新浇大坝基础混凝土爆破安全震动速度研究

在考虑动荷载效应、微裂隙影响、骨料粒径效应等因素对混凝土极限拉应变影响的条件下,提出了全级配混凝土容许拉应变计算公式.在此基础上,结合早期混凝土力学性能及拉应变增长规律,推算了新浇大坝基础混凝土7d内的爆破安全峰值震动速度.与水工建筑物岩石基础开挖工程施工技术规范比较,发现现行规范规定的龄期超过1d的新浇筑混凝土的容许质点峰值震动速度偏于安全,而龄期小于1d的容许质点峰值震动速度则较理论推算值大,可能会引起工程质量事故.

Research on safety vibration velocity for freshly mixed concrete of dam foundation under loading of blasting vibration

Taken into account the factors such as the dynamic loading, the microcrack, the size of aggregate etc., a model for calculating allowable tensile strain for full-graded concrete is proposed. On the base of the model proposed the mechanical properties and the development of the strength of concrete at early ages, the safety peak particle velocity (PPV) for freshly mixed concrete which is in the zone of base-constraint and with an age lower than 7 days is decided. Comparing with the criterion proposed by the Technical Standard for Rock Foundation Excavation of Hydraulic Structures, it was found that the criterion proposed PPV for freshly mixed concrete older than one day is conservative , while PPV for freshly mixed concrete with an age less than one day is less than the calculated, it may result in quality problems.