【摘要】 随着盾构隧道的大量兴建,掘进面稳定性的合理分析显得十分重要。采用有限差分法程序对应变软化砂土的剪切带进行模拟,分别与实验结果和解析结果比较,验证了数值方法的正确性。建立盾构隧道的三维数值模型,分析不考虑渗流时土体应变软化对掘进面极限支护压力的影响,对比渗流条件下考虑应变软化和不考虑应变软化时盾构掘进面极限支护压力的差别,以及相应的土体位移、塑性区范围和地表沉降的不同。结果表明,考虑应变软化时数值都明显增大,更容易导致掘进面失稳。同时探讨了剪胀角和内摩擦角的不同软化行为对掘进面稳定性的影响。最后,考虑了土体的应变软化行为,对天津地铁九号线施工中的支护力进行预测,预测的结果与工程监测值相吻合。更多还原

【Abstract】 With the construction of shield tunnel,the reasonable analysis of stability of excavation face is very important.Finite difference program is used to simulate shear band in the strain-softening sand.The accuracy of numerical method is verified by comparing numerical results with experimental and analytic solutions.Then,3D numerical model of shield tunnel is created.The influence of strain softening on limit supporting pressure of excavation face is analyzed without regard to seepage.When considering seepage,a comparative analysis of the limit supporting pressure,the displacement,plastic zone and ground settlement is conducted on two conditions: taking and not taking account of the strain softening.The results show that the values increase sharply with consideration of strain softening,and more easily cause the instability of excavation face.The effect of face stability with different strain softening behaviors of dilation and friction is also discussed.Finally,considering strain softening of soils the support pressure used in construction of the line 9 of Tianjin metro is predicted.And the forecasts agree well with the monitoring values.更多还原