# Research on the Safety Assessment of Corbel Beams of Reservoir Radial Gates Based on Real States
## 2 Corbel Beam Structural Quality Inspection and Analysis
### Concrete Quality Inspection Results and Analysis of Corbel Beam Structure  
A total of 21 core specimens were tested to determine the strength of the concrete dam; the test pictures are shown in Figure 4 and the test results are shown in Table 2. The minimum compressive strength value was 26.2 MPa and the maximum value was 55.4 MPa. According to the relevant specifications of _the Technical Regulations for Testing  
Figure 3: Illustration of on-site core sampling. Figure 2: Sketch of the structure of the corbel beam of the outlet entrance. _Concrete Strength by Core Drilling Method_ (CECS 03-2017) [24], abnormal data are removed, and reasonable data are processed according to the table coefficients. The upper and lower limits of the presumed strength range are 33.6 MPa and 26.7 MPa. The static compressive elastic modulus of the concrete test was determined in accordance with the _Test Code for Hydraulic Concrete_ (SL352-2020) [25] in the test protocol for the downstream face of the dam, the upstream face, and the top part of the core; each core \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Core Samples** & **Coring Position** & **Test Piece** & **Core Sample Diameter** & **Compressive Strength** \\
**Number** & **Coring Position** & **Number** & **(mm)** & **(MPa)** \\ \hline \multirow{4}{*}{1} & The left side of the first layer & LQ-1-1 & 149.4 & 38.6 \\  & of the treistle bridge near the & LQ-1-2 & 148.8 & 40.0 \\  & shoulder of the dam & LQ-1-3 & 150.8 & 45.9 \\  & The middle of the first layer & LQ-2-2 & 149.3 & 30.9 \\  & of the trestle & LQ-3-1 & 149.5 & 39.9 \\  & The right side of the first & LQ-3-2 & 149.9 & 32.8 \\  & layer of the trestle bridge & LQ-3-3 & 149.7 & 26.2 \\  & near the shoulder of the second & LQ-4-1 & 148.7 & 40.6 \\  & layer of the trestle bridge & LQ-4-2 & 150.1 & 42.6 \\  & near the shoulder of the dam & LQ-4-3 & 150.2 & 40.6 \\  & & LQ-5-1 & 150.4 & 40.9 \\  & The middle of the second & LQ-5-2 & 150.4 & 40.5 \\  & layer of the trestle & LQ-5-3 & 150.8 & 43.5 \\  & The left side of the second & LQ-6 & 150.4 & 45.9 \\  & & near the shoulder of the dam & LQ-7-1 & 150.5 & 42.5 \\  & The right side of the third & LQ-7-2 & 150.3 & 45.4 \\  & layer of the trestle bridge & LQ-7-3 & 150.4 & 41.9 \\  & near the shoulder of the dam & LQ-7-4 & 150.3 & 49.4 \\  & The middle of the third layer & LQ-8-1 & 150.3 & 48.4 \\  & of the trestle & LQ-8-2 & 150.2 & 55.4 \\  & The top of the dam near the & & & \\  & right shoulder & LQ-11-1 & 150.1 & 43.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Compressive strength test results of core specimens. Figure 4: Core testing of concrete strength. sample was processed into a specimen with dimensions of \(\Phi\)150 \(\times\) 300 mm. Six sets of tests were conducted, as shown in Figure 5.  
The static compressive modulus of elasticity takes the tangent of the stress from 0.5 MPa to 40% of the failure stress, and the calculation formula is shown in Formula (1):  
\[E_{f}=\frac{\Delta\sigma}{\Delta\varepsilon}\div 1000 \tag{1}\]  
where:  
\(E_{f}\)--Static compressive elastic modulus, GPa;  
\(\Delta\sigma\)--Stress increase value from 0.5 MPa to 40% failure stress, MPa;  
\(\Delta\varepsilon\)--The strain increase value from the corresponding strain of 0.5 MPa to the corresponding strain of 40% failure stress. In the formula, stress \(\sigma\) and strain \(\varepsilon\) are calculated according to Formulas (2) and (3):  
\[\sigma=\frac{\mathrm{P}}{\mathrm{A}}\times 1000 \tag{2}\]  
\[\varepsilon=\frac{\Delta\mathrm{L}}{\mathrm{L}_{0}} \tag{3}\]  
where:  
P--load, kN;  
A--The bearing area of the test piece, mm\({}^{2}\);  
\(\Delta\mathrm{L}\)--deformation value, mm;  
\(\mathrm{L}_{0}\)--Measuring the deformed gauge length, mm. The elastic modulus tangents of the six groups of tests are shown in Figure 6. In Figure 6, the horizontal axis is the strain value in the range from 0.5 MPa to 40% failure stress, and the vertical axis is the corresponding stress value.