混凝土块体静态破碎试验研究

Experimental study on static crushing of concrete block

为探究静态破碎过程中孔径与约束程度对开裂时间和破碎效果的影响规律,开展了13个素混凝土试件的单孔静态破碎试验.将试件内切圆内混凝土面积与破碎剂面积之比定义为约束比,并用其表示混凝土对破碎剂的约束程度.使用破碎剂体积膨胀率表示试件的破碎效果.试验结果表明:单孔下混凝土块体破碎后一般会产生3条或4条裂缝,3条裂缝的情况居多,裂缝发展稳定后,其分布形态有"人"字形、"T"字形和"十"字形3种;试件开裂后破碎剂体积膨胀率的时程曲线呈二次抛物线形式,前期发展较快,后期发展缓慢并逐渐趋于稳定;孔径和约束程度均会对破碎剂体积膨胀率产生较明显的影响,孔径增大,破碎剂体积膨胀率随之增大,破碎效果越好,约束比增大,破碎剂体积膨胀率随之降低,破碎效果减弱;当约束比较小时,孔径对开裂时间起主要影响,孔径越大,开裂时间越短,当约束比较大时,约束比对开裂时间起主要影响,约束比越大,开裂时间越长.

To explore the influence of pore diameter and constraint degree on cracking time and crushing effect in static crushing process,static crushing tests of 13 plain concrete specimens were carried out.The ratio of concrete area in inscribed circle of test specimen to crushing agent area was defined as constraint ratio,which was used to express the constraint degree of concrete to crushing agent.Volume expansion rate of crushing agent was utilized to indicate the crushing effect of specimens.Results show that:3 or 4 cracks appeared after the broken of the concrete blocks under a single hole,and 3 cracks were the commonest,when the cracks became stable,the distribution forms were in the shapes of"Y","T",and"cross";The time-history curve of the volume expansion rate of crushing agent after cracking was in the form of quadratic parabola,which developed rapidly in early stage,slowly in later stage,and gradually became stable;Both pore diameter and constraint degree had obvious effects on volume expansion rate of crushing agent,the larger the pore diameter was,the larger the volume expansion rate of crushing agent became,and the better the crushing effect was,as constraint ratio increased,volume expansion rate of crushing agent decreased,and crushing effect was weakened;When constraint ratio was small,pore diameter had major effects on cracking time,where the larger the pore diameter was,the shorter the cracking time became,when constraint ratio was large,constraint ratio had major effects on cracking time,where the larger the constraint ratio was,the longer the cracking time became.