Microscopic Pull-Out Model Of Rock-Anchor Solid And Its Application In Slope Support Engineering

There are various types of slope prevention and protection.Flexible supports such as anchor bolt(cable)play an important role in slope prevention projects by virtue of its fast construction speed,remarkable reinforcement effect and high economic benefits.In order to improve the anchoring effect,scholars have carried out a lot of research.However,as a covert project,anchorage engineering has complex internal interaction relations,which makes it difficult for traditional simplified theoretical analysis to meet the research needs.Numerical simulation is often needed for analysis.As the main force transfer component in anchoring engineering,how to establish the anchoring model between bolt and surrounding rock is a very key scientific problem.At present,most relevant researches adopt one-dimensional line element or directly assume undisturbed soil as reinforced soil for simulation.Although this simplifies the analysis process,it has certain influence on the accuracy of the results.Meanwhile,it is difficult to study the action process of each component in the anchorage structure.Based on this,on the basis of relevant researches at home and abroad,this paper analyzes and studies the anchorage structure from microscopic to macroscopic through numerical simulation.Firstly,the mesoscopic anchoring model of "bolt-grout-rock mass" was established,and the pull-out load and compressive shear load were simulated to analyze the failure law.Then,the mesoscopic anchoring model is applied to the macroscopic anchoring slope to study the supporting effect of lattice anchoring support on the anchoring slope under dead weight,rainfall and earthquake loads.The main research contents and conclusions are as follows:(1)Analysis of failure law of anchorage structure considering pull-out load and compressive shear load.Cohesive slip criterion was used to simulate the bonding conditions of each interface in the anchorage structure,and a mesoscopic model of the anchorage structure was constructed.The pull-out load and compressive shear load were simulated for the model,and the possible failure modes of the anchorage structure under the action of load and the deformation characteristics of each component during the failure were analyzed.(2)Analysis of the sensitivity of anchorage parameters to support effect.By changing the length of bolt and the cohesive force between grout and rock mass,the deformation characteristics and the variation rule of slope stability are analyzed.The results show that with the increase of the length of anchor bolt,the slope sliding surface expands to the deep depth continuously,but its safety factor increases obviously at first and then has no obvious change.With the increase of cohesive force,the safety factor of slope has no obvious change.(3)Analysis of the anchorage effect of slope under the external dynamics such as rainfall and earthquake.The slope model under the influence of rainfall and earthquake is designed to analyze the deformation of unanchored slope and anchored slope under the external dynamic load.The results show that the anchorage support can effectively restrain the overall deformation of slope and reduce the occurrence of landslide disaster.(4)The lattice anchoring model is applied to practical engineering to analyze its anchoring effect.Taking the slope of a project in northwest Hubei as an example,the self weight and rainfall load are applied to analyze the stability of the slope.The results show that the stability of slope model can be improved obviously after adding lattice anchorage support.