瓦斯爆炸隧道内冲击波特征及衬砌损伤机制数值研究

Explosive Shock Wave Characteristics of Gas in Tunnel and Numerical Study of Lining Damage Mechanism

为探究隧道瓦斯爆炸致灾机制,以成都洛带古镇隧道瓦斯爆炸为工程背景,基于等效爆能理论对隧道内积聚瓦斯进行量化研究,采用LS-DYNA中ALE技术建立与隧道几何结构一致的流固耦合数值模型,以RHT模型模拟衬砌并修正关键参数,研究隧道内冲击波特征并与经验解析式计算结果对比,同时将衬砌损伤特征的数值模拟结果与现场调研情况进行对比。结果表明:1)流固耦合模型可以再现隧道内的爆炸过程; 2)受衬砌约束,爆炸冲击波在隧道内发生反复、无规则反射,致使其强度剧增、衰减缓慢且流场复杂,曲边墙脚处的反射效应最强; 3)爆心距5 m范围内的衬砌在冲击波剧烈冲压作用下完全破坏,5～10 m的衬砌在较高压、拉应力共同作用下严重受损,10 m外的衬砌主要在较高拉应力下形成损伤裂缝。经对比,衬砌损伤的数值模拟结果与现场情况基本一致。

In this paper,the quantitative research of accumulated gas is carried out on Luodaiguzhen Tunnel in Chengdu based on equivalent explosive energy theory;and then the fluid-solid coupling model in accordance with tunnel geometric structure is established by means of ALE technique of LS-DYNA software;the tunnel lining is simulated by RHT model and key parameters are modified;the characteristics of explosive shock wave are studied and compared with calculation results of empirical analysis formula;finally,the numerical simulation results of lining damage are compared with site surveying results.The study results show that:(1)The fluid-solid coupling model can reappear the gas explosion process in tunnel.(2)Due to the tunnel lining,the explosive shock wave reflects repeatedly and irregularly,which rapidly strengthens the wave,slows down the decay and complexes the flow field;and the strongest reflection effect occurs on the corner of tunnel sidewall.(3)The lining is completely destroyed under the action of violent stamping of explosive shock wave within 5 m of explosion center and badly damaged under the action of large pressure stress and tensile stress in the scope of 5 m to 10 m of explosion center;and the damage cracks are formed under large tensile stress beyond 10 m of explosion center.The numerical simulation results of lining damage are basically consistent with the site surveying results.