维多利亚褐煤的固结和渗透特性试验研究
Experimental study on consolidation and hydraulic behaviors of Victorian brown coal
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摘要: 维多利亚褐煤一般被认为是一种中级岩土材料(IGMs),其岩土工程性质介于常规土体和岩石之间。褐煤富含有机质,其自然结构和物理组分比较复杂。褐煤具有不同于常规软黏土的基本岩土参数,包括自然密度和相对密度低、天然含水率高、孔隙比大,渗透系数相对较低等。采用原状褐煤试样开展了标准室内固结试验,褐煤材料的固结变形曲线主要表现为:初始阶段变形明显且很快完成,初始阶段变形占比很大,在数分钟内应变可达50%,在较明显的拐点之后,后续变形相对较缓慢。标准Terzaghi固结并不能很好地适用于褐煤材料。设计开展了褐煤材料的常水头渗透试验,基于不同超静孔压消散路径采用2种方法测量了褐煤的渗透系数,试验测得的褐煤材料渗透系数值相对较小。Abstract: The Victorian brown coal is usually considered as a kind of intermediate geotechnical material (IGM), which has the properties between traditional rocks and soft soils. The brown coal is rich in organic matters and has complex textures and physical composition. It has different basic geotechnical index values from soft clays including low density and specific gravity, high water content, large void ratio and a relatively low hydraulic conductivity. The consolidation tests are carried out using the undisturbed brown coal samples, and the test results show special deformation behaviors of the brown coal. There is an instantaneous settlement at the early stage of the consolidation process, and the immediate settlement contributes to more than 50% of the total settlement occurring in the first several minutes. The Casagrande graphic method is not applicable to the brown coal to determine parameter t90 and other parameters. Even the traditional Terzaghi’s consolidation theory can not describe the consolidation curves appropriately. The constant head tests are designed and carried out under relatively low confining pressures. The test results show that the brown coal has a relatively low hydraulic conductivity.