Statistical Evaluation of Material Strength

将分岔理论应用于砂和混凝土抗压强度统计数据库，研究了砂和混凝土抗压强度的统计变化规律。对于混凝土，在圆柱形试样上进行了一系列的压缩试验，以获得应力与应变曲线的集合。首先用0.5mm、1.0mm、2.5mm的玻璃珠进行聚集体，观察粒径对聚集体的影响。通过分岔理论的应用，发现当尺寸小时以分岔为主，而当尺寸大时以断裂为主。接下来，通过改变水灰比的26%、35%和62%的值来研究水灰比的影响，注意到当水灰比的值较大时，分叉占主导地位。对于砂土，在Toyoura圆柱砂试件上进行了50组三轴压缩试验，获得了完整的应力-应变曲线。由于本理论仅适用于分岔模态唯一的情况，因此在试验过程中对试件进行了照片和素描，以识别分岔模态，并根据这些分岔模态对曲线进行了分类。以这种方式分类的曲线准确地遵循了分岔理论；这就评估了理论的有效性。

The statistical strength variation of sand and concrete is investigated through the assemblage of statistical data bank of their compressive strength and the application of the bifurcation theory to the data.For concrete, a series of compression tests are conducted on cylindrical specimens to obtain an ensemble of stress versus strain curves. First gless beads of the size of 0.5mm, 1.0mm, and 2.5mm were used for sggregates to observe the influence of the size. Through the application of the bifurcation theory, it has been noted that bifurcation is predominant when the size is small, whereas fracture is predominant when large. Next the influence of the water cement ratio was investigated by varying its values by 26%, 35%, and 62% to note that bifurcation is predominant when its value is large.For sand, a set of 50 triaxial compression tests were conducted on cylindrical Toyoura sand speciments to obtain an ensemble of stress versus strain curves. Since the present theory is applicable only for the case where the bifurcation mode is unique, the photos and sketches of the specimens were taken during the tests to identify the bifurcation modes, and those curves were categorized in view of these modes. The curves categorized in this manner accurately followed the bifurcation theory ; this assesses the validity of the theory.