# Integrating Root Morphology Based on Whole-Pullout Test of Model Roots: A Case Study
## 3 Results  
### Experimental Data Processing  
After completing the experiments, load-displacement curves (\(Q\)-\(S\) curves) were plotted based on the experimental data. If the load-displacement curve showed a steep upward trend, the load (\(Q\)) at the point of abrupt displacement change was selected as the vertical pullout resistance (\(T\)) of the root system. Taking Figure 4a as an example, the \(Q\)-\(S\) curve for the A\({}_{1}\)B\({}_{2}\)C\({}_{3}\)D\({}_{2}\) scheme exhibited a steep ascending trend in all three trials. The first two trials showed a first inflexion point at \(Q\) = 60 N, and the curve for the third trial had an inflection point at \(Q\) = 65 N. Therefore, the three measured \(T\) values for the A\({}_{1}\)B\({}_{2}\)C\({}_{3}\)D\({}_{2}\) scheme (the first experiment group) were 60 N, 60 N, and 65 N, respectively. Similarly, for the scheme A\({}_{1}\)B\({}_{3}\)C\({}_{1}\)D\({}_{4}\) shown in Figure 4b, the three measured \(T\) values were 65 N, 70 N, and 65 N.  
If the \(Q\)-\(S\) curve rose slowly and the displacement (\(S\)) readings continued to increase for three consecutive readings within 3 min at a certain load, the next load was applied. The corresponding change in \(S\) readings was observed, and if the rate of increase became significant, the current \(Q\) value was taken as \(T\). Using Figure 4c as an example, the \(Q\)-\(S\) curve for the A\({}_{2}\)B\({}_{4}\)C\({}_{3}\)D\({}_{3}\) scheme showed a gradual upward trend with no apparent inflection points. However, the \(S\) readings for all three trials at \(Q\) = 140 N within 3 min continuously increased, and the rate of increase became significant. Therefore, the three measured values for the A\({}_{2}\)B\({}_{4}\)C\({}_{3}\)D\({}_{3}\) scheme (the third experiment group) were all \(T\) = 140 N. Similarly, for the scheme A\({}_{3}\)B\({}_{3}\)C\({}_{2}\)D\({}_{3}\) shown in Figure 4d, the three measured \(T\) values were 90 N, 90 N, and 100 N.  
For each set of experiments, the range and the mean of the three measured \(T\) values were compared. If the range was less than 30% of the mean value, in accordance with the regulations from the section on shallow plate load testing specified in the \"Code for Design of Building Foundation\", the mean value was taken as the characteristic value of the vertical pullout resistance. Any significantly unreasonable values were considered due to error factors and were discarded. Thus, for the first experiment group, the range of measured values (5 N) was less than 30% of the mean (19 N), and the characteristic value of vertical pullout resistance was the mean of the measured \(T\) values, which was 61.7 N. Similarly, for the third experiment group, the range of measured values (0) was less than 30% of the mean (42 N), and the characteristic value of vertical pullout resistance was the mean of the measured \(T\) values, which was 140 N. Similarly, the characteristic value of vertical pullout resistance for the fifth experiment group was 66.7 N, and for the tenth experiment group, it was 93.3 N. The results of the remaining experimental groups are presented in Table 3.  
Figure 3: The compaction unit weight of sand in experimental groups 5–8.