大断面隧道台阶法爆破开挖围岩损伤特征研究Damage Characteristics of Surrounding Rock for Large-section Tunnel Excavated by Bench Blasting
张波
摘要(Abstract):
钻爆法开挖岩体同时,势必会对围岩造成一定程度的损伤,明确隧道爆破开挖围岩损伤特征,对隧道支护设计和长期稳定性有着重要的指导作用。以赣深高铁龙南隧道Ⅲ级围岩台阶法爆破开挖为例,采用跨孔声波法对隧道断面不同部位的围岩声波波速进行了测试,分析了爆破前后隧道围岩声波降低率分布特征,确定了隧道不同部位围岩的损伤深度,揭示了围岩损伤程度和损伤深度的关系。基于LS-DYNA数值模拟软件,模拟了相同工况下8个循环台阶爆破开挖作用下隧道围岩的损伤演化和分布特征,与通过声波测试率判断的围岩损伤分布特征基本一致。现场声波测试和数值模拟结果表明:台阶法隧道上台阶拱脚处围岩损伤程度最大,但损伤深度最小;隧道围岩损伤最深处位于仰拱底部。基于隧道围岩损伤分布特征,根据工程类比法和相关规范规定,确定龙南隧道Ⅲ级围岩的初期支护锚杆长度应为3.5~4 m。
关键词(KeyWords): 隧道爆破;围岩损伤;台阶法爆破;声波测试
基金项目(Foundation): 国家自然科学基金资助项目(41972286)
作者(Author): 张波
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