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长沙市浏阳河公路隧道是一座水下浅埋暗挖小净距隧道,从河两岸对头施工,四洞在河底两两先后贯通时,不仅要考虑四洞施工的相互影响,还要考虑水渗流的影响,施工风险高。结合数值模拟与现场实测,首先比较了4种贯通方案以选择最优方案,然后研究了关键部位在贯通过程中的力学性状并提出了相应的施工措施,最后分析了贯通效果与贯通后的延续影响。结果表明:应采用两贯通处纵向间隔23 m、先后单向施工到贯通处的贯通方案;贯通处岩柱的最大压应力出现在岩柱底部,贯通处岩柱呈现顶窄底宽的楔形状态有利于岩柱受力;在贯通时,不用施作临时支护,应快速将隧道上台阶贯通处岩柱从上至下一次性全挖掉后施作初衬;应关注河床沉降的变化;隧道贯通力学行为对于围岩应力场与渗流场的影响具有时间效应;隧道安全贯通而且贯通的效果较好。所得结论可为类似高风险水下隧道的安全贯通提供参考。
Liuyang River Road Tunnel in Changsha City is a shallow underground tunnel excavation of a small clear distance between the two sides of the river construction of the opposite, four holes in the river after another two through, not only to consider the interaction of four-hole construction, but also consider the water The impact of seepage, high construction risk. Combining the numerical simulation and field measurement, four kinds of penetration schemes were compared to select the optimal scheme. Then the mechanical behavior of the key segments in the penetration process was studied and corresponding construction measures were put forward. Finally, the effects of penetration and continuation influences. The results show that the maximum through-hole stress of the rock column at the through hole should appear at the bottom of the rock column, and the rock column at the through point should have a wedge shape with a narrow bottom and a wide bottom Is conducive to the rock column force; in the through, do not be used for temporary support, should be quickly on the tunnel through the steps of the rock column from top to bottom disposable all digging out after the initial lining; should pay attention to changes in riverbed settlement; tunnel through The mechanical behavior has a time effect on the stress field and the seepage field of the surrounding rock. The tunnel is safe and well-penetrated and has a good effect. The conclusions can provide reference for the safety of similar high-risk underwater tunnels.