隧道近距下穿山坡楼房爆破振动测试研究

Blasting vibration characteristics monitoring of tunnel under-passing hillside buildings in short-distance

以成渝客运专线新红岩隧道为工程背景,测试了隧道近距下穿山坡楼房爆破时引起的地面振动。通过对隧道浅埋侧(隧道地表斜坡下部)和深埋侧(隧道地表斜坡上部)的地表振动数据分析,研究了地表的振动速度、振动主频及振动安全评价方法。结果表明:在浅埋隧道爆破的近区,入射纵波为主要载体,地表水平和竖直方向振动的主要成分可以认为是入射纵波在水平和竖直方向的投影,浅埋侧和深埋侧地表水平和竖直方向振速的大小取决于爆心距和入射纵波与竖直方向的夹角两个因素;隧道采用电子雷管进行单孔连续起爆,相比非电雷管爆破,可以有效降低地表振动强度,同时能够提高地表振动主频;地表振动主频方面,地表竖直方向振动主频普遍高于水平方向,而且浅埋侧地表竖直和水平方向主频大多高于深埋侧地表对应方向的主频;隧道近距下穿山坡楼房进行爆破施工时,建议在浅埋侧和深埋侧地表同时布置爆破振动监测测点,并根据浅埋侧和深埋侧地表测点的峰值振速、爆破振动主频与建筑物固有频率的关系对地表振动安全进行评价,以减少隧道施工爆破对地表环境和周围建筑物造成的振动破坏。

Blasting vibration characteristics of shallow tunnel under-passing hillside buildings in short-distance were investigated. Based on the engineering background of New Hongyan tunnel of Chengdu-Chongqing High-speed Railway, the vibration characteristics of tunnel blasting were measured. Then by analyzing the results of ground vibration on shallow buried side （the lower part of slope） and deep buried side （the upper part of slope）, the characteristics of vibration velocity, principal vibration frequency and safety assessment method were discussed. In the blasting near zone of shallow tunnel, the incident p-wave is the primary wave. Moreover, the major components of the horizontal and vertical ground vibrations can be considered as the projection of the incident p-wave in both horizontal and vertical directions. Besides, the ground vertical and horizontal velocities in shallow and deep buried sides have relationship with the distance from explosive source to measurement points and the angle between the incident p-wave and the vertical direction. Compared with applying non-electronic detonators for the tunnel blasting, using digital detonators one by one can effectively reduce the ground vibration strength and improve the ground vibration principal frequency. In addition, the ground vertical principal vibration frequencies are generally higher than the horizontal principal vibration frequencies. Furthermore, the ground vertical and horizontal principal vibration frequencies of the shallow side are higher than the corresponding directions principal frequencies of the deep buried side. With respect to shallow tunnel under-passing hillside buildings in short-distance, the blasting vibration characteristics should be measured in the deep and shallow buried sides simultaneously. The safety of structures nearby can be assured by judging the vibration velocity and the relationship between the principal vibration frequencies of the deep and shallow buried sides of tunnel and buildings simultaneously.