## 3 Laboratory Test Results  
Variations in Dry Unit Weight and Uniaxial Compressive Strength for Hardfill Mix Conditions with Different Aggregate Size Distributions and Water Content per Unit Volume  
Figures 6 and 7 show the relationship between the unit water content and dry unit weight and between the unit water content and uniaxial compressive strength for the fabricated large hardfill specimens, respectively. These specimens were fabricated by mixing aggregates with the upper-limit (fine) and lower-limit (coarse) particle size distributions as described in Section 2.1 with a unit cement content of 80 kg/m\({}^{3}\) and three unit water contents of 70, 85, and 100 kg/m\({}^{3}\), respectively. Since three specimens were fabricated and tested for one mixing condition, the average values for the corresponding mixing conditions are shown together with the measured values for each specimen.  
The dry unit weight increases with the unit water content for both aggregate mixes with the upper-limit and lower-limit PSDs. The increase rate of dry unit weight is slightly higher in the aggregate mix with the upper-limit PSD condition than that with the lower-limit PSD condition (Figure 6). At the smallest unit water content (i.e., 70 kg/m\({}^{3}\)), the dry unit weight of the aggregate mix with the lower-limit PSD slightly exceeds that of the aggregate mix with the upper-limit PSD (2410 vs. 2357 kg/m\({}^{3}\)). However, the dry unit weights are similar at the largest unit water content (i.e., 100 kg/m\({}^{3}\)) (2468 vs. 2470 kg/m\({}^{3}\)). Meanwhile, the uniaxial compressive strength according to the unit water content change tends to increase gradually with the unit water content for both aggregate mixes with upper- and lower-limit PSDs (Figure 7). The ranges of the uniaxial compressive strengths  
Figure 5: Input seismic waves used in FE analysis. (**a**) Hachinohe wave; (**b**) Ofunato wave; (**c**) artificial wave.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **Unit** & **Cohesion** & **Friction** & **Elastic** & **Poisson’s** & **P-Wave** & **S-Wave** & **Shear** & **Dashpot** & **Coefficient** \\  & **Weight** & **(kPa)** & **Angle (\%)** & **Modulus** & **Ratio** & **Velocity** & **Velocity** & **Modulus** & **Cr (=\(\rho\)V\({}_{P}\))** & **C\({}_{5}\) (=\(\rho\)V\({}_{A}\))** \\ \hline Soil & 18.0 & 5 & 25 & 20 & 0.38 & 450 & 63.2 & 7.2 & 810 & 114 \\ Soft rock & 24.0 & 200 & 34 & 1500 & 0.27 & 2000 & 496.1 & 590.6 & 4800 & 1191 \\ Moderate rock & 25.0 & 350 & 37 & 4000 & 0.24 & 2300 & 803.2 & 1612.9 & 5750 & 2008 \\ Hard rock & 26.0 & 2000 & 44 & 8000 & 0.20 & 3000 & 1132.3 & 3333.3 & 7800 & 2944 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Finite element method (FEM) model parameters for the ground.  
according to the unit water content change are 3.152-4.106 MPa for the aggregate mix with the lower-limit PSD and 1.619-2.094 MPa for the aggregate mix with the upper-limit PSD. As a result, the uniaxial compressive strength of the aggregate mix with the lower-limit PSD exceeds that of the aggregate mix with the upper-limit PSD for the entire unit water content range.  
Figure 6: Change in dry unit weight according to hardfill unit water content.  
Figure 7: Change in hardfill’s uniaxial compressive strength according to unit water content.