考虑注浆作用的矩形顶管竖向土压力计算模型

针对矩形顶管上竖向土压力计算模型研究较少的现状,借助Terzaghi土压力计算理论,结合矩形顶管工程特点建立了考虑注浆作用的矩形顶管竖向土压力计算模型,提出了改进的竖向土压力计算公式;依托苏州某矩形顶管工程中竖向土压力实时监测数据,探究了其变化规律并验证了该计算公式的准确性。研究结果表明:土体中的剪切带从管道外壁两侧产生并沿竖直方向发展,且可贯穿至地表;临界状态下剪切带上的膨胀角完全发挥,以临界内摩擦角及其正弦值计算剪切带上的摩擦系数;不同的注浆压力下,管道上方可能出现“主动土拱”和“被动土拱”。计算值与实测值的对比分析表明,改进后的计算方法能够较好地包络矩形顶管竖向土压力范围。

Vertical soil pressure calculation model of rectangular box jacking considering grouting effect

In view of the current situation that there are few studies on the calculation model of the vertical soil pressure on the rectangular box jacking, the calculation model of the soil pressure on the rectangular box jacking considering the grouting effect is established based on the Terzaghi soil pressure calculation theory and combined with the characteristics of the rectangular box jacking engineering, and an improved calculation formula of the soil pressure on the rectangular box jacking is proposed.Based on the real-time monitoring data of vertical soil pressure in a rectangular box jacking project in Suzhou, the variation rules were explored and the accuracy of the calculation formula was verified.The results show that the shear zone in the soil is generated from both sides of the pipe wall and develops in the vertical direction, and can penetrate to the surface; under the critical state, the frictional angle of the shear zone is fully developed, and the friction coefficient of the shear zone is calculated by the critical internal friction angle and its sinusoidal value; under different grouting pressures, "active soil arch" and "passive soil arch" may appear above the pipeline.The comparative analysis between the calculated value and the measured value shows that the improved calculation method can better envelop the vertical earth pressure range of the rectangular box pipe.