饱和土盾构施工引起的三维土体变形及孔隙水压力研究

Three-dimensional deformation and pore pressure caused by shield construction in saturated soil

推导半无限空间饱和土中盾构施工切口附加推力、盾壳摩擦力和盾尾注浆压力参数变化引起的任意点土体竖向变形和超孔隙水压力计算公式;结合实际工程参数,采用数值积分的方法计算软土区盾构掘进引起的土体变形和超孔隙水压力,并与实测数据进行对比。研究结果表明:本文方法计算所得地表变形与实测值接近,比Mindlin解的预测更合理;在盾构穿越断面的过程中,盾构开挖面到达和盾尾通过时引起的土体孔隙水压力较大,开挖面到达时的孔隙水压力主要由切口附加推力和盾壳摩擦力引起,盾尾通过时的孔隙水压力则由盾尾注浆压力和盾壳摩擦力引起。

The theoretical formulas of soil deformation and pore water pressure caused by the additional thrust,shield shell friction and pressure of shield-tail grouting of the earth-pressure balance shield in the semi-infinite space of saturated soil were deduced.Numerical integration method was used to calculate the soil deformation and excess pore water pressure induced by shield excavation in soft area.The calculated results were compared with measured data,showing that the calculated results are close to the measured values.The proposed method is more practical than the Mindlin solution.In the whole process of shield tunneling,the pore water pressure increases when the shield workface is approaching and when the shield tail is departing this section.When the shield workface is approaching,the pore water pressure is mainly induced by the additional thrust and the friction of shield shell.The increasing of pore water pressure during the departure of shield tail is due to shield-tail grouting and shield shell friction.