| 摘 要： |
Large quantities of loose glacial sediments (tills) in alpine mountain areas, exposed because of glacier retreat under global warming, are becoming the main source material of glacier-related hazards, especially debris flows. This study collected glacial till samples from the source area of a debris flow gully in the Parlung Tsangpo Basin. Geotechnical properties of the tills were analyzed using field investigations, in situ tests, and multiple laboratory tests to explore their influence on debris flows. The values of two indexes (mu: representing the fine particle content and Dc: representing grain size range) adopted to reflect the grain composition of the glacial tills varied within the range of 0.015-0.20 and 5.01-23.59, respectively, and different lithological areas were characterized by obviously different mu intervals. Natural density decreased with mu in the form of a power law. The shear strength of the glacial tills first increased and then decreased with increasing mu, reaching a minimum value when mu was 0.12-0.13; the increase of Dc exhibited the opposite trend. Strain softening, which can be quantified using the static liquefaction potential index (SLPI), was observed in the undrained triaxial tests on the samples. With increasing mu, the SLPI value first increased and then decreased, and values of mu of 0.11-0.12 corresponded to the critical particle size that produced the maximum SLPI value. This study demonstrated the applicability of the SLPI for evaluating soil destruction potential, which could support further exploration of the formation mechanism of glacier-related geological hazards in alpine areas. |
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