The Evolution Law Of Mechanics Performance Of Anchorage In Underground Engineering Based On The Concept Of Degradation

The long-term stability of rock and soil anchorage engineering is the focus of current research,it is one of the key problems affecting the safety performance of anchor solid engineering in service.In the whole life cycle of geotechnical anchorage engineering,Due to the influence of the working environment load change and the deterioration of the bolt performance,the working load of the anchor will increase continuously,the mechanical properties continue to deteriorate,this seriously affects the safety and stability of rock and soil anchorage engineering.Therefore,it is of great practical significance to study the long-term stability of geotechnical anchorage engineering.This paper takes anchor solid as the research object and adopts the method of indoor simulation test,according to the concept of degradation,acid solution is used to corrode anchor solids and bolts,to simulate the deterioration of mechanical property of anchorage in engineering site.An acid solution and its conduit are used to simulate the corrosion environment of anchor solids,the degree of damage and deterioration of anchor solids was simulated by the concentration of acid solution and the number of corroded bolts.Furthermore,the deterioration of mechanical properties of anchor solids in underground engineering with the change of corrosion conditions is studied,The specific research process is as follows:Firstly,A test system is designed to test the deformation characteristics of anchoring rock mass under the condition of chemical etching and creep,the rock-rock anchor solid sample is made by rock-rock similar material;The prepared sample was corroded by acid solution according to the test design,The deterioration process of mechanical properties of anchor solids was simulated by the corrosion solution concentration and the number of corrosion bolts and the corrosion time,The resistance strain gauge in the horizontal and vertical loading directions is pasted around the anchor solid sample,In this way,the strain data of anchor solids under corrosive environment can be obtained.Secondly,speckle treatment was carried out on the sample surface,a high-speed camera is used to obtain the characteristic pictures during the experiment,the surface strain of the sample is measured in full section.The digital image correlation(DIC)method and MATLAB are used to calculate and analyze the characteristic images.Finally,the creep strain of anchor solids with different degrees of mechanical deterioration was analyzed,the creep characteristics and evolution of anchor solids in underground engineering under corrosive environment are obtained.The evolution law of mechanics performance of anchorage in underground engineering based on the theory of degradation is obtained.The results prove that:(1)The corrosion environment will cause some damage to the anchoring rock,In the creep test,when the corrosion time is the same as the number of corroded bolt,the larger the concentration of the corrosion solution is,the greater the strain change of the sample will be,The damage degree of anchor solids also increases with the increase of corrosion solution concentration.(2)The damage degree of anchor solids will increase with the increase of corrosion time,the compressive strength of anchor solids treated by corrosion is obviously less than that of non-corrosive anchor solids,and with the increase of corrosion time,The damage effect of anchor solid has changed from the strain variation of sample to the failure of sample at different loading stages.(3)In the case that anchor solid corrosion time is the same,the anchor solid samples with the same compressive strength are made of the same rock and similar materials,In the creep test,the influence of the number of corroded bolt is greater than that of the concentration of corroded solution.(4)When the corrosion solution concentration reaches a certain degree and the corrosion time is relatively long,The effect of corrosion time on the deterioration of mechanical properties of anchorage is much greater than that of the number of corroded bolts and the concentration of corroded solution.(5)For the creep of anchorage rock mass under the corrosive environment,the strain in the lower part of the sample is generally larger than that in the upper part of the sample.In addition,the failure of this group of samples in the loading process is mostly split failure.Basically,the fracture is generated along the trend of strain cloud diagram,and shear failure occurs with the extension and diffusion of the fracture.The results can provide reference for the research on the long-term stability of rock and soil anchorage engineering and the creep characteristics of anchor solids under the influence of corrosive environmental conditions.