Resilient modulus is one of the important parameters used in the analysis and modelling of subgrade behaviour and it is directly related to the safety, economic and lifetime of roads structures. The determination of Resilient Modulus (MR) using repeated load triaxial (RLT) test is expensive, cumbersome and time consuming. Therefore, a new research approach has been adopted in this study based on performing cyclic light weight deflectometer (LWD). The objective of the cyclic loading is to bring the soil to its near elastic behaviour and then measure the dynamic deformations moduli (Evd). The cyclic LWD tests were performed in the field and in the laboratory and the measured Evds values were compared to the resilient moduli measured by RLT tests conducted under similar testing conditions. The number of LWD test cycles required to bring the soil to its elastic state can be decided directly during the test by using a new multifunctional LWD manufactured solely for the purpose of this study. It has been found that the required number of LWD repetitions (cycles) to conduct Evd moduli close to MR moduli depends on many influencing factors, namely, the moisture contents, lateral confinement and the maximum vertical axial stress levels during testing. Based on this study, it can be inferred that the cyclic LWD test can be used to predict simply and quickly the resilient behaviour of the tested soil with good precision and reliability.

弹性模量是用于路基行为分析和建模的重要参数之一，它直接关系到道路结构的安全性，经济性和使用寿命。使用重复载荷三轴（RLT）测试确定弹性模量（MR）是昂贵，麻烦且费时的。因此，在这项研究中采用了一种新的研究方法，即基于循环轻型偏转仪（LWD）。循环荷载的目的是使土壤达到其接近弹性的状态，然后测量动态变形模量（Evd）。在野外和实验室中进行循环LWD测试，并将测得的Evds值与通过在类似测试条件下进行的RLT测试测得的弹性模量进行比较。使土壤达到其弹性状态所需的LWD测试循环次数可以在测试过程中直接确定，方法是使用专为本研究目的而制造的新型多功能LWD。已经发现，进行接近MR模量的Evd模量所需的LWD重复（循环）次数取决于许多影响因素，即水分含量，侧向限制和测试过程中的最大垂直轴向应力水平。根据这项研究，可以推断出循环LWD试验可用于以良好的精度和可靠性简单，快速地预测被测土壤的回弹行为。已经发现，进行接近MR模量的Evd模量所需的LWD重复（循环）次数取决于许多影响因素，即水分含量，侧向限制和测试过程中的最大垂直轴向应力水平。根据这项研究，可以推断出循环LWD试验可用于以良好的精度和可靠性简单，快速地预测被测土壤的回弹行为。已经发现，进行接近MR模量的Evd模量所需的LWD重复（循环）次数取决于许多影响因素，即水分含量，侧向限制和测试过程中的最大垂直轴向应力水平。根据这项研究，可以推断出循环LWD试验可用于以良好的精度和可靠性简单，快速地预测被测土壤的回弹行为。