基于动接触力理论的岩-砼界面动力响应机理研究

The partial softening of rock-concrete interface is one of the main causes that lead to dynamic damages of rock mass and supporting structure,the dynamic response of rock mass and supporting structure is complexly influenced by multiple critical factors. Unfortunately, the related researches are still rare.This project is aimed at investigating the dynamic damage and softening failure of rock-concrete interface under impact load by means of macro- and meso-experiments,theory and numerical simulation. In the lab experiments, the ultra high speed photographic system will be used for following the interface crack in real time.And it is creative that the cloud image processing is going to conduct the tracing line analysis of ageing expansion rules of interface crack；By scanning the 3D morphology of fracture and turning the morphology into a mathematical characterization, it is intended to straighten out the critical factors of rapid crack propagation of rock-concrete interface in meso-scale；It is going to establish the quantitative association of dynamic damage parameters of dilatancy in the interface neighborhood and determine the threshold quantities of crack initiation,propagation and acceleration dynamic strengths. Based on the dynamic contact force theory and adopted the cementation and friction element to simulate the local softening deformation of interface, it will construct the evolution equations of damage flexibility tensor of rock-concrete interface and a constitutive model of rock-concrete structure. With these above works, a nonlinear finite element numerical simulation will be written to verify the macro- and meso-experiment results. The research results of this project will contribute to understand the mechanics response law of rock-concrete interface during the earthquake, blasting and under other dynamic loads. In that sense, the project has originality and a potential application prospect.

岩砼界面的局部软化是岩体与支护结构动力破坏的主要原因之一，其动力响应的多重关键因素影响复杂，相关研究尚不多见。项目拟通过宏细观实验、理论和数值模拟对冲击载荷下的岩砼界面动力损伤软化失效问题进行深入探讨。通过超高速摄影对界面裂纹进行实时追踪，创新性采用云图信息处理技术进行界面裂纹时效扩展规律的迹线解析；对破坏前后的断口进行3D 形貌扫描并作出数学表征，理清细观尺度下的岩砼界面裂纹快速扩展失效的关键因素；弄清接触界面邻域发生“剪胀”或“压胀”的动力损伤参量之间的定量关联，确定裂纹萌生、扩展、加速的动强度参数临界值；基于动接触力理论，引入胶结元和摩擦元模拟界面局部弱化变形，构建岩砼界面柔度变化的损伤张量演化方程，提出岩砼二元体的本构模型，编制非线性有限元数值验证宏细观实验结果。项目的研究结果有助于了解岩体与混凝土结构接触界面在地震、爆破等动态载荷作用下的力学响应机制。课题具有创新性和潜在应用前景。

组成岩（土）体和混凝土结构的天然地质体与支护工程结构受到地震、爆炸等动力载荷作用后，往往造成岩（土）体与混凝土结构的接触界面损伤弱化，进而引起岩（土）体与支护结构的失稳破坏，其二者复杂非线性的接触效应对岩（土）体与结构的整体稳定性产生极大影响，是值得深入研究的热点和难点问题。本研究通过实验、理论和数值模拟对岩（土）体与混凝土接触界面动力损伤软化失效问题进行研究。根据岩块与混凝土接触条件，采用节理弱面剪切实验的方法，完成了6种岩性共计23组的岩砼二元结构静力载荷作用下的接触效应实验；采用素混凝土模拟岩体，加筋混凝土模拟支护结构，制作了200余块共计5种不同接触类型的岩砼二元结构试样，通过SHPB实验装置，完成了动力冲击试验；采用超高速摄影对岩石受到点冲击载荷的接触界面裂纹进行了实时追踪，观察了裂纹扩展规律，通过形貌表征参数，理清了裂纹快速扩展失效的关键因素，确定了裂纹萌生、扩展、加速的动强度参数临界值。基于动接触力理论，通过岩土体与工程体界面接触条件，推导了岩土与结构接触界面的接触力及法向和切向接触力解析算法；建立了界面局部弱化变形的岩砼二元体本构模型，编制了非线性有限元数值模型验证了岩砼在SHPB装置下动力冲击作用的实验结果。基于项目研究结果，对地震、爆破等动态载荷作用下的隧道衬砌结构和围岩体力学响应机制进行了研究，得到如下结果：隧道在地震横向作用下产生较大的横向位移，不同管片接头模型中管片的位移时程随着管片刚度减小而增大，但均比地表土体横向位移小很多，随着管片刚度减小，管片横向方向和剪切方向的应力均减小，弯矩最大值位于隧道两拱腰处。爆破荷载作用对隧道管片的影响较大，而对地表的影响较小，其竖向位移随地表与爆炸源正上方位置距离的增大逐渐减小，管片内力随时间先增大后减小，整体管片内力分布不均匀。课题研究结果具有一定的创新性和广泛的应用前景。