曲线盾构隧道掘进地表沉降计算模型

Theoretical Model for Surface Settlement Induced by Curved Shield Tunneling

盾构隧道掘进过程中产生的地层损失和施工荷载是引起地表沉降的主要因素,曲线盾构隧道的非对称性使得掘进引起的地表沉降规律更加复杂。基于直线盾构隧道掘进引起地表沉降的研究成果,考虑实际工程中隧道会由于自重而沉降到土体边界底部,以及曲线盾构隧道地层损失的非对称特征,建立了曲线盾构隧道掘进引起地表沉降的地层损失模型,同时将建立的模型与已有曲线隧道地层损失模型进行对比研究。结果表明:本文建立的地层损失模型引起的地表沉降变形值更大,受转弯半径的大小影响,当隧道转弯半径大于800 m时,曲线隧道与直线隧道地层损失引起的地表沉降值变化较小;当隧道转弯半径小于300 m时,地表沉降值对隧道转弯半径的敏感性较高;本文建立的计算模型很好地体现出小转弯半径隧道对其引起的地表沉降值的影响程度更大。通过将两种不同地层损失模型引起的地表变形与实际工程进行比较分析,验证了本文建立的计算模型与实际数据更接近,误差更小,显示该模型能够较好地反映实际情况。研究成果可为曲线盾构隧道掘进引起地表沉降分析和预测提供参考。

The primary factors contributing to surface settlement during curved shield tunneling are ground loss and construction load.The asym-metry inherent in curved shield tunneling complicates the prediction of surface settlement.Drawing from existing research on surface settlement resulting from linear shield tunneling,we establish a ground loss model to compute surface settlement induced by tunneling.This model accounts for the self-weight settling of the tunnel to the bottom of the soil boundary in real-world scenarios and integrates considerations for the asymmet-ric nature of shield tunneling.We then compare this developed model with an existing ground loss model designed for curved tunnels.Our find-ings indicate that the surface settlement deformation predicted by the stratigraphic loss model proposed in this study is more significant and influ-enced by the turning radius size.Specifically,when the tunnel’s turning radius exceeds 800 meters,the surface settlement caused by ground loss in curved and straight tunnels varies minimally.Conversely,for turning radii less than 300 meters,the surface settlement value exhibits higher sensitivity to the tunnel’s curvature.Our model effectively compares surface deformations predicted by two distinct ground loss models with real-world project data,demonstrating closer alignment with actual observations and reduced error.The calculated results from our model closely match empirical data,affirming its ability to accurately represent real-world conditions.These research findings offer valuable insights for analyz-ing and predicting surface settlement associated with curved shield tunneling.