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为探讨水力路径对膨胀土土水特征与体变特征影响中的滞回效应,以压实度为90%的荆门弱膨胀土为研究对象,采用轴平移技术和等压湿度控制法,开展了控制吸力条件下的脱、吸湿试验,获得了0~391000kPa吸力范围内的孔隙比-含水率-吸力关系的滞回效应规律,结论如下:(1)重力含水率-吸力关系的滞回效应显著。吸力小于10000kPa的区域,脱湿边界线与吸湿边界线间涵盖了较大范围;吸力大于10000kPa的区域,滞回效应弱化。脱湿与吸湿边界线并不平行,前者拐点处的斜率明显大于吸湿边界线的相应值。Fredlund-Xing模型能够很好描述土水特征的脱湿与吸湿边界线。脱、吸湿边界线均可分别通过2个特征点划分为:边界效应区、过渡区与残余区;残余吸力与进水值均可取为359100kPa;进气值为72kPa;出气值为10kPa。(2)孔隙比-吸力关系呈现出显著的滞回效应。利用3参数指数函数可以很好地分别描述主脱、吸湿路径下的孔隙比-吸力关系。(3)孔隙比-重力含水率关系的滞回效应并不显著。采用2参数指数函数可较好地统一描述不同水力路径下的孔隙比-重力含水率关系。(4)饱和度-吸力关系呈现出显著的滞回效应,其脱、吸湿边界线也可用Fredlund-Xing模型分别描述。(5)体变特征的脱湿速率效应显著。
In order to investigate the hysteretic effect of hydraulic path on the characteristics of soil-water volume and volume change in expansive soil, taking Jingmen weak expansive soil with 90% compaction as the research object, axial translation technology and isobaric humidity control method Under the control of suction and off-moisture absorption test, the law of hysteresis of the void ratio-water content-suction relationship within the suction range of 0-391000 kPa was obtained. The conclusions are as follows: (1) The hysteresis effect of gravitation- . When the suction is less than 10000kPa, the dewetting boundary line and the moisture absorption boundary line cover a large area. When the suction force is larger than 10000kPa, the hysteresis effect is weakened. Dewetting and moisture absorption boundary line is not parallel, the former inflection point slope was significantly greater than the corresponding value of moisture absorption boundary line. The Fredlund-Xing model provides a good description of the dehumidification and hygroscopic boundary of soil-water features. Off and moisture absorption boundary lines can be divided into two boundary points: boundary effect zone, transition zone and residual zone respectively; the residual suction force and influent value can be taken as 359100kPa; the inlet air value is 72kPa; the outlet air value is 10kPa. (2) The void ratio-suction relationship shows significant hysteresis effect. Using the 3-parameter exponential function, the pore-to-suction relationship under the main off-take and hygroscopic paths can be well described. (3) Hysteresis effect of pore-gravity-water ratio is not significant. The 2-parameter exponential function can be used to better describe the relationship between void ratio and gravitational water content under different hydraulic paths. (4) The saturation-suction relationship shows a significant hysteretic effect, and the detached and hygroscopic boundary lines can also be described separately by the Fredlund-Xing model. (5) The body-changing characteristics of the rate of dehumidification significant effect.