富水砂层土压平衡盾构施工渣土改良试验

Soil Improvement for Earth Pressure Balance Shields Construction in Watered Sandy Stratum

摘要:

针对深圳的富水砂层，采用泡沫、膨润土以及高分子聚合物等添加剂，改良盾构施工渣土，进行现场坍落度试验.基于现场试验结果，通过对土样进行电镜扫描以及压缩、渗透等室内试验研究，分析了改性渣土细观结构以及渗透、压缩特性的变化.对添加剂改善富水砂性土的流塑性、保水性以及开挖面动态土压平衡机理作了较深入的探讨.结果表明,富水砂层中,采用质量比为1∶7、外掺量为8%~10%的膨润土进行渣土改良,可满足施工需求.

Abstract:

In order to improve the residue in shield construction, slump tests for watered sandy stratum in Shenzhen were conducted by using foam, bentonite and polymer. Based on the results of field test, laboratory tests including electron microscope scanning, permeability test and compression test were performed. The variation of soil sample properties as meso structure, the seepage and squeezing were analyzed. Based on the tested data, the effects of additives on improving plasticity fluid and capability of retaining water of sandy strata as well as the balance mechanics of shield work face were discussed in detail. As reasonable proportion, bentonite with mass ratio of 1∶7, incorporation 8% to 10% were determined providing valuable experience for shield construction in the similar strata.