【摘要】 以浅埋盾构隧道开挖面被动失稳模式为研究对象，对楔形体计算模型进行改进，提出了一种新的开挖面等效法，将楔形体计算模型里的倒棱台筒仓改进为倒圆台筒仓，推导了开挖面被动失稳极限支护压力计算公式。主要结论有：楔形体倾角（α）与土体内摩擦角（φ）有关，α最优值为40°-φ/2。通过与既有开挖面被动失稳的极限支护压力解析解及数值解对比，发现改进后的楔形体模型计算结果更接近数值解，说明本文推导的计算公式是可靠的。更多还原

【Abstract】 Based on the passive instability of shallow shield tunnel excavation face, improvement of calculation model of wedge and ultimate support pressure calculation formula of excavation face were studied. A new equivalent method of excavation face was proposed and the chamfered platform in calculation model of wedge was improved to the circular platform, meanwhile, the calculation formula of ultimate support pressure about the passive instability of shallow shield excavation face was established. The results show that, the wedge inclination angle α is related to the internal friction angle φ of soil, and the optimal value of α is 40°-φ/2. By comparing with the results of existing calculation formulas and numerical solution, it is found that the calculation formula of the improved wedge calculation model is closer to the commonly used numerical solution, which shows that the improved calculation formula deduced is reliable.更多还原