Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test

Ground reinforcement is a method used to reduce the damage caused by earthquakes. Usually, cement-based reinforcement methods are used because they are inexpensive and show excellent performance. Recently, however, reinforcement methods using eco-friendly materials have been proposed due to environmental issues. In this study, the cement reinforcement method and the biopolymer reinforcement method using sodium alginate were compared. The dynamic properties of the reinforced ground, including shear modulus and damping ratio, were measured through a resonant-column test. Also, the viscosity of sodium alginate solution, which is a non-Newtonian fluid, was also explored and found to increase with concentration. The maximum shear modulus and minimum damping ratio increased, and the linear range of the shear modulus curve decreased, when cement and sodium alginate solution were mixed. Addition of biopolymer showed similar reinforcing effect in a lesser amount of additive compared to the cement-reinforced ground, but the effect decreased above a certain viscosity because the biopolymer solution was not homogeneously distributed. This was examined through a shear-failure-mode test.

Correction of Young’s Modulus Calculation in the Flexural Mode of Resonant Column Test

The resonant column test includes torsional and flexural modes that can be used to obtain reduction curves for the shear modulus and Young’s modulus of the soil, respectively. When the resonant column test is performed under flexural mode, Young’s modulus is calculated mainly using the measured resonant frequency following the formula proposed by Cascante et al. However, this formula does not consider the rotational inertia effect of the electromagnetic drive disk of the resonant column apparatus and thus may inaccurately calculate Young’s modulus. In this study, the formula was modified by considering the rotational inertia effect of the electromagnetic drive disk, and its accuracy was verified by using three aluminum calibration rods with different diameters as a dummy specimen for the resonant tests in flexural and torsional modes.

Laboratory Investigation of the Mechanical Properties of a Rubber–Calcareous Sand Mixture: The Effect of Rubber Content

This paper introduces a rubber–calcareous sand mixture as a lightweight building material in offshore engineering. The mechanical properties of mixtures of varying rubber contents were investigated by performing a one-dimensional (1-D) compression test in a modified oedometer cell, as well as a resonant column test. A discussion on the test results, along with detailed interpretations regarding the role of rubber chips in the mixtures, are provided. It was found that the virgin compression curves of the rubber–calcareous sand mixtures tended to converge at a certain stress level, whilst the stress level depended on the rubber content. Moreover, the relative breakage was examined by comparing the particle size distribution curves of the calcareous sand before and after the compression test. It was shown that the grain crushing of calcareous sand was less remarkable with the inclusion of rubber chips. Furthermore, the small strain shear modulus (G0) of the mixtures decreased with the rubber content, yet the modulus reduction and damping curves exhibited little difference for the specimens of varying rubber contents.

A proposed method to determine in-situ shear modulus and shear strain decay curves in different structured soil

This paper illustrates the application of the self-boring pressuremeter test and the seismic dilatometer test to acquire the in-situ decay curves of stiffness with shear strain level (G-γ decay curves) of three types of structural soil, which are granite residual soil, structural soft soil and expansive soft rock. The proposed approach in combines the functions of SBPT and SDMT to provide the high standard of accuracy for the small-strain stiffness (from SDMT) and the major attenuation stage of stiffness (from SBPT). Using the proposed mathematical model can properly describe the tendency in typical in-situ G-γ decay curves based on the data of tests. To analyse the suitability of the proposed approach, the G-γ curve obtain from the resonant column test of granite residual soil is also employed to compare with the in-situ curves. The shear modulus G obtained from laboratory tests is found to be smaller and the stiffness attenuation rate is found to be faster than the curve of the in-situ test, which reflects the process of sampling, transporting and preparation of soil samples could cause unrecoverable damages in soil.

Identification on rock and soil parameters for vibro-cutting rock by disc cutter based on fuzzy radial basis function neural network

A single-POF model of disc cutter with rock and soil has been established according to the dynamical feature and vibration mechanism of disc cutter vibro-cutting rock to solve problem of self-adaption vibro-cutting rock for disc cutter, and identification on rock and soil parameter of disc cutter vibro-cutting rock has been carried out by using fuzzy radial basis function neural network. The experimental result of identification simulation and resonant-column test showed that compared to inherent frequency of a hard sandy which was tested by resonant-column test method, the relevant error of rock and soil parameter identification value of disc cutter vibro-cutting rock is 0.87 %, with high estimation accuracy.

Resonant Column Test on the Frozen Silt Soil Modulus and Damping at Different Temperatures

The shear modulus and damping ratio of frozen soil are thebasic parameters of its dynamic properties and are often testedwith the dynamic triaxial apparatus. However, the resonantcolumn apparatus is more suitable for the testing at the microstrainlevel. A resonant column apparatus was here used toidentify the varying modes with negative temperature of theinitial shear modulus, modulus ratio, and damping ratio of frozensilt. Correction factor curves indicate that the temperaturehas a great effect on the shear modulus and damping ratio offrozen silt. The curves also show that, within the sensitive stage,the temperature significantly affects the modulus and damping.Within the insensitive stage, the modulus and dampingwere insensitive to the temperature. The experimental resultsand analysis given here provide support for improving seismicdesign codes and offer reasonable parameters for seismicresponse analysis in engineering construction in cold regions.