考虑蠕变、老化影响的土工格栅与土界面机理及加筋土承载特性研究

It is called as reinforced soil technique (RST)to improve strength and stability of soil by using the inter action of reinforcement and the soil.This technique has been widely used in road,dam,slop and foundation due to simple construction method and low cost.Geogrid,possessing light weight,high strength ,and friendly interface property,becomes one of the most popular reinforcements.The creep and aging of geosynthetic materials interfere directly with the working effectiveness of the interface between reinforcement and the soil,in turn interfere with the engineering proerties of reinforced soil,which are related to the safety and durability of the project.Based on gathering and study the literaries,this project will look into the effections of various factors such as types of geogrids,types of soil,degree of aging,and creep on the interface action and bearing characteristics of geogrid reinforced soil foundaton by conducting material tests,interface tests,and large scale model tests,a systematic experiment study from material to structure model.Comparison with numerical simulation and theoric analysis,the relationship among creep,aging shearing strength along the interface of reinforce and soil will be analyzed, the bearing design model and settlement calculating of geogrid reinforced soil foundation will be developed by taking into accound of long time loading acting and degree of geogrid aging.The research results are expected to further deepen the theory of reinforced soil technique and develop the reliability and durability of reinforced soil foundation.The economical and social benefits resulting from the research outcome will be significiat as the important data and theory for widely application of this kind of foundation will be made available.

加筋土技术是利用筋材与土的相互作用而达到提高土体的强度和稳定性的一种土工增强技术，广泛应用于道路、坝体、边坡和建筑地基工程中。土工格栅因其轻质高强，筋土作用友好而受到亲睐，成为常用的加筋材料之一。合成材料蠕变和老化直接影响到了加筋土筋土界面的共同工作效应，从而影响加筋土结构或地基的工程性状，关系到工程项目的耐久性和安全可靠性。本项目通过材料、筋土界面、加筋土地基模型的试验，从材料到结构，从细观到宏观的手段，对不同土工格栅类型、不同填土材料组成，时间效应作用和老化程度等因素作用下，土工格栅加筋土界面相互作用和加筋土地基承载特性进行系统试验研究，结合数值模拟分析，揭示筋材蠕变和老化对加筋机理的影响规律，建立考虑蠕变和老化影响的土工格栅加筋土地基的计算模型和承载力与沉降计算方法。研究成果将丰富加筋土技术的理论，提高加筋土地基的可靠性和耐久性，为加筋土地基的推广应用提供试验数据和基础理论。

加筋土技术是利用筋材与土的相互作用而达到提高土体的强度和稳定性的一种土工增强技术，广泛应用于道路、坝体、边坡和建筑地基工程中。土工格栅因其轻质高强，筋土作用友好而受到亲睐，成为常用的加筋材料之一。合成材料蠕变和老化直接影响到了加筋土筋土界面的共同工作效应，从而影响加筋土结构或地基的工程性状，关系到工程项目的耐久性和安全可靠性。本项目以不同型号的土工格栅为研究对象，通过一系列室内试验，从材料到结构，从细观到宏观的手段，对不同土工格栅类型，时间效应和老化程度等因素作用下，土工格栅加筋土界面相互作用和加筋土地基承载特性进行系统试验研究。通过土工格栅室内蠕变试验，得到土工格栅蠕变加卸载全过程曲线、等时蠕变曲线、加速蠕变曲线。建立了能够反映土工格栅瞬时变形-衰减蠕变、稳定蠕变、加速蠕变加卸载全过程的黏弹塑性模型。应用扫描电子显微镜技术对不同蠕变条件下的聚丙烯双向土工格栅试样进行了测试分析，得到了微裂纹在格栅节点和纵、横肋表面分布的方向、数量、尺寸变化规律。基于灰色预测模型对光氧老化后的土工格栅抗拉强度保持率随光氧老化时长变化的规律进行了预测。揭示了筋材蠕变和老化对加筋机理的影响规律，提出了老化蠕变耦合折减系数，建立了考虑土工格栅蠕变、老化作用的加筋砂土地基承载力计算公式。自行研制了室内模型试验箱，得到了加筋作用、桩径大小、格栅预应力、格栅老化时长以及预应力和老化耦合条件对刚性基础下桩-网复合地基的沉降、桩侧摩阻力、筋材应力等力学性能的影响规律。开展了土工格栅加筋桩网复合地基的现场实体建筑地基的测试试验，得到了刚性基础施工荷载作用下桩-网复合地基的受力与变形规律。通过室内大型直剪试验，得到了渣土粒径、渣土级配、格栅类型对筋土界面摩阻特性的影响，提出了土工格栅-建筑渣土界面摩擦强度的一般表达式。研究成果丰富了加筋土技术的理论，为加筋土地基的推广应用提供试验数据和基础理论。