Study On The Anchor Stress Characteristics Of The Coal With Expansive Soil Slope Under The Rainfall

The southwestern of Jiangxi Province exist many coal measure strata.The coal measure soil contains mineral components such as illite and montmorillonite.It is a kind of expansive coal measure soil.Under the condition of rainfall,this coal measure expansion soil is easy to soften and disintegrate,cause slope collapse and affect road traffic.Its stability restricts the safe operation of transportation.As a common slope support method,bolts are used in a large number of slope treatments.However,there are few reports on the mechanism of action between bolts and coal-expanded soils.Based on relevant research results at home and abroad,through theoretical analysis,numerical simulation calculation and model test,promote the stability of coal-expanded soil slope and the stress characteristics of bolts under rainfall.The main work is as follows:1.Searching for the literature and reviewing of Anchor force mechanism at home and abroad,summarizes the Anchorage mechanism of the four full-length bond Anchorage rods,simplifies the common sliding types of slopes into linear and arc types,and summarizes the two types of sliding anchorage force expression;Refining the previous research results,got the expression forms of anchor shaft force and shear stress distributed along the length of anchor rod.Through the analysis of soil bodies of different strengths,obtain the laws of anchor shaft force and shear stress with soil strength changes.Provides a theoretical basis for analyzing the change law of anchor shaft force at sliding surface.2.Experimental study on slope model of expansive soil of coal under rainfall conditions.Based on the actual engineering,made an large-scale outdoor model of the expansive soil slope,use rainfall device system carry out the continuous rainfall test on the slope model,monitoring the variation of water content and substrate suction of the slope and observing the deformation and failure patterns of the coal expansive soil slope under continuous rainfall;Using fiber grating sensing technology monitor the change law of anchor shaft force in coal expansion soil slope during the time of rainfall.3.Numerical simulation of slope stability and axle force of coal expansion soil under rainfall conditions.Using the finite element software(Midas)carried out the numerical simulation of slope model,analysis the stability of slope under different rainfall periods and the changing law of anchor shaft force.Comparing the numerical simulation results with the experimental results of anchor shaft force change.According to the change of axial force of the model predict the plastic zone of slope,The predicted results are close to the numerical results,verified its feasibility and provides a new idea for monitoring and warning of slope safety.