尾矿砂与土工织物界面宏细观力学特性及协同变形机制研究

On the background of the application of geotextile in tailings dam project, study the macro-meso mechanical properties of interface and collaborative deformation mechanism between tailings sands and geotextiles. Laboratory drawing tests were conducted to get the interface strength, so as to study the law of interface strength characteristic affected by the physical and mechanical parameters of geotextiles and tailings sands. DPDM technology was adopted to get mesoscopic images of interface between geotextiles and tailings sands, space-time evolution law of shear strain concentration zone and particle motion was studied, mathematical relationship of interface mesoscopic mechanics parameters, such as the particle size, the contact stiffness, the friction coefficient and the bond stiffness of the geotextile, and macroscopic mechanical strength and deformation parameters were established, constitutive model that using continuous media mesoscopic mechanics parameters to describe bulk solid medium interface was built at last.The mechanism and method of macro-meso model parameters intelligent interaction was proposed, and interface constitutive model was applied to the finite element calculation program which was embedded into the mathematical model for tailing dam stability analysis, the stability of tailings dam under different operating conditions was discussed. Mechanism of tailings sands particle movement and geotextiles tensile deformation effecting on strength of reinforcement and deformation characteristics was clarified. Above results can proved theoretical basis and technical support for geotextile materials reinforcement tailing dam engineering application.

以土工织物在尾矿库筑坝工程中的应用为背景，研究尾矿砂与土工织物界面宏细观力学特性及协同变形机制。采用室内拉拔实验，测定尾矿砂与土工织物界面强度，研究土工织物和尾矿砂物理力学参数对界面强度特性的影响规律；采用无标点数字图像量测技术采集土工织物与尾矿砂界面细观图像，研究界面剪应变集中带演化和颗粒运动规律，建立尾矿砂颗粒集度、接触刚度、摩擦系数与土工织物粘结刚度等界面细观参数和宏观力学强度、变形参数之间的数学关系，构建用非连续介质细观参数描述的散体介质界面本构模型；提出宏细观模型参数智能互演的机制和方法，实现所构建的界面本构模型在有限元计算中的程序化；将建立的界面本构模型嵌入到尾矿坝稳定性分析的数学模型中，优化土工织物的设计参数，研究不同运营工况下尾矿库稳定性，阐明尾矿砂颗粒运动和土工织物拉伸变形对加筋体力学强度和变形特性的影响机制。为土工合成材料加筋尾矿坝的工程应用提供理论依据和技术支撑。

尾矿坝的稳定性关系到尾矿库下游人民生命财产安全，是矿山安全生产的重要组成部分。将土工合成材料应用于尾矿库筑坝工程中，可显著提高尾矿坝稳定性。项目采用室内试验、数值模拟、理论分析、模型试验及现场试验等方法研究了尾矿砂与土工合成材料界面宏细观力学特性及协同变形机制研究。取得了如下主要成果：（1）研制了一套加筋土界面特性宏细观分析的试验系统，可开展不同土工合成材料与填料的直剪和拉拔试验，试验过程中可连续采集细观图像，实现了宏观力学数据和细观特征的同步采集。（2）开展了土工织物和土工格栅加筋尾矿的直剪和拉拔试验，研究了尾矿砂含水率、试验拉拔速率及竖向压强对土工合成材料-尾矿界面特性的影响规律，确定了土工格栅加筋尾矿的合理网孔尺寸。（3）研究了土工合成材料-尾矿界面细观参数与宏观响应之间的联系，开发了空间对称形状的离散元颗粒流模型计算程序，应用PFC3D建立三维数值模型，进行单因素改变条件下的数值三轴试验，分析了用于模拟散粒状土的线性接触模型的细观参数与宏观力学参数之间的关联性。（4）针对土工格栅和土工布拉拔时出现的应变硬化和应变软化现象，提出了双线性剪应力-位移弹塑性硬化模型和三线性剪应力-位移弹塑性软化模型；依据表征土工格栅长期低应力荷载作用下的力学特性的非线性四参数粘弹塑性模型，建立了粘弹塑性土工格栅弹塑性加筋尾矿的简化流变模型。（5）通过开展加筋尾矿堆积坝模型试验和现场原型试验，获得了不同加筋层数、上覆压力、含水率、筋材类型和堆积坝外坡比情况下坝顶表面位移、坝体内部浸润线和竖向土压力的变化规律，得到了常规坝、格栅加筋坝和土工布加筋坝在排浆后坝体内部孔隙水压力和土压力的变化规律，揭示了土工合成材料和散体材料力链传递和协同变形作用机理。