堆石料与土工格栅间拉拔特性试验研究

Experiments on Pullout Behavior of Geogrid Under Rockfill Materials

针对目前土石坝工程中最常采用的双向塑料焊接土工格栅和双向涤纶经编土工格栅,采用大型拉拔试验设备完成了两种格栅在堆石料中的拉拔试验,以研究其与堆石料的相互作用机制及加筋效果。试验结果表明:拉拔位移较大时,塑料焊接格栅的格栅节点达到极限强度而发生剥离破坏,造成拉拔力的阶梯式衰减,节点强度是控制界面强度的重要因素且法向作用的荷载大小对节点强度的影响不大;而涤纶经编格栅拉拔力"硬化"现象明显,试验初段,由于格栅材质柔度较大,横肋阻力作用不明显,抗拉拔力由纵肋摩阻力和节点端承阻力提供,经过较大的拉拔位移后,格栅节点并未发生剥离破坏。

Geogrids are increasingly applied in seismic strengthening of earth-rockfill dam slopes,which mainly include biaxial plastics welded geogrids and biaxial polyester warp-knitted geogrids. To better understand the mechanism and effect of these two types of geogrids,the pullout tests were conducted using these two types of geogrid specimens and large-scale pullout devices. By analyzing experimental data,some conclusions were drawn that the debonding between longitudinal and transversal ribs in plastics-welded geogrid nodes cause the stepped decay of pullout force at large pullout displacement,so the junction strength of welded geogrid is the controlling index to the effect of welded geogrids reinforcement. Based on the pullout test data of polyester warp-knitted geogrids,the‘hardening＇of pullout force is obvious,the pullout force is composed of friction resistance of longitudinal geogrid ribs and transverse geogrid ribs,resistance of transverse geogrid ribs and the junctions. The resistance of transverse geogrid ribs doesn＇t work at the beginning of test due to its great flexibility.