单支墩大头坝初始表面裂纹形成的热流变断裂学研究(英文)

THE THERMORHEOLOGICAL FRACTURE RESEARCH ON THE FORMATION OF INITIAL SURFACE CRACKS AT THE SINGLE BUTTRSS DIAMOND DAM

本文从对裂纹扩展过程中流变与耗散现象的大量观察与研究,根据非局部场理论,导出了裂纹体在裂纹扩展过程中的热力平衡方程,为更加精确地描述裂纹扩展问题提供了理论基础;同时指出,在裂扩展过程中局部质量、动量、动量矩和能量均不守恒,并给Griffith表面能以新的定义。将单支墩大头坝初始表面裂纹的形成与扩展视为不可逆热力学过程,在不可逆过程必然伴有熵产生的原则下,引入了一个耗散势函数,通过对裂纹扩展过程中Clausius非补偿热和耗散势函数的研究,重新建立了断裂判据;在适当地引入裂纹系统偏离平衡态的距离之后,可导出经典的屈服、强度和断裂理论中的各种判据;同时,通过耗散势函数,把流变、断裂和不可逆过程有机地结合起来了,形成了统一的流变断裂学。最后,将大坝混凝土定义为热流记忆性材料,依试验和实测数据,采用本文给出的热流变断裂学研究,对单支墩大头坝初始表面裂纹的形成进行了计算,其结果与现场观测基本一致,为单支墩大头坝的设计提供了进一步改进的依据。

In this paper, the thermodynamic equilibrium equation of crack body in the courseof crack propagation has been derived from a lot of observation and researchment torheological and dissipating phenomena appeared in crack propagation, therefore the baseof theory is provided for the crack propagation problem being described more accurat-ely; at the same time, it points out process of crack propagation, the local mass, localmomentum, local angular momentum and local energy are all unconservation, a newdefinition has been given out to surface energy of Griffith. Regarding the formationand propagation of initial surface crack of single buttress diamond dam as an irrevel-sible courese of thermodynamics, by the principle of adjoint production of entropy inirreversible process, a dissipation potential function is introduced, and by researchingthe noncompensation heat and the dissipation potential function of Clausius in crackpropagation, the fracture criterion has been rebuilt, when suitably introducing the'distance ' deviating the equilibrium state by crack system, all kinds of criteria forclassical yeild, strength and fracture theory could be derived, with the dissipation po-tential function, rheology, fracture and irreversible course could be combined orqani-cally, forming a uniform Rheollgical Fracture. Fanally, the concrete of the diamonddam is defined as the thermorheological memory material, with the data from cxperi-ments and actual measurements, and making research by the thermorholoqical fractureprovided in this paper, a calcultion has been carried out to the formation of the init-ial surface crack at the single buttress diamond dam. the results are in correspondencewith the observation at the field, thus an important basis for further improving thedesign of the single buttress diamond dam has been given out.