砂土地层盾构隧道开挖面支护压力与地表变形关系模型试验研究

Model Test of the Relationship Between the Face Support Pressure and Ground Surface Deformation of a Shield-Driven Tunnel in Sand Stratum

为研究砂土地层盾构隧道开挖面支护压力和地表变形的关系,文章通过自制模型试验系统,测量了砂土土样地表变形和开挖面支护压力,分析研究了地表沉降、隆起与开挖面支护压力之间的关系。通过测量不同覆土厚度情况下的扰动区域范围,建立了开挖面前方土体沉降和隆起破坏模型;试验得到了开挖面支护压力和地表变形相关关系曲线,在此基础上,提出了以0.2%开挖洞径变形量作为实际支护压力设定的参考点,并结合朗肯土压力公式给出了维持开挖面稳定的极限支护压力上下限值。为便于应用,建议了维持地表特定变形量下的支护压力值。

In order to study the relationship of the face support pressure and the ground surface deformation of a shield-driven tunnel, a self-made model testing system is used to measure the ground surface deformation and the face support pressure of a sand sample, and the relationship between the two is then analyzed. A failure model for soil settlement and heaving ahead of the excavation face is established by measuring the disturbance area at different overlying depths. Based on the gained relation curves of the face support pressure and the ground surface deformation, a deformation of 0.2% of the excavation diameter is taken as a reference value for setting the face support pressure, and the upper and lower limits of the ultimate support pressure for maintaining face stability are given by considering the Rankine earth pressure formula. For convenience of application, the required support pressure values for keeping specific ground surface deformations are suggested.