Research On The Type And Damage Of Caves On The North Bank Of Jing River In Pingliang City

Nowadays,many cave dwellings are still being used.Under the current global environmental deterioration problem,the resources on the ground are becoming increasingly tense.Cave building can not only exploit and utilize underground space and resources,but also have high cultural value.This paper takes the caves on the loess slope belt of the north bank in Pingliang City,Gansu Province as the research object,meanwhile,field geological surveys,data analysis,physical and mechanical tests,3D model demonstration and numerical simulation are used to discuss the types,distribution characteristics,damage types,damage factors and damage mechanisms of cave dwellings in the study area This paper reappears the evolutionary process of cave destruction and analyzes the interaction between slope evolution(landslides,collapses,excavation of high slopes,etc.)and cave damage.The main research results are as follows:(1)The lithology of cave-excavation strata in the study area can be divided into 5 types: Malan loess,Malan loess and Lishi loess,Lishi loess,Lishi loess and mudstone,mudstone;Slope morphology are classified into 3 types: straight,convex,and concave.According to the combination of lithology and slope morphology existing in the caves,that is,the occurrence conditions of slope structure,the caves are divided into 15 types.(2)Controlled by safety,convenience(traffic,water source)and construction difficulty,the distribution of cave dwellings on the slopes of the study area is dense and sundry in different gullies.The distribution of cave dwellings in the branch gully is symmetrical;In different lithologic distribution,the loess caves are mostly excavated by single lithology;The number of caves decreases as the excavation height decreases in the distribution of different elevation.(3)There are 6 types of cave damage in the study area,including cracks,seepage in the kiln,roof fall of the caves,cave slump,cave local collapse and cave overall collapse.There are great differences in the type,scale and degree of cave damage with diverse lithologic excavations,and there are transformations between different types of cave damage.(4)The influencing factors of cave damage include internal factors and external factors.The internal causes include stratum lithology,paleosol,joints and topography and so on,the external causes include the excavation construction mode,the spacing of the caves,the size of the cave,rainfall,freeze-thaw effect,biological effect,human activities,slope evolution(landslides,collapses,and excavation of high slopes)etc.(5)The excavation of the caves changes the conditions of the slope and accelerates the landslide process,the sliding of the landslides results in the destruction of the caves;The cave's face soil joints are penetrating,the collapse of the cave's face causes the upper loess to collapse,and the collapsed soil piled up together to block the entrance of the caves;The excavation of the loess high slope would cause different degrees of damage to the caves on both sides of the slope foot.