【作者】 邵勇；

【导师】 王向东；

【作者基本信息】 河海大学 ， 固体力学， 2005， 硕士

【摘要】 在坝工设计中，拱坝常由于荷载如温度荷载、水荷载、泥沙荷载等作用下在坝踵处产生过大的梁向拉应力，从而导致坝踵开裂。对于宽河谷、坝高300米级的特高拱坝，情况更为严重。而一旦开裂，再在高压水的作用下，裂缝可能进一步扩展，甚至破坏止水帷幕，从而导致严重后果。因此，常常采取各种措施来避免在拱坝内部产生过大的拉应力。这些措施主要分成两类：一是进行坝体体型优化设计、控制施工时混凝土的入仓温度等；二是采取有效的结构措施，如设诱导缝、周边缝、底缝等。 采取结构措施在目前的坝工设计中存在比较大的争议，既有一些成功的先例，也有惨痛失败的例子。本文首先阐述了在高拱坝中设置底缝的思想来源，接着介绍了断裂力学的基本理论以及断裂有限元的计算原理，然后以小湾高拱坝设20m深的底缝方案作为研究对象，计算了设置底缝前后坝踵处的应力，分析了设置底缝后拉应力释放的情况以及位移场的变化对拱坝的影响，并定性地分析了坝肩处的应力场及稳定性。通常设计中仅考虑了设置底缝后坝体——坝基整体稳定性，而忽略了底缝作为人工裂缝其本身的稳定性，本文对底缝本身的稳定性进行了分析，采用断裂有限元法，用Williams公式计算出底缝尖端的应力强度因子值，再根据复合型裂缝断裂的K判据来判别底缝的稳定性。最后得到的结论是：小湾拱坝20m深底缝方案对于释放坝踵处的过大拉应力具有明显的效果，同时坝体的位移场、坝肩处应力场在设缝前后变化不大；底缝本身基本处于稳定，但中间坝段处底缝相对薄弱，工程上需要调整并加以关注。更多还原

【Abstract】 During the design of dams, usually there is too lager beam-axial tension stress on the foot of arch dams under the loads of temperature, water, soil, etc., and then it will cause crazing on that zone. As soon as broad river valley and high arch dams of 300 meters high concerned, the situation will be worse. Once the foot of arch dams craze, cracks maybe continue to expand under the high-press water, even destroy the preventing water purdah. For the reason, designers often take all measures avoid the appearance of tension stress in arch dams. All these measures can be specified into 2 classes: no.1 is to optimize the arch dam’s bodily form or to control the concrete’s temperature before casting into storehouse etc.; no.2 is to take effect structure measures, for revulsive joint, peripheral joint, and base joint etc.There are relatively many disputed problems about the structure measures in current dams design. Some succeeded, and some failed painfully. In this paper, first I expatiate the resource of base joint method in high arch dams then introduce the elementary theory of fracture mechanics and the computational theory of fracture finite element. In succession, I put the 20m depth base joint project of Xiao-Wan arch dam as a research item, and calculated the tension stress on the foot of arch dam before and after setting base joint, analyzed the situation of tension stress releasing and the influence to arch dam of displacement’s variety, and also analyzed the stress field on arch dam’s shoulder and its stability. Designers, usually, only consider the whole stability of body-foundation of the dam after setting base joint, while ignore the stability of base joint itself. In this paper, the method of fracture finite element was applied, by applying Williams’s formula I calculated the stress intensity factor of base joint after knowing the displacement field of tip of base joint then distinguished the stability of base joint by terms of composite crack’s K fracture criterion. The result is: the project of 20m depth base joint of Xiao-Wan arch dam has obvious effect to release the too lager tension stress on the foot of arch dam, at the same time the differences of the displacement field of dam body and stress filed of dam shoulder are potty, the base joint itself exists in rough stability, but the middle dam bodies need some partial adjustment.更多还原