小湾拱坝湿筛混凝土动态弯拉力学特性试验研究

结合小湾拱坝,试验研究了湿筛混凝土动态弯拉力学特性。试验采用MTS322动静万能试验机和简支梁三分点加荷法。静载试验加载速率为250N/s。动载试验考虑了不同初始静载(0%、40%、80%、90%)和不同动态加载方式(冲击和变幅三角波)。40%、80%和90%初始静载分别取18.6kN、37.2kN和41.8kN,以静载速率加载至初始静载值,再施加动态荷载。冲击波形加载速率是250kN/s。变幅三角波形加载频率是1Hz,每个加载台阶含3个周期,相邻加载台阶差值是20kN。湿筛混凝土试验结果表明:(1)初始静载对混凝土动态极限弯拉强度影响很大;(2)合适比例的初始静载对混凝土动态极限弯拉强度有利,80%初始静载时动态弯拉强度提高最大,冲击试验DIF高达1.49;(3)同静载相比,冲击加载时混凝土动态极限弯拉强度提高,弯拉极限拉伸值略小,弹性模量提高不多,纯弯区正截面中和轴位置没有变化;(4)往复加载对混凝土存在低周疲劳的不利影响。对比分析表明,三级配混凝土与其湿筛混凝土动态弯拉力学特性,定性规律相似,但定量结果尚得不出来,进行高拱坝抗震设计时,应采用全级配混凝土动态试验结果。

Experimental study on dynamic flexural-tensile mechanical behavior of wet sieving concrete of Xiaowan Arch Dam

The experiment on dynamic flexural-tensile mechanical behavior of wet sieving concrete for the Xiaowan Arch Dam was carried out.The test was performed by using the third point loading method for simply supported beam with MTS322 testing machine.In the static loading tests,the loading rate was 250N/s.In the dynamic loading tests,different initial static load(90%,80%,40%and 0%)and different dynamic load patterns(impact wave and triangle wave with variable amplitude),were considered.When the initial static loa...