Abstract To investigate the effects of water content on the damage degradation and deformation failure characteris? tics of red sandstone under high geostress conditions, conventional triaxial tests and triaxial creep tests were conducted on red sandstone samples with four different water content states under a high confining pressure of 20 MPa.The results show that: (1) As the water content increases, the peak stress and characteristic stress of red sandstone decrease to varying degrees, and the ratio of swelling stress to peak stress also decreases. Rock samples with higher water content generate new cracks earlier and experience swelling earlier. (2) When the water content is 3%, an accelerated creep phase appears where strain increases gradually with time. After the stress reaches the peak strength,microcracks inside the specimen maintain a“gradual cracking-sustained deformation”process under high confining pressure, with cracks slowly developing and ultimately leading to failure. (3) Based on the experimental results, the softening effect of groundwater on the gradual cracking and sustained deformation of red sandstone can be divided into three stages: the hindering deformation stage (rock pore compaction stage), the promoting deformation stage(elastic deformation stage and stable crack development stage), and the aggravating deformation stage (rapid crack expansion stage).
Abstract：
To investigate the effects of water content on the damage degradation and deformation failure characteris? tics of red sandstone under high geostress conditions, conventional triaxial tests and triaxial creep tests were conducted on red sandstone samples with four different water content states under a high confining pressure of 20 MPa.The results show that: (1) As the water content increases, the peak stress and characteristic stress of red sandstone decrease to varying degrees, and the ratio of swelling stress to peak stress also decreases. Rock samples with higher water content generate new cracks earlier and experience swelling earlier. (2) When the water content is 3%, an accelerated creep phase appears where strain increases gradually with time. After the stress reaches the peak strength,microcracks inside the specimen maintain a“gradual cracking-sustained deformation”process under high confining pressure, with cracks slowly developing and ultimately leading to failure. (3) Based on the experimental results, the softening effect of groundwater on the gradual cracking and sustained deformation of red sandstone can be divided into three stages: the hindering deformation stage (rock pore compaction stage), the promoting deformation stage(elastic deformation stage and stable crack development stage), and the aggravating deformation stage (rapid crack expansion stage).
ZHANG Shan MENG Lubo QU Xiaoqi LI Tianbin ZHANG Yu
.Experimental Study on the Deformation and Failure Mechanism of Red Sandstone under Groundwater Softening[J] MODERN TUNNELLING TECHNOLOGY, 2025,V62(1): 201-211
2025, Vol. 62 