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在膨胀土地基中进行了双隧道对群桩影响的三维离心模型试验,目标地层损失比为2%,着重研究引起的地基沉降槽、附加弯矩、轴力的变化规律。试验得出:膨胀土地基中每个隧道开挖形成的地表沉降槽仍符合Peck高斯曲线,双隧道共同作用形成的沉降槽可以看作是每个隧道单独作用形成的沉降槽的叠加;两个隧道开挖引起的前后桩弯矩规律类似,最大附加弯矩均出现在拱冠附近,但存在明显的前桩遮拦效应;随着第一个隧道开挖的临近及远离,前后桩轴力会发生明显不同变化,而第二个隧道影响明显不同,附加轴力最大值约为工作荷载的10%。
In the expansive soil foundation, a three-dimensional centrifugal model test with double tunnels on the effects of pile groups was carried out. The target formation loss ratio was 2%. The variation law of foundation settlement tank, additional bending moment and axial force was mainly studied. The test results show that the surface subsidence groove formed by each tunnel excavation in expansive soil foundation still meets the Peck Gaussian curve. The sedimentation tank formed by the double tunnels can be regarded as the superposition of the sedimentation tanks formed by each tunnel alone. The law of bending moments around the tunnel caused by tunnel excavation is similar to that of the tunnel. The maximum additional bending moment appears near the crown, but there is a clear effect of front pile covering. As the first tunnel excavation approaches and moves away, Significantly different changes occurred, while the second tunnel significantly different impact, the maximum additional axial force of about 10% of the work load.