Abstract: Widely-graded gravelly soil is composed of gravelly and clayey material in a certain proportion. It has the characteristics of low compressibility and high shear strength. At present, it is widely used as the core material for embankment dams and subgrade filling. Due to the low permeability of well-graded gravelly soil, the consolidation process is slow in conventional consolidated- drained (CD) triaxial tests, resulting in a long test period. In order to improve the efficiency of consolidation process, a quick triaxial CD test method with cylindrical sand core in the center of specimen is proposed in this paper. A comprehensive study on the influence of various factors on the quick triaxial CD test of well-graded gravelly soils is performed by changing types of sand cores, diameters of core sand cylinder and gravel contents. Results show that the proposed quick triaxial CD test method can effectively accelerate the consolidation process of the specimen, thus speeding up the whole test. Various factors including type of sand core, diameter of core sand cylinderand gravel content show different levels of influence on the speed of consolidation process and the stress-strain curve in the subsequent shearing stage. The smaller the diameter of the sand core is, the closer the test results are to those of specimens without sand cores.

Key words: widely-graded gravelly soil, quick triaxial CD test, sand core cylinder specimen, type of sand cores, gravel content