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针对传统仪器无法考虑岩土工程中温度和荷载等因素综合作用的缺陷,研制了一套多功能土-水特征曲线试验仪。以粉土为研究对象,开展了不同固结应力作用下粉土的土-水特征曲线试验,并测量其增减湿过程中土体的体积胀缩量,以便修正体积变化对其体积含水率的计算误差。结果表明,粉土在减湿过程中,土体的体积发生明显的收缩。其收缩量与固结应力水平有关,固结应力越小,则减湿引起的体缩量越大。但土体在增湿过程中的体积则基本保持不变。固结应力对粉土土-水特征曲线的进气值、增减湿速率影响较大,固结压力越大,其进气值越大、减湿速率也越大。最后,为揭示固结应力对土的持水性能的影响机制,开展了不同固结应力作用下土体的细观试验。结果表明,固结应力主要改变了土体团粒间的大孔隙,而对黏土颗粒之间的孔隙影响较小。土体的持水性能与土体的孔隙大小和分布模式密切相关,大孔隙主要影响土体的进气值,而其孔隙分布模式则控制其增减湿湿速率。
Aiming at the defect that the traditional instruments can not consider the combined effect of temperature and load in geotechnical engineering, a set of multifunctional soil-water characteristic curve tester was developed. Taking silt soil as the research object, soil-water characteristic curve test of silt under different consolidation stress was carried out. The volume expansion and shrinkage of soils during the process of increasing and decreasing wetting were measured in order to correct the effect of volume change on the volumetric water content The calculation error. The results show that during the dehumidification of silt soil, the volume of soil significantly shrinks. The shrinkage is related to the level of consolidation stress. The smaller the consolidation stress, the greater the body shrinkage caused by dehumidification. However, the volume of soil in the humidification process is basically unchanged. The consolidation stress has a great influence on the air intake value and the rate of increase and decrease of the soil-water characteristic curve of silt, and the larger the consolidation pressure, the larger the air intake value, the greater the rate of dehumidification. Finally, in order to reveal the mechanism of the effect of consolidation stress on the water-holding capacity of soil, the mesoscopic experiment of soil under different consolidation stresses is carried out. The results show that the consolidation stress mainly changes the macropores of soil aggregates, but has little effect on the porosity of clay particles. The water holding capacity of soils is closely related to the pore size and distribution pattern of the soils. Large pores mainly affect the inflow values of the soils, whereas the pore distribution patterns control the increase and decrease of the wetting rates.