隧道爆破下既有结构的高阶模态振动效应与损伤特性研究

When the drilling and blasting method is used to build the tunnels adjacent to existing buildings in urban district, the local members of buildings are primarily prone to suffering damage subjected to tunnel blasting vibration. Currently，the damage characteristics of buildings under tunnel blasting was focused on dynamic response of structural bearing members and low order global modes. But the dynamic response of non-load-bearing members and high order local modes are still lack of study. So it is difficult to explain the phenomenon that massive damage happens in local members of buildings under tunnel blasting vibration. According to the modal tests of the existing buildings under the transient high frequency blasting vibration, the 3D elaborate structural model are established in consideration of bearing and non-load-bearing members. The natural frequencies and mode shapes of high order local modes of the building are obtained. Based on the structural dynamics and high order modes theory, by analyzing the relationships between dominant frequencies of the blasting vibration and natural frequencies of high order modes of buildings, the vibration effect under high frequency tunnel blasting are explored. By means of theoretical analysis, numerical simulation and structural vibration tests, the peak particle velocity and stress of local members under tunnel blasting are analyzed. The damage mechanism and delicate members of the buildings are interpreted under tunnel blasting. The works above will lay a theoretical foundation for vibration-reducing blasting, damage assessment and identification of existing buildings.

采用钻爆法修建近距穿越城区既有建筑结构的隧道时，爆破振动经常造成建筑物局部构件的损伤开裂。当前，高频瞬态隧道爆破下建筑结构的损伤特性研究主要集中在结构承重构件和低阶整体模态上，缺乏对易损的结构非承重构件和高阶局部模态的研究，故难以解释隧道爆破下结构局部构件发生大量损伤的现象。为此，本项目通过进行隧道爆破振动下既有建筑结构的模态试验，构建同时考虑承重构件和非承重构件的三维精细化建筑结构模型，探究结构高阶局部模态的固有频率和振型特征；基于结构动力学和高阶模态理论,分析爆破振动主频与结构高阶模态频率之间的关系，探索建筑结构在隧道爆破下的振动效应特征；采用理论分析、数值计算和结构振动试验方法，探究隧道爆破下建筑结构局部构件的峰值振速和峰值应力特性，诠释爆破振动下建筑结构的损伤机理，辨识爆破振动下建筑结构的易损构件，为隧道近距穿越既有建筑结构的减振爆破、爆破损伤评估和鉴定提供重要的理论支撑。

城区隧道采用钻爆法修建时，常常会近距下穿大量既有建筑结构，过大的爆破振动经常造成建筑物局部构件的损伤开裂，影响建筑物的正常使用。当前，高频瞬态隧道爆破下建筑结构的振动响应和损伤机理研究主要集中在结构梁、板、柱和低阶整体模态上，缺乏对易损的结构非承重构件和高阶局部模态的研究，故难以解释隧道爆破下结构局部构件发生大量损伤的现象。本项目以二层和多层砌体楼房为例，通过进行隧道爆破振动下既有建筑结构的模态试验，构建同时考虑承重构件和非承重构件的三维精细化建筑结构模型，探究结构高阶局部模态的固有频率和振型特征，高阶局部模态中右侧墙体、前端墙体、顶部楼板和中隔墙等部位变形较大。隧道爆破振动主要引起建筑物局部构件的较大振动。采用理论分析、数值计算和结构振动试验方法，探究隧道爆破下建筑结构局部构件的峰值振速和峰值应力特性。随着峰值振速的增加，砌体局部构件的应力也会随之增大，发生破坏的构件也会越来越多；隧道爆破振动下，二层砌体房屋的主拉应力峰值比随着峰值振速增大而减小，五层砖混房屋主拉应力峰值比随着峰值振速增大而增大，二层砌体和五层砖混建筑上的最大应力出现的位置不完全相同，表明结构动力响应除了与爆破地震波有关，还与结构本身的动力特性和结构型式等有关。诠释了隧道爆破振动下建筑结构的损伤机理，辨识爆破振动下建筑结构的易损构件，砌体结构上的门角、窗角等应力集中部位最容易受损开裂，其次是在峰值振速较高时，局部振动较大的女儿墙、中隔墙等部位及砖墙与混凝土接触的部位也可能受损开裂。隧道爆破振动下建筑物结构的动力反应及损伤分析方法应综合建筑物的高阶模态分析和应力分析，为隧道近距穿越既有建筑结构的减振爆破、爆破损伤评估和鉴定提供重要的理论支撑。