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目前加筋土结构设计中筋材的抗拉强度都是根据室内标准无约束拉伸试验而得到的,不能反映筋材与土存在相互作用下的真实力学特性。采用土工格栅进行了一系列模拟加筋土实际受力状态的侧限约束拉伸试验和蠕变试验,结果表明,常规无约束条件下获得的格栅抗拉强度与实际情况相差很大,不同类型土工格栅在砂土侧限约束下的拉伸强度和延伸率变化规律与上覆荷载及拉伸速率有关,但割线模量都比无约束情况下有显著增大;侧限约束下格栅的蠕变量明显降低。因此,在加筋土结构设计中,筋材的抗拉强度指标宜采用符合工程实际受力状态的侧限约束拉伸试验强度值。另外,以无约束试验得到的筋材蠕变安全系数过于保守,侧限约束下筋材的蠕变临界应力水平有所提高。
At present, the tensile strength of the reinforced material in the reinforced earth structure design is obtained according to the unconstrained tensile test in the indoor standard and can not reflect the true mechanical properties under the interaction of the reinforcement material and the soil. A series of constrained tensile tests and creep tests were carried out using geogrids to simulate the actual state of the reinforced soil. The results show that the tensile strength of the grating obtained under conventional unconstrained conditions is quite different from the actual situation, The variation of tensile strength and elongation of different types of geogrids under the confinement of sand soil is related to the overburden and tensile rate, but the secant modulus is significantly larger than that of the unconfined ones. The creep of the lower grille is significantly reduced. Therefore, in the design of reinforced earth structure, the tensile strength index of tendons should adopt the lateral restraint tensile strength value in line with the actual state of the engineering force. In addition, the creep safety coefficient of the tendon obtained by the unconstrained test is too conservative, and the creep critical stress level of the tendon under the confinement constraint is increased.