生石灰膨润土泥浆土压盾构渣土改良试验研究

Soil Improvement for Earth Pressure Balance Shields Construction with Lime Bentonite Clay

土压平衡盾构在砂性地层施工中,常出现盾构刀盘磨损严重、扭矩过大、土压舱土体难形成塑流状态等问题,施工中常使用膨润土泥浆作为土体改良剂对切削渣土进行改良来解决上述问题。本文以膨润土和生石灰为原料配制土体改良剂,通过采用泥浆粘度和相对密度为参考指标优选出合适的泥浆作为土体改良剂对渣土进行改良,并对改良渣土开展坍落度试验和剪切试验来综合评价生石灰含量对渣土改良效果的影响。试验结果表明:对于生石灰掺量为0%~2.8%的膨润土泥浆,随着生石灰含量的增加,泥浆的粘度和相对密度有所增加,改良后渣土的抗剪强度有所降低,在生石灰含量为1.4%时坍落度能较好的满足施工要求。

EPB shield is commonly used during the construction of sand stratum.However,some problems such as serious wear of shield cutter,excessive torque and the difficulty in forming the plastic flow state have been bothering the industry.In order to solve problems,sediment improvement with bentonite has been commonly used as the soil conditioner to modify the cutting waste residue.In the study,the soil conditioner made of bentonite and quick lime was examined.Suitable mud was selected as the conditioner by means of examining the mud viscosity and relative density to improve the sediment.The influence of quick lime content on sediment improvement was comprehensively evaluated via the slump test and shear test.The results show that when the quick lime content is 0~2.8%,with the increase of the content of quick lime,the mud viscosity and relative density increase but the shear strength of the improved residue reduces.When the content of quicklime is 1.4%,the slump can meet the construction requirement well.