对西宁城区古近系泥岩工程地质特性的新认识

New Knowledge on Paleogene Mudstone Engineering Geological Characteristics in Xining Urban Area

西宁城区古近系泥岩分布范围很广,遍及城中、城东、城西、城北四区,是西宁地区高层建筑工程建设中常见的岩土体。在本次勘察中,对泥岩的工程地质特性提出新的认识:一是发现泥岩中存在裂隙水,呈脉状分布,有较高的承压水头;二是在泥岩中确实存在溶洞,认为其形成与成岩程度和石膏与芒硝的富集有关。结合工程实例,对泥岩的工程地质特性进行了详细的分析和评价,提出了泥岩分布区域工程地质勘察要点及设计施工中应注意的主要问题。

The Paleogene mudstone is vastly distributed in the Xining urban area, spread all over middle, east, west and north city districts, a familiar geotechnical mass in high rise building engineering construction in Xining area. During the present exploration, new knowledge of mudstone engineering geological characteristics put forward： the first is fissure water existed in mudstone, takes on vein-like distribution with rather high artesian head; the second is karstic caves existed in mudstone, their formation and diagenetic degree are related to the enrichment of gypsum and mirabilite. Combined with project examples, analyzed and assessed mudstone engineering geological characteristics in detail, put forward mudstone distributed area engineering geological investigation essentials and major issues need to be noted in designs and constructions.