【作者】 张妮；

【导师】 梁收运；

【作者基本信息】 兰州大学 ， 地质工程， 2012， 硕士

【摘要】 滑带土是滑坡滑动的历史产物,记载着滑坡失稳滑动的大量信息。本文以泄流坡滑坡两个滑带剖面滑带土为研究对象,采用筛分法和光学法、XRD、XRF、穆斯堡尔谱和同步辐射、扫描电子显微镜等方法对其粒度、矿物成分、化学成分、铁和硫元素的赋存状态、微观结构等特征进行了研究。主要得出以下结论：(1)泄流坡滑坡滑带土大于2mm的颗粒含量基本都在25%-50%之间,按土质分类命名为砾砂；两个滑带剖面上滑体、滑带、滑床样品的级配都不良。(2)Ⅰ号剖面上,滑体样品在矿物成分上与滑带样品具有相似的特征,铁白云石的含量较高,方解石被溶解,石膏伴随而生：滑床样品中方解石的含量较高。Ⅱ号滑带剖面上,滑体和滑床样品的方解石含量较高；滑带中铁白云石的含量较高,有少量的石膏。滑带中的方解石被溶解,降低了滑带土的抗剪强度,是泄流坡滑坡在滑带失稳的主要原因之一。(3)铁和硫元素赋存状态显示：两个剖面滑体的赋存状态不同,Ⅰ号剖面上滑体样品具有与滑带相似的特征,处于还原环境中；Ⅱ号剖面的滑体以relax.+Para-Fe3+为主以及样品中只有硫酸盐态硫,说明滑体处于氧化环境。两个剖面上,滑带的赋存环境相似,都以Para-Fe2+为主和单质态硫的存在,说明其处于还原环境；滑床的赋存环境也一致,以Para-Fe3+为主以及样品中只有硫酸盐态硫,说明其处于较强的氧化环境中。滑带处于还原环境中有利于铁白云石的形成积累以及Fe3+/Fe2+的比值小于1是滑带土呈现灰黑色的主要原因。(4)滑体和滑床样品以方解石颗粒为骨架结构,滑带土颗粒主要是集粒的片状矿物,成层分布,使得滑带土容易顺层滑动失稳,是泄流坡滑坡失稳发生在滑带内的主要原因之一。(5)滑体样品的孔隙特征不同于滑带土的孔隙特征,而且滑带土在两个相互垂直的方向上孔隙特征差别明显,平行滑面上孔隙多而大,形态呈近圆状；垂直滑面上的孔隙相对少而小,平面形态呈狭长状。Ⅰ号剖面上,滑带土的平面孔隙率变化复杂,反映了滑带多期演化过程的复杂性；Ⅱ号剖面上,滑带土的平面孔隙率随剖面从上到下依次减小。滑带土平面孔隙率的极小值出现在滑面附近,与频率曲线均值的极小值特征相吻合,揭示了滑带形成环境的相对单调性。更多还原

【Abstract】 Sliding mud, the landslide product of sliding, records all information of landslide in sliding process. In the thesis, geochemical characteristic and micro structure of sliding mud in two slip zone profiles of Xieliupo landslide of Zhouqu county have been studied, including particle size, mineral and chemical composition, element species and microstructure using sieving method and optical method, XRD and XRF, Mossbauer spectroscopy and XANES, SEM, respectively. The main conclusions are as follows:(1) The content of sliding mud particle (>2mm) in Xieliupo landslide ranged from25%to50%, and meanwhile this kind of sliding mud was called gravel sand by soil classification. The soil of sliding body, slip zone and bedrock was bad gradation in both profiles.(2) In the profile Ⅰ, there were similar characteristics between the samples of sliding body and slip zone in mineral composition, both of them were rich in ankerite, and calcite was dissolved with gypsum formed; bedrock samples also had many ankerite. In the profile Ⅱ, the samples of sliding body and bedrock had more calcite, however, sliding mud had more ankerite and a little gypsum. One of the reasons of Xieliupo landslide instability was that calcite was dissolved and the shear strength of sliding mud was decreased.(3) Iron species and sulfur species revealed that the sliding body samples of profile I were similar with sliding mud in reduced condition, but the sliding body samples of profile II were in oxidation condition. The sliding mud and bedrock of both profiles were in reduced condition and oxidation condition respectively, characterized by more Para-Fe2+and sulfur in the samples, more Para-Fe3+and only sulfate in the samples, respectively. It was because the slip zone was easy to form ankerite in reduced condition and the ratio of Fe3+/Fe2+was less than1that the sliding mud was gray/black.(4) The samples of sliding body and bedrock were mainly calcite, while sliding mud was main schistose particle and layered structure, which was one of main reasons of Xieliupo landslide instability in slip zone.(5) The pore characteristic of sliding body was different from sliding mud’s, the pore of parallel sliding plane of sliding mud closed to round and vertical section’s was long and narrow. In the profile Ⅰ, area fraction varied in complex revealed sliding mud self-complexity. In the profile Ⅱ, area fraction was decreased along profile from sliding body to bedrock. The minimize of sliding mud area fraction reflected near sliding plane, which was similar with the minimize of frequency curve’peak, revealed the period of forming time of slip zone to some degree.更多还原