Pull-out test study on interface characteristics of geogrid-connector composite

Objective The geogrid-connector composite is a key component of composite rigid panel retaining wall structure. The mechanical properties of interface between geogrid-connector composite and sand are not yet clear. The study investigates the interface mechanism and key influencing factors. Method Three types of geogrids were classified according to different rib-removing methods, and then assembled with connectors to form composites. The pull-out test was carried out by using self-developed equipment. The influences of normal stress and geogrid longitudinal ribs proportion on the geogrid-soil interface interaction characteristics were studied. Result The stress measured at model box bottom is smaller than that applied at top. The drawing force of ribs increases with the increase of normal stress. The greater the displacement of drawing end, the greater the drawing force required under the same normal stress. The greater the geogrid longitudinal ribs proportion, the greater the drawing force. Under the same normal stress, the drawing force of geogrid-connector composite is much greater than that of connector only. The peak drawing force in full ribs condition is 134.31% higher than that in connector condition under the normal stress of 20 kPa. The strain of connector increases with the increase of drawing force. Compared with the condition without geogrid, the cohesion in the condition with geogrid is significantly improved. The cohesion in full ribs condition is 115.12% higher than that in the connector condition. The interface friction coefficient decreases with the increase of normal stress. Conclusion The geogrid-connector composite would provide higher drawing force in the condition of smaller pull-out end displacement, ensuring the overall stability of structure. The normal stress has significant influences on the strain of geogrid longitudinal ribs. In practical engineering, the influence of overlying load on geogrid strain should be considered. The study result would provide a certain reference for the design and construction of reinforced soil engineering.