侧爆作用下土中竖井结构弹塑性变形特征分析及计算

Analysis and Calculation of Elastoplastic Deformation Characteristics of Shaft Structure in Soil Under Side Blast

摘要:

针对土中钢板?钢筋混凝土竖井结构在常规武器爆炸作用下塑性铰线形成前的动力响应问题，综合采用模型试验、有限元数值仿真方法，分析了竖井结构中远距离爆炸作用下的变形过程及特征，确定了以量纲一环向相对位移α1作为结构变形程度的判据。推导了土中竖井结构在常规武器爆炸作用下的动力响应理论解，分析了按照弹性理论计算的量纲一环向相对位移α1e和有限元计算得到的弹塑性量纲一环向相对位移α1p的关系及其比值α1p/α1e的影响因素，构建了基于弹性解的弹塑性量纲一环向相对位移α1p工程算法。提出了以量纲一环向相对位移α1作为结构变形程度的判据，并确定了结构闭环塑性铰线出现、破坏模式改变的阈值为α1=3%；对比了理论与数值模拟计算结果，验证了提出的理论计算方法可以较好地计算钢板?混凝土竖井组合结构在常规武器爆炸作用下弹性阶段的动力响应；结构长径比、结构缩尺比例、装药量大小对α1p/α1e随α1e的变化规律的影响可以忽略；等效厚径比、钢板与混凝土厚度比较大及结构的相对高度较小时，计算得到的α1e偏小，α1p/α1e较大。混凝土强度较大时，α1e相同情况下结构塑性变形较小，α1p/α1e较小。

Abstract:

In order to study the dynamic response of steel plate-reinforced concrete shaft structure in soil before the formation of plastic hinge line under the action of conventional weapon explosion， based on the model experiment and finite element numerical simulation calculation method， the deformation process and characteristics of shaft structure under medium or long distance explosion were analyzed. The dimensionless circumferential relative displacement was determined as the criterion of structural deformation degree. The theoretical solution of the dynamic response of the shaft structure in soil under the explosion of conventional weapons was derived. The relationship between the dimensionless circumferential relative displacement calculated according to the elastic theory α1e and calculated by the finite element method α1p were analyzed ，and the influencing factors of the ratio α1p/α1e were discussed. The engineering algorithm of elastic-plastic dimensionless circumferential relative displacement α1p based on the elastic solution was constructed.The dimensionless circumferential relative displacement was proposed as the criterion of structural deformation degree， and the threshold value for the occurrence of plastic hinge line and the change of failure mode was determined as 3%. It was verified that the proposed theoretical calculation method can well calculate the dynamic response of steel plate-concrete shaft structure in elastic stage under conventional weapon explosion through the comparison between theoretical and numerical simulation results. The influence of the length-diameter ratio， the scale ratio of the structure and the mass of charge can be neglected. When the equivalent thickness-to-diameter ratio_e， the thickness ratio of steel plate to concrete are large and the relative height of the structure is small， α1e descreases and α1p/α1e increases. When α1e is equal， the plastic deformation of the structure， and α1p/α1e decreases， with the increase of concrete strength.