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针对穿越既有人防工程的软弱围岩公路隧道,采用小进尺的微差光面爆破技术,合理安排施工顺序,减小爆破振动效应及其影响,结合施工监测并及时反馈,通过调整爆破参数和施工工艺,使爆破振动得到有效控制,在保证既有人防工程安全的同时也使公路隧道得以安全、顺利地通过既有人防工程区段。监测结果表明:隧道开挖方案、施工工艺及爆破控制措施是影响近接人防工程安全的重要因素;对于Ⅳ、Ⅴ级围岩爆破施工中,不同方向的主振频率和能谱分布及幅值差异很大,沿隧道轴向的主振频率分布于0~20 Hz的低频段,而横向和竖向振动的主振频带较宽(0~200 Hz),前者功率谱峰值是后者的10倍以上;在监测过程中,应特别注意主振频率在20 Hz以下,速度大于50 mm/s的振动对人防工程的安全影响;人防仓库底板位移和围岩压力变化均未超过规范规定的限值。
Aiming at the weak surrounding rock road tunnel through existing civil air defense projects, the micro-scale micro-smooth blasting technology with small footage is adopted to arrange the construction sequence reasonably and reduce the blasting vibration effect and its influence. Combined with construction monitoring and timely feedback, Construction technology, so blasting vibration be effectively controlled, while ensuring the safety of both civil air defense projects at the same time also make the road tunnel safely and smoothly through the existing civil air defense section of the project. The monitoring results show that the tunnel excavation scheme, construction technology and blasting control measures are the important factors that affect the safety of the civil air defense projects close to the next. In the blasting construction of Ⅳ and Ⅴ surrounding rock, the differences in amplitude and amplitude of the main vibration frequency and energy spectrum in different directions The main vibration frequency along the tunnel axis is distributed in the low frequency range of 0 ~ 20 Hz, while the main vibration frequency band of the transverse and vertical vibration is wide (0 ~ 200 Hz). The peak power spectrum of the former is 10 times of the latter During the monitoring process, special attention should be paid to the safety impact of the vibration with the main vibration frequency below 20 Hz and the speed greater than 50 mm / s on the civil air defense projects. The changes of floor displacement and surrounding rock pressure of the air defense shelves did not exceed the limits specified in the code .