Evaluation of resilient moduli for recycled crushed-rock-soil-mixtures using in-situ seismic techniques and large-scale resonant column tests

Abstract

The objective of the paper is to develop a resilient modulus prediction model for load-bearing compaction fills of crushed-rocksoil-mixtures which start being recycled from adjacent cutting and tunneling in the recent construction of highways and high-speed railways in mountainous sites in Korea. Often, the mixture is scarcely engineered except for controlling the maximum grain size in the range of 100-300 millimeters and the grain distribution was simply represented median grain diameter (D 50 ) in the order of 10-60 millimeters. The evaluation of resilient moduli, using the "orthodox" repeated loading tri-axial test, is not even conceivable for such a large-size gravelly material. A realistic alternative is to utilize the well-developed techniques which are currently used for measurements of subtle different modulus, such as shear modulus. The prediction model was developed by: (1) defining the model as the combination of maximum Young's modulus and its normalized reduction curve for high strain, (2) adopting the modified hyperbolic model of modulus reduction curve, and (3) converting the model parameters from in-situ maximum shear moduli and the reduction curves of modeled materials using the large-scale free-free resonant column tests. The values of model parameters were listed for the limited sites. It should be noted that, if the gradation curve widely stretched including quite an amount of fines, scalped specimens may be used to evaluate the model parameters of such a "dirty" material.

Research on the Resonance Characteristics of Rock under Harmonic Excitation

“…e basic characteristic parameters of the rock are tested based on the acoustic and electromagnetic resonance principles. More specifically, elastic modulus [5][6][7], compressibility, density [8], shear modulus, and damping ratio [9] of the rock can be obtained by resonance ultrasonic spectrum and the pore characteristics, saturation [10], and sediment characteristics [11] of the rock can be extracted by nuclear magnetic resonance technology. Besides, the resonance characteristics of various structures of rocks are identified and analyzed based on the principle of seismic resonance measurement so as to provide a better guidance for environmental safety [12][13][14].…”