土压平衡盾构穿越富水砂层施工技术探讨
Construction technology of earth pressure balance shield in watery sandy stratum
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摘要: 结合土压平衡盾构机穿越长345m富水砂层段工程实例,基于朗金土压力理论对配置了双螺旋出土输送器的盾构机在渗透系数较高的富水砂层中实现土压平衡模式掘进的性能进行了分析计算。结果表明:在正常状态下设备对富水砂层的适应性良好,然而一旦发生地下水大量渗入,仍有水土突涌的可能,需要采取相应的工程措施,来降低水土突涌的风险。通过室内试验进行了淤泥质砂层的碴土改良技术研究,结果表明气泡剂效果最优,高分子聚合物在喷涌事故发生时应急使用效果较好,现场监测结果表明碴土改良效果良好。最后探讨了气刨剂的掺入量与掘进机工作参数的关系。Abstract: Considering the engineering case that earth pressure balance shield machine passes through watery sandy stratum 345 m in length,the balance problem of double screw conveyors of the shield machine passing through the sandy stratum with high coefficient is discussed based on the Rankin’s earth pressure theory.The calculated results show that the shield machine has good adoptability to the watery sandy stratum.However,if groundwater infiltration happens,it is possible that inrushing of water and soil will happen,therefore some engineering measures to reduce risk induced by the inrushing of water and soil should be taken.Furthermore,the laboratory modified tests on silty sandy stratum are done.The research results show that the modified effect of bubbles is the best,and high molecule polymerization can be used to avoid spewing accidents.Field monitoring shows that the modified effect of residual soil is good.Finally,the relationship between the incorporation of bubbles and the working parameters of tunneling machine is discussed.