桩锚支护体系基坑稳定性分析方法及应用研究

发布时间：2018-01-29 14:05

本文关键词： 深基坑桩锚支护稳定性强度参数折减法滑向应力有限单元法　出处：《南京理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：桩锚加上部土钉组合支护结构是一种较新的支护体系,它已被较广泛应用于深基坑支护和边坡防滑工程。这种支护结构因为许多优点而在实际中被广泛采用。但是到目前为止,关于这类支护基坑的稳定性的数值计算和应用研究还很不够。基坑边坡稳定性分析对其设计和施工都是重要内容。从理论和算法两方面对稳定性分析的传统极限平衡法,抗剪强度参数折减有限元法和滑面应力有限元分析法进行了对比,分析了极限平衡法的力学原理和不足,对抗剪强度参数折减有限元法和滑面应力有限元分析法的特点和实施程序进行了分析探讨,从理论上阐述了抗剪强度参数折减算法和滑面应力有限元算法的可取性。基于抗剪强度参数折减算法,采用PLAXIS程序对一上部设计为土钉,下部桩锚的复杂支护深基坑的滑动面和稳定性安全系数进行了模拟和计算,结果显示,两种方法得到的安全系数存在一定差别,分析了产生差别的原因。认为主要原因是有限元模拟方法考虑了支护桩和锚索与土体之间的一定程度的相互作用,并且有限元采用的是上部土钉与下部桩锚整体化计算模型,而传统极限平衡法不能很好地考虑支护结构(桩和锚杆)与土体的相互作用。有限元计算结果还显示,上部土钉的内力与土钉高度位置和其下桩锚支护段的施工挖土等有关。顶层土钉的内力较小。每一层土钉的内力显示随该土钉下面土层的开挖而累计变化,随模拟开挖深度增加内力增大。抗剪强度参数折减有限元法和滑面应力有限元分析方法的应用,能为桩锚复杂支护基坑的设计和施工提供较好的指导。
[Abstract]:Pile anchor combined with soil nailing is a new support system. It has been widely used in deep foundation pit support and slope anti-slip engineering. This kind of support structure is widely used in practice because of many advantages. But so far. Numerical calculation and applied research on the stability of this kind of supporting foundation pit are not enough. The stability analysis of foundation pit slope is an important content for its design and construction. The traditional limit equilibrium method for stability analysis is presented in theory and algorithm. The shear strength parameter reduction finite element method and the sliding surface stress finite element analysis method are compared, and the mechanical principle and shortcomings of the limit equilibrium method are analyzed. The characteristics and implementation program of shear strength parameter reduction finite element method and sliding surface stress finite element analysis are analyzed and discussed. The desirability of shear strength parameter reduction algorithm and sliding surface stress finite element method are discussed theoretically. Based on the shear strength parameter reduction algorithm, PLAXIS program is used to simulate and calculate the sliding surface and stability safety factor of a complex retaining deep foundation pit with the upper part designed as soil nailing and the lower pile anchor. The results show that there are some differences in the safety coefficient between the two methods. It is considered that the main reason is that the finite element simulation method takes into account the interaction between supporting pile and anchor cable and soil to a certain extent. The finite element method adopts the integral calculation model of the upper soil nailing and the lower pile anchor, but the traditional limit equilibrium method can not take into account the interaction between the supporting structure (pile and anchor) and soil. The finite element results also show that. The internal force of the upper soil nailing is related to the height of the soil nailing and the construction and excavation of the supporting section under the pile and anchor. The internal force of the top soil nailing is relatively small. The internal force of each layer of soil nailing shows that the internal force varies with the excavation of the soil layer below the soil nailing. The internal force increases with the increase of simulated excavation depth. The application of shear strength parameter reduction finite element method and sliding surface stress finite element analysis method can provide better guidance for the design and construction of pile-anchor complex supporting foundation pit.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU470

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