循环荷载下加筋砂土累积应变特性试验研究

Experimental research on cumulative strain characteristics of reinforced sand under cyclic loading

摘要:

为研究加筋在砂土循环加载过程中产生的影响,以高密度聚乙烯(HDPE)网格作为加筋材料,对实际工程场地所取砂土试样开展动三轴试验,研究不同加筋层数和不同加筋间距下砂土轴向累积应变的演化趋势,并对筋材在试验过程中发挥影响作用的机制进行分析。研究结果表明:加筋能减少砂土轴向累积应变,加筋层数越多，对轴向累积应变的削减作用越强,但通过增加筋材层数带来的加筋效果增幅逐渐减小;不同加筋间距下轴向累积应变曲线均符合改进Monismith模型,在间距为80 mm时,轴向累积应变显著降低。加筋在砂土中产生影响作用的方式主要有两种:一是通过自身的弹性性能发挥作用,筋材的弹性变形恢复,导致其附近砂土颗粒的位移减少;二是在筋土界面处产生更好的咬合作用以形成似黏聚力,从而产生影响。研究结果可为加筋作用机理的深入研究提供参考。

Abstract:

To investigate the influence of reinforcement under cyclic, high-density polyethylene (HDPE) geogrids were used as reinforcement materials. Triaxial dynamic tests were conducted on sand samples taken from actual engineering sites to study the evolution of axial cumulative strain with varying reinforcement layers and spacings. The mechanism by which reinforcement influences the test process was also analyzed. Results indicate that reinforcement significantly reduces the axial cumulative strain of the sand. Adding more layers of reinforcement significantly reduces the axial cumulative strain, although the marginal benefit decreases with each additional layer. All axial cumulative strain curves for different reinforcement spacings conform to the modified Monismith model, showing a noticeable reduction at a spacing of 80 mm. Reinforcement affects the sand in two primary ways. First, the elastic properties of the reinforcement material contribute to the elastic deformation recovery, which decreases the displacement of nearby sand particles. Second, improved interlocking at the reinforcement-soil interface creates a pseudo-cohesive force that stabilizes the soil. These findings offer provide insights for further research into the reinforcement mechanisms.