爆破影响下砌体结构振动效应及其安全性评价

Dynamic Response Characteristics and Safety Evaluation of Frame Structure Under Blasting Impact

城市地下工程在进行爆破施工时,邻近建筑结构的安全和稳定至关重要。基于武汉地铁8号线二期联络通道的爆破开挖工程,根据工程现场监测,建立LS-DYNA动力有限元3D数值计算模型并进行了详细分析。研究可知,数值模型质点振速变化和频率特征与工程现场测试基本一致,数值参数和计算方法合理。在振动响应方面,砌体结构主要表现为高度方向的振动,振动最大的点位于结构柱顶、柱脚,振速较大。砌体结构单元动应力沿结构长度方向先增大后减小,沿宽度方向则震荡减小。结构振速与有效应力具有对应关系,根据极限抗拉强度计算得砌体结构的安全控制振速为1.18 cm/s;结构爆破峰值振动速度在安全控制范围以内,单元的峰值有效应力不大于抗拉强度,结构处于安全状态。

It is important to the safety and stability of the adjacent building structures in the blasting construction of urban underground projects.Based on the Wuhan Metro Line 8 Phase II liaison channel blasting excavation project,the dynamic response characteristics of the adjacent 6-story brick structure under the action of the connecting passage blasting excavation were analyzed using a combination of on-site monitoring and LS-DYNA 3D finite element numerical simulation to evaluate its safety.The study shows that the peak vibration velocity and frequency characteristics of the numerical calculation model are consistent with the field measured data,and the numerical calculation model and parameters are reasonably selected;the vibration response of the masonry structure is dominated by the vibration in the height direction,and the maximum vibration points appear in the foot and top of the column at the location closer to the blast source;the dynamic stress shows a trend of increasing and then decreasing in the length direction,and the oscillation decreases along the width direction trend,the location of the effective stress for the location near the source of the blast;structure vibration speed and effective stress have a corresponding relationship,according to the ultimate tensile strength of the masonry structure is 1.18 cm/s calculated as a safe control vibration speed,the structure is in a safe state.