断层破碎带突水最小安全厚度的筒仓理论分析

Analysis of the minimum safe thickness of water inrush in fault fracture zone based on the silo theory

摘要:

隧道临近富水断层破碎带时易发生突水突泥灾害,防突岩盘最小安全厚度的确定是关键问题.为此,基于筒仓理论和极限平衡方法,分别建立隧道轴线与掌子面正交和平行时的断层破碎带突水力学模型并且推导防突岩盘所受地应力的计算公式.在此基础上,得出富水断层破碎带突水突泥的力学判据,并分析断层破碎带宽度对防突岩盘最小安全厚度的影响.最后,将理论研究成果应用于永莲隧道和祁连山隧道工程中.理论分析表明:断层破碎带宽度小于200 m时,断层破碎带宽度对防突岩盘最小安全厚度的确定影响显著.经过计算,永莲隧道的防突岩盘最小安全厚度为7.34 m,实际工程中未预留足够安全厚度而发生突水事故；祁连山隧道F6、F7断层破碎带的防突岩盘最小安全厚度分别为10.22和11.59 m,实际工程中预留了12 m顺利通过断层带,表明理论计算值与工程实际比较符合,具有一定的可靠性.

Abstract:

When a tunnel is near a water-rich fault fracture zone, water and mud inrush disaster easily occurs, where the determination of the minimum safe thickness of water-resistant rock mass is a key issue. Based on the silo theory and the limit equilibrium method, models of water inrush in fault fracture zone were established under the conditions that the tunnel axis is orthogonal and parallel to the tunnel face respectively. The analytic formulas of the water-resistant rock mass influenced by ground stress were obtained. Then, the criterion of water inrush in fault fracture zone was established, and the influence of the width of the fault fracture zone on the minimum safe thickness of the water-resistant rock mass was analyzed. Finally, the research result was applied to the Yonglian tunnel and the Qilianshan tunnel. Results showed that the width of the fault fracture zone had a significant influence on the determination of the minimum safe thickness of the water-resistant rock mass when the width of the fault fracture zone was less than 200 m. The minimum safe thickness of the water-resistant rock mass of Yonglian tunnel was calculated as 7.34 m. Water inrush occurred in Yonglian tunnel due to the insufficient safe thickness. The minimum safe thickness of the water-resistant rock mass value of F6 and F7 faults in Qilianshan tunnel were 10.22 and 11.59 m respectively. In the construction of Qilianshan tunnel, it is safe to pass F6 and F7 faults with 12 m water-resistant rock mass, which indicates that the theoretically calculated value is relatively close to the actual value and has certain reliability.