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针对大厚度黄土湿陷变形室内试验评价不准确,现场原位浸水试坑试验评价方法周期长、费用高且难以适应线性工程技术要求等不足,提出了一种新的现场试验评价方法:砂井浸水试验方法。其核心是利用湿陷变形土体与未湿陷变形土体之间产生相对沉降差及地裂缝,通过湿陷性黄土场地设置砂井,将水直接导入某一深层湿陷性黄土地层及砂井圆周边土体,以此来测定砂井井底下地层和砂井孔深范围内黄土的湿陷变形量。该方法具有操作简便、花费小、周期短和灵活性高等特点。依托宝兰客专建设项目,在具有代表性的大埋深自重湿陷性黄土场地开展了4个不同深度的砂井浸水试验,测试了砂井场地的沉降变形及井底湿陷性土层的沉降变形,同时配合井底土层含水量的量测,分析了井底黄土的湿陷性变形特征。参考现有规范中建议的该地区自重湿陷量修正系数,对比砂井浸水试验结果与室内试验结果,初步论证了砂井浸水试验的合理性,及其在大厚度湿陷性黄土线性工程上运用的优势。
Aiming at the inaccurate evaluation of large-thickness loess collapse deformation in-house test, the in-situ immersion test pit test evaluation method is long, costly and difficult to meet the requirements of linear engineering, a new field test evaluation method is proposed: Immersion test method. Its core is to make use of the relative settlement difference and the ground fissure between the collapsible soil and the undisturbed deformed soil and set the sand well through the collapsible loess site to direct the water into a deep collapsible loess formation and sand So as to determine the amount of deformation of the loess in the area below the sand hole and the depth of the sand hole. The method has the advantages of simple operation, small cost, short cycle and high flexibility. Relying on the construction project of Baolan Passenger Dedicated Project, four sand immersion tests at different depths were carried out on the representative deep buried deep self-weight collapsible loess site. The settlement deformation of the sand well site and the collapsible bottom soil layer At the same time, with the measurement of water content in the bottom hole, the collapsible deformation characteristics of bottom hole loess are analyzed. Referring to the correction coefficient of self-contained collapsing amount in the existing code, comparing the sand immersion test result with the indoor test result, the rationality of the sand well immersion test is preliminarily demonstrated and the results are validated in the linear engineering of large-thickness collapsible loess The advantages of using.