| 摘要 |
PURPOSE:To measure the strength of the ground by a detection system in which a pressure cell incorporated with AE (acoustic emission) sensor is inserted into a pit excavated underground and a load is applied to the substratum in the place where the pressure cell is inserted to detect AE. CONSTITUTION:A support pipe 2 provided with a pressure cell 3 is inserted into a pit 34 formed underground, and then a liquid 35, e.g., water, etc., is injected into the pressure cell by a water injector 4, whereupon the pressure of the liquid to be injected into a rubber tube 13 is gradually raised, each pressure cell 3 is expanded, and a load corresponding to the sum of the injection pressure and the head of the liquid 35 is applied to the stratum in the place where the pressure cell is inserted. According to the magnitude of loads at each stage, AE (acoustic emission) generated from the stratum is detected by an AE sensor 8 and converted into an electric signal, and signal alone within 1-60KHz is extracted by a filter 26, amplified by a main amplifier 27, and recorded on a tape recorder 28. Thus, the stress characteristics of the stratum can be known from the N-P curves of an analytical graph. |
