【作者】 朱杰；

【导师】 汪仁和； 徐颖；

【作者基本信息】 安徽理工大学 ， 地质工程， 2014， 博士

【摘要】 随着我国西部大开发战略的实施和能源需求的增长,煤矿建设重点也在向西部转移。西部矿区白垩系地层以砂岩和泥岩等为主,强度低、胶结弱,属于软岩。在白垩系地层中进行冻结法凿井时,冻结壁的变形和稳定性直接决定于软岩冻结后的力学性状。通过大量的岩石瞬时和蠕变试验,结合损伤和流变力学理论,建立能反映白垩系地层冻结软岩力学规律的本构模型。本文所做工作如下：对白垩系地层软岩在不同温度下进行三轴压缩试验,获得了瞬时力学参数与温度、围压的关系。在同温下,软岩峰值强度、弹性模量均随围压的增加而提高,而同压下两者则随温度的降低而增大。为正确描述白垩系地层冻结软岩的五阶段应力-应变曲线,假定软岩存在初始损伤,建立损伤恢复变量,获得了裂隙压密段的损伤表达式,认为软岩微元强度符合Weibull概率分布,并考虑到材料损伤部分应力由残余强度承担,建立了冻结软岩的增量型统计损伤本构模型,将模型嵌入ABAQUS有限元程序,对三轴试验进行模拟,验证了模型的正确性。通过不同温度下的三轴蠕变试验结果可知,白垩系地层冻结软岩具有明显的三阶段蠕变性质,且随着温度降低,软岩总蠕变量减少,长期强度升高。利用Mohr-Coulomb屈服准则修正西原模型的黏塑性元件,同时引入改进的Kachanov蠕变损伤律,建立了可描述冻结软岩三阶段蠕变特征的蠕变损伤本构模型。推导了蠕变损伤模型的有限元解析方法,对ABAQUS软件进行二次开发。利用ABAQUS对泊江海子矿井筒开掘进行数值模拟,并获得在不同段高条件下,冻结壁的应力场和位移场分布,确定了井帮最大径向位移与时间的关系,将模拟值与实测值比较,结果一致,证明了本文建立的蠕变损伤本构模型是可靠的,能够为冻结壁设计和施工提供指导。更多还原

【Abstract】 Along with the implementation of west development strategy in our country and the growth of energy demand, the focus of coal mine construction is also moved to the west. The cretaceous strata of western mine is given priority to sandstone and mudstone which have many engineering characteristics such as argillaceous cementation, low strength, and they belong to soft rock. With shaft sinking by freezing method in the cretaceous strata, the deformation and stability of the frozen wall directly depend on mechanics properties of the soft rock after freezing. Through a large number of Instantaneous and creep experiments, the constitutive model which could describe the mechanics law of frozen soft rock of cretaceous formation is built combined with damage and rheological mechanics. This work is as follows:Many triaxial compression tests are conducted under different temperatures about soft rocks of cretaceous strata, by which the relationship between the instantaneous mechanic parameters and the temperature and confining pressure is acquired. At the same temperature, both the peak intensity and elasticity modulus of soft rock improve with the increasing of the confining pressure. At the same confining pressure,they increase with the decreasing of temperature.In order to correctly describe the stress-strain process of five stages for soft rock, damage recovery variable is established and damage expression of fracture pressure section is obtained presuming initial damage exists in soft rock. Supposing the infinitesimal strength is coincided with the weibull probability distribution,and considering the strength of material damage part as residual strength,an incremental statistical damage constitutive model describing the frozen soft rock is established. In order to conduct numerical simulation for triaxial test,the model is embedded in ABAQUS finite element program and correctness of the model is verified.Many triaxial creep tests under different temperatures are conducted. Through the analysis, the creep deformation curve of frozen soft rock of cretaceous formation has very obvious character of three stages. With the decreasing of the temperature, the total creep value reduces and the long-term strength increases.By introducing Mohr-Coulomb yield criterion, the viscoplastic element of XiYuan-model is improved, and creep damage constitutive model that can describe three stages of creep characteristics is established with the introduction of improved Kachanov creep damage rate.Finite element analysis method of the creep damage model is derived,and the constitutive model is embedded into ABAQUS finite element program.The simulation for the digging of tube of Bojianghaizi mine is conducted,by which the stress and displacement field distribution of frozen wall are abtained under different section high,and the relationship between maximum radial displacement of well sidewall and time is determined. Compared with the measured value, the results of simulation of displacement are coincident which proved the correctness of the creep damage constitutive model of this paper, and it could provide guidance for the design and construction of the frozen wall.更多还原