分级加卸载条件下软弱复杂矿岩蠕变规律研究

STUDY ON CREEP RULES OF SOFT AND INTRICATE ORE-ROCK UNDER STEP LOAD AND UNLOAD

采用集众优点于一体的分级增量循环加卸载方式,对金川有色金属公司III矿区软弱复杂矿岩进行蠕变试验,试验数据按可恢复的瞬时弹性应变与滞后黏弹性应变,以及不可恢复的瞬时塑性应变与黏塑性应变进行分析,得出软弱复杂矿岩黏弹塑性特性的基本规律。在对试验数据深入分析和对比研究的基础上,将Burgers黏弹蠕变模型与Mohr-Coulomb准则相结合,形成新的黏弹塑性模型,以研究复杂条件下软弱岩石的变形特性,并编制改进的Burgers蠕变模型试验数据处理程序,对模型参数进行拟合和加权平均取值。试验结果表明,金川III矿区矿岩蠕变试验曲线与理论曲线较为吻合,改进的Burgers蠕变模型能较好的描述岩石的蠕变特性。

A circular increment step load and unload method with many advantages is employed; and a set of creep experiments are performed to study the viscoelasto-plastic characteristics of soft and intricate ore-rock in Jinchuan Mine Ⅲ. The experimental data were analyzed according to the retrievable instantaneous elastic strain and lagged viscoplastic strain, and the post-retrievable instantaneous plastic strain and viscoplastic strain, and the essential rules of viscoelasto-plastic characteristic of the soft and intricate ore-rock are obtained. Based on scientific analysis and comparative study, Burgers creep model was combined with Mohr-Coulomb criterion; and a new viscoelasto-plastic model was formed to study the characteristics of soft rock creep under intricate conditions. Some programs about Burgers model were developed to deal with the experimental data. The creep characteristic curves were obtained; and the model parameters and the values were achieved through weighted means. The test results show that the creep testing curves of the ore-rock of Jinchuan Mine Ⅲ are coincident well with the theoretic curves; and the modified Burgers creep model can be applied to characterize the creep of Jinchuan ore-rock.