三角形土工格栅加筋土筋土界面特性分析

As a reinforced material, the geosynthetics was put into soil and formed a composite system. The interaction between geosynthetics and soil would be produced when the system deformed under dead weight and load. The new triangular geogrid products with a triangular aperture shape recently introduced into the market are expected to have a more stable grid structure, which can provide more uniform resistance in all directions. However, limited test data related to triangular geogrid-reinforced soil has been published so far. Therefore, tests are needed to evaluate their behavior and mechanisms when used in the reinforced structures. Based on the pre-results got at Ph.D study, the triangular geogrid and two different backfill materials are selected in this research. More research will be done to study the reasons why both cohesion and friction angle were increased.The impact factors of interface properties will be investigated. A parameter is selected to evaluate the interface properties between triangular and different backfill materials. By comparing the test results with biaxial ones, the advantages of triangular aperture are confirmed.The interface failure mechanisms between geogrid and backfill materials will be investigated under different test conditions,which will provide a theory background for reinforced soil and the stability of reinforced structure. The success of the interface failure mechanisms will also have a active affect for our economic construction and social development.

作为加筋材料，土工合成材料埋置在土体内，与周围土体构成复合体系。当加筋土复合体系在外荷及自重作用下产生变形时，筋土界面将产生相互作用。作为一种新型土工格栅，三角形土工格栅有着更稳定的网格结构，可以提供更均匀的约束。目前世界上各国对于该土工格栅的基础理论研究和应用技术刚刚起步，研究数据还非常有限，特别是在筋土界面特性方面的研究几乎为空白。基于申请者博士试验研究结果，本项目拟以三角形土工格栅和两种不同填料为研究对象，进一步研究三角形土工格栅加筋土似粘聚力和摩擦角同时增加的现象，探讨影响三角形土工格栅加筋土筋土界面特性的因素，对三角形土工格栅筋土界面特性进行评价，验证其栅三角形栅孔的优越性，分析总结其筋土界面破坏的机理，为建立考虑土工格栅栅孔形状的加筋土理论体系和提高加筋土结构的稳定性提供理论基础，对我国的国民经济建设和社会发展具有积极意义。

作为加筋材料，土工合成材料埋置在土体内，与周围土体构成复合体系。当加筋土复合体系在外荷及自重作用下产生变形时，筋土界面将产生相互作用。作为一种新型土工格栅，三角形土工格栅有着更稳定的网格结构，可以提供更均匀的约束。本项目以三角形土工格栅为研究对象，开展了室内大型模型直剪试验，探讨了影响三角形土工格栅加筋土筋土界面特性的因素，验证其栅三角形栅孔的优越性。分别研究了填料相对密实度变化、填料含水率变化、剪切速率改变对筋土界面特性的影响。结果表明，随着填料相对密实度的增加，界面的峰值强度逐渐增大，但填料含水率变化对筋土界面强度的影响不甚明确。研究发现，随着剪切速率的增加，筋土界面出现破坏的时间略有减缓，峰值有缓慢增加的趋势同时，开展了室内大型拉拔试验和室内单面剪切试验，以对比分析试验方法的优劣。基于损伤模型参数，分别对不同程度损伤的双向土工格栅呵呵三角形土工格栅进行不同方向拉力作用下的模型分析，研究其在损伤条件下极限抗拉强度的变化。结果表明随着损伤程度的增加，两种格栅的强度近似呈线性递减，30°方向抗拉强度变化较其它方向变化大。双向土工格栅极限抗拉强度受施工损伤的影响较三角形土工格栅敏感。建议三角形土工格栅的施工损伤折减系数以30°方向下25%~75%损伤范围内取值。