新疆昭苏县草甸土的工程性质试验研究
Experimental study on engineering properties of meadow soil in Zhaosu County of Xinjiang
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摘要: 由于目前对草甸土的工程性质了解甚少,一方面引起了草甸土与草炭土,泥炭等的混淆,另一方面导致了在设计过程中不知如何选择相应的处治措施.鉴于此,以新疆伊犁昭苏县草甸土层为研究对象,参照一般土体的室内土工试验方法,测试了草甸土的比重,重度,烧失量,渗透系数,抗剪强度,无侧限抗压强度等物理力学指标,并将试验结果与国内外草炭土,泥炭,泥炭质土的工程特性进行了对比分析.结果表明:按照有机质含量分类,新疆昭苏县草甸土属于泥炭质土;其含水率处于泥炭质土的低限附近,而重度则高于一般泥炭和泥炭质土的重度,具有较好的渗透性,很高的压缩性;草甸土中的草根可以显著提高土体的黏聚力,但对内摩擦角的影响不明显;无侧限抗压强度试验过程中草甸土未发生类似于一般黏土的剪切破坏,而是产生了很大的压缩变形和鼓胀变形;草甸土在受荷载后主固结沉降完成很快,其主固结系数随着固结压力的增大线性减小;当固结压力超过100 kPa时,草甸土的主固结比较小,说明此时草甸土的次固结变形量不容忽视,地基沉降计算中应予以考虑.Abstract: Few research results about engineering properties of meadow soil are available, which makes it difficult to distinguish meadow soil from peaty soil. At the same time, the ground treatment measures cannot be chosen appropriately during construction. Based on the meadow soil in Zhaosu County of Xinjiang Uygur Autonomous Region, according to Chinese laboratory geotechnical tests on soils, many indexes of the meadow soil are investigated, such as specific gravity, bulk density, water content, loss on ignition, coefficient of permeability, shear strength, unconfined compressive strength, and they are compared with those of worldwide meadow soil, peat and peaty soil. The test results show that the meadow soil can be classified as a kind of peaty soil based on its loss on ignition. Its water content is near the lower limit of the peaty soil, and its bulk density is larger than that of the peaty soil. The meadow soil has high permeability and compressibility, and it also has high cohesive strength because of the grass root in it. The grass root has little effect on the internal friction angle. The compressive distortion and bulging distortion of meadow soil are large, and its failure mode during the unconfined compressive tests is not shear destruction. The primary consolidation of the meadow soil is completed in short time, and its primary consolidation coefficient decreases with the increasing stress. When the consolidation stress is larger than 100 kPa, the primary consolidation ratio is small, which means that the secondary consolidation of the meadow soil cannot be ignored during the settlement calculation.