Assessment methods and criterion of EDZ for underground caverns
EDZ concept is defined, and it is subdivided into inner zone and outer zone. Four monitoring methods, i.e., elastic wave velocity, multipoint displacement meter, BTV and AE, are suggested for engineering practice after insight reviewing of the all monitoring methods. The main research results are as follows. Based on the acoustic wave test, the EDZ of the surrounding rock can be determined by analyzing the velocity-depth curve and calculating the damage factor D.Based on the results of multi-point displacement meter and BTV, the EDZ of surrounding rock can be determined by calculating the displacement (opening)-depth curve and the strain of each section. Through analyzing the number of AE events and their frequency, the EDZ depth can be determined. Compared with the qualitative classification of single index, the first proposed EDZ comprehensive discriminant method and discriminant criterion have the characteristics of objective and comprehensive, which can discriminate the depth of EDZ qualitatively and quantitatively.
excavation damaged zone (EDZ)elastic wave velocitymultipoint displacement meterborehole television (BTV)acoustic emission (AE)