盾构水平偏角变化对盾构-土相互作用影响

Influence of Shield Yawing Angle Variation on Shield-soil Interaction

为了探明盾构掘进过程中机-土相互作用的机理,指导盾构姿态的控制和调整,针对水平偏角变化对盾构与土相互作用的影响这一问题,对作用于盾壳周围土压力的理论计算方法以及水平偏角预测模型进行研究。首先基于地基反力曲线,通过等效弹簧近似建立盾构与土的相互作用模型,同时基于几何分析可计算盾构水平偏角变化过程中周围土层发生的位移,从而得到作用于盾构外壳的周围土压力的理论计算方法。然后引用改进的松动土压力计算方法,得到盾构初始土压力的计算方法,解决盾构水平偏角计算的初始边界问题,并结合土对盾构作用荷载的计算方法得到盾构水平偏角计算方法。基于所建立的理论计算模型,对盾构机质量、地层类型以及地层开挖损失率等因素对盾构-土相互作用的影响进行分析和讨论。最后,结合济南地铁R2线盾构隧道工程,对盾构的水平偏角以及相关掘进参数进行实时监测,并与盾构水平偏角理论值进行对比分析。研究结果表明:盾构质量以及地层开挖损失率对盾构在水平面上进行姿态的影响较小;不同地层类型以及地层的土压力系数对盾壳与土相互作用的影响较大;通过工程应用发现盾构水平偏角理论值的变化趋势与实测值基本一致,但由于盾构自身施加的调姿弯矩无法完全作用于盾构机,因此理论值普遍大于实测值。

To determine the shield-soil interaction mechanism during the shield tunneling process,and to guide the control and adjustment of the shield attitude,considering the influence of the yawing angle variation on the shield-soil interaction,the theoretical calculation method of the earth pressure around the shield shell and the prediction model of the yawing angle were studied.First,based on the foundation reaction curve,an equivalent spring approximation model was used to establish the shield-soil interaction model.The displacement of the surrounding soil layer during the yawing angle variation was calculated based on the geometric analysis.The theoretical calculation method of the surrounding earth pressure acting on the shield shell was established.Then,the improved loose earth pressure calculation method was conducted,and the calculation method of the initial earth pressure of the shield was established.The initial boundary problem of the yawing angle calculation was solved,and the calculation method of the yawing angle of was obtained by combining the calculation method of the action load of the soil with that of the shield.Then,based on the established theoretical calculation model,the effects of shield mass,stratum type,and stratum excavation loss rate on the shield-soil interaction were analyzed and discussed.Finally,combined with the Jinan Metro R2 shield tunnel project,the yawing angle of the shield and other driving parameters were monitored in real time and compared with the theoretical value of the shield yawing angle.The results demonstrate that the influence of shield quality and formation excavation loss rate on the shield attitude in the horizontal plane is small;the different types of strata and the earth pressure coefficient of the stratum have a greater influence on the shield-soil interaction;the trend change of the theoretical value of the shield yawing angle is basically consistent with that of its measured value.However,because the bending moment applied by the shield itself cannot fully affect the shield machine,the theoretical value is generally greater than the measured value.