研究目的:兰青二线、兰新第二双线以及西宁火车站改造等重点铁路工程的勘察设计结果表明,西宁地区第三系地层泥岩夹石膏岩具有特殊的岩土工程性质.本文从第三系泥岩夹石膏岩的基本力学特征及崩解性分析入手,对其膨胀性依据规范进行判定,讨论泥岩夹石膏岩对钢筋混凝土是否存在腐蚀性问题,以研究其对铁路工程的影响.研究结论:西宁地区第三系泥岩夹石膏岩的力学性质在一定的环境下,表现出不同的特征,在自然状态下,其工程性质较好,但在浸水及长时间暴露在空气中后,极易膨胀、溶蚀、软化、崩解,其强度和基本承载力降低,并会使环境水具腐蚀性.铁路路堤、路堑、隧道工程应对其膨胀特性采取相应工程措施,桥梁、房建桩基应考虑泥岩夹石膏岩溶蚀引起环境水对钢筋混凝土的腐蚀性问题.%Research purposes: The survey and design results of the second line of Lanzhou - Qinghai Railway, the second double line of the Lanzhou - Xinjiang Railway and the upgrading of the Xining Station show the tertiary mudstone with gypsum rock of the tertiary strata in Xining has the special engineering properties. This paper analyzes the basic mechanical characteristics and the disintegration of the tertiary mudstone with gypsum rock fist, then compares and determines the specification of its expansibility, and discusses the problem of whether there is corrosion existed in the mudstone with gypsum rock to the reinforced concrete, and finally analyzes the impact on the railway engineering. Research conclusions: In a certain environment, the mechanical properties of the tertiary mudstone with gypsum rock in Xining have the different characteristics. In the natural state, it has good engineering property, but after being immersed into water and exposed to the air for long time, it easily swells, corrodes, softens and disintegrates, resulting in reduction of its intensity and basic bearing capacity and making the environmental water corrosive. The engineering measures should be taken for its expansion characteristics in building railway embankment, cutting and tunnel and in building bridge and construction of the pile foundation of building, the attention should be paid to the environmental water corrosion to the reinforced concrete caused by mudstone with gypsum rock dissolution.
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