高中低拉拔速率下筋土界面拉拔试验分析

Pullout Tests and Analysis of Reinforced Soil Interfaces at High,Medium and Low Pullout Rates

边坡及挡墙倒塌破坏会导致土工格栅与土之间快速滑动,筋土界面相互作用较为复杂。通过对不同拉拔速率下界面筋材受力和变形特性的研究,有助于加深对筋-土界面工作特性的认识。基于此,采用拉拔试验以拉拔速率和法向荷载为研究因素探讨了9种拉拔速率和3种法向荷载对筋-土界面作用特性的影响规律。结果表明:峰值拉拔力随着拉拔速率由低到高变化增大幅度逐渐变缓,界面黏聚力与拉拔速率呈正相关变化趋势,最大增大了278%;界面摩擦角呈负相关变化趋势,最大减小了19.1%。格栅应变在低速时受拉拔速率影响较大,随着拉拔速率的增大而增大;当拉拔速率超过5 mm/min时,格栅应变变化幅度减小,抗拔刚度增大。界面剪胀量随拉拔速率的增大呈增大趋势,随法向荷载的增大呈减小趋势。高速时界面剪胀量约为低速时的1.56倍、中速时的1.13倍。

Landslide and retaining wall collapse damage will cause rapid sliding between geogrids and soil,and the interaction of reinforced soil interfaces is complicated.It helps to deepen the understanding for mechanical characteristics of reinforced soil interfaces by studying the force and deformation characteristics of reinforced materials at interfaces at different pollout rates.Thus,the pullout tests with nine pullout rates and 3 normal loads were conducted,which were expected to explore the effect laws of pullout rates and normal loads on mechanical characteristics of reinforced soil interfaces.The results showed that the increase degrees of peak pullout force gradually slowed down with the increase in pullout rates.The interfacial cohesion was positively correlated with pullout rates,and it had grown by a maximum of 278%;the interfacial friction angle was negative correlated with pullout rates,and it had decreased by a maximun of 19.1%.The strain of the geogrids was more seriously influenced by pullout rates at low speeds and increased with the increase in pullout rates;when the pullout rate exceeded 5 mm/min,the strain variance of geogrids decreased and the pullout stiffness of geogrids increased.The interfacial shear dilation increased with the increase in pullout rates,and decreased with the increase in normal loads.The interfacial shear dilation at high speed was about 1.56 times of that at low speed and about 1.13 times of that at medium speed.