To reveal the failure mechanism of intermittent jointed rock in deep-buried engineering

true triaxial compression tests of intermittent jointed sandstone with different joint occurrences (dip and strike) were carried out

and acoustic emission (AE) system was used to monitor the failure process of specimens in real-time. The influences of joint occurrence on sandstone failure form

strength

deformation characteristics

AE evolution characteristics

and characteristic stresses were systematically analyzed. The results show that under the condition of true triaxial stress

when the intermittent joint strike is parallel to

the specimens with joint dip angles of 0°

30°

and 45° exhibit tensile-shear mixed failure

while the specimens with joint dip angles of 60° and 90° exhibit slipping-shear failure and conjugate shear failure

respectively. When the intermittent joint strike is parallel to

the failure mode of the samples with different joint angles is “internal shear and external spalling”

indicating that the joint strike has a greater influence on the failure mode of the specimens than the joint dip angles. The strength

crack initiation stress

damage stress

elastic modulus

and peak strain of specimens all decrease first and then increase with the increase of joint dip angle. The strength

initiation stress

damage stress

and peak strain of the specimens with joint strike parallel to are lower than those with joint strike parallel to

and the influence of joint strike on the elastic modulus of specimens is minimal. In addition

the duration of the AE quiet period and the proportion of AE high-frequency signal during this period decrease first and then increase with the increase of joint dip angle. When the intermittent joint strike is parallel to

the cumulative number of AE hits during the failure process of the specimen decreases first

then increases

and then decreases with the increase of the joint dip angle. When the intermittent joint strike is parallel to

the cumulative number of AE hits during the failure process of the specimen increases first and then decreases with the increase of the joint dip angle. The research results provide a scientific basis for the failure mechanism analysis of intermittent jointed rock mass and the prevention of engineering geological disasters in deep-buried engineering.