Application of light-weight deflectometer for evaluation of stress level-dependent constrained modulus of a soil

Abstract

Resilient modulus  is one of the important parameters used in the design and analysis of pavement materials. In general,  is usually evaluated by laboratory repeated load triaxial (RLT) test, which is complicated and time-consumed. To solve these problems, many researches have been studied to find out other methods for determining  in a simple manner. In this paper, an application of impact load method by a dynamic hammer (DH) on a crushed rock sample compacted in CBR mould
was attempted for evaluating the soil stiffness , and a method for analysing constrained modulus  for various stress levels was proposed. Then, the  was compared with the constrained modulus  for various stress levels obtained performing one-dimensional compression test. The material used in this study was a well-graded crushed rock. The followings
are found from the results of this study. Firstly, in a series of DH tests with the same falling height, the  value gradually increases with the number of drops , approaching a stable value when  approaches infinity. The  value corresponding to  equal to infinity  can be determined by a hyperbolic method. Secondly, the constrained modulus by DH test  can be determined by the true  values determined for different stress levels  depending on different falling heights used in DH test. Lastly, the  relationship agrees with the  relationship, however the former exhibited large data scattering.