植物根系长度对生态袋加筋土挡墙稳定性的影响

在生态型加筋土挡墙中,植物根系能发挥立体加筋效果。为了探索植物根系对生态袋加筋土挡墙的作用效果,该研究对不同根系长度(无根系、生态袋内根系伸出袋外10、20和30 cm)的4组生态袋加筋土挡墙模型进行加载试验。因植物根系不易取材,易枯萎失去强度,而棕榈叶不易枯萎且枯萎后仍然具有较大的抗拉强度,试验中用棕榈叶来替代植物根系。研究了挡墙水平位移、面墙后水平土压力、加筋体末端水平土压力、筋材拉应变随根系长度和荷载增加的变化规律。通过试验发现:4组模型试验中水平位移、面墙后水平土压力、加筋体末端水平土压力、格栅拉应变随荷载增加的变化规律基本一致,相同荷载作用下,相比无根系时,含根系的挡墙中4个参量的值均减小,且随着根系长度的增加,值减小得越多。其中水平位移、面墙后及加筋体末端的水平土压力3种参量在加载初期减幅较小,在加载后期,减幅大大提高。说明根系增加了生态袋面墙的整体刚度,根系对面墙后土体起到了加筋作用,使得加筋土挡墙的承载能力提高,加筋土挡墙内部和外部的稳定性增加。随着根系长度增加,这种增强作用越明显。最后对4种参量受根系长度影响的敏感性进行了分析,得到4种参量的敏感性从大到小依次为:面墙...

Effects of plant root lengths on stability of ecological bag reinforced retaining wall

In the flexible ecological reinforced retaining wall, the vegetation can not only play a greening and environmental protection role, but also the growing plant roots have a three-dimensional reinforcement effect. In order to explore the effect of plant roots on stability of the ecological bag reinforced retaining wall, In this study, three round-trips vertical load tests were carried out on four groups of ecological bag reinforced retaining wall models with different root lengths. That were, no root in the ecological bag, and the roots extended out ecological bag of 10, 20 and 30 cm respectively. Palm leaves were selected to replace plant roots in the tests due to plant roots are easy to wilt and lose strength, while palm leaves are not easy to wilt and still have large tensile strength after wilting. The variations of four parameters, horizontal displacement of ecological bag reinforced retaining wall, horizontal earth pressure behind the ecological bag wall-plate and near reinforced body end, the tensile strain of geogrid, were studied with root length and load. The results showed that the variation rules of the four parameters with the increase of load in the four sets of model tests were similar. Through the comparative analysis of the test data, it was found that the presence of roots increased the overall rigidity of the ecological bag wall-plate, under the same load, compared with no root, the horizontal displacement in the three types of retaining walls with different root lengths all decreased, and the more root length increased, the more the values decreased. The horizontal displacement had slightly decrease in load less than 80 kPa, while obviously decrease in load more than 100 kPa. The horizontal earth pressures behind the ecological bag wall-plate without roots in different wall heights were all greater than that of the rooted reinforced retaining wall under the same load, especially the roots extended out the ecological bag of 30 cm. The horizontal earth pressures near reinforced body end and tensile strain of the geogrid had similar trends with the horizontal earth pressures behind the ecological bag wall-plate，and they were gradually decreased under the same load with the root length increased. Then the sensitivities of the four parameters affected by the root length were analyzed, and the sensitivities of the four parameters were in order from high to low as follows: horizontal earth pressure behind the ecological bag wall-plate, horizontal displacement of retaining wall, horizontal earth pressure near reinforced body end, tensile strain of geogrid. The two parameters, horizontal earth pressure behind the ecological bag wall-plate and horizontal displacement of ecological bag reinforced retaining wall, were more sensitive to the change of root length. The results showed that the plant roots could improve the integrity and stiffness of the ecological bag wall-plate, and increased the internal and external stability of flexible ecological reinforced retaining wall. With root length increased, the strengthening effect became more obvious. The successful implement of this research can provide important experimental basis for understanding the nature of the role of plant roots on flexible ecological reinforced retaining walls.