季节冻土区预应变加筋土挡墙的作用机理及冻融稳定性研究

Prestrained reinforcement method is introduced based on reinforced soil, for frost damage prevention and control problems of retaining wall in seasonal frozen region. First of all, based on the drawing and friction test under different reinforcement anchorage length, different temperature and moisture content of soil, reinforcement strain distribution law will be analyzed to put forward calculation method of effective length of reinforcement, and the influence law of many parameters on reinforcement-soil interface parameters will be revealed. Second, the test on reinforced soil retaining wall will be conduced under different reinforcement prestrain and condition of freezing and thawing of retaining wall, to get retaining wall rupture surface mode ,the schema of horizontal frost heaving force along the wall back and the maximum horizontal frost heaving force, revealing the inhibition mechanism of prestrained reinforcement method on horizontal frost heaving force and deformation of the retaining wall. Finally, internal stability safety coefficient of prestrained reinforced soil retaining wall will be calculated based on the strength subtraction of finite element, to reveal the influence law of freezing and melting process, the initial value of prestrain, initial moisture content, freezing temperature, seasonal freezing and thawing layer thickness on retaining wall stability safety factor. Through the research of reinforced soil retaining wall, analysis, test and design methods of reinforced soil retaining wall on freeze-thaw stability performance with prestrained reinforcement method will be established, to provide a scientific basis of promoting applications of prestrained reinforcement soil retaining wall in seasonal frozen.

针对季节冻土区挡土墙的工程冻害防治问题，基于加筋土发展了预应变加筋法。首先，通过对不同筋材锚固长度、不同温度、不同填料含水率下的拉拔摩擦试验研究，分析筋材应变分布规律并提出筋材有效长度的计算方法，探寻多试验参数对筋土界面特性参数的影响规律；其次，进行不同筋材预应变、不同挡墙冻融条件下加筋土挡墙的冻融试验研究，获取挡墙的破裂面形式及水平冻胀力沿墙背的分布图式和最大水平冻胀力值，揭示预应变加筋法对水平冻胀力及挡墙融沉变形的抑制机理。最后，基于有限元的强度折减法计算季节冻土区加筋土挡墙的内部稳定安全系数，探求冻融过程、筋材预应变、初始含水量、冻结温度、季节冻融层厚度等因素对挡墙内部稳定安全系数的影响规律。通过上述加筋土挡墙的系统研究，建立与预应变加筋法相适应的加筋土挡墙冻融稳定性能的分析、试验与设计方法，为推广预应变加筋土挡墙在季节冻土区应用提供科学依据。

防治季节冻土区挡土墙冻害是工程建设成败的关键，不仅要选择加筋土挡墙作为季节冻土区理想的挡土构筑物，更要应用预应变加筋法这一途径实现筋材的理想受力机制。本项目围绕季节冻土区预应变加筋土挡墙的作用机理及冻融稳定性展开研究，旨在充分发挥筋材的受力机制、提高加筋效果，揭示温度变化条件下的筋土界面特性及筋材的作用机理，以提高季节冻土区加筋土挡墙的冻融稳定承载力和抗冻害能力。完成了低温条件下筋土界面特性拉拔摩擦试验以及预应变加筋土挡墙冻融试验，结合数值模拟分析技术，分析了筋材应变分布规律及负温对筋土界面摩擦力的影响规律，给出了冻融过程及加载过程挡墙土压力及位移的变化规律，获取了挡墙的破裂面形式及水平冻胀力的分布规律，揭示了预应变加筋机理，基于强度折减法研究了关键参数对挡墙内部稳定安全系数的影响规律。研究成果对于解决季节冻土区挡土墙的工程冻害防治问题，促进预应变加筋法的工程应用具有重要的理论和实践意义。