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The completely decomposed granite formation features looseness, low strength, poor self-stability and high disintegration exposed to water. It can easily cause geological disasters such as water inrush and mud gush during tunnel construction and seducing secondary disasters especially in the strongly disturbed regions. The specific full-section curtain grouting is proposed to deal with the strongly disturbed and completely decomposed granite formation. The meticulous exploration which combined the geological exploration holes and transient electromagnetic is adopted to detect the hydrogeology conditions and the main water supply channel in the strongly disturbed region. Based on the control principles of grouting amount and pressure as well as the selecting principles of grouting material, we applies the multistage casing segregation technique to reinforce the strongly disturbed region. This achievement performed well in the treatment of water inrush and mud gush in the construction of Junchang tunnel in Guangxi province, and realized safe excavation of the right tunnel which is located in the strongly disturbed region. Also it can provide model significance to the similar constructions.

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Cement-sodium silicate grout (CSG) is now widely adopted in water plugging engineering to prevent water inrush disasters, and the gelation and consolidation characteristics of CSG in water environment significantly affect the grouting effect. To obtain an in-depth understanding of the performance of CSG in water, the CSGs with different water-cement ratios and volume ratios were tested, and the gelation properties, the deposition characteristics and the diffusion process of CSG within water were examined. The compressive strength and microstructure of CSG consolidation formed in air and water were also analyzed comparatively. The test results indicate that the CSG consolidation exhibits obvious stratification and segregation phenomena in water, which can be divided into three layers with different substance compositions. The compressive strength of CSG consolidation formed in water is much lower than that of the grout consolidation formed in air, indicating that the water environment has a significant weakening effect on the consolidation properties of CSG. The hydration products and microstructure of CSG consolidation in water change clearly due to the dilution effect of water.