Study on the correlation of metasandstone, slate and phyllite chemical weathering coefficient based on elements migration and long-term strength near the Jinsha River Bridge (Bai Yu, China) on the Sichuan-Tibet Railway
2021
Wang, Yawei | Zhang, Shuhao | Wu, Guang
The Jinsha River Bridge (Baiyu, China) site has obvious weathering characteristics, which affects the construction of the project. To establish the correlation between the chemical weathering coefficient and the rocks mechanical characteristic, the analysis of the chemical composition of surface water and rocks (metasandstone, slate and phyllite) in the study area was conducted, and the long-term strength of the rock by the creep test was obtained. It is determined that the main driver of the hydrochemical composition is the chemical weathering of silicate and carbonate rocks. By investigating the mobility of elements in water and rocks, seven major elements, namely, SiO₂, TiO₂, Al₂O₃, Fe₂O₃, MgO, K₂O, and Na₂O were used to obtain the rock chemical weathering discriminant based on the calculations performed with SPSS.22. Then the correlation between weathering coefficient and long-term strength was analyzed by regression analysis, and the results indicate that the higher the rock chemical weathering coefficient is, the higher the long-term strength it has. Moreover, a confining pressure of 20 MPa is observed to be the point at which rock chemical weathering affects the rock mass engineering characteristics, and this finding has a certain significance in terms of engineering guidance. In summary, this fitted discriminant coefficient is suitable for assessing rock chemical weathering of weakly to moderately weathered metamorphic rock in the study area and can effectively characterize and predict the rock weathering degree and mechanical properties in the study area, providing support to engineering design and construction.
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