山区桥梁墩柱抗落石冲击防护措施的耐撞性

Crashworthiness of the protective measures for mountain bridge piers under impact load of rockfall

为了研究山区桥梁钢筋混凝土桥梁墩柱抗落石冲击防护措施的耐撞性,基于现场调查,采用显式非线性动力分析方法,结合部分模型试验结果,针对外套钢板筒与加厚素混凝土保护层这两种典型的防护措施展开了数值模拟。采用Holmquist-Johnson-Cook(HJC)损伤本构模拟钢筋混凝土,落石冲击模型则参照欧洲被动防护网试验规范;结合桥墩受落石冲击破坏的特点,对落石试验模型的撞击面做了加肋处理。研究了钢板筒厚度、混凝土保护层厚度变化对耐撞性的影响。结果表明,当钢板筒厚度大于20 mm、保护层厚度大于100 mm时,方可获得较好的耐撞性,同时针对粘结式外套钢板筒防护措施的不足,进一步提出了分离式外套钢板筒的改进措施。

In order to investigate erashworthiness of the protective measures for mountain bridge piers under impact load of rockfall, numerical simulations were conducted according to two typical protective measures, adding steel plate tube and thickening concrete protective layer, with the methods of explicit nonlinear dynamic analysis based on field investigation and some model test results. Holmquist-Johnson-Cook （HJC） damage constitution model was chosen to simulate reinforced concrete,and the rockfall specimen was built with reference to the test specification of the European passive safety net. According to failure characteristics of bridge piers under impact load,the contact surfaces of rockfall specimen were stiffened with three steel plates. The influence of the thickness variation of concrete protective layer and steel plate tube on crashworthiness was analyzed. The results indicated that a better crashworthiness could be obtained when the thickness of steel plate tube was greater than 20 mm or the thickness of protective layer was greater than 100 mm. Furthermore, an improvement measure that was separate-contacted steel plate tube was raised to overcome the disadvantage of bonded steel plate tube.