高渗透地层土压盾构渣土改良试验研究

Experimental Research on the Earth Pressure Balance Shield Soil Condition of High Permeability Strata

土压平衡式盾构施工在砾砂地层中容易出现螺旋排土器喷涌等问题,为了维持开挖面稳定,使盾构顺利掘进,需要对土压舱内的渣土进行改良.传统的渣土改良方案如加膨润土泥浆和气泡很难满足改良要求,文章通过对砾砂地层土颗粒的级配特征进行分析,发现砂砾地层缺少0.075~0.05 mm和0.25~0.01 mm粒组,通过粉土补充该粒组即在膨润土泥浆中掺入粉土对渣土进行改良,渣土的渗透系数大幅下降,改良效果良好.

In gravel sand,the earth pressure balance shield tunneling is easy to appeare the problems such as spewingin screw conveyor and forming mud cake in soil cabin,in order to maintain the stability of the excavation surface toensure the smooth of shield tunneling,we need to make the soil condition in soil cabin.The traditional soil conditionprograms such as mix bentonite mud and bubbles are hard to meet the requirements of improvement.This paperfinds gravelly sand strata are lack particles from0.075-0.05mm and0.25-0.01mm,and supplement this group bysilt with bentonite mud to made improvement for residue.The permeability coefficient of residue have fallen sharplyand the improved effect is fine.