三向受力条件下淡水冰破坏准则研究

EXPERIMENTAL RESEARCH ON FAILURE CRITERIA OF FRESHWATER ICE UNDER TRIAXIAL COMPRESSIVE STRESS

为了更清楚地认识含冰冻结壁力学特性、解决复杂冰岩耦合问题以及给冰工程设计和数值仿真分析提供参数,有必要对冰在三向受力条件下的力学特性进行深入研究.以内蒙古自治区东胜煤田石拉乌素矿立井井筒建设为背景,参考现场水文地质资料在室内制作相似冰样,利用TDW-200低温冻土试验机,进行了4组温度和7组围压的人工淡水柱状冰三轴压缩强度试验,加载速率为0.5 mm/min,加载方向垂直于冰的晶轴方向.结果表明:在恒定温度条件下,柱状冰随围压增大塑性增强,而恒定围压条件下,柱状冰随温度降低脆性增强;在试验温度范围内,淡水柱状冰和多晶冰强度均随围压、温度升高而增大,但同条件下柱状冰强度高于多晶冰;采用D-A模型、Teardrop模型解释了高压下偏应力与围压之间的非线性关系,从不同角度对拟合得到的破坏准则综合考虑,认为D-A准则更适合用于描述淡水冰的破坏特征.研究结果可为后期同条件冰-岩耦合、数值模拟研究提供参考.

In order to know the mechanical properties of frozen wall which contain ice,solve the ice-rock couplingproblems,provide believable parameters for ice engineering design and numerical simulation analysis,it is necessary toresearch the ice mechanics under triaxial compressive stress.Taking the frozen shaft construction of Shilawusu coal minein Inner Mongolia Autonomous region Dongsheng coal field as the project background of the research.The similaritycolumnar ice specimens are fabricated in the laboratory based on the field data.A series of tests were performed onartificial freshwater columnar ice under triaxial compression at4group temperatures and7group confining pressures byusing the TDW-200frozen soil triaxial test system.The loading rate of the series of tests is0.5mm/min,and the loadingdirection is perpendicular to the crystal axis of ice.The results show that,when the experimental temperature is constant,the plasticity of columnar ice increases with increasing confining pressures.When the experimental confining pressureis constant,the brittleness of columnar ice increases with decreasing temperature.Within the range of test temperature,the strength of columnar ice and polycrystalline ice increase with the increase of confining pressure and temperature.Thestrength of columnar ice is higher than polycrystalline ice at the same conditions.The non-linear relationship between deviatoric stress and confining pressures is explained by D-A model or Teardrop model.From the point of view ofintegrated advisement,the D-A failure criteria is more reasonable to describe the failure characteristics of the freshwaterice.The conclusions can provide some scientific references for ice-rock coupling research and numerical simulation underthe same conditions.