爆破振动对新浇混凝土影响的试验研究

为探究新浇混凝土受爆破振动作用下的安全振速,以保证混凝土结构的可靠性,采用露天深孔爆破作为振源,对龄期为6 h、12 h、36 h、48 h和72 h的C40混凝土分别在2~10 cm/s的爆破振速下进行试验。通过测试各龄期试件在受振动扰动后的纵波波速及抗压强度,分析得出:龄期为6 h和12 h时,2.3 cm/s的爆破振速能够使混凝土产生大于0.05的损伤以及5%以上的强度折减;龄期为36 h和48 h时,能够对混凝土造成损伤和强度折减的振速为4 cm/s,36 h龄期为混凝土抗振能力提升的拐点;龄期为72 h时,混凝土表现出明显的抗振性能。最后,以损伤不大于0.05和强度折减不大于5%双重指标,给出龄期为6 h、12 h、36 h、48 h和72 h的混凝土安全振速分别为2 cm/s、2 cm/s、4 cm/s、5 cm/s、7cm/s。为完善新浇混凝土在爆破振动下的安全标准提供参考。

Experimental study on the influence of blasting vibration on fresh concrete

In order to inspect the safety vibration velocity of fresh concrete under blasting vibration,and ensure the reliability of concrete structure,open-pit longhole blasting was used as a vibration source to test the C40 concrete at the vibration velocity of 2-10 cm/s and the age of 6h,12h,36h,48h and 72h. The following results were obtained by testing the longitudinal wave velocity and compressive strength of specimens at various ages under vibration effect: at the age of 6h and 12h,2.3 cm/s of blasting vibration velocity may cause damage degree greater than 0.05 and strength reduction greater than 5%;at the age of 36h,48h and 72h,the vibration velocity which can cause damage and strength reduction of concrete is 4 cm/s,and the age of 36h is the inflection point of raising the anti-vibration ability of concrete;at the age of 72h,the concrete shows proper anti-vibration performance obviously. Finally,with the double index of damage degree no greater than 0.05 and strength reduction no greater than 5%,the safety vibration velocities of concrete at the age of 6h,12h,36h,48h and 72h were determined: 2 cm/s,2 cm/s,4 cm/s,5 cm/s and 7 cm/s,respectively. The results provide reference for improving safety standards of concrete under blasting vibration.