Application of fiber bragg grating displacement sensors to geotechnical model test of underground salt rock gas storages

DUAN Kang 1,2,ZHANG Qiang-yong 1,ZHU Hong-hu 3,XIANG Wen 1,CAI Bing 1,XU Xiao-bin 1

(1. Geotechnical & Structural Engineering Research Center, Shandong University, Jinan 250061, China;

2. Department of Civil Engineering, The University of Hong Kong, Hong Kong, China

3. School of Earth Science, Nanjing University, Nanjing 210093, China)

Rock and Soil Mechanics, Vol.34 Supp.2  Oct. 2013

Abstract: In order to investigate the effect of pressure variation on the deformation of surrounding rock, a rod-type fiber-optic displacement sensor based on the fiber Bragg grating(FBG) sensing technology was developed and successfully used for displacement monitoring in the geomechanical model test of salt rock gas storages. The test results show that: the gas injection and extraction rate is an important factor affecting the operation safety of salt rock gas storages. Convergence displacement is monitored during gas injection while expansion is monitored during gas extraction. Both of the displacements increase with time and pressure variation rate. In the space domain, the pressure variation has most obvious effect in the middle part of the caverns. In order to ensure the operation safety of the caverns, the maximum gas extraction rate for the studied caverns should be less than 0.65 MPa/d; the maximum gas injection rate should be less than 0.75 MPa/d.

Key words: fiber bragg grating; salt rock gas storages; model test; fiber optic displacement sensor; gas extraction rate