基于Peck公式的双线盾构引起的土体沉降预测

基于Peck公式,对双线水平平行盾构隧道施工中土体损失引起的三维土体沉降计算方法进行研究。考虑先行隧道施工对后行隧道的影响和两条隧道开挖面的不同位置,建立修正的三维Peck公式;通过分别计算先行盾构隧道和后行盾构隧道施工引起的土体沉降,叠加得到双线水平平行盾构施工引起的总的三维土体沉降。算例分析结果表明:预测值与实测值比较吻合;随着两条隧道开挖面前后距离的逼近,地面最大沉降量会逐渐增大;随着土体深度z的增大,沉降略增大、沉降槽宽度则略减小;当两条隧道轴线水平距离L较小时,地面沉降量较大,符合正态分布规律;随着L的增大,最大地面沉降量会逐渐减小,沉降曲线形状慢慢由V型转变成W型。

Prediction of soil settlement induced by double-line shield tunnel based on Peck formula

Based on Peck formula, the calculation approaching to study the three-dimension soil settlement caused by ground loss during double-line parallel shield tunnel (DLPST) construction is proposed. Considering the influence of first tunnel construction on second tunnel and different excavation face positions of two tunnels, modified three-dimensional Peck formula is established. It was used to calculate soil settlement caused by both the first and the second shield tunnel construction and combined the results, then the total soil settlement induced by DLPST is obtained. It is indicated that this method forecast value almost satisfied the measured value. With two tunnels excavation facing before and after distance of approximation, the maximum soil settlement volume will gradually increase. With the depth of z increasing, the settlement slightly increases and the settlement slot width slightly reduces. When the two tunnel axis level distance (L) is small, the soil settlement volume will be larger, and it is accord with normal distribution. The maximum soil settlement volume will gradually reduce and the settlement curve shape will slowly change by V type into W type as the increase of L.