非均匀膨胀力作用下隧道二次衬砌安全性研究

Study on Safety of Tunnel Secondary Lining under Non-Uniform Expansion Force

膨胀岩遇水发生膨胀变形,并产生膨胀荷载。基于荷载结构法理论,针对不同膨胀位置和不同膨胀荷载,对膨胀岩隧道二次衬砌结构各部位安全系数大小和分布进行计算和研究,同时对比分析不同仰拱矢跨比下结构安全系数的变化规律,结果表明①当膨胀荷载为100~200 kPa时,结构各部位安全系数均大于2.0,结构安全,当膨胀荷载为300,400,500 kPa时,结构局部安全系数小于2.0,无法满足承载力要求。局部发生膨胀比全环发生膨胀时对结构的危害更大;②当仰拱局部产生300,400 kPa膨胀荷载时,提高仰拱矢跨比可有效改善结构安全状态,当产生500 kPa膨胀荷载时,需采取其他有效工程措施;③仰拱矢跨比增大到一定范围后,安全系数增长越不明显,设计时应采取一种或多种工程措施组合的方式保证结构的稳定性。

Expansive rock will expand and deform when it encounters water,and generates expansion loads.Based on the theory of load structure method,the size and distribution of the safety factor of each part of the secondary lining structure for different expansion positions and different expansion loads are calculated and studied,and the variation law of the safety factor of the structure under different inverted arch rise span ratio are compared and analyzed.The research results show that:①when the expansion load is 100~200 kPa,the safety factor of each part of the structure is greater than 2.0,and the structure is safe.When the expansion load is 300,400 and 500 kPa,the local safety factor of the structure is less than 2.0,which cannot meet the bearing capacity requirements.The local expansion is more harmful to the structure than the full ring expansion;②When the inverted arch locally generates 300 kPa and 400 kPa expansion load,increasing the rise span ratio of the inverted arch can effectively improve the structural safety state.When the inverted arch generates 500 kPa expansion load,other effective engineering measures need to be taken;③When the rise span ratio of inverted arch increases to a certain range,the increase of safety factor is less obvious.One or more engineering measures should be taken to ensure the stability of the structure.