磁化水改良黏性土路基压实特性的试验研究

发布时间：2018-02-27 20:53

本文关键词： 路基工程黏性土磁化水压实机理结构优化团聚体　出处：《南京大学》2014年硕士论文　论文类型：学位论文

【摘要】：本文从黏性土压实的微观机理入手,在系统分析水-土-盐(离子)相互作用的基础上,提出了在施工期使土结构软化,增强施工期压实效果,进而达到降低路基土在运营期的压缩量,提高路基土强度的作用。基于磁化水在混凝土工程、盐渍土脱盐以及锅炉除垢等领域中应用的微观机制分析的基础上,论文提出采用磁化水处理路基土的设想,并围绕这一设想进行了大量的室内试验研究。试验结果表明：利用磁化水处理路基土,提高路基土强度和干密度的设想是可行的,并给出了磁化水改良路基土的初步设计方案。由于磁化水改良路基土的相关研究工作在国内外并未见可供参考的报道,因此,本次工作仅仅是探索性研究课题,并取得了一些有价值的成果,具体包括：(1) 根据磁化水在土-水-盐相互作用中的特殊作用,提出了土体微细观结构优化思想。磁化水在施工期导致土颗粒接触点的结构强度发生弱化,从而使土颗粒在承受同样外部荷载(压实功)后,经磁化水润湿的土体发生结构塌陷,土颗粒向更紧密排列的趋势发展,这样可大大降低土的孔隙比、提高土的压实性能；(2) 与普通水相比,磁化水处理后的土样的各项物理和水理性质指标均发生不同程度的变化。其中自由膨胀率有所提高,塑限含水量增加而液限含水量下降,并导致塑性指数下降。而团粒分析成果显示,在磁化水作用下,土中的粗粒组颗粒(团聚体)向粉粒组以及黏粒组转化,说明土颗粒团聚体在磁化水作用下发生了瓦解。但加入分散剂的粒度分析试验显示,在磁化水作用下,黏粒组也会向粉粒组方向转化,说明在磁化水作用下,凝聚与分散作用也能同时发生；(3) 渗透、击实和剪切试验进一步证实了磁化水对土体结构的优化作用。经磁化水处理的土样由于团聚体的瓦解,颗粒更加分散,在相同干密度的情况下,磁化水制样的黏性土的渗透系数变小。在相同击实功下,磁化水润湿的土样的最大干密度增大,对应的最优含水量有所下降。剪切试验表明,与普通水相比,磁化水制备的相同干密度土样的内聚力和内摩擦角均有所增大,从而提高了土的抗剪强度；(4) 不同磁感应强度、不同温度、不同水流速度以及不同性质土的试验结果显示,磁化水对黏性土性质的改良效果受到非常复杂的因素影响。最佳磁化参数以及该方法适用的土的类型有待进一步研究确认。
[Abstract]:Based on the microcosmic mechanism of clay compaction and the systematic analysis of water-soil-salt (ion) interaction, this paper puts forward that the soil structure will be softened during the construction period and the compaction effect will be enhanced. Based on the micro-mechanism analysis of magnetized water applied in concrete engineering, salinized soil desalination and boiler scale removal, the compression of subgrade soil in operation period can be reduced and the strength of roadbed soil can be improved. The paper puts forward the idea of using magnetized water to treat subgrade soil, and carries out a lot of laboratory experiments around this assumption. The experimental results show that it is feasible to increase the intensity and dry density of roadbed soil by using magnetized water to treat roadbed soil. The preliminary design scheme of magnetized water improved subgrade soil is also given. Since the related research work on magnetized water improved subgrade soil has not been reported for reference at home and abroad, this work is only an exploratory research subject. And some valuable results have been achieved, including: 1) according to the special role of magnetized water in soil-water-salt interaction, The idea of soil micro-structure optimization is put forward. The structure strength of the contact point of soil particles is weakened by magnetized water during the construction period, which makes the soil particles bear the same external load (compaction work). The structure of the soil wetted by magnetized water collapses and the soil particles are arranged more closely, which can greatly reduce the void ratio of the soil and improve the compaction performance of the soil. The physical and hydrological properties of the soil treated with magnetized water have changed in different degrees, in which the free expansion rate has been increased, the plastic limit water content has increased, and the liquid limit water content has decreased. The results of agglomeration analysis showed that, under the action of magnetized water, the coarse particles (aggregates) in soil were transformed into silt and clay groups. The results of particle size analysis with the addition of dispersant showed that the clay group would also transform to the silt group under the action of magnetized water, which indicated that under the action of magnetized water, the clay particle group would change to the silt group, which indicated that under the action of magnetized water, the clay particle group would be transformed to the silt particle group. Coacervation and dispersion can also occur at the same time. Compaction and shear tests further confirm the effect of magnetized water on the optimization of soil structure. The particles of the soil treated with magnetized water are more dispersed due to the disintegration of aggregates. Under the condition of the same dry density, the permeability coefficient of clay soil prepared by magnetized water becomes smaller. Under the same compaction work, the maximum dry density of soil sample wetted by magnetized water increases, and the corresponding optimum moisture content decreases. Compared with ordinary water, the cohesive force and internal friction angle of the same dry density soil samples prepared by magnetized water have been increased, thus increasing the shear strength of the soil. The experimental results show that the effect of magnetized water on the improvement of clay properties is affected by very complicated factors. The optimum magnetization parameters and the types of soils suitable for this method need to be further studied and confirmed.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

【相似文献】