Evaluating Deformational Behaviors of Crushed-Rock-Soil Mixtures Using Field and Large-scale Resonant Column Testing

摘要

Crushed-rock-soil-mixtures, produced from adjacent cutting or tunneling, are being recycled to load-bearing compaction fills in the recent construction of high ways and high-speed railways in mountainous areas. The objective of the paper is to develop a resilient modulus (E_R) prediction model for the compaction fills of recycled crushed-rock-soil-mixtures. The evaluation of E_R, using the "orthodox" repeated loading tri-axial test, is not realistic for such a large-grain-size material. The realistic alternative is to utilize the well-developed techniques which are currently used for measurements of subtle different modulus, such as shear modulus (G). The prediction model was developed by: (1) adopting the modified hyperbolic model of shear modulus curve, and (2) determining the model parameters (A_E, n_E, ε_r and a) from in-situ measured G_(max) and the reduction curves of modeled materials using the large free-free resonant column tests. The values of A_F increase from 8731 to 13135 as the overall grain distribution (represented by Dmax, D_(50) and C_u) varies. The values of n_E fall in the range from 0.35 to 0.47 and turn out to be not much affected by D_(50) in general. For determination of the model parameters ε_r and a, the modeled materials were reconstructed by shifting the typical gradation curve of the original material. The effect of confining pressure on the parameters is minimal and in turn the parameters were evaluated from the mean curve. Also the effect of grain size turns out to be insignificant as long as C_u maintains in the gradation shifting. The values of ε_r and a proposed are 0.0135 and 0.80, respectively, for the typical crushed-rock-soil-mixtures. 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.