Permeability and Direct Shear Tests Characteristics of Railway Subballast

Abstract

Permeability, filtration and shearing strength were widely considered to be the key properties in evaluating the performance of railway subballast. An investigation on these key properties of railway subballast was presented in this paper. A constant head permeability test and a middle scale direct shear test of railway subballast were conducted in the research, aiming to investigate the subballast permeability and shear direct tests characteristics. Four different designed gradations within the standards were subjected to the investigation in order to study the particle size distribution effect on permeability performance of subballast. Lab results showed that drainage capacity and shearing strength of subballast highly correlated with each other. Subballast with more large-size particles and a low coefficient of uniformity were proved to acquire good drainage of water and strong resistance ability to shear.