil parameters on the deformation of the underground diaphragm wall were analyzed. The above studies show that, underground diaphragm wall with combined cross section could reduce the lateral displacement of diaphragm wall effectively; however, the trend of lateral displacement along the depth of diaphragm wall varying with stiffness of wall is opposite. The ability of underground diaphragm walls to control the lateral displacement of wall in descending order are lattice-type, T-shaped, double-walled and single-walled underground diaphragm wall; but T-shaped diaphragm wall has an advantage of controlling lateral displacement over the others, when they have the same volume. The finite element analyses also show that strength parameters of soil and coefficient of later soil pressure effect the working performance of underground diaphragm wall obviously; on the contrary, dilatancy angle of soils has no effect on the lateral displacement of underground diaphragm wall.