穿江泥水盾构环流系统及泥浆携渣计算研究

Study on Circulation System of Slurry Shield Crossing River and Calculation of Sludge Carrying Slag

泥浆环流系统作为泥水盾构工作重要组成部分,直接影响到盾构施工效率。以南昌地铁4号线穿江盾构隧道为工程背景,针对三种典型掘进地层(砂砾层、上软下硬层和泥质粉砂岩地层),根据物质守恒原理对环流系统进行计算分析,并分别运用杜兰德公式和费祥俊公式计算泥浆不淤流速,从而确定泥浆携渣能力。结果表明:在上软下硬地层中,泥浆的携渣能力较弱,排浆管道易发生渣土沉淀;泥水分离系统中筛分设备的优化,增加粉粘性颗粒筛除量,在泥质粉砂岩地层盾构掘进中,可以较好地防止泥浆比重增长过快;在管道不淤流速设计计算中,杜兰德公式适用于富含粉粘颗粒的泥浆,而费祥俊公式适用于含有大粒径颗粒的泥浆。

As an important part of the mud water shield,the mud circulation system directly affects the construction efficiency of the shield. Taking the Nanchang Metro Line 4 river crossing shield tunnel as the engineering background,aiming at three typical excavation strata( sand gravel layer,upper soft and lower hard layer and argillaceous siltstone strata),the circulation system was calculated and analyzed according to the principle of conservation of matter,and Durand formula and Fei Xiangjun formula were used to calculate the non-sludge flow rate of the mud to determine the mud carrying capacity. The results show that in the upper soft and lower hard strata,the mud carrying capacity is weak,and the mud sedimentation of the slurry pipeline is prone to occur. The optimization of the screening equipment in the mud-water separation system increases the amount of powdery and viscous particles to be screened. During the shield tunneling in the muddy siltstone formation,it can better prevent the mud proportion from increasing too fast. In the design calculation of the non-silt flow rate of the pipeline,the Durand formula is suitable for the mud with rich powder and sticky particles,while the Fei Xiangjun formula is suitable for the mud containing large particles.