真空加载方式对吹填流泥加固效果及土颗粒移动的影响研究

Study of impact of vacuum loading mode on dredger fill flow mud consolidation effect and soil particles moving

考虑加载方式的影响开展室内模型试验,对4组相同性质的泥浆试样(含水率为100%)分别采用不同的加载方式,即-80 kPa、-60 kPa→80 kPa、-40 kPa→-80 kPa、-20 kPa→-80 kPa进行加载,加载过程中对试样的出水量、沉降量和侧向变形进行跟踪监测,并对处理后土体的含水率、塑性指数和十字板剪切强度等的空间分布与变化规律进行研究。试验结果表明,(1)真空加载方式对吹填流泥的固结具有比较明显的影响;(2)初始真空荷载为-20 kPa时所得到的土体沉降量最大、强度最高,始终保持-80 kPa荷载情况下所得到的土体沉降量最小、强度最低;(3)从塑性指数的分布特征来看,土颗粒随着土中水的排出发生移动,初始真空荷载越大,这种趋势越明显,部分土颗粒会聚积在排水板周围而导致土体渗透性能的降低,严重时会影响土体的后续固结。建议在流泥淤泥的真空固结过程中采用低初始荷载方式进行加载。

vacuum loading mode are generally not considered in Traditional vacuum preloading method in the reinforcement of soft soil. This paper carried out indoor model test, it tested four groups of the flow mud soil samples the water content of which is 100%, the vacuum loading mode are -80 kPa, -60 kPa→80 kPa, -40 kPa→-80 kPa, -20 kPa→-80 kPa, Water, settlement and lateral deformation was monitored during the loading of the sample in the course of the test, and changes of the water content, plasticity index and vane strength was studied after the test. The test results showed that： （1） Vacuum loading mode significantly effects on＇ consolidation of dredger fill flow mud. （2） Soil settlement is largest and strength is highest when the initial vacuum value of-20 kPa better than the others; soil settlement is smallest, and strength is lowest when the initial vacuum value of -80 kPa better than the others. （3） From the distribution characteristics of the plasticity index, soil particles move with water in the soil discharge, inital vacuum load value larger this trend is more obvious; the part of the soil particles will accumulate around of plastic vertical drain and so as to reduce soil permeability; severe cases will affect soil consolidation of follow-up. Finally, it is recommended that a lower initial load mode to loading in the flow mud vacuum consolidation process.