ANALYSIS OF LONG-TERM STABILITY OF GYPSUM PILLARS
BASED ON CREEP TESTS
YANG Yongjie1，XING Luyi1，ZHANG Yangqiang2，MA Depeng1
(1. State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology，Shandong University of Technology，Qingdao，Shandong 266590，China；2. China Coal Technology Engineering Group Chongqing Research Institute，Chongqing 400039，China)
Abstract：The long-term stability of gypsum pillars in Luneng Taishan Gypsum Mine was investigated with laboratory experiments，numerical analysis and in-situ monitoring. The results of uniaxial compression creep experiments showed that the strength of creep fracturing of gypsum was 72%–77% of the instantaneous strength and the previous modified Burgers model described better the creep properties of the gypsum. Based on the test results，the simulation on the long term stability was carried out to the gypsum pillar at 4301 workface. The deformations of roof and floor were found not in synchronous. The roof tended to be stable in about 3 years after mining，and the two sides tended to be stable in about 2 years after mining，but the floor tend to be stable as early as 1 year after mining. In about 10 years after mining，the deformations of roof-to-floor and the two sides are 155 and 68 mm respectively. The in-situ monitoring results demonstrated the creep of surrounding rock after mining. The deformation speed was bigger within 100 days after mining，and then it presented a fluctuated decreasing trend，but the deformation was still in slow growth. The stable time of roof-to-floor and two sides were different. The deformation of two sides tended to be stable within 400 days after mining and the deformation of roof-to-floor tend to be stable after 640 days.
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2015, Vol. 34 
