在地震荷载作用下,混凝土重力高坝含水裂缝快速张开闭合导致水体压缩,产生附加水压,极易引起裂缝失稳。为了探究地震荷载作用下裂缝内水压变化规律,假定裂缝形状为椭圆形,推导出裂缝在地震荷载作用下附加水压计算公式。通过实例分析地震荷载作用对裂缝内附加水压及裂尖应力强度因子在不同方向、不同尺寸以及不同排水率条件下的影响。研究表明:在地震荷载作用下,计算实例的最大附加水压达到初始水压的7.55倍;随着初始裂缝宽度的增大,最大附加水压和裂尖附加应力强度因子快速减小,且初始裂缝宽度越小,排水率对附加水压的影响程度越大;裂缝倾斜角度对裂尖附加应力强度因子影响不显著。研究结果可为进一步研究地震荷载作用下重力高坝中裂缝的稳定性提供理论基础。
Abstract
Water-containing cracks on concrete gravity dam are susceptible to instability due to additional water pressure generated by water compression caused by the rapid opening and closing of cracks under seismic load. In an attempt to obtain the variation law of water pressure in cracks under seismic load, we deducted the formula of additional water pressure in cracks under seismic load based on the assumption that the crack is oval. By case study, we analyzed the changes of additional pressure and factor of stress intensity at crack tip in different directions in the presence of varying crack size and drainage rate. Results revealed that the maximum additional water pressure of the calculation case reached 7.55 times of initial water pressure under seismic load. Meanwhile, with the increase of initial crack width, the maximum additional water pressures and the factor of stress intensity at crack tip declined rapidly; with the decrease of initial crack width, the influence of drainage rate on additional water pressure became more evident. In addition, the inclination angle of crack had no obvious impact on the factor of stress intensity at crack tip.
关键词
裂缝 /
地震荷载 /
计算模型 /
最大附加水压 /
应力强度因子
Key words
crack /
seismic load /
calculation model /
maximum additional water pressure /
stress intensity factor
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