基于S准则发展的混凝土动态多轴强度准则

通过对经典强度理论或准则的强度参数分析,将强度参数转化为由混凝土的单轴压缩和单轴拉伸强度表示,结合S准则给出的混凝土单轴强度的率效应规律,得出了强度参数受应变率影响的率效应函数,进而将常用的静态多轴强度准则摩尔-库伦强度理论、松岗-中井强度理论、德鲁克-普拉格强度理论、拉得-邓肯强度准则和胡克-布朗强度准则发展为动态多轴强度准则.利用混凝土动态单轴压缩和动态单轴拉伸试验结果统计分析给出的S准则率效应参数,分析了5种强度准则中强度参数随应变率的变化规律以及取值范围.基于混凝土单轴压缩和单轴拉伸强度,分别给出了5种强度准则在子午面、偏平面和平面应力条件下的强度曲线与主应力空间中的强度曲面,对比分析了5种强度准则间的异同,以及每种强度准则随应变率的变化规律.利用混凝土材料的动态双轴和动态真三轴强度试验结果,分析评价了5种动态多轴强度准则,并且阐述了各动态多轴强度准则的应变率适用范围.德鲁克-普拉格强度理论与试验结果相差甚远,不适于描述混凝土材料的强度规律.动态双轴加载时,在拉压区各强度准则差别不大,都可较好地描述试验规律;在压压区各强度准则差别较大,松岗-中井强度理论与试验结果吻合最好.在动态真三轴比例加载时,摩尔-库伦强度理论和胡克-布朗强度准则无法考虑中主应力的影响;松岗-中井强度理论和拉得-邓肯强度准则都可较好地描述试验规律. 

DYNAMIC MULTIAXIAL STRENGTH CRITERION FOR CONCRETE DEVELOPED BASED ON THE S CRITEIRON

The classical strength criteria including Mohr-Coulomb strength theory, Drucker-Prager strength theory, Matsuoka-Nakai strength theory, Lade-Duncan strength criterion and Hoek-Brown strength criterion are developed into dynamic multiaxial strength criteria by deriving the strain-rate-dependent strength parameters of each static strength cri-terion. The strain-rate-dependent strength parameters are obtained by combing the dynamic uniaxial S criterion and the basic strength indexes of concrete material. Then the change rules and value range of strength parameters of five strength criteria are analyzed by these statistical material parameters of S criterion. On the basis of the uniaxial compressive and tensile strengths of concrete, the strength curves of each dynamic multiaxial strength criterion at plane stress condition, meridian plane, deviatoric plane and the strength surfaces in the principle stress space are given. Then the differences of the five dynamic multiaxial strength criteria are analyzed. The five dynamic strength criteria are evaluated by the dynamic biaxial and true triaxial strength tests. The dynamic Drucker–Prager criterion shows big differences with the dynamic test results of concrete. All of the dynamic strength criteria are able to reasonably describe the strength rules under biaxial compression-tension. It also shows big difference among these dynamic strength criteria, while the dynamic Matsuoka–Nakai criteria describes the strength rules better than others. Under dynamic true triaxial proportional loading, Mohr–Coulomb and Hoek–Brown strength criteria cannot consider the influences of intermediate principal stress, while the Matsuoka–Nakai and Lade–Duncan strength criteria are capable of well describing the test results of concrete.