Abstract
In order to support the dynamic design of subgrade filling engineering, an experiment on the dynamic shear modulus (G) and damping ratio (D) of clay–gravel mixtures (CGMs) was carried out. Forty-two groups of resonant column tests were conducted to explore the effects of gravel content (0%, 10%, 20%, 30%, 40%, 50%, and 60%, which was the mass ratio of gravel to clay), gravel shape (round and angular gravels), and confining pressure (100, 200, and 300 kPa) on the dynamic shear modulus, and damping ratio of CGMs under the same compacting power. The test results showed that, with the increase of gravel content, the maximum dynamic shear modulus of CGMs increases, the referent shear strain increases linearly, and the minimum and maximum damping ratios decrease gradually. In CGMs with round gravels, the maximum dynamic shear modulus and the maximum damping ratio are greater, and the referent shear strain and the minimum damping ratio are smaller, compared to those with angular gravels. With the increase of confining pressure, the maximum dynamic shear modulus and the referent shear strain increase nonlinearly, while the minimum and maximum damping ratios decrease nonlinearly. The predicting equation for the dynamic shear modulus and the damping ratio of CGMs when considering confining pressure, gravel content, and shape was established. The results of this research may put forward a solid foundation for engineering design considering low-strain-level mechanical performance.
Highlights
Clay–gravel mixtures (CGMs) constitute a great engineering material, which is widely utilized in subgrade engineering, rock-fill dams, and sea filling [1,2,3,4]
Based on subgrade filling engineering with CGMs in Ganzhou, Jiangxi province, China, 42 groups of resonant column tests were performed to investigate the low-strain dynamic characteristic of CGMs under the same compacting power, and the following conclusions could be drawn from this study
(1) For measuring the dynamic properties of soft materials at low strain, improvements regarding the resonant column of GZZ-50 type were conducted and the corresponding installation and data deal processes were detailed
Summary
Clay–gravel mixtures (CGMs) constitute a great engineering material, which is widely utilized in subgrade engineering, rock-fill dams, and sea filling [1,2,3,4]. Medani et al [17] studied the dynamic shear modulus and damping ratio of CGMs under the same mass density, and some conclusions regarding the effect of granular shape on dynamic properties of CGMs were obtained. In subgrade filling engineering with CGMs (which is a typical two-phase material), the gravel shape is not usually similar, and the difference in gravel shape leads to different dynamic properties, especially in a high-gravel content mixture. Gravel content, and Sustainability 2020, 12, 1616 shape were taken into account to design a CGM test and establish the predicting equation of dynamic shear modulus and damping ratio of CGMs. An electron microscope and Computer tomography (CT) were introduced to interpret the dynamic properties’ mechanism of CGMs
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