Research And Application Of Flexural Strengthening Law Of Anchored Rock Beams With Different Height-span Ratios And Number Of Layers

In the project site,roof accidents occur frequently in mine tunnels,and bolt support can significantly improve roof stability.At present,if the roof is regarded as a rock beam model,the research on the enhancement of the bending performance can still be carried out further considering the bolt support.This paper uses laboratory tests,numerical simulations,theoretical analysis,and other methods to study the flexural performance and failure characteristics of rock beams with different height-span ratios,number of layers,anchor support density,and anchor preload force.influences.main tasks as follows:Through laboratory experiments,the self-made rock-like specimens were changed in height,layered,and bolts with different intervals were installed to realize different influence factors.By comparing the flexural strength,equivalent tensile modulus and other mechanical parameters of different specimens,the effects of different height-span ratios,delamination conditions,and anchor support density on the flexural performance of the specimens were analyzed.As a whole,the flexural performance is enhanced with the increase of the high-span ratio,and it is weakened when the layer is not layered,and it is enhanced as the supporting density increases.Through the comparison of acoustic emission ringing count,energy and other characteristic parameters,the effects of different height-span ratios,layering conditions,and bolt support density on the failure characteristics of the specimen were analyzed from a microscopic perspective.The discrete element simulation software is used to study the failure modes and bending mechanical properties of rock beams under different conditions.Establish a three-point bending numerical model for rock beams,and specifically study the following:(1)the influence of the ratio of rock beam height to its bending performance;(2)the influence of the number of layers on the bending performance of the rock beam;(3)the effect of the preload of the anchor on the bending performance of the rock beam;Influence on the flexural performance of rock beams.The influence of different factors on the failure mode and bending performance of the model is analyzed.Supplement the law obtained from the experiment.Finally,consider the different constraints on the roof rock beam:fixed support,simple support,and foundation,and analyze the mechanical characteristics of the beam under three different constraints.And combined with the site,using the elastoplastic foundation beam model from the perspective of the bolt support density,the test is used to obtain the strengthening law,and the on-site bolt support is initially evaluated for safety.