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详细介绍了由长江科学院引进的国内第一台GDS非饱和土直剪系统(UBPS)的结构、功能及特点,开展了相应的标定工作,并利用它对河南南阳原状中膨胀土的剪切性状开展了一系列的直剪试验研究工作,得到以下初步研究成果:土样在较低的吸力(<100 k Pa)下,基本上表现出剪切硬化的趋势,且强度峰值不明显;当吸力较大时,则表现出剪切软化的趋势,表现出明显的峰值强度;非饱和中膨胀土的黏聚力在低吸力范围内随吸力线性增大,这表明非饱和土双变量强度理论适用于原状中膨胀土。由于原状土的裂隙及铁锰结核分布不均匀,选择干密度相近、无明显裂隙的原状土样进行分组试验对于其抗剪强度指标的确定至关重要。
This paper introduces the structure, function and characteristics of the first domestic GDS unsaturated soil direct shear system (UBPS) introduced by the Yangtze River Scientific Research Institute and carries out corresponding calibration work. The shear deformation of expansive soil A series of direct shear experiments were carried out. The results of the preliminary research were as follows: The soil samples basically showed the tendency of shear hardening under the low suction (<100 kPa) with no significant peak intensity; when the suction When it is large, it shows the trend of shear softening and shows obvious peak strength. The cohesion of expansive soil in unsaturated soil increases linearly with the suction in the range of low suction, which indicates that the theory of bivariate strength of unsaturated soil applies In the original expansive soil. Due to the fractures of undisturbed soil and the uneven distribution of Fe-Mn nodules, it is very important to choose the group of undisturbed soil samples with similar dry density and no obvious fractures to determine the shear strength index.