千枚岩隧道二衬开裂防治措施探讨

The discussion on secondary lining crack prevention measures in phyllite tunnel

分析千枚岩隧道二次衬砌开裂特征及工程地质条件,得出二衬开裂的主要原因是围岩压力过大,导致拱腰、边墙处出现拉应力过大。针对二次衬砌开裂原因,采取加强支护参数的防治措施,并利用数值模拟分析边墙、拱腰处二次衬砌内力变化情况。分析得出,原设计支护条件下边墙、拱腰处二次衬砌内侧拉应力较大且接近混凝土抗拉强度标准值,采取防治措施条件下边墙、拱腰处的二次衬砌内侧拉应力明显降低,证明该防治措施对千枚岩软岩隧道二次衬砌开裂取得了有效的防治效果,为下阶段设计施工提供参考借鉴。

By analyzing the secondary lining cracking characteristics and engineering geological conditions of the phyllite tunnel ,the paper concludes that the main cause of secondary lining cracking is too large pres‐sure of surrounding rocks ,creating higher tensile stress in the hance and side wall of secondary lining .In view of the causes of secondary lining cracking ,it takes preventive measures by strengthening the support‐ing parameters ,and uses numerical simulation to analyze the change of internal stress of side wall and hance of secondary lining .The analysis shows that the tensile stress of side wall and hance of secondary lining is larger and close to the standard tensile strength of concrete under the original design supporting condi‐tions .While the tensile stress of side wall and hance in secondary lining significantly decreased under the preventive measures .So it proves good effect to prevent secondary lining cracking in phyllite tunnel and provides a reference for the next stage design and construction .