Pullout mechanism of the bearing reinforcement embedded in claystone soil of Mae Moh mine

Abstract

Bearing reinforcement, which is composed of a longitudinal member (steel deformed bar) and transverse (bearing) members (a set of equal angle steel), has been established as an effective earth reinforcement material. The equation for estimating the pullout resistance of this reinforcement in coarse-grained soils has been previously developed but not for fine-grained soil. Claystone soil, abundant in Mae Moh mine, is a fine-grained material when crushed and compacted. It was proposed to be a backfill material in the Bearing Reinforcement Earth (BRE) wall for mining activities. The pullout resistance mechanism of the bearing reinforcement embedded in the claystone soil is presented in this paper. The total pullout resistance is the sum of the pullout friction and bearing resistances. The pullout friction resistance is approximated from soil shear strength and interaction factor α . The bearing pullout resistance of a single isolated transverse member can be approximated from the punching shear mechanism. The transverse member interference is classified into three zones, depending upon spacing and dimension of transverse member, S/B ratio. Based on a critical analysis of the test results, the pullout resistance equations for bearing reinforcement with different normal stresses, dimensions and spacing of transverse members embedded in claystone soils compacted at optimum point (optimum water content and maximum dry unit weight) are developed in term of total strength parameters.