泥浆粗粒材料对泥水盾构泥膜闭气时间的影响

Effects of coarse material in slurry on the airtightness time for the filter cake in slurry shield tunneling

通过自制仪器,对添加有不同含量粗粒材料的泥浆进行成膜闭气试验,分析泥浆中粗粒含量对泥膜闭气时间的影响,以揭示含粗粒材料泥膜的闭气机理并根据不同含量粗粒材料泥浆成膜效果和闭气性能的差异分析;研究粗粒材料、地层和泥浆颗粒形成的网架结构对泥膜闭气性的影响,以确定提高泥膜闭气性能的粗粒材料合理添加量。结果表明,添加的轻质砂能有效加快泥膜形成及增强泥膜的闭气性能,当泥浆中轻质砂添加量大于1.8g/L时,泥膜的闭气时间有较大的提升,但当添加量达到3g/L时,增加轻质砂添加量对泥膜闭气时间提升效果下降。

In order to reveal the airproof mechanism of filter cake and evaluate the effects of coarse grain content on airproof time, a series of filter cake formation and airproof experiments were conducted on self-made instrument by employing slurries with dif-ferent contents of coarse grain materials. Coarse grain materials, soil grains and slurry particles can form network structure. Effects of the network structure can be obtained and the appropriate content of coarse grain materials can be determined based on the evaluation of filter cake formation and airproof capability with different contents of coarse grain materials. The results showed that light sand additives can accelerate the formation of filter cake and strengthen the airproof capability. In addition, airproof time greatly increased when employing specific slurry with 1. 8 g/L light sand. But once the additive content reached 3 g/L, the effect of increasing airtightness time for filter cake will be reduced with the additive content of light sand being increased.