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将C35强度等级混凝土试件在常温20℃及高温加热(200,400,600,800℃)后分别经自然冷却和浸水冷却处理后,利用波形整形器改进后的直径100 mm的分离式霍普金森压杆(SHPB)装置,对其进行不同加载率(冲击速度8.2,14.56,18.78 m/s)下的冲击压缩试验。研究表明:在同一加热温度下,随着加载率的增大,混凝土试件的峰值应力增大,相应破碎程度明显增加;而随着加热温度的提高,试件破碎由劈裂破坏向压酥破坏转变。对比分析自然冷却和水冷却处理试件的试验结果,表明:经过水冷却的试件强度在加热温度为400℃之前,等于或略高于相同加载率下自然冷却的试件强度,而加热温度高于400℃后则明显低于自然冷却的试件,因此可近似取400℃是高温水冷却损伤的阈值。通过物理化学分析得出其动力学特性影响的内在机理,主要体现在内外温差产生的内应力、二次水化反应、化学作用产生的分解和膨胀作用等。
After the specimens of C35 strength concrete were heated at 200 ℃, 400 ℃, 600 ℃ and 800 ℃ respectively at normal temperature and cooled by soaking water, the split Hopkinson pressure bar (SHPB) with the diameter of 100 mm was improved by the waveform shaper. The apparatus was subjected to impact compression tests at different loading rates (impact velocity 8.2, 14.56, 18.78 m / s). The results show that under the same heating temperature, the peak stress of concrete specimen increases with the increase of loading rate, and the corresponding degree of crushing increases obviously. With the increase of heating temperature, the specimen crushing is changed from cleaving to crushing Destroy the transformation. The results of natural cooling and water cooling test are compared and analyzed. It shows that the strength of the specimen cooled by water is equal to or slightly higher than the strength of specimen naturally cooled at the same loading before the heating temperature is 400 ℃, while the heating temperature Above 400 ℃, it is obviously lower than the naturally cooled specimen, so the approximate 400 ℃ is the threshold of high temperature water cooling damage. Through the physical and chemical analysis of the kinetic characteristics of the intrinsic mechanism of its impact, mainly reflected in the internal and external temperature difference caused by internal stress, the second hydration reaction, chemical decomposition and expansion of the role.