浅埋暗挖隧道施工引起的地面沉降预测

Prediction of Surface Settlement Induced by Shallow Excavation Tunneling

对浅埋暗挖隧道施工引起的土体变形机理进行分析,比较了暗挖法与盾构法土体变形机理的不同。提出浅埋暗挖隧道施工引起的横向土体变形是由土体损失引起的均匀收敛和初期支护椭圆化变形两部分引起。采用随机介质理论推导了浅埋暗挖隧道施工引起的地面沉降计算公式。通过3个算例与实测值进行了比较,结果表明:用文中方法计算得到的地面沉降曲线与实测值非常吻合;初期支护椭圆化变形引起的地面变形比较明显,不容忽视;Peck公式假定地面沉降均由土体损失引起,在计算暗挖隧道时会高估土体损失量。

The soil deformation mechanism induced by shallow underground tunnel construction is analyzed. The difference of soil deformation mechanism induced by between shallow underground tunnel and shield tunnel is compared. This paper suggests the soil deformation for the transversal section of tunnel excavation is caused by both uniform convergence mode by soil loss and elliptical deformation of early support structure. Calculation formula for surface settlement induced by shallow underground tunnel excavation is deduced using the stochastic medium theory. Three actual tunnels cases are verified, and theoretical values are compared with measured data. The results show that： the predicted surface settlements are in good agreement with the observed settlement;The soil deformation induced by elliptical deformation of early support structure is obvious, and can not be neglected; Surface settlement is induced by ground loss in Peck formula. So the ground loss will be over-valuation when Peck formula is used in shallow underground tunnel.