混凝土材料的层裂特性

利用Hopkinson压杆作为实验设备，通过试件后面吸收杆上应变波形研究了混凝土材料的层裂特性。不同强度混凝土在不同加载率下的实验结果表明，混凝土层裂强度与其压缩强度以及加载速率有关，给出了层裂强度和压缩强度以及加载率之间关系的经验公式，并指出不同加载速度下混凝土裂纹扩展方式不同是层裂强度率效应的主要原因。加载压缩波损伤的影响、重复加载实验以及多次层裂的顺序都表明，损伤对混凝土的层裂过程有重要影响。

Spall characteristics of concrete materials

The Hopkinson pressure bar tests were performed to explore the spall characteristics of concrete materials by analyzing the strain waves of the buffer bar. The experimental results, for concretes with different spall strengths at different load rates, indicate that the spall strength of concrete is related with its compressive strength and load rate. An empirical formula was proposed to describe the functional relationship between spall strength, compressive strength and load rate.  The rate effect of spall strength mainly results from the different expending paths of crack in concrete at different load rates. Some special efforts, which include the effect of the load compressive wave damage on concrete spall fracture, the results of reduplicate load experiments and the sequences of the multiple spall process, explain that damage plays an important role in the spall fracture of concrete.