基于最小渗流法并考虑注浆影响的水下隧道最小覆盖层厚度研究

Study on Minimum Overburden Thickness of Underwater Tunnel Considering Grouting Effect and Based on Minimum Seepage method

江西蓉江新区过江隧道围岩裂隙发育,破碎严重,遇水易软化,失水易崩解,隧道开挖风险极大。为保证隧道的安全开挖,基于最小渗流法并考虑注浆影响,采用理论和数值模拟方法对渗流量、注浆范围与最小覆盖层厚度之间的关系开展研究,计算隧道最小覆盖层厚度。结果表明,采取日本最小渗流法和数值模拟方法得出的最小覆盖层厚度分别为12.4 m、14 m,误差为11.4%,说明数值模拟方法的可信度;注浆范围为2 m、4 m、6 m时的最小覆盖层厚度分别为10.62 m、10.34 m、10.12 m,为保证隧道安全,综合来看,隧道最小覆盖层厚度可取11 m。

The surrounding rock of the river crossing tunnel in Rongjiang new area of Jiangxi Province is rich in cracks,seriously broken,easy to soften when encountering water,easy to collapse when losing water,and the tunnel excavation risk is great.In order to ensure the safe excavation of the tunnel,based on the minimum seepage method and considering the influence of grouting,this paper used theoretical and numerical simulation methods to study the relationship between seepage flow,grouting range and the minimum overburden thickness,and calculated the minimum overburden thickness of the tunnel.The results showed that the minimum overburden thickness obtained by the Japanese minimum seepage method and the numerical simulation method were 12.4 m and 14 m respectively,with an error of 11.4%,indicating the reliability of the numerical simulation method;When the grouting range was 2 m,4 m and 6 m,the minimum overburden thickness was 10.62 m,10.34 m and 10.12 m respectively.In order to ensure the safety of the tunnel,comprehensively speaking,the minimum overburden thickness of the tunnel could be taken as 11 m.