土工格栅界面摩擦特性试验研究

Experimental studies on interface friction characteristics of geogrids

土工格栅与土的界面作用特性直接影响着加筋土挡墙的安全与稳定性。因此,土工格栅与填料的界面技术指标在加筋土挡墙的设计中至关重要。本文在从试验方法、加载方式、试验箱侧壁边界效应和尺寸效应、填料厚度、压实度以及筋材夹持状况等几方面分析土工格栅界面摩擦特性影响因素基础上,进行了土工格栅在砂砾料和粘性土中的拉拔试验和直剪试验。试验结果表明:土工格栅与砂砾料接触面抗剪强度较高,而与粘土接触面抗剪强度很低;对于加筋土挡墙拉拔力较大的层位,应选用刚度大的土工格栅和砂砾料为填料。直剪摩擦试验不适合确定土工格栅接触面的抗剪强度。该试验结果对土工格栅加筋土挡土墙的设计具有重要的参考价值。

The interface characteristics of geogrids would directly influence the safety and stability of reinforced soil retaining wall. So the interface index of geogrids in different materials was important when the reinforced soil retaining wall was designed. The main influential factors in the interface characteristics of geogrids, such as test method, load mode, effect of boundary and size of test, thickness and degree of compacting of the soil, and clip of the reinforcement, were analyzed in this paper. The direct shear and pullout tests were done for geogrids in clay and coarse gravel in laboratory. Some conclusions were found from the tests that the shear strength of the interface between geogrids and the coarse gravel was high, yet the shear strength of the interface between geogrids and the clay was low. The geogrids with large stiffness and the coarse gravel backfill materials should be selected to be used for high reinforced soil retaining wail. And the shear strength of the interface between geogfids and the clay should not be determined with the direct shear friction test.