侧向约束桩—复合地基加固斜坡软基工作机制与设计理论研究

With the lateral deformation controlled strictly ,composite foundation with lateral constraint piles has been widely used for the soft ground reinforcement on slope,but the calculating of overall stability and horizontal displacement is difficult,so the specific study on working mechanism and design theory of the combined piles composite foundation is of important practical significance and theory value. Based on model test and centrifugal model test, all of the stress distribution between piles and soil, the internal force variation of inclined piles, the lateral soil pressure distribution law of the lateral constraint piles, the pattern of lateral soil movement, and the interrelation between stability and deformation coefficient will be fully tested and analyzed.Elastic-plastic property of the soil will be simulated by the Drucker-Prager yield criterion and the large deformation of soil will be considered,pile-soil interaction of the inclined piles under soft soil movement action will be analyzed with 3-D finite element analysis. With composite foundation sliding sideways , soil arching effect principle will be studied, calculating method of soil pressure on the lateral constraint piles will be advanced, and the internal force and displacement transfer law of single-raw piles will be analyzed by poulos elastic theory method and p-y curve method. The relationship between stability and soft soil bottom slope of the combined piles composite foundation will be analyzed by Swedish slice method, transmit coefficient method and finite element method. The interrelations between stability and deformation coefficient will be built with overall stability and displacement calculation. Based on the monitoring data, the design theory of controlling both of the deformation coefficient and the stability coefficient will be proposed, the safety evaluation method with actual lateral displacement volume will be formed,and the basis for the revision of specification will be provided.

侧向约束桩-复合地基重点控制侧向变形，在斜坡软基工程中广泛应用，但其整体稳定性分析和水平位移计算较困难，对其工作机制和设计理论进行研究，具有重要的工程意义和理论价值。采用室内模型（槽）试验和土工离心模型试验，测试并分析桩土荷载分担、斜桩内力变化、侧向约束桩侧土压力分布、复合土体侧移模式以及变形系数与稳定系数的相互关系；以D-P材料模拟土体的弹塑性性质、考虑大变形,对软土运动作用下的斜桩-土相互作用进行三维有限元分析；研究土拱原理，提出复合地基侧移时侧向约束桩侧土压力计算方法，综合采用Poulos弹性理论法和p-y曲线法，分析单排桩内力和位移传递规律；采用条分法、传递系数法和有限元法分析该地基稳定性及其与软基底面坡度的关系，配合位移计算，建立稳定系数和变形系数之间的相互关系；结合监测数据进行验证，提出"稳定系数-变形系数双重控制"设计理论，形成实际侧移量时安全性评价方法，为修订规范提供依据。

侧向约束桩-复合地基在斜坡软基工程中广泛应用，但其整体稳定性分析和水平位移计算较困难。采用室内模型试验和数值模拟研究桩体复合地基重复加卸载过程中侧向约束桩水平变位规律与工程特性、倾斜基底上复合地基桩在循环加卸载下桩身位置变化规律和侧向约束桩工程特性、倾斜桩复合地基变形特征与破坏模式、倾斜桩复合地基受压特性及对临近桩影响、含缺陷桩复合地基受压工程特性、含缺陷桩复合地基重复加卸载下临近桩顶侧移规律，为侧向约束桩-复合地基优化设计提供依据。