Huafeng Coal Mine, Shandong Energy Xinwen Mining Group

为反映地下工程掘进过程中风化砂岩所受的应力状态,该文开展不同恒定轴压作用下的恒轴压逐级卸荷三轴蠕变试验,通过卸荷过程中各级轴向瞬时应变量、蠕应变量、轴向应变速率对不同轴力及围压作用下的岩石蠕变特征进行分析,在Burgers体基础上构造改进型黏弹塑性非稳态蠕变模型来模拟蠕变全过程,并对试验结果进行验证。结果表明:同一轴向荷载下风化砂岩变形量随围压的减小而增加;相同围压条件下,轴向载荷越大,试块变形越强烈,具有较大瞬时应变及蠕变速率,且所经历卸荷级数较小,试块越早发生失稳破坏;改进模型对卸载蠕变全过程的计算结果和实验值均有较强相关性。该结果为精确认识风化砂岩在动态荷载作用下的蠕变特征具有重大意义。

To reflect the stress state of weathered sandstone during underground engineering excavation process, this paper conducts constant axial pressure step-by-step unloading triaxial creep tests under different constant axial pressure actions. The rock creep characteristics under different axial forces and confining pressure actions are analyzed through axial instantaneous strain amount, creep strain amount, and axial strain rates at each level during the unloading process. An improved type viscoelastic plasticity non steady state creep model is constructed based on the Burgers body to simulate the entire creep process, and the test results are verified. The result indicates that the deformation amount of weathered sandstone increases with the decrease of confining pressure under the same axial load; Under the same confining pressure condition, the larger the axial load, the stronger the deformation of the test block, with a larger instantaneous strain and creep rate, and a smaller stage number of unloading experienced, leading to earlier occurrence of test block instability and failure; The improved model has a relatively strong correlation between the calculated results and experimental values of the entire unloading creep process. This result is of great significance for accurately understanding the creep characteristics of weathered sandstone under dynamic loading action.