# Application Study of the High-Strain Direct Dynamic Testing Method
## 4 Conclusions  
This paper focuses on the application study of a recently proposed dynamic testing method for pile-bearing capacity--the high-strain direct testing method. Using a bridge project in Zhuhai as the engineering background, field tests were conducted to verify the feasibility and reliability of this method in practical engineering applications. The main conclusions are as follows:  
1. The high-strain direct testing method was implemented in a bridge project in Zhuhai, Guangdong Province. The measured bearing capacities of four test piles were 11,415.5 kN, 9733.3 kN, 10,788.4 kN, and 12,851.3 kN, with end resistance ratios of 41.8%, 38.3%, 28.4%, and 31.8%, respectively, consistent with the bearing capacity characteristics of rock-socked piles at the site. The calculated distributions of side and end soil resistance matched the soil layer distributions under the four arch bases, confirming the feasibility of the high-strain direct testing method in engineering applications.
2. A static compression test was conducted on a single pile, and the results were compared with those from the high-strain direct testing method. The error range between the two methods was found to be between \(-9.5\%\) and \(3.7\%\), demonstrating the reliability of the high-strain direct testing method in predicting the bearing capacity of single piles and identifying the sources of error in its practical application.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Number (\#)**} & \multirow{2}{*}{**Length (m)**} & \multicolumn{2}{c}{**Dynamic Load Test**} & \multicolumn{2}{c}{**Static Load Test**} \\ \cline{3-6}  & & **Displacement** & **Ultimate Bearing** & **Displacement** & **Ultimate Bearing** \\  & & **(mm)** & **Capacity (kN)** & **(mm)** & **Capacity (KN)** \\ \hline
1–5 & 34 & 4.24 & 11,415.5 & 5.60 & 11,005.7 (3.7\%) \\
2–7 & 42.5 & 2.13 & 9733.3 & 3.90 & 10,096.0 (\(-3.6\%\)) \\
3–9 & 48 & 3.44 & 10,788.4 & 7.12 & 10,946.6 (\(-1.4\%\)) \\
4–17 & 68 & 3.36 & 12,851.3 & 6.70 & 14,196.8 (\(-9.5\%\)) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison between the results of the dynamic load test and the static load test.  
Finally, the high-strain direct dynamic testing method calculates the bearing capacity of pile segments directly through the dynamic equilibrium equation, ensuring an accurate and unique ultimate bearing capacity for single piles, independent of the operator's experience. This method provides a more precise description of the static soil resistance distribution along the pile shaft in various soil layers. The inferred soil parameters are more accurate, better reflecting the actual soil conditions on-site. Future researchers can integrate the field measurements obtained by this method with numerical simulation techniques to perform inverse analysis of the mechanical parameters of the soil surrounding the pile. This combined approach offers reliable data for engineering applications.  
Conceptualization, H.Q., H.H., M.A. and W.H.; formal analysis, H.H. and M.A.; investigation, H.Q., H.H. and M.A.; writing--original draft preparation, M.A. and H.H.; supervision, H.Q. and M.A. All authors have read and agreed to the published version of this manuscript.  
The publishing of this paper was financially supported by the National Natural Science Foundation of China (No. 11672215).  
Not applicable.  
The data presented in this study are available on request from the corresponding authors.  
The authors declare no conflict of interest.