风积沙-土工格栅界面摩擦特性拉拔试验研究

Pullout test study of frictional resistance characteristics of geogrids and aeolian sand interface

土工格栅可以增加土体强度,提高路基稳定性,已在沙漠铁路的建设中得到应用。为研究风积沙-土工格栅界面摩擦特性,考虑法向应力和压实度等因素,对2种土工格栅开展一系列拉拔试验研究,分析法向应力、压实度和不同土工格栅对界面摩擦特性的影响。研究结果表明:界面剪应力-拉拔位移关系曲线呈非线性,曲线在低法向应力时为软化型,在高法向应力时为硬化型。法向应力越大,界面剪应力越大。风积沙填料的压实度越大,界面剪应力也越大。横肋较厚的土工格栅界面摩擦特性较横肋厚度小的土工格栅更加优越。界面摩擦强度与法向应力呈线性关系。似摩擦因数和界面内摩擦角随压实度的提高而增大,而表观黏聚力随压实度的提高变化不大。在压实度0.90~0.95范围内,2种土工格栅的界面内摩擦角约为17.74°~29.24°,表观黏聚力约为9.22~12.36kPa。拉拔摩擦因数与法向应力的关系曲线可用幂函数拟合,拟合参数与表观黏聚力和似摩擦因数有关。相同压实度条件下,法向应力越大,拉拔摩擦因数越小;相同法向应力条件下,压实度越大,拉拔摩擦因数也越大。界面摩擦因数比随压实度的提高而增大。因此,要保证风积沙填料有较高的压实度,并且将土工格栅埋置在一定的深度,才能发挥土工格栅的加筋作用。研究结果可为风积沙加筋路堤的设计和施工提供参考。

The geogrid, which can increase the strength of the soil and the stability of the subgrade, has been applied on the construction of desert railway. In order to study the frictional resistance characteristics of geogrids and aeolian sand interface, a series of pullout tests were conducted, considering the influence of different normal stress and compactness by using two kinds of geogrids. The rules of the frictional resistance characteristics of geogrids and aeolian sand interface under different normal stress, compactness and two kinds of geogrids was analyzed. The rules of the frictional resistance characteristics of geogrids and aeolian sand interface under different normal stress, compactness and two kinds of geogrids was analyzed. The results are drawn as follows.The curves of shear stress-pullout displacement are nonlinear. It exhibits softening behavior in terms of low normal stress, and it exhibits hardening behavior in terms of high normal stress. The shear stress increases with increasing normal stress. Also, the shear stress increases with increasing compactness of aeolian sand. The interface friction characteristics of geogrids with thicker transverse ribs are better than those of geogrids with thinner transverse ribs. The strength of the interface frictional resistance increases linearly with the normal stress.The quasi-friction coefficientand the friction angle of the interface increases with the increase of compactness, but it seems that compactness behaves no effect on the apparent cohesion.With the compactness ranging from 0.90 to 0.95, the interface internal friction angel of the two types of geogrids ranges from 17.74° to 29.24°, and the apparent cohesion of the two types of geogrids ranges from 9.22 to 12.36 kPa. The relationship between the pullout friction coefficient and the normal stress can described by the power function. The fitting parameters are related to apparent cohesion and quasi friction coefficient. The pullout friction coefficient decreases with the increase of the normal stress. The pullout friction coefficient increases with the increase of compactness. The pullout friction coefficient increases with the increase of compactness at the same normal stress. The friction coefficient ratio of geogrids interface increases with the increase of compactness. So, it is significant that a high compactness of the aeolian sand filler and a certain burial depth of geogrids must be guaranteed to fully perform the reinforcement effect of the geogrids. The work can provide references for the design and construction of reinforced aeolian sand embankment.