## 3 Experimental Design
### Measurement System  
In this test, measurements were taken for explosive loads, wall displacement, and acceleration acting on the support structure. The macroscopic deformation and damage of each test section were also recorded in detail during the test. The measurement system mainly consisted of various types of sensors (including 6 pressure sensors, 8 displacement sensors, and 6 acceleration sensors), shielded cables (pressure and acceleration sensors are connected to the instrument through coaxial shielded cables, and displacement sensors are connected to the instrument through four-core shielded cables), charge amplifiers, DH5960G dynamic acquisition instrument and DHDAS ultra-dynamic signal acquisition and analysis system, and a measuring computer. During the test, UPS DC power was used to supply power to each acquisition equipment to avoid signal interference caused by unstable AC current. The schematic diagram of the measurement system is shown in Figure 10.  
The piezoelectric pressure sensors and IPEE acceleration sensors output voltage signals through charge amplifiers, and the pull-rod displacement sensors output voltage signals, which are collected in real time by the DH5960G ultra-high-speed dynamic acquisition instrument. The explosion load signal is usually at the millisecond level. To ensure that the signal characteristics are not lost, a sampling frequency of 1 MHz was selected. Due to the high sampling frequency and short sampling time of the explosion pressure time-history signal, manual control of signal acquisition is not feasible. Donghua Testing  
Figure 8: Installation schematic of the acceleration sensor.  
Figure 7: IPEE-type piezoelectric acceleration sensor.  
System provides four common triggering methods, including manual triggering, external triggering, signal triggering, and timing triggering. Among them, high-level triggering is a relatively simple and safe external triggering method that is commonly used. A signal wire is led out in the external triggering channel of the testing system, connected to a constant power supply, and the enameled wire at the front end is wound around the explosive package. After the explosion, the TNT explosive rapidly expands, simultaneously producing high-temperature and high-pressure blast products, causing the enameled wire to break and the circuit to disconnect, and the signal changes suddenly to the constant power supply voltage, triggering automatic acquisition. Although this automatic triggering method does not consider the time error during the process from ignition to explosive expansion causing the triggering wire to break, it is generally considered to be very short and will not significantly affect the measurement results. The test acquisition time was set to 200 ms, and a negative delay was used to ensure the integrity of the data signal. The negative delay was set to 20 ms.  
As this test had two test sections and ordnance was detonated sequentially from the inside to the outside (that is, the RDEA-bolt-reinforced section was detonated first, followed by the conventional steel-bolt-reinforced section), so during the on-site measurement,  
Figure 10: A schematic diagram of the measurement system.  
Figure 9: Acceleration measurement point layout diagram: (**a**) conventional steel-bolt-reinforced test section and (**b**) RDEA-bolt-reinforced test section.  
measurement work for pressure, acceleration, and displacement could only be conducted on the detonated test section to minimize signal interference caused by too many wire connections.