# Potential of Computer-Aided Engineering in the Design of Ground-Improvement Technologies
## 5 Results and Discussion
### Computation of Mud Discharge Quantitity  
Table 3 shows the numbers of soil particles, water particles, and cement slurry particles collected at different time periods during the simulation. The measurement was conducted for all three probe regions and the obtained data were compared with each other. Figure 9 shows the patterns of the total mud discharge particles accumulating at each time frame in different probe regions. Particles keep accumulating throughout the process and attain the maximum value at the end of the process. However, the same cannot be said for the cement particles or the water particles. The number of cement particles ejected as mud discharge is found to be 0 at all times, while the number of water particles keeps changing slightly at the given times. Next, the highest number of particles is not maintained at all times by either probe region. There are cases when each probe region contains the highest number of particles at a certain time frame. For the probe region of 1.8 m diameter, the particle number is highest at 50 s and 60 s, at 40 s and 78 s for the probe region of 1.6 m diameter, and at 20 s and 30 s for the probe region of 1.4 m diameter. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Time after the Start of Construction (s)**} & **20** & **30** & **40** & **50** & **60** & **78** \\ \hline \multirow{3}{*}{Number of particles for probe diameter of 1.8 m} & Cement grout & 0 & 0 & 0 & 0 & 0 \\  & Ground & 64 & 168 & 462 & 591 & 596 & 859 \\  & Water & 5 & 4 & 0 & 4 & 5 & 5 \\ \hline \multirow{3}{*}{Number of particles number for probe diameter of 1.6 m} & Cement grout & 0 & 0 & 0 & 0 & 0 \\  & Ground & 209 & 320 & 532 & 533 & 538 & 892 \\  & Water & 4 & 4 & 3 & 4 & 4 & 4 \\ \hline \multirow{3}{*}{Number of particles for probe diameter of 1.4 m} & Cement grout & 0 & 0 & 0 & 0 & 0 \\  & Ground & 364 & 440 & 466 & 466 & 498 & 878 \\ \cline{1-1}  & Water & 8 & 7 & 6 & 8 & 8 & 8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Numbers of individual mud discharge particles. Figure 9: Total mud discharge particles for each probe region. From the visual confirmation, it can be confirmed that only a very small amount of the cement particles moved toward the surface and what seems like a large number of water particles moved toward the surface. However, the computation data conflict with the visual information as it clearly states that more ground particles were ejected and only a very small amount of water particles was ejected. In a real case scenario, fluid mixtures of water, soil, and some cement grout are ejected as mud discharge. The mixing of these substances causes the solution to change in color and state of matter. The previously solid/semi-solid/powder soil particles are mixed with fluids (water and cement grout) and change into a paste or a thick fluid depending upon various case scenarios. In this simulation, no such distinct situations were observed but, what initially seemed like water particles only were ground particles mixed with water particles and were ejected mostly. Regarding the validity of the ground particles being higher in the ejected particles, it can be considered as true because there is no doubt that the cement grout was filled into the space previously occupied by the soil. The only logical explanation is that the replaced soil was ejected as mud discharge. The fluctuation in water particles at any time hints that the reading shows the amount of mud discharge particles accumulated at that time frame rather than the cumulative mud discharge particles. In jet-grouting construction, based on the empirical rule, the quantity of the mud discharge is equivalent to 1.2-times the amount of fluid injected during the construction. This includes both the water particles during drilling and the cement grout particles during the formation of the soil-improved body. The water was injected at 80 L/min for 20 s and the cement grout at 90 L/min for 58 s; thus, the total injected amount was about 0.113 m\({}^{3}\).