Suffusion response of well graded gravels in roadbed of non-ballasted high speed railway

Abstract

The suffusion mechanism of well graded gravels in the application of high speed railway roadbed is still not fully understood. Field inspections of high speed railway show that suffusion of well graded gravels can result in mud pumping and affect the normal operation of high speed trains. This paper reports a total of 12 laboratory suffusion tests on well graded gravels typically used in Chinese high speed railway roadbed under three different degrees of compaction (93%, 95% and 97%). The influence of degree of compaction and initial fines content on the critical hydraulic gradient of roadbed materials and the characteristics of suffusion is systematically investigated. The results show that well graded gravels suggested by the design code can experience suffusion once the hydraulic gradient reaches a critical value. The critical hydraulic gradient generally increases with the degree of compaction and the initial fines content. An empirical equation is proposed to predict the eroded mass of fine particles, which can reasonably reproduce the experimental measurements for well graded gravels under different failure hydraulic gradient.