| With the development and construction of major foundation projects in China,the scale of rock mass engineering involved is increasing.The anchoring effect of bolt can affect the safety and reliability of the whole project,and it is of great significance to carry out relevant research for the development of geotechnical engineering.The bolt profiles such as rib spacing and rib angle affects the anchoring effect by affecting the mechanical properties of bolt-mortar interface.Therefore,it is of great significance to study the influence of bolt profiles on the mechanical properties of bolt-mortar interface to improve the anchoring effect and increase the stability and safety of anchoring engineering.In this paper,the shear characteristics of bolt-mortar interface under different bolt profiles are studied by combining theoretical analysis with laboratory tests.The main research contents are as follows:1、The influence of bolt profiles on shear stress distribution characteristics of bolt-mortar interface is expounded.According to the stress characteristics,a new test method is designed to expand the bolt-mortar system into a plane specimen,and a two-dimensional shear model of the bolt-mortar interface is established.2、The steel mould with size 200mm×100mm×50mm is prepared to simulate the bolt plane,and the same size gypsum specimen simulates mortar,then the steel mould and gypsum are poured into a combination simulated bolt-mortar system.The shear test scheme of bolt-mortar interface under different rib spacings and rib angles is designed and the direct shear test of bolt-mortar interface is carried out under different normal stress boundary conditions.3、Based on the shear test results,the effects of rib spacing,rib angle and normal stress on the shear characteristics of bolt-mortar interface are analyzed.The results indicate:(1)The shear stress-displacement curves of bolt-mortar interface under different rib spacings are in accordance with the typical peak curve;The shear stress-displacement curves of interface under different rib angles are mainly divided into peak type and no peak type.(2)The shear strength and residual strength changes with the increase of rib spacing and rib angle.As the normal stress increases,the shear strength and residual strength increase gradually,which meets to the Mohr-Coulomb strength criteria.(3)The trend of shear displacement-normal displacement curve of interface under different rib spacings and rib angles is basically the same and the curve has obvious stage characteristics,but there are some differences in the trend of each curve in different stages.(4)With the increase of rib spacing and rib angle,the proportion of shear-slip failure mode and shear-break failure mode of interface in composite failure mode is changed. |
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