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黄土的胶结连接是黄土湿陷的重要内在因素,对其湿陷敏感性有着直接影响。为了对胶结连接在黄土湿陷敏感性中的作用有更清楚的认识并提出一个能科学的判定黄土湿陷敏感性的评价方法,在黄土湿陷性试验的浸入水溶液里添加不同浓度的硝酸,测试在酸性环境中,不同压力下黄土的湿陷系数、稳定时间、湿陷速率等湿陷敏感性指标。同时用扫描电镜观察试验前后土样的孔隙、结构变化情况。试验结果表明:在酸性溶液中,湿陷性黄土在低压状态下的湿陷系数增大较多,在各级压力下的湿陷稳定时间均有所延长;在水溶液和酸性溶液中,黄土有着不同的湿陷敏感压力区间;湿陷性黄土的结构强度对湿陷性黄土的深度有着重要影响等。在此试验基础上,吸取前人的经验,提出用完成90%湿陷量的用时和湿陷系数这2个指标对黄土及其场地进行湿陷敏感性评价,并以发生过湿陷的场地——抽黄渠为实例对此方法进行验证。验证结果表明,该方法能准确地反映湿陷场地的湿陷敏感性,对湿陷场地上的工程建设具有一定的指导意义。此外,该方法简单、科学,又能与现行规范相结合,因此,易于被业界接受并推广,是对现有少数关于黄土湿陷敏感性研究的有益补充。
The cemented connection of loess is an important intrinsic factor of loess collapsibility, which has a direct impact on its wettability. In order to know the effect of cementing connection on the sensitivity of loess collapsibility and to provide a scientific method for evaluating the sensitivity of loess collapsibility, different concentrations of nitric acid were added into the immersion water solution of loess collapsibility test, In acidic environment, under different pressures, the collapsibility coefficient of loess, the stability time and the rate of collapsibility were tested. At the same time, with the scanning electron microscope observation of soil samples before and after the pore structure changes. The experimental results show that the collapsibility of loess in acidic solution increases greatly at low pressure, and the wetting stability time is prolonged under all pressures. In loess and acidic solution, loess has Different wetting sensitive pressure interval; the structural strength of collapsible loess has an important influence on the depth of collapsible loess and so on. On the basis of this experiment, drawing on the experience of predecessors, we proposed to evaluate the wettability of loess and its site by using two indices of 90% of the collapse time and collapse coefficient. - pumping yellow canal as an example of this method to verify. The verification results show that this method can accurately reflect the wettability of the collapsed site, and is of guiding significance to the engineering construction on the collapsed site. In addition, the method is simple and scientific, and can be combined with the existing norms. Therefore, it is easy to be accepted and popularized by the industry and is a useful supplement to the existing studies on the sensitivity of loess collapsibility.