混凝土类材料动态压缩强度在多维应力状态下的应变率效应  

Stain-rate effects on the dynamic compressive strength of concrete-like materials under multiple stress state

作　　者：刘锋 李庆明[2] LIU Feng;LI Qingming(Shandong Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,Shandong,China;School of Engineering,University of Manchester,Manchester M139PL,UK)

机构地区：[1]山东科技大学山东省土木工程防灾减灾重点实验室,山东青岛266590 [2]曼彻斯特大学工程学院,英国曼彻斯特M139PL

出　　处：《爆炸与冲击》2022年第9期123-138,共16页Explosion and Shock Waves

基　　金：国家自然科学基金(11272060,52078283,12172198)。

摘　　要：对混凝土类材料动态压缩应变率效应研究的发展及问题进行了概述,对比不同应力状态下混凝土类材料动态压缩应变率效应的表现特征,揭示了不同加载路径下实测动态强度提高系数的显著差异。研究表明,在高应变率下,基于初始一维应力加载路径的试件将因横向惯性效应导致的侧向围压而演化至多维应力状态,传统霍普金森杆技术无法获得高应变率下基于真实一维应力路径的动态强度提高系数,在强度模型中直接应用实测数据将过高估计材料的动态强度。鉴于应变率效应的加载路径依赖性,将仅包含应变率的强度提高系数模型扩展至同时计及应变率和应力状态的多维应力状态模型,并结合Drucker-Prager准则在强度模型中给予了实现。针对具有自由和约束边界试件开展的数值霍普金森杆实验表明,多维应力状态下的应变率效应模型可以考虑应变率效应随应力状态改变的特点,从而准确预测该类材料的动态压缩强度。研究结果可为正确应用霍普金森杆技术确定脆性材料的动态压缩强度提供参考。This paper first reviews the development and relevant issues in relation to the strain rate effects on the compressive strength of concrete-like materials. For different characteristics of strain-rate effects on the dynamic compressive strength of concrete-like materials under various stress states, it reveals the significant discrepancies in the measured dynamic increase factors(DIF) under different loading paths. At high strain-rate loading, the test specimen based on the initial 1D-stress state gradually evolves to a multiaxial one due to the increasing lateral confining pressure caused by the lateral inertia effect. The traditional split Hopkinson pressure bar(SHPB) test cannot obtain the genuine DIF data under real 1D-stress state at high strain rates. The strength models based on the direct adaptation of the experimentally measured DIF using SHPB overestimate the dynamic strength of these materials. Considering the loading-path dependence of the strain-rate effect, this study extends the DIF model depending only on strain-rate to a more general DIF model depending on both the strain-rate and the stress state,which is then implemented into the Drucker-Prager strength model. Numerical SHPB tests are conducted on samples with free and constrained boundaries. The comparison between test data and numerical predications shows that the proposed DIF model can describe the stress state dependency of the strain rate effect, and hence can predict the dynamic compressive strength of concrete-lime materials more accurately. The present study is of great significance for correctly applying SHPB technology to determine the dynamic compressive strength of brittle materials.

关 键 词：应变率效应 霍普金森杆 混凝土类材料 压缩强度 应力状态 

分 类 号：O347.3[理学—固体力学]