Composite soil nail-anchor supporting walls have been widely used in practice because of their flexibility,strong supporting capacity,short construction period and low cost. However,researches of composite soil nail-anchor supporting walls leg engineering practices and the working mechanisms are not fully understood,which may lead to some uncertainties in design. Combining three-dimensional(3D) discrete element method(DEM) and experimental model test,displacement field,motion trace,porosity and shear stress of sand particles as well as anchorage resistance during the process of pulling anchor were investigated at the mesoscopic level. The results reveal that the larger the diameter of the anchorage plate,the larger the vertical influence range,and that the displacement field has a convergent bell-mouth shape. During the process of anchor-pulling,sand particles between anchors and soil nails tending to rotate or slide can be divided into three zones with different particle movements for each zone. When the anchor spacing is twice the diameter of the anchorage plate,the composite soil nailing method can achieve an optimum result. Meanwhile,dilatation and contraction occur in sand. The change of the porosity can be described by sinusoidal wave curve and the minimum porosity appears around the nails. Sand particles are squeezed together and blocked by the soil nails,which enhances the synergistic effect of composite soil nail-anchor supporting system. The results presented in this study may provide useful references for upgrading current design methodology of composite soil nail-prestressed anchor supporting system.
Chinese Journal of Rock Mechanics and Engineering
composite soil nail-anchor wall
physical model test