Block. In the process of observation, it is often necessary to drill holes to install settlement measuring points and take samples. After the observation, these boreholes need to be plugged to ensure the safety and stability of the airport foundation. The main purpose of hole plugging is to avoid foundation instability caused by air circulation and water flowing into the hole. Settlement observation of high-fill airport refers to monitoring and recording the settlement of high-fill airport to ensure the normal operation and safety of the airport.