摘要
南京城墙作为现存的世界第一城垣,对其安全性进行科学评估尤为重要。包山式城墙为南京城墙的主要形式之一,由于其与土体相连,受力特点不同于常规的自承重城墙。本研究整理了包山式城墙的6种典型病害,并提出了包山式城墙的数值建模方法,将其简化为城墙-粘结界面-土体的模型。利用ABAQUS软件,结合工程实例模拟土坡强度折减后包山式城墙的鼓胀。研究结果表明:随着土体的强度下降,包山式城墙的位移不断增大形成鼓胀现象,最终发生倾覆坍塌,可通过墙体底部拉应力-顶点位移曲线中的明显拐点确立监测变形预警值;在此基础上,讨论土坡高度对整体坍塌的影响,并给出放坡角度的合理取值;城墙底部的积水浸泡会导致底部强度折减进而发生相对错动,可通过底部墙体达到极限抗拉强度时的最大相对位移确立监测变形预警值。最后,提出了包山式城墙的修缮保护建议。
The Nanjing City Wall is the largest existing city wall in the world and it is important to evaluate its safety scientifically.The portion of the wall leaning against mountain is one of the main forms of the Nanjing City Wall,the loading characteristics of which are different from those of the self-bearing city wall because it is connected with soil.Our study summarizes six typical diseases of the portion of the wall leaning against mountain,and proposes a numerical modeling method for it to simplify it as a city wall-bonding interface-soil model.Using ABAQUS software,and in combination with corresponding engineering examples,a pre-warning analysis of overall collapse was carried out on the bulging deformation of the wall.The results show that with the decrease of soil strength,the displacement of the wall increases continuously,forming a bulge that will lead to collapse.[The pre-warning of deformation value can be established through the obvious inflection point on the city wall bottom tensile stress-top displacement curve.]Based on this value,the influence of the soil slope height on the overall collapse is discussed,and a reasonable value of slope angle is given.The soaking and swelling of the city wall bottom could reduce the strength of the bottom and result in a large relative displacement there.A warning can be alarmed when the bottom wall has the ultimate tensile strength based on observed maximum relative displacement.Finally,suggestions for the restoration and conservation of the wall are proposed.
作者
程浩然
敬登虎
CHENG Haoran;JING Denghu(School of Civil Engineering,Southeast University,Nanjing 211189,China)
出处
《文物保护与考古科学》
北大核心
2023年第2期143-152,共10页
Sciences of Conservation and Archaeology
关键词
包山式城墙
典型病害
鼓胀
渗水
预警分析
City wall leaning against mountain
Typical disease
Bulging
Water seepage
Pre-warning analysis
