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为了更全面地了解支护时机对软弱围岩公路隧道力学特征的影响,运用研制的地质力学模型试验简便实用的隧道开挖工具与方法,系统开展了基于先加载后开洞思路的公路隧道模型试验,研究了支护时机对软弱围岩公路隧道围岩压力、衬砌切向应力大小与分布规律的影响。试验结果表明:支护时机对软弱围岩公路隧道围岩压力、衬砌切向应力的大小及分布影响显著;在不同应力场的软弱围岩(原岩弹模为210 MPa)中开挖隧道,当开挖洞径为12 m左右时,200 mm左右的变形预留量是较为合适的。该工况下衬砌的切向应力、围岩压力均较小,而且各位置分布也比较均匀,对衬砌的受力最为有利。在实际工程中应加强监控量测,不断总结经验,尽可能地选择最佳时机支护以达到衬砌受力较小的目的。
In order to fully understand the influence of supporting timing on the mechanical characteristics of soft surrounding rock road tunnels, a simple and practical tool and method for tunnel excavation was developed by using the developed geomechanical model. A tunnel tunnel model Experiments were carried out to study the influence of supporting timing on the surrounding rock pressure and the stress distribution and the magnitude of the tangential stress in soft surrounding rock tunnels. The test results show that the timing of support has a significant effect on the surrounding rock pressure and the magnitude of the tangential stress and the distribution of the lining tangential stress in the weak surrounding rock tunnel. Excavating the tunnel in the weak surrounding rock with different stress fields (original rock elastic modulus of 210 MPa) When the caving diameter is about 12 m, a deformation reserve of about 200 mm is more suitable. Under this condition, the liner’s tangential stress and surrounding rock pressure are small, and the distribution of each location is also more uniform, which is most beneficial to the lining. In the actual project should strengthen the monitoring measurement, continue to sum up experience, as far as possible to choose the best timing support in order to achieve the purpose of lining the smaller forces.