南京纬三路过江通道在竖井施工和盾构始发段掘进过程中产生了大量废弃的黏土,如何经济环保地处理废弃土成为工程面临的一大难题。工程盾构段约40%的地层是粉细砂地层,该地层对泥浆指标要求较低,考虑利用废弃黏土来配制掘进泥浆。采用填土、淤泥质粉质黏土、膨润土分别与泥浆增黏剂混合配浆,使用自制的泥浆渗透仪测定泥浆的滤失量和成膜质量,最后结合现场施工监测数据验证泥浆配比的可行性。结果表明,采用始发段废弃淤泥质粉质黏土配制的泥浆稳定性较好,形成的泥膜致密、泥浆失水量小,能够满足粉细砂地层的盾构掘进。
The construction of the vertical shafts and the shield launching sections of Nanjing Weisanlu Yangtze River Crossing Tunnel produced a huge amount of waste clay.On the other hand,40% of the shield-bored section of the mentioned tunnel is located in fine silty sand strata,which requires that the slurries to be used need not have high performance.As a result,the waste clay produced is reused to prepare slurries for slurry shield boring.The waste clay is mixed with fill,muddy-silty clay and bentonite to prepare slurry.The filter loss and filter membrane quality of the slurry prepared are tested by means of self-made slurry infiltration testing device.The mixing proportion of the slurry is verified by the site monitoring data.The study shows that the mentioned slurry with waste clay mixed has such advantages as good stability,compact filter membrane and low slurry loss,and it can meet the requirements of shield boring in fine silty sand strata.