土工格栅拉拔试验及筋材摩擦受力特性研究

Research on pull-out test and frictional resistance characteristic of geogrids

土工格栅与土的相互作用特性是影响土工格栅加筋结构稳定性的重要因素。通过室内拉拔试验,针对不同的上覆荷载,对土工格栅受拉时表面摩擦力分布特征进行了研究。试验结果表明,格栅表面摩擦力沿着格栅纵向逐渐向后传递,并在拉拔的前期增长明显,后期趋于一个稳定值;利用S型曲线模拟了土工格栅的应变与拉拔时间的相关关系。通过不同埋设位置的检测点所得到的格栅即时应变数据,拟合出格栅的三维应变曲面ε(x,t);对格栅表面上的摩擦力进行全段积分,得到格栅拉拔力的时程函数T(t)。该试验结果对土工格栅加筋结构设计具有一定的参考价值。

The interaction property between geogrids and soil is fundamental and important factor on stability of geogrids-reinforced earth structure. A series of experiments to investigate the friction on the surface of pulled geogrids are conducted in the laboratory under various levels of externally-applied load. By analyzing experimental data, some conclusions were drawn that the friction on the surface of geogrids gradually transfers backwards along it, which rapidly increases in early time of the pull-out test and approaches to some stable value ultimately. The relationship between the strain of the geogrids and pulling time is simulated by the sigmoid curve. Based on the experimental data of the strain of the geogrids at different embedments, a three dimensional strain surface that represents a function of coordinate and time is obtained. The time function for pull-out force of geogfids is deduced through integration of friction along total length of geogrids. The experimental data is of referring value for design of geogrids-reinforced earth structure.