考虑盾构隧道壁后间隙与注浆分布模式的地表沉降随机预测方法

Stochastic Prediction Method for Ground Settlements Considering Gaps behind the Lining and Grout Distribution Modes

盾构隧道施工中的壁后间隙、注浆分布模式、开挖面土体变形是影响地表沉降的三个主要因素,而这些因素又与地层条件和施工工艺密切相关,但现有研究中对这些因素量化分析的成果较少。文章基于随机介质理论,将上述三个影响因素分别用等效间隙量Δ1、等效间隙分布角α和负土体损失量Δ2来表示,推导出了盾构隧道施工中三维地表沉降预测公式,并将计算参数Δ1和α对地表沉降的影响进行量化分析;同时,根据实际工程中的沉降监测数据对参数取值进行反演分析,得出了盾构隧道施工中预测地表沉降的三维解。将文章提出方法的计算值与实测沉降值、修正Peck公式的计算值分别进行对比发现,该方法能更真实地预测实际地表沉降的大小和分布特征,证明了提出方法的合理性和反分析参数的可靠性。

The three main factors affecting ground settlement in shield tunnelling are the gap behind the tunnel lin- ing, the distribution mode of the grout and the deformation of soil at the excavation face, all of which are closely re- lated to soil conditions and construction technology. There is not adequate quantitative research on these factors. Based on the stochastic medium theory, and the three parameters of equivalent gap value A1 , the distribution angle c~ of equivalent gap and negative ground loss value A2 were introduced to represent the three factors above, and a for- mula was deducted to predict 3D ground settlement in shield tunnelling. A quantitative analysis of the ground settle- ment affected by the parameters of A1 and c~ was performed. Based on the measured settlement data, a back-analy- sis was conducted to obtain the 3D solutions for predicting settlement values. The values of ground settlement calcu- lated by this method were compared with the on-site measured data and the values of ground settlement calculated by a modified Peck formula, which shows the method proposed in this paper can predict the values and distribution characteristics of ground settlement more accurately, therefore verifying the reasonableness and reliability of this method.