单洞四车道隧道开挖室内模型试验研究

Investigation on Excavating a 4-Lane Road Tunnel Through Indoor Model Test

沈大高速公路改扩建工程韩家岭单洞四车道超大跨公路隧道,拟采用台阶法开挖方案进行施工.通过室内相似模型试验对台阶法开挖方案进行研究,揭示了开挖过程中围岩的力学行为及其变化规律,为判定该开挖方案的可行性、防止施工过程中可能出现的塌方等事故提供依据.研究结果表明:最大位移发生在拱顶,拱顶下沉应作为围岩稳定判据的关键因素;如果严格控制循环进尺长度,及时施作初期支护,台阶法开挖能够满足隧道快速、安全施工的要求.

The feasibility of introducing benching technique in excavating a longspan 4-lane road tunnel named Hanjialing, which is an important reconstruction/expansion project of the Shenyang-Dalian Speedway, was investigated through an indoor model test. The results revealed the mechanical behavior of surrounding rock in excavating process, thus providing a basis on which the feasibility mentioned above can be judged so as to prevent the potentially disastrous accidents such as collapse in tunnel construction. It was also revealed that the maximum displacement will take place at tunnel arch apex, and the subsidence of arch apex should be regarded as the decisive factor as the stability criterion of surrounding rock. A conclusion is thus drawn that benching technique can make the tunnel construction safe and quick if controlling strictly the footage schedule in sequence with early supporting operation provided reliably in time.