马 铢,伍鹤皋,石长征
AuthorsHTML:马 铢，伍鹤皋，石长征
AuthorsListE:Ma Zhu,Wu Hegao,Shi Changzheng
AuthorsHTMLE:Ma Zhu，Wu Hegao，Shi Changzheng
Unit:武汉大学水资源与水电工程科学国家重点实验室，武汉 430072
Unit_EngLish:State Key Laboratory of Water Resources and Hydropower Engineering Science， Wuhan University，Wuhan 430072，China
Abstract_Chinese:钢衬钢筋混凝土管道在设计上允许外包混凝土开裂，确定其裂缝发展规律和结构的承载特性是评估管道能 否长期安全稳定运行的前提，但现有的解析公式多是半理论半经验公式，不同的公式计算结果误差较大，有限元法 成为了主要的分析方法．以往的有限元模型多基于损伤或者断裂理论，较少考虑二者的耦合作用，本文结合三峡水 电站大比尺试验模型，建立了基于黏聚裂缝模型的有限元模型，在管道混凝土中插入内聚单元综合模拟了混凝土开 裂过程中的损伤和断裂特性，得到了管道结构开裂前后的钢材应力变化规律、裂缝扩展形态以及裂缝宽度，进一步 系统地讨论了内聚参数和网格尺寸的影响．有限元模拟裂缝扩展形态与模型试验时裂缝宽度中间宽、两侧较小的结 论一致．管腰和管顶典型部位的裂缝宽度值与模型试验误差在 10%以内，且钢材应力起伏与裂缝位置相呼应．更改 内聚参数和网格尺寸发现，在合理的取值范围内，混凝土裂缝扩展、钢材承载规律与试验结果基本一致，但内聚刚 度取值过小会导致混凝土开裂提前，黏结系数取值过大或者单元尺寸过大会使计算结果的精度降低．因此在采用黏 聚裂缝模型模拟管道混凝土开裂时，应在保证计算收敛的前提下，尽可能取较小的黏结系数和足够大的内聚刚度， 以提高计算结果的精度．
Abstract_English:Steel-lined reinforced concrete penstock is designed to allow concrete cracks. The crack propagation and bearing characteristics of the penstock after having cracks is a prerequisite for assessing whether the pipe can operate safely and stably for a long time. However，the existing formulas of steel stress and crack width are mostly semiempirical that do not agree with each other. As a result，the finite element model gradually became the most popular analysis method instead of an analytical approach. Existing finite element methods are primarily based on damage or fracture theory and are rarely considered to have a coupling effect. In this study，a finite element model based on a cohesive crack model is developed using a large-scale test model of the Three Gorges Hydropower Station. Cohesive elements are inserted into the concrete pipe to simulate damage and fracture characteristics in concrete cracking and obtain the structure bearing characteristics，crack propagation，and crack width. Furthermore，cohesive parameters and element size are discussed systematically and show that the finite element simulation and model test are in good agreement. The cracks are in the shape of‘eyes’，consistent with the width of the model test that is wide in the middle and small on both sides. The results show that the error of the crack width between the cohesive crack model andmodel test is less than 10%，and the stress fluctuation of steel corresponds to the crack. Finite element simulation can get accurate results within a reasonable range by changing the cohesive parameters and element size. However，too small penalty stiffness will lead to the early cracking of concrete，and too large viscous regularization or element size will reduce the accuracy of calculation results. Hence，a smaller viscous regularization coefficient and a larger penalty stiffness are necessary as much as possible on the premise of ensuring the convergence of calculation when the cohesive model is used to simulate the cracking of concrete.
Keyword_Chinese:钢衬钢筋混凝土管道；数值模拟；黏聚裂缝模型；裂缝扩展；裂缝宽度；承载特性
Keywords_English:steel-lined reinforced concrete penstock；numerical simulation；cohesive crack model；crack propagation；crack width；bearing characteristics

PDF全文下载地址:http://xbzrb.tju.edu.cn/#/digest?ArticleID=6729