Test Study on Creep Character of Anchor Rod in Argillaceous Soft Rock: Fid-Bau Portal

Test Study on Creep Character of Anchor Rod in Argillaceous Soft Rock

Fan, Qiu-Yan / Liu, Cai-Lin / Yang, Ke-Qing / Wang, Mei-Qian

The creep character of anchor rod in argillaceous soft rock is remarkable. The big undisturbed mudstone samples in Nanning Basin as a typical argillaceous soft rock is chosen to the research object in this paper. The laboratory simulated destructive tests and the creep tests of full grouted anchor rod have been down. Through the destructive tests of mudstone sample, the instantaneous adhesive strength between the anchor body and mudstone in Nanning Basin is 70kPa. By analyzing the creep curves of anchor rod, a conclusion is that there is a long-term adhesive strength of anchor rod in argillaceous soft rock. When the design adhesive strength of anchor rod is less than the long-term adhesive strength, eventually the anchor rod is stable during the process of long-term pull-out. When the design adhesive strength of anchor rod is greater than the value, the creep of anchor rod with the time will do not stop until the anchor rod failure. The greater difference value between the instantaneous and long-term adhesive strength, the faster the rate of creep, the faster the anchor rod failure. Finally, for the permanent support engineering design of anchor rod in argillaceous soft rock, the paper gives two principles, as follows: (1) the design of anchor rod in argillaceous soft rock must be determined according to the long-term adhesive strength. (2) by using variety of technical measures, the impact of various factors on the creep of anchor rod will be decreased.