钢筋混凝土管片极限承载力计算模型及数值模拟分析

Calculation model and numerical simulation analysis of ultimate bearing capacity of reinforced concrete segment

钢筋混凝土管片是地铁开挖支护中常见的支护构件,其受力性能决定了工程质量优劣及工程安全稳定性,故研究其在极限状态下的破坏模式尤为重要。基于钢筋混凝土管片常见的4种破坏模式,以天津地铁6号线为例,分析其在4种不同轴力下的破坏形态,同时用数值模拟进行了验证。结果表明:本案例模型符合模式4的破坏形态,即混凝土达到极限状态,受拉钢筋达到屈服状态,且混凝土先达到极限强度,而受拉钢筋未达到极限应变;对比模式4和用MIDAS数值模拟计算的受压区钢筋应力、受拉区钢筋应变以及弯矩,发现数值模拟计算值要稍低于计算模型计算值,但整体变化规律一致,即随着轴力的增加,其均成线性增加,且在4种轴力下,最大偏差均不超过10%。

Reinforced concrete segment is a common supporting component in the process of subway excavation and support.Its mechanical property determines the quality,safety and stability of the project.Therefore,it is particularly important to study the failure mode of reinforced concrete segment in the limit state.Based on the four common failure modes of reinforced concrete segments,taking Tianjin Metro Line 6 as an example,the failure modes under four different axial forces are analyzed and verified by numerical simulation.The results show that the case model accords with the failure pattern of mode 4,that is,the concrete reaches the ultimate state,the tensile reinforcement reaches the yield state,and the concrete reaches the ultimate strength first,while the tensile reinforcement does not reach the ultimate tensile strain.Comparing mode 4 with the steel bar stress in compression zone,steel bar strain in tension zone and bending moment calculated by MIDAS numerical simulation,it is found that the numerical simulation value is slightly lower than that calculated by the calculation model,but the overall change law is the same,that is,with the increase of axial force,it increases linearly,and the maximum deviation is less than 10%under the four axial forces.