TEST STUDY ON THE INTERFACE FRICTION CHARACTERISTICS OF COAL GANGUE-GEOGRID-SAND LAYERED SYSTEM

Based on the engineering practice，a new type reinforced soil composed of coal gangue-geogrid-sand was put forward． By direct shear tests and pull-out tests，the interface characteristics of the layered structure in different normal stress were tested and compared with that of common type of geogrid reinforced coal gangue． The results showed that the interface properties of the layered system were similar to those of a common reinforced earth system． Due to filling effect of sand，the compactness of reinforced layer was improved and the interface between filling and reinforcement was increased，the interface strength was higher and played earlier． Moreover，the new layered reinforced system could provide drainage channels for reinforced coal gangue that could avoid softening of coal gangue．