Mechanical Properties and Microstructural Features of Weathered Granite in a High-speed Railway Tunnel
In order to study the mechanical properties and macro and micro structures of weathered granite at the base of high-speed rail tunnels,the relationship between the mineral composition and the relationship between the mineral composition and the macro and micro structures of the weathered granite was analyzed by carrying out consolidation tests,triaxial tests,XRD(X-ray diffraction)composition analysis and SEM(scanning electron microscopy)scanning of the weathered granite.The conclusions show that the mineral components of weakly weathered granite are mainly quartz,albite and microcline,while the minerals of fully weathered granite are affected by weathering,mainly kaolinite and illite.The weakly weathered granite has good structure,the crystals are closely connected,the fractures are clear steps,the internal structure of the fully weathered granite is loose,the large and medium pores are honeycomb-like distribution,and the surface is loosely distributed with flocculent debris.The expansion of hydrophilic minerals can lead to the development of internal pores and even structural destruction of fully weathered granite.The results can provide a reference for the analysis of the strength deterioration mechanism and microstructure of fully weathered granite,and provide basic physical parameters for the design and construction of fully weathered granite tunnel structure,so as to facilitate the timely adjustment of the corresponding support measures and ensure the smooth progress of tunnel construction.
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