冻结裂隙砂岩解冻后蠕变力学特性研究

富水洛河组砂岩地层人工冻结法施工后，在长期应力作用下斜井井壁围岩会发生蠕变破坏。为了研究解冻后不同裂隙倾角岩石的蠕变破坏机理，以可可盖煤矿洛河组砂岩为原岩，制备预制不同角度裂隙的类砂岩，研究其解冻后三轴压缩蠕变力学特性。试验结果表明：岩样预制的三种倾角中，倾角45°时内部新生裂纹沿着预制裂隙发育与扩展程度更大，产生的轴向蠕变量更大且变化速率更快；其次是裂隙倾角0°时，最后为裂隙倾角75°。根据试验结果，基于西原体蠕变模型，引入裂隙塑性体元件及蠕变全过程劣化演化方程，建立考虑原生节理影响的非线性蠕变模型并且进行三维推广，并利用最小二乘法进行求解并拟合，拟合结果与试验数据基本吻合。

Creep mechanical properties analysis of frozen fractured sandstone after thawing

The main inclined shafts of some coal mines in sandstone strata of Fushuiluohe Formation are constructed by artificial freezing method, and the surrounding rock of the inclined shaft wall will undergo creep failure under long-term stress after thawing. In order to study the creep failure mechanism of rocks with different fracture dip angles after thawing, taking the sandstone of Luohe Formation in a mine as the original rock, the sandstone-like rocks with prefabricated fractures of different angles were prepared, and the mechanical properties of triaxial compression creep after thawing were studied. The experimental results show that : Among the three inclination angles of sandstone-like prefabricated, when the inclination angle is 45°, the development and expansion of internal new cracks along prefabricated cracks are greater, and the generated axial creep is larger and the change rate is faster. The second is fracture dip angle 0°, the last is fracture dip angle 75°. According to the test results, based on the Nishihara creep model, the fractured plastic body elements and the degradation evolution equation of the whole creep process are introduced to establish a nonlinear creep model considering the influence of the original joints and carry out a three-dimensional extension. The least square method is used to solve and fit, and the fitting results are basically consistent with the experimental data. The research results have certain reference value for disaster mechanism analysis and long-term safety evaluation of artificial freezing inclined shaft after thawing.