Study On The Expansibility And Corrosiveness Of Gypsum Breccia In North China

China is very rich in the mineral deposit of hydatogenic rock and the evaporite-solution breccia whose causes of formation is closely related to hydatogenic rock.One kind of breccia was found in the construction process of Taihang Mountains tunnel. The breccia has extremely special project behavior and physical & mechanical properties, such as heterogeneity of composition, losseness of structure, heterogeneity of structure, low strength, the structure of the heterogeneity and low Strength, highly rational water, weak to moderate expansion, as well as corrosive and soluble. According to large amount of survy on outcrops, observations on drill core rock samples, analysis of micro-slice of fabric of rick samples, this paper named this kind of breccia as Gypsum breccia.In this paper, we will obtain the indicator of physical & mechanical properties and the project behavior of the Gypsum breccia, then we define the exactly type of the Gypsum breccia. In order to work out our result, we collect differernt kinds of Gypsum breccia samples from Shijiazhuang-Taiyuan passenger railway line in North china, and do indoor experiments on these rock samples. After that, we will make some conclusions about the causes formation of gupsum breccia through comprehensive analysis.On the basis of existing research outcomes of gypsum breccia from Shijiazhuang-Taiyuan passenger railway line and current conditions, we determined the main contents of this thesis as follows:Firstly, study of the distribution and lithologic characters of middle ordovician in North China platform, and discuss the relation between gypsum horizon and Gypsum breccia.Secondly, infer the causes formation of Gypsum breccia through comprehensive analysis of the research information on middle ordovician gypsum breccia and Taihang Mountain Tunnel area breccia from Shijiazhuang-Taiyuan passenger railway line.Thirdly, quantitative analyze substance composition of Gypsum breccia, especially do detail research on those clay mineral and material components which are soluble, such as salt, gypsum and anhydrite by the methods of scanning electron microscope and spectrum analysis, x-ray diffraction of powder crystal analysis.Finally, do indoor test of the rock samples from hijiazhuang-Taiyuan passenger railway line Taihang Mountain Tunnel, combine the historical experiment data, study project behavior and physical & mechanical properties of these samples.