加筋粗粒土大型拉拔模型试验分析

为明确加筋砾类粗粒土筋土界面之间的相互作用以更好地指导工程实践,在土工格栅加筋粗粒土上采用基于自主设计的可视化大型拉拔设备完成拉拔试验。采用高清数码跟踪技术研究加筋粗粒土拉拔界面的形成演化规律,探讨粗粒土的P_5粗粒含量、土工格栅嵌入长度以及上覆应力的变化对筋土界面性质的影响。结果表明,格栅嵌入长度、粗粒含量、上覆应力的增加均可有效提高拉拔力峰值和剩余抗拔力;土工格栅嵌入长度短且粗粒含量低的情况下,筋土拉拔界面位移带形成较早;通过加入更多粗粒量与缩小嵌入长度,可以使拉拔试样内摩擦角与表面黏聚力提升;上覆应力在0～50 kPa范围中升高,可大幅度降低似摩擦系数,上覆应力超过50 kPa时,似摩擦系数下降趋势保持平缓状态。建议工程实际应用中优先考虑提高粗粒含量。所得结果对于合理控制粗粒含量,改善加筋土韧性,提高相关工程结构的稳定性与安全性具有一定的借鉴价值。

Analysis on large scale pull-out model test of reinforced coarse-grained soil

In order to clarify the interaction between the reinforced gravel coarse-grained soil and the interface to better guide the engineering practice, the self-designed large-scale visual drawing equipment was used to complete the pull-out test on the geogrid reinforced coarse-grained soil. The formation and evolution of reinforced coarse-grained soil pull-out interface were studied by using high-definition digital tracking technology, and the influence of P5 coarse material content, embedded length of geogrid and change of overlying stress on the properties of reinforced soil interface was discussed. According to the test data, the increase of embedded length of geogrid, coarse material content and overlying stress can effectively improve the peak value of drawing force and the remaining pull-out resistance; when the embedded length of geogrid is short and the content of coarse material is low, the displacement band of the drawing interface of reinforced soil forms earlier; the internal friction angle and the surface cohesion of the drawing sample can be increased by adding more coarse material and reducing the embedded length. If the overlying stress increases in the range of 0kPa to 50kPa, the quasi friction coefficient can be greatly reduced. When the overlying stress exceeds 50kPa, the decline trend of the quasi friction coefficient remains smooth. It is suggests that the increase of coarse material content should be given priority in practical application, and the results provide some reference for the control of coarse material content, the amelioration of the toughness of reinforced soil and the improvement of the stability and safety of related engineering structures.