Abstract:  To solve the problem of crystalline blockage of tunnel geotextiles, an indoor model test is conducted, and the onsite geotextile samples and test samples are analyzed using SEM scanning electron microscope. Furthermore, the bonding method between the crystal microscopic morphology and the geotextile is investigated. The influence of geotextile material, geotextile mass per unit area, and geotextile placement slope on crystallization blockage is as follows: (1) Under 9 working conditions, the crystallization rate in the first 7 days of the test is 2.4 times faster than the rest of the cycle, and then decreases in different degrees; under the same geotextile material conditions, the crystallization rate of the 500 g/m2 geotextile is 99% and 37% faster than that of the 300 g/m2 and 400 g/m2 geotextiles. (2) When the unit area mass of the geotextile is equal, the surface crystallinity of the composite geotextile is less than that of the filament geotextile and the staple fiber geotextile; when the mass per unit area increases to 500 g/m2, the surface crystallinity of the filament geotextile exceeds that of the other two geotextiles. (3) Under the conditions of the same quality and material per unit area, when placed with a slope of 0° (dome position), the crystallization amount of filament, staple fiber, and composite geotextile is the largest, which are 153.09, 203.97, and 63.67 g, respectively; when placed with a slope of 90° (the arch foot position), the crystalline amounts of filament, staple fiber and composite geotextile are 59.44, 71.43, and 25.35 g, respectively, indicating that the test slope will affect the crystallization of the geotextile. The smaller the placed slope, the faster the crystallization rate.

Key words: karst tunnel, drainage system, geotextile, crystal blockages