Stability Analysis And Support Measures Of Rock Slopes With Soft Interlayers And Gently Dipping Bedding

This article relies on the engineering background of gently dipping bedding rock slopes with weak interlayers,and is based on the traditional limit equilibrium principle and Mohr Coulomb's strength theory.The slope engineering is analyzed by the methods of theoretical calculation,engineering support design,monitoring data analysis and numerical simulation.The main research results are as follows:(1)The classic theories for analyzing slope stability are reviewed,the factors affecting the stability of bedding rock slopes and the sliding mechanism are summarized,the physical and chemical properties and engineering characteristics of weak interlayers are introduced,and the evolution mechanism of weak interlayers is discussed.The instability modes of various types of rock slopes with weak interlayers are summarized,and it is considered that the main failure modes are slip-cracking,and the typical reinforcement methods of this kind of slopes are summarized.(2)The stereographic projection method is used to preliminarily determine that the sliding mode of this slope is layer-to-layer slip-cracking,and the existence of weak interlayer is the main factor affecting the stability of the slope of the project.The shear strength index of the weak structural surface is determined by the on-site direct shear test(C=26.8k Pa,=11.2°),and the sliding force and anti-sliding force of the slope are calculated.The support schemes were fully compared and selected,and the optimal schemes were calculated for the structure.(3)The slope engineering monitoring items and deformation control indicators are listed.Through on-site monitoring,the relationship between monitoring data such as the horizontal and vertical displacement of each measuring point of the slope and the deep horizontal displacement of the supporting pile during the construction process and the construction conditions are analyzed.Provide technical basis for dynamic design and information construction.(4)Based on actual engineering,the slope stability with different structural surface inclination angles is numerically analyzed.The results show that: clearing and deloading improves the safety of the slope,but the excavation changes the stress balance of the original slope,reduces the favorable dead weight load of the overlying soil,releases the initial stress of the slope,and increases the tangential displacement of the slope.The area where the slope surface line and the weak structural plane intersect after cutting is the weak area after cutting;the safety factor of slopes with different inclination angles after cutting is greatly improved compared with the overall natural slope.(5)Studies have shown that the stability of the gently dipping downhill slope with a weak interlayer is inversely related to the thickness,inclination angle,and weight of the upper rock and soil of the interlayer.19°?30° is the sensitive inclination angle of the structural surface of the slope.In this range,the slope is easy to produce trailing edge tension cracks as the angle increases.After cutting the slope,the slope shear stress from 9°?14°?19°shows a similar decreasing distribution,which is concentrated on the trailing edge of the slope from top to bottom.The increase of the slope angle has little effect on the shear stress of the trailing edge of the slope.At this time,the weight of the upper sliding body of the weak layer becomes the main factor affecting the shear strength of the trailing edge.When the gentle inclination angle of the weak structural surface is less than 14°,the safety of the slope mainly depends on the nature of the rock and soil and the boundary conditions.The 20 mm thick soft interlayer has no obvious impact on the safety of the slope.14°?24°is the sensitive angle that affects the safety of the natural slope.In this range,the safety factor decreases as the angle increases.When the inclination angle is 9°,the gravity of the overlying rock and soil on the structural surface of the natural slope is more unfavorable for slope stability than the inclination angle of the structural surface.