对穿CFRP锚杆加固故宫城墙结构的力学性能

Mechanical Properties of Imperial Palace Wall Structure Strengthened with Two-Ended CFRP Bolts

故宫城墙由内芯土和外包砖砌体组成,是具有代表性的古代城墙结构,降雨入渗是故宫城墙结构失稳破坏的主要原因.为了提高故宫城墙结构的安全性,本文提出了一种采用对穿CFRP锚杆加固城墙结构的新方法.通过有限元软件ABAQUS建立了故宫城墙结构的非线性有限元分析模型;设计了考虑不同CFRP锚杆直径和锚杆水平间距的加固方案,对降雨入渗时故宫城墙结构的位移和应力沿路径的变化曲线进行了对比分析;采用强度折减法得到了故宫城墙结构的最小安全系数,进而全面分析了加固后故宫城墙结构的力学性能和稳定性.分析结果表明,沿城墙高度中部区域的锚杆对抵抗降雨入渗时城墙砌体结构和上覆土体的变形效果显著.为了获得最优的加固效果,应将CFRP锚杆的水平间距设置为4m,直径为30mm的CFRP锚杆布置在沿城墙高度中部,直径为24mm的CFRP锚杆布置在城墙上部和下部.

The Imperial Palace wall is composed of inner core soil and outer brick masonry,which is a representative ancient wall structure.Rainfall infiltration is the main reason which causes instability failure and collapse of the Imperial Palace wall structure.In order to improve the safety of the Imperial Palace wall structure,a new strengthening method with two-ended CFRP bolts was proposed in this paper.The nonlinear finite element analysis model of the Imperial Palace wall structure was established by ABAQUS.The strengthening schemes of CFRP bolts with different diameters and horizontal spacing were designed.The variable curves of displacement,stress and strain of the Imperial Palace wall structure along the path under rainfall infiltration were compared and analyzed,and the minimum safety factor of the wall structure was obtained by strength reduction method.And then the mechanical properties and stability of the Imperial Palace wall structure strengthened with CFRP bolts were analyzed more comprehensively.The analytical results show that the CFRP bolts along the middle part of the wall height have a remarkable effect on the deformation control of the wall structure and the overlying soil when resisting rainfall infiltration.To achieve the optimal retrofit effect,the horizontal spacing of the CFRP bolts should be set to 4 m,CFRP bolts with diameter of 30 mm should be arranged along the middle part of the wall height,and CFRP bolts with diameter of 24 mm should be used in the upper and lower parts of the wall structure.