Study On Damage Of Capillary Water To Kaifeng City Wall

Kaifeng city wall has been listed as the fourth batch national key cultural relics protection units since 1996.In history,the wall was suffered from floods many times.The existing city wall was built in Qing Dynasty.In order to strengthen the protection and management of Kaifeng city wall,Kaifeng Municipal government has organized several times to carry out the restoration project of Kaifeng city wall.However,with the time going on,the city wall of Kaifeng is still destroyed by peeling,cracking,local collapse and other damages,which affects the overall appearance of the city wall and causes potential safety hazards.This paper takes the north section of Daliangmen of Kaifeng city wall as the research object,and studies the damage of capillary water to Kaifeng city wall.The main contents are as follows:(1)Explore the basic properties of Kaifeng city wall materials.Based on the existing literature at home and abroad and the field sampling test,study the material types and data of wall brick and wall soil.Testing the physical properties of brick and soil of Kaifeng city wall,such as moisture content,modulus of elasticity and so on,provides data for the destruction test and numerical simulation of city wall brick and soil.(2)Explore the damage of capillary water to wall soil.Taking the wall soil as the research object,after the capillary water intrudes into the wall soil,the wall soil will produce uneven settlement,bulging and other deformation due to the degradation of its own materials,which will be reflected on the outsourcing brick,and finally will have a certain impact on the wall brick.Based on the field investigation of the destruction form of the wall soil,designed the freeze-thaw cycle test and shear test to study the destruction of the capillary water on the Kaifeng city wall.(3)Study the destructive effect of capillary water on city wall brick.Kaifeng has a high groundwater level and poor water quality,which contains a lot of soluble salts and other impurities,making the wall prone to appear crystalline bloom and other diseases,thus affecting the appearance and strength of the wall.Based on the investigation of Kaifeng water quality,prepare different concentration of solution,carried out capillary water intrusion test,unconfined compression test and SEM test,to study the influence of mineral erosion on the compressive strength of wall brick.(4)Simulate the damage of the capillary water to the brick and soil of the city wall.Combined with the research forms of ancient city wall structure at home and abroad,based on ABAQUS FEM software,establish a brick soil combination model of city wall is.By changing the materials' modulus,internal friction angle,cohesion and other parameters,to analyse the main influence factors of stability of Kaifeng city wall,and to study the influence form of wall brick and soil degradation on Wall.Propose the main countermeasures of Kaifeng city wall against capillary water disease.