深部坚硬细砂岩长期强度试验

Long-Term Strength Test and Application of Hard Fine Sandstone in Deep Site

从单向抗压强度试验得到深部细砂岩的强度极限为83.698 2 MPa,残余强度为0.单轴8级加卸载蠕变试验得到深部细砂岩的蠕变下限为27 MPa,各级蠕变加载水平下的初期衰减蠕变阶段相似;破坏前的细砂岩不包含应变率ε>0的稳态蠕变阶段,达到破坏级加载水平时,岩石直接呈现以瞬间急速破坏为主要特征的包含3阶段的蠕变全过程.细砂岩长期强度与瞬时强度之比达94.39%,其强度与时间的相关性很弱.综合单向抗压强度及蠕变试验成果,该层细砂岩可作为深部岩石工程整体稳定性的重要依托岩层,且主要依据的力学指标为单向抗压强度.

Based on uniaxial compressing strength test,the ultimate strength of fine sandstone in deep site is 83.698 2 MPa and its remaining strength is 0.Creep test with 8 classes of loading and unloading has been designed to determine the creep lower limit 27 MPa,beyond which the deep fine sandstone may have a creep behavior.Initial stages,i.e.,attenuating creep phases of different loading and unloading levels,are similar in creep displacements.Before destruction,every creep curves of fine sandstone specimen have not been involved in a steady creep state that the strain ratio is beyond zero.Up to specially designed loading,the complete creep course include 3 stages which has an important property of accelerative failure of the rock.The ratio of long-term strength to instantaneous strength of the fine sandstone is as high as to 94.39%,which indicates its strength has only weak relativity to time.Based on results of uniaxial compressing and creep tests,the fine sandstone is a key stratum to whole stability of rock engineering in deep site,and the determined mechanical index must be the uniaxial compressive strength.