利用Peck公式计算双线隧道开挖引起的地表沉降时,有多个参数会影响到计算结果的大小与沉降曲线的形状。从数学角度对隧道轴线埋深h和两隧道间距L的比率及沉降槽宽度参数K对地表沉降曲线的影响进行研究,得到以下结论在h/L比率逐渐增大的过程中,地表沉降曲线变化过程为较陡峭的W型—较平缓的W型—∪型—U型—V型;相同比率下的地表沉降曲线都呈现相同的型式,与隧道埋深无关;在K=0.600的情况下,沉降曲线由W型向U型转变,h/L的临界值为0.825,而后发现在不同K值下,存在h/L临界值使得不同埋深下的沉降曲线都呈现U型,得到了沉降槽宽度参数K与其对应h/L临界值的最优拟合方程。基于h/L临界值的分析结果,提出了双线隧道远近界线的判别公式,并与现有方法及规范进行对比,结果表明判别公式能较好地界定双线隧道远近距离。同时,对Peck公式预测隧道开挖引起地表沉降的机理进行了推测,并利用颗粒流软件对隧道开挖进行模拟,结果表明压力拱曲线符合高斯曲线。研究成果可为双线浅埋隧道设计、施工提供依据。
Abstract
When Peck’s formula is used to calculate surface settlements caused by tunneling, the calculation results and the shape of settlement curves are affected by multiple parameters. In the present research, the effects of the ratio of depth of tunnel axis (h) to chamber distance (L) and the settlement tough width parameter K on the ground surface settlement curve were analyzed in a mathematical sense. Results revealed that as the value of ratio of h/L increases, the shape of surface settlement curve transformed from steep dual peak (W) to flat dual peak, and then to U-shape and V-shape successively. The shape of the curves remained the same under the same h/L ratio, but had nothing to do with the value of h. In the case of K = 0.600, when the value of h/L was equal to 0.825, the settlement curves changed from W-shape to U-shape exactly. Moreover, in the presence of different K values, a unique critical value of h/L existed when the shape of settlement curves achieved critical U-shape. The fitting curve was obtained to express the relation between the critical value of h/L and K. Furthermore, the formula for the critical distance of twin tunnels is proposed based on the relation between the critical value of h/L and K by comparing the formula with other methods and current specification, and the result indicates that the proposed formula is reasonable and accurate. According to the above results, the mechanism of predicting excavation-induced surface subsidence by Peck’s formula is presented. Simulation on the excavation by particle flow code indicated that the pressure-arch corresponded to Gaussian curve. The research provides reference for the design and construction of shallow twin tunnels.
关键词
双线隧道 /
地表沉降 /
Peck公式 /
远近距离界线 /
颗粒流
Key words
twin tunnels /
surface settlement /
Peck’s formula /
critical distance /
particle flow code
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基金
国家自然科学基金项目(41002089,41102162)
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