预留核心土法爆破开挖下隧道初期支护动力响应特性  

Dynamic Response Characteristics of Primary Tunnel Support under Blasting Excavation with Reserved Core Soil Method

作　　者：徐昊 何如 李栋伟 季安 何锦 代四龙 XU Hao;HE Ru;LI Dong-wei;JI An;HE Jin;DAI Si-long(School of Civil and Architectural,East China University of Technology,Nanchang 330013,China;China Nuclear Huatai Construction Co.,Ltd.,Shenzhen 518055,China)

机构地区：[1]东华理工大学土木与建筑工程学院,南昌330013 [2]中核华泰建设有限公司,深圳518055

出　　处：《爆破》2024年第1期37-43,105,共8页Blasting

基　　金：江西省地质环境与地下空间工程研究中心开放基金项目(JXDHJJ2022-005);国家自然科学基金项目(42061011);东华理工大学博士科研启动基金项目(DHBK2019236);东华理工大学研究生创新基金(YC2022-s611)。

摘　　要：初期支护是隧道施工阶段的主要承力结构,爆破施工动力扰动下初期支护的响应规律及安全控制对确保隧道安全快速施工有着重要意义。为研究预留核心土法爆破开挖影响下软岩隧道初期支护的动力响应特征及其安全控制,以林场隧道爆破施工为工程背景,依据隧道初期支护现场爆破振动监测结果,利用ANSYS/LSDYNA建立三维有限元数值计算模型,结合预留核心土法爆破作业特点,研究了两个不同距离爆源同时作用下隧道初期支护的应力分布特征,利用萨道夫斯基经验公式获得了预留核心土法爆破振动传播衰减规律,提出了以应力为控制标准的两侧下台阶同时起爆条件下隧道初期支护的爆破振动速度安全判据。结果表明:不同于全断面法和台阶法爆破,预留核心土法两侧下台阶同时起爆时,最大振动速度出现于隧道初期支护拱脚处,而非隧道底板或拱顶;仰拱未回填区域的存在显著影响爆破应力波传播路径,相较于右侧拱脚,隧道初期支护左侧拱脚处的振动速度更大,且随距离增加而衰减的更明显;初期支护结构稳定性受拉应力控制,最大拉应力及剪应力出现于隧道左侧拱脚处,最大拉应力为7.544 MPa,最大的剪应力为2.78 MPa,均超过规范允许值;根据建立的应力-振速线性关系,提出基于极限强度的隧道初期支护爆破振动安全判据;在林场隧道爆破条件下初期支护的爆破振速安全阈值为10 cm/s。研究成果为隧道爆破施工设计以及安全控制提供理论研究基础。The primary support is the main load-bearing structure in the tunnel construction stage,the response rule and safety control of the primary support under dynamic disturbance are of great significance to ensure the safe and rapid construction.Figuring out the dynamic response characteristics and the safety control of the primary support is an important issue for the blasting excavation of a soft rock tunnel with reserved core soil.A three-dimensional fi-nite-element numerical model was established by ANSYS/LSDYNA for the Linchang tunnel blasting excavation,and the reliability of the numerical model was verified by the field vibration monitoring data.The stress distribution char-acteristics of the primary tunnel support under the simultaneous action of two blast sources was studied combined with the construction characters of the reserved core soil method.The attenuation law of blasting vibration was obtained by using Sadovsky empirical formula.The safety criterion of blasting vibration velocity for the primary tunnel support un-der the simultaneous blasting excavation of both sides of the lower bench was proposed by taking stress as the control standard.The results show that the maximum vibration velocity appears at the arch foot of the primary support rather than at the tunnel floor or vault,which is different from the full section method and bench blasting method.Mean-while,the propagation path of the blasting stress wave is dramatically affected at the un-backfilled area of the tunnel invert.The vibration velocity of the primary tunnel support is larger and attenuates faster on the left arch foot versus right arch foot.The maximum tensile stress and shear stress appear on the left arch foot of the tunnel under simulta-neous blasting with 7.544 MPa and 2.78 MPa,respectively,which exceed the allowable value of the specification.According to the established linear stress-vibration velocity relationship,a blasting vibration safety criterion of prima-ry tunnel support is proposed based on the ultimate strength.In ad

关 键 词：爆破振动 初期支护 质点峰值振速 动力响应 安全判据 

分 类 号：U455.6[建筑科学—桥梁与隧道工程]