# Lateral Pressure of Poured Concrete: Arguments from Ultra-Deep Diaphragm Wall (120 m) Construction
## 3 Results  
The time recorded on site was subject to the arrival of the concrete tanker at the site. When the concrete actually reached the designated position, it needed to pass through a pipeline of corresponding length. According to this theory, the time recorded on site needs to be deducted in some cases. \[t=\frac{Q}{v}=\frac{\pi r^{2}l}{Q_{i}/l_{i}}, \tag{1}\]  
where \(t\) is the flow time of concrete in the pipe (s), \(t_{i}\) is the concrete casting time for the \(i\)-_th_ concrete tanker (s), \(r\) is the pipe inner diameter (0.15 m), \(l\) is the casting length of the same length as the instrument position(m), \(Q\) is the concrete capacity of the pipeline within flow length (m\({}^{3}\)), \(Q_{i}\) is the capacity of the \(i\)-_th_ concrete tanker (m\({}^{3}\)) and \(v\) is the average flow velocity of concrete according to the casting velocity when the location is submerged by concrete (m/s). For example, the 100 m location was submerged by the fourth concrete tanker, so this velocity is the casting velocity of the fourth concrete tanker. Because the vehicle models were the same, the capacity of each concrete tanker was 18 m\({}^{3}\). Taking the  
Figure 1: Construction site pictures. (**a**) Notch of the underground diaphragm wall; (**b**) lateral pressure gauge on the reinforcement cage; (**c**) hoisting the reinforcement cage; (**d**) pouring concrete. Figure 2: Diagram of pressure sensor locations. (**a**) Placement of pressure sensors on the cross section; (**b**) placement of the measuring instrument in the vertical direction. 100 m position as an example, the flow length of the sensor concrete at \(-100\) m is 100 m, and the concrete casting time for the fourth concrete tanker (\(t_{4}\)) is 18 min, so the calculated time (\(t\)) is 7 min. When the \(-100\) m, \(-80\) m and \(-40\) m positions were submerged by concrete, they were the 4 th, 7 th, 14 th and 15 th loads, respectively, and the casting time was 18 min, 18 min, 25 min and 22 min, respectively, with the casting time at the 40 m position was taken as 23.5 min. According to the above formula, the delay times were 7 min, 5.6 min and 3.7 min, respectively. Considering the recording time as the vehicle approach time, and deducting a 5 min delay, the actual delay times corresponded to 12 min, 10.6 min and 8.7 min. At the heights of \(-100\) m, \(-80\) m and \(-40\) m, the initial mud pressure in the lateral direction before casting was 1.3 MPa, 1 MPa and 0.52 MPa, respectively, which was about 1.3 times higher than the hydrostatic pressure. According to monitoring data, the lateral pressure gradually increased and then decreased as concrete casting progressed. The peak pressures at the three measurement points were 1.6 MPa, 1.4 MPa and 0.9 MPa. In general, the results show that the lateral pressure increased by 30% to 50% relative to the initial slurry pressure during the casting process. When the concrete was finally set, the final value of the lateral pressure was almost the same as the initial value. Figure 3 shows the development of the lateral pressure at the three measured points from the beginning of the cast. The lateral pressure meter at the \(-100\) m measurement point was damaged six hours after casting. The monitoring meter data was lost after twelve hours of casting, and the monitoring ended. For each measurement point, time points four hours before and after the peak were selected for further analysis; the data are detailed in Figure 4 and Table 3.  
Figure 3: Development of lateral pressure during the filling process. In Table 3, the negative value of the lateral pressure increments at the \(-100\) m measurement point caused by the fourth car casting is the results of test errors and falls within the allowable error range. The lateral pressure at each measurement point is positive until it reaches its peak and then appears negative because each cast before reaching the peak affects the cohesion of the unconsolidated concrete, reducing it again and increasing the concrete fluidity.