Research On Rock Mass Quality Evaluation Method Of Shock Slope

Earthquakes can cause geological disasters such as slope collapses and landslides.At the same time,it will also cause seismic crack damage of the slope,make the rock mass loose and destroy the integrity,thus reducing the stability of the slope.The slope damaged by a large number of earthquake cracks is the main source of secondary disasters after the earthquake,which poses a great threat to life and property.Therefore,the reasonable evaluation of the rock mass quality of the cracked slope is particularly important for the safety treatment of the slope.In this paper,based on more than 130 cracked slopes after the Jiuzhaigou earthquake,the development characteristics of seismic cracks in the cracked slopes are classified,and the variation characteristics of the structural plane of the cracked slopes and the macroscopic deformation characteristics of the cracked rock mass are summarized.Based on the analysis of the existing slope rock mass quality classification methods RMR and SMR methods,referring to the correction method of CSMR method,and combining with the post-earthquake characteristics of earthquake-cracked slopes,a rock mass quality classification system ESMR method suitable for earthquake-cracked slopes is put forward.Based on the investigation and analysis of the typical bedding,anti-dipping and oblique cracked slopes after the Jiuzhaigou earthquake,the crack characteristics of the cracked slopes are divided into four types: transverse slope type,penetrating type,downslope type and surface type.It is mainly distributed at the top of the slope,at the steep-gentle junction and at the ridge.Seismic cracks are generally characterized by long extensibility and large opening.The permeability of the slope is enhanced after the earthquake,which belongs to the highly permeable section.The opening degree of the structural plane of the cracked slope generally increases,and there is no filling or a small amount of filled debris between the structural planes,and the number of unfilled structural planes increases gradually with the increase of elevation.The indoor dynamic uniaxial tests were carried out on the samples with different lithology,and the strength loss increased gradually with the increase of loading frequency,but the strength loss was different for the samples with different lithology.The displacement and acceleration response laws of lithologic slopes in different strata under earthquake are analyzed by numerical simulation,and it is found that the displacement and magnification factor of soft rock are larger than those of hard rock slope.The quasi-horizontal orthogonal tests of the middle slope height,slope,slope shape and empty surface of the topography are designed,and the numerical simulation method is used to analyze the displacement and magnification effect characteristics of the slope under earthquake.The influence of various factors on slope deformation from large to small is slope > slope height > slope shape > open surface.By using the analytic hierarchy process,the evaluation system of slope crack damage is established based on the factors such as slope height,topographic slope,slope shape,empty surface,seismic intensity,slope structure and stratum lithology,etc.,and then the correction coefficient of earthquake crack damage is introduced.According to the structural plane characteristics of the cracked slope,the original structural plane coefficient is modified.Finally,on the basis of SMR method,based on the crack damage correction coefficient and structural plane correction coefficient,a suitable slope rock mass quality classification method,ESMR method,is put forward,and verified by the earthquake disaster survey samples after the Jiuzhaigou earthquake,the evaluation result is closer to the real state of the slope.