大断面矩形顶管施工地表沉降的空间效应研究

Research on Spatial Effect of Surface Settlement for Pipe Jacking Construction with Large Rectangular Section

顶管施工过程中的地层损失是引起地表沉降的重要因素,且施工过程具有明显的空间效应,不能简化成二维平面应变问题进行分析。本文考虑顶管施工过程中的三维空间效应,即考虑掌子面前方的预收敛、掌子面后方的收敛变形以及掌子面挤出变形,引入弹塑性围岩纵向变形曲线,建立了适用于顶管通道的地表沉降计算公式。通过与现场监测数据对比,证实了本文计算公式的可靠性。同时算例分析表明,相比其他经验方法,采用本文计算方法得到的纵向地表沉降曲线更符合隧道施工过程中的地层损失空间变化规律,证实了本文方法的合理性。

An important factor resulting the surface settlement is the ground loss during construction of pipe jacking. And the obvious spatial effects exist during the construction so that this problem cannot be simplified into a two-dimensional plane strain model. In this paper, the three-dimensional space effect during pipe jacking construction is considered, including the pre-convergence in front of the tunnel face, the convergent deformation behind the tunnel face, and the extrusion deformation on the tunnel face. And then the longitudinal deformation profile curve of elastoplastic surrounding rock is introduced to establish a procedure of surface settlement suitable for pipe jacking. A comparison is attempted for validating the proposed method in this paper. And the results of examples show that the longitudinal deformation profile obtained by the proposed method is more consistent with the spatial evolution law of ground loss during tunnel construction than the other empirical methods, which verifies the rationality of this method.