LABORATORY INVESTIGATION OF SCALE STRENGTH CHARACTERISTICS OF WIDELY-GRADED GRAVELLY SOIL

The widely-graded gravelly soil is widely distributed in the prone area of debris flow. Its strength characteristics are the key to correctly evaluate the startup and prevention design of debris flow. This paper aims to explore the relationship between the strength parameters and the maximum particle size and particle grading of widely-graded gravelly soil. It carries out the triaxial consolidated undrained strength tests for three kinds of the widely-graded gravelly soil with the maximum particle size of 30mm,20mm,10mm,5mm,respectively. The results show that the widely-graded gravelly soil has liquefaction characteristics. The test curves show three forms including strain softening,strain hardening and strain softening hardening. The effective internal friction angle of all liquefaction or effective liquefaction failure specimens increases linearly with the increase of maximum particle size. The effective internal friction angle increases quadratic polynomial with the increase of uniformity coefficient and increases piecewise linearly with the increase of characteristic particle size. The research results provide some reference support for the selection of parameters of the prediction of debris flow startup and the design of debris flow control engineering.