疏浚土的附着力特性试验研究

土的附着力是港航疏浚工程中一项重要技术指标,它可为抓挖机械的选取及其操作技术提供合理建议,为航道、港池等开挖工程以及吹填工程提供设计与施工参数,但目前对其研究仍处初步阶段。通过对7种典型疏浚土进行物性试验与附着力试验,从土力学角度关联土的物理指标与附着力,从土质学角度探讨土的粘附机理。结果表明,土的黏粒含量越高,附着力越大。随着含水率的增加,附着力逐渐增大,当含水率接近液限时附着力达到峰值,此后逐渐减小。附着力的产生与变化机理主要是由于结合水性质与含量发生变化,进而引起接触物—水—土—电解质系统吸附力与解离力的产生、发展、平衡、破坏所导致。研究还表明,该区土在天然含水率状态下土的附着力在数值上约为其塑性指数的5倍。疏浚工程中,淤泥厚度大地区,可采取冲水条件下开挖;含较多砾、砂、粉的土体可采取增加排水措施,用以提高掘进与排泥速率。

Test research on adhesion characteristics of dredged soils

The adhesion of soil is a very important technical indicator in the dredging engineering, which can provide reasonable suggestions for the selection and operation technique of digging machine and offer design and construction parameters for the excavating and jetting-filling projects of channel, harbor basin, but the research of adhesion is still at a preliminary stage now. Seven typical soils in dredging engineering were chosen to do physical property and cohesion tests, connecting the physical indexes and cohesion of soil at soil mechanics level and discussing the adhesion mechanism of soil at soil properties level. The results showed that, the higher the clay content of soil, the larger the adhesion. The adhesion increased gradually with the increasing of moisture content and reach peak when the moisture content was closed to liquid limit and then decreased gradually. The generation and variation mechanism of adhesion were mainly due to the change of properties and content of bound water, which caused the generation, development, equilibrium and damage of adhesion and dissociation force in water-soil-electrolyte system. The results also showed that, the adhesion of soil in natural moisture content was about 5 times the plasticity index numerically. In dredging engineering, the area with large thickness muck should be excavated with water filling and for soil containing more gravel, sand and silt drainage measure should be enhanced to increase the digging and spoil disposal speed.