Research On Anchoring Mechanism Of Slate Slope And The Influence Of Anchorage Failure On Slope

Anchored support structure has been widely used in various projects because of its advantages of economy,efficiency,convenience,stability and flexibility.However,due to the complexity and uncertainty of the natural environment,there are many factors that cause damage to the anchorage system and even lead to failure.In real projects,accidents caused by various engineering instability can often be found,which poses a great threat to the life safety and property safety of the people.Therefore,it is of great practical significance to explore the anchorage mechanism and failure mode of anchorage.In this paper,two methods of similar model test and numerical analysis are used to study the stress distribution characteristics of the anchorage section and the stability of the slope due to the failure of the bolt.The main work is as follows :(1)Development of similar materials.According to the principle of orthogonal test,the preparation test of similar materials was designed,and the sensitivity analysis and linear regression analysis were carried out on the factors affecting the physical and mechanical parameters of similar materials,so as to prepare the similar materials needed for the test.It was found that the iron powder ratio was large,and the effect on density was the largest,and the weight gain effect was better than that of barite powder.Cement and gypsum are used as cementing materials.The setting time of gypsum is short,and the improvement of internal friction angle and cohesion is more obvious than that of cement.The linear regression equation is used to fit the factors,so that the relationship between the influencing factors and the physical and mechanical parameters is quantified.(2)On the basis of similar pull-out test and numerical simulation,the stress distribution law of anchorage section is analyzed theoretically and experimentally,and the stress distribution characteristics and anchorage mechanism of anchorage section are discussed.Through the pull-out test,it can be obtained that the peak area of axial force and shear stress is distributed in the first half of the anchorage section,accounting for more than 83 %.The axial force reaches the maximum at the orifice,and the axial force and shear stress approach zero at the end of the bolt.The distribution of shear stress under different drawing forces is different : when the drawing force does not reach the failure threshold of the cemented surface,it shows an approximately linear attenuation and the rate is slow;when the pullout force reaches the failure threshold of the cementation surface,the shear stress reaches the peak value.When the anchorage section reaches a certain length,the ultimate pullout resistance will not increase with the increase of the anchorage section.(3)For the bolt-reinforced slope,as the load on the slope top increases step by step,the specimen gradually begins to deform.Before the shear slip surface appears,the upper row of anchors is forced first,and after the shear surface appears,the lower row of anchors begins to be forced,and the displacement of the slope surface and the slope top increases.When the upper anchor cable fails,it has the greatest influence on the stability of the slope,which causes the slope load to be borne by the middle and lower rows,and the compression zone between the anchor bolts is weakened.When the anchor rod fails,the more the anchor rod adjacent to the failed anchor rod is affected,the more the anchor rod is far away from the failed anchor rod,the smaller the impact;the failure of the bolt increases the failure probability of the adjacent bolt,which leads to the chain failure one by one,and finally makes the whole anchorage system fail.