大骨料混凝土在不连续点处应力和变形研究

Research on stress and strain of big aggregate concrete at discontinuous points

通过试验研究大骨料三级配混凝土与其湿筛二级配混凝土在双轴受力状态下的特性,比较了二者于双轴拉压受力情况下在不连续点处的强度和变形特性,并给出了破坏准则.三级配混凝土的最大骨料尺寸为80 mm,试件最小横向尺寸为250 mm;湿筛混凝土的最大骨料尺寸为40 mm,试件最小横向尺寸为150 mm.描述了试件设计、材料配比、加载设备、减摩措施.通过对试验结果的分析看出,不论混凝土试件的骨料和尺寸大小如何,其不连续点处的两轴应力包络线都是相似的,并都可近似于一直线.混凝土在不连续点处的拉应变值与其平均应力具有较高的相关性.

Characteristics of three-graded big aggregate concrete and the corresponding wet-screened two-graded concrete were experimentally studied. The strength and deformation feature at discontinuous point of the two parts in biaxial compressive-tensile stress state were compared and their failure criteria were developed. In the three-graded concrete, the maximum dimension of aggregate is 80 mm, and the minimum dimension of the specimen cross section is 250 mm, which is respectively 40 mm and 150 mm in wet-screened two-graded concrete. Specimen design, material composition, loading equipment and friction reducing action were also described. The results show that no matter how large the dimension of specimen or aggregate is, the envelope curves at the discontinuous points are in the same shape and approximate to straightline. There is a higher correlation between the tensile strain and the average stress at discontinuous points.