Discrete Element Simulation And Experimental Study Of Interface Bond Behavior Of Reinforcement Embedded In Cemented Soils

The technology of reinforced cement-soil pile and anchor support is an effective new technology for foundation pit support and soil reinforcement.This technology usually forms a reinforced cement-soil pile and anchor structure by inserts stiff materials such as profiled steel,steel bars,FRP bars into the cement-soil,which can give full play to the compressive performance of cement and soil and the tensile properties of stiff materials.At present,reinforced cement pile anchor structure has been applied in coastal areas and soft soil roadbed engineering practice,achieved good results.However,the theoretical research ofthis technology is still in the preliminary exploration stage,especially the research on the bearing mechanism of the interface between cement-soil and reinforced body and the characteristics of stress and deformation need to be deepened.The load-bearing performance of the reinforced cement-soil structure depends on the interface bond behavior of the reinforcement embedded in cement soils.At present,there are relatively few studies on the interface bond behavior of the reinforcement embedded in cement soils.Therefore,this paper carries out experimental research and discrete element numeric analysis on the bond characteristics of the interface between reinforcement and cement-soil.The main work and results in this article are as follows:Firstly,a bond behavior test scheme for the interface between reinforcement and cement-soil considering the effects of rib height and rib spacing was designed,and 10 sets of bond slip curves corresponding to different rib heights and spacings at the interface between reinforcement and cement-soil were obtained by pullout test;the effects of rib height and spacing on the bonding characteristics of the interface between reinforcement and cement-soil were investigated by analyzing the damage pattern of the test sample and the relationship between rib height and spacingand the peak bond strength of the interface.Secondly,a two-dimensional discrete element numerical model of the interface between reinforcement and cement-soil pullout test was established using the domestic matrix discrete element software MatDEM to numerically simulate the whole process of bond-slip damage at the soil-reinforcement interface.The reliability of the numerical model was verified by comparing the interfacial bond-slip curves obtained from numerical simulations with the experimental results.The evolution of the displacement field of the reinforcement-soil interface,the development of the shear band,and the evolution of the cementation failure were interpreted to characterize the interface bond-slip behavior of reinforcement embedded in cemented soils from the microscopic view.And the influence law of rib height,rib spacing and surrounding pressure of the reinforcement body on the bond-slip characteristics of the cement-rib interface was studied by parametric analysis.Finally,the main research results of this paper are applied to practical engineering cases.A 3D discrete element model was established by MatDEM for afull-length floating anchor with a full footage pullout test in an engineering example.Comparison of the adhesion slip curve of the floating anchor-cement mortar interface obtained by numerical simulation and field test,further validatedthe rationality and effectiveness of using discrete element modeling.And combining field tests with discrete element model setup conditions,the parametric analysis of the influence of the diameter and anchorage length of the anti-floating anchors on the adhesive slip of the anti-floating anchor-cement mortar interface wascarried out.