考虑时间效应的超高填方涵洞废旧轮胎减载机理及工作性状研究

According to the difficulties to determine the long-term performances and the earth pressures of culverts treated with the existing load reduction methods, the time-dependent behavior and the working mechanism of ultra-high embankment culverts treated with waste tires for load reduction will be studied. Based on the mechanical properties of waste tire and its reinforcement, theoretical analysis and numerical simulation will be carried out to investigate the distribution and the transfer laws of the earth pressure, the relationship between the earth pressure and the deformation of load reduction structure will be established, and the load reduction mechanism of ultra-high embankment culverts treated with waste tires will be revealed. A series of model tests and numerical simulations will be carried out to clear the influencing factors on earth pressures around culverts and deformations of load reduction structure, and the factors will be classified into primary and secondary according to their influencing degree. The sliding surface and the pressure between soil particles will be observed by the digital imaging technology and discrete element simulations. Based on the results of mechanism and influencing factors analyses, the time-dependent behavior model of the ultra-high embankment culvert with waste tire will be established, and the expressions of the earth pressures on the culvert and the deformations of the waste tires will be deduced by theoretical analysis, field tests will be employed to verify the proposed theoretical methods as well. .This project aims at revealing the load reduction mechanism of ultra-high embankment culverts treated with waste tires, clearing the influencing factors and their effects on load reduction, establishing the time-dependent earth pressure calculation theory, and providing key theoretical basis for the design and application of waste tires on load reduction of ultra-high embankment culverts.

针对现有减载措施土压力和长期服役性能难以确定等问题，基于“以废治害”思想，本项目对超高填方涵洞废旧轮胎减载方法和长期工作性状进行研究。在获取废旧轮胎及其加筋土力学特性的基础上，通过理论分析和数值模拟研究土压力分布规律和传递规律，建立土压力与减载结构变形间的关系，揭示废旧轮胎加筋减载机理；通过模型试验和数值模拟研究涵周土压力和减载结构变形的影响因素，并根据影响程度将各因素进行主次划分；利用数字成像技术和离散元模拟，确定涵周填土滑动面发展和土压力传递规律；结合机理和影响因素分析成果，建立超高填方涵洞减载工作性状时间效应模型，推导考虑时间效应的超高填方涵洞土压力及轮胎结构受力和变形的计算公式，并利用现场试验对理论模型及计算方法进行验证。本项目旨在揭示超高填方涵洞废旧轮胎减载机理，确定减载效果影响因素及影响规律，建立考虑时间效应的土压力计算理论，为超高填方涵洞废旧轮胎减载方法的应用奠定理论基础。

针对现有减载措施土压力和长期服役性能难以确定等问题，基于“以废治害”思想，本项目对超高填方涵洞减载方法和长期工作性状进行了研究。研究了废旧轮胎及其加筋土的力学特性：确定了废旧轮胎材料的应力－应变关系和力学参数；研究了废旧轮胎与填土之间的界面摩擦特性，确定了轮胎条、片与不同土类之间的界面强度指标，轮胎加筋土的压缩系数和变形模量等参数。揭示了超高填方涵洞废旧轮胎减载机理：研究了采用减载后涵顶平面、涵洞台背的土压力分布规律和土压力随填土高度的变化规律；对废旧轮胎减载结构的变形和应力进行测试，确定了涵周土压力、填土位移与废旧轮胎减载结构变形和应力之间的对应关系；通过理论分析，考虑地基－涵洞－填土－减载结构的相互作用关系，揭示了废旧轮胎加筋减载机理。确定了废旧轮胎减载效果影响因素：研究了不同尺寸和结构类型的涵洞，在不同填土高度条件下的减载效果；重点考虑了涵洞埋设条件（上埋式或沟埋式），废旧轮胎加筋土所形成减载结构的尺寸、形状、层数，土体的模量、内摩擦角及黏聚力等因素对涵顶和涵侧土压力、减载结构变形及涵周填土的位移和滑动面发展模式的影响规律。建立了减载条件下涵洞土压力计算方法：建立减载涵洞土压力的力学计算模型和超高填方涵洞减载工作性状时间效应模型，同时，考虑减载结构的变形特性，研究加筋结构拉力传递规律，建立了多种超高填方涵洞土压力的计算方法。本项目研究为超高填方涵洞废旧轮胎减载方法的应用奠定了理论基础。