Study On Adhesion And Weakening Mechanism Of Epoxy Bonded Bolt System Interface Under The Action Of Water

The resin bolt(cable) support technology has become the main development direction in the field of controlling deformation of surrounding rock in tunnel in our country. Howerver, when the fractures for tunnel excavation throughed the surrounding rock aquifer, and the water would infiltrating along the fractures or hole, which caused adhesion weakening of epoxy bonded bolt system interface, seriously, supporting system failure would appear. Studying on adhesion weakending mechanism of epoxy bonded bolt system interface under the action of water is very inmportant to mater epoxy bonded bolt system failure mechanism in water-enriched roadways and improve the range of application of resin bolt support technology in this condition.“water-epoxy bonded bolt system” as research object, the essay is trying to do a early-stage exploration n on the law of bolt pull-out force damage and shear strength weakening of rock-resin interface under the action of water by the way of tests. Elastic-softening cohesive zone model for the rock-resin interface has been built, and analysis weakening mechanism of its shear strength by the way of theoretical calculation method. The following aspects were carried out in this research work:(1) The damage evolution law of resin bolt pull-out force under the action of water studied. In addition we have analysis the influence factors and deduced that mechanical property weakening function of rock-resin interface was more obvious in bolt hole which contains rich water. The axial force distribution and bearing behavior of epoxy bonded bolt was studied by the test of anchor bolt strain testing system.(2) The paper has designed water absorption tests of single rock and rock-resin combination. The law of its moisture content variation with time was mastered. Experimental system of interface stress involution of rock-resin was built, which helped the process of ring shear test. The interface states have gone through three stages: elastic stage, softening stage, de-bonding stage. The weakening law of its shear strength under different moisture content in the condition of water absorption tests style of single rock and rock-resin combination.(3) Elastic-softening cohesive zone model for the rock-resin interface has been built based on its shear deformation. According to building model, shear stress formula under different interface states was derived firstly, and second, discriminant relation between maximum shear stress and rock moisture content under elastic state was put out. At last, we got the conclusion that the main influence factors for shear strength of rock-resin interface under the action of water were rock elastic modulus and interface shear modulus.