A hollow cylinder torsional simple shear apparatus capable of a wide range of shear strain measurement
A hollow cylinder torsional simple shear apparatus capable of a wide range of shear strain measurement
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一种可进行大范围剪应变测量的空心圆柱扭转单剪装置
DOI：
10.1520/gtj10262j
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发表时间：
1993
影响因子：
1.6
通讯作者：
F. Tatsuoka
中科院分区：
文献类型：
--
作者：
H. Pincus;S. Ampadu;F. Tatsuoka
由于缺乏单调载荷下小应变的高质量数据，导致在小应变分析中假设线弹性，并使用低刚度值来分析工作载荷下的岩土结构。此外，由于大多数简单的剪切装置无法测量侧向应力，因此必须做出各种假设才能根据主应力定义破坏强度。本文描述了一种空心圆柱扭转简单剪切系统，除了测量所有应力分量之外，该系统还能够准确测量从小至 10−6 的应变水平到失效的剪切应变。该系统还能够沿着正常和超固结应力路径固结样本，并且在剪切过程中能够施加极小的载荷反转，而几乎没有或没有间隙效应。利用该系统的特殊功能，研究了高岭土样品在从非常小的应变到破坏的各种应力历史下的行为。结果表明，无论固结应力历史如何，主应力旋转的主要部分发生在不排水简剪的早期阶段，并且峰值强度附近的最终方向始终低于45°几度。小应变行为表明存在 2 × 10−5 剪切应变量级的非常小的弹性区，并且超出该区域的行为是高度非线性的。该系统中获得的峰值强度随 OCR 变化的趋势与文献中报道的传统简单剪切装置中获得的趋势相似。
The lack of high-quality data at small strains under monotonic loads has led to the assumption of linear elasticity in small strain analysis and the use of low values of stiffness for analysis of geotechnical structures under working loads. In addition, since most simple shear apparatuses cannot measure lateral stresses, various assumptions have to be made in order to define the failure strength in terms of principal stresses. In this paper a hollow cylinder torsional simple shear system that is capable of measuring shear strains accurately from a strain level as small as 10−6 to failure in addition to measuring all stress components is described. This system is also capable of consolidating specimens along both normal and overconsolidated stress paths and during shearing is able to apply extremely small load reversals with little or no backlash effect. Using the special features of this system, the behavior of kaolin specimens under various stress histories from very small strains to failure was studied. The results show that irrespective of the consolidation stress history, the major part of the principal stress rotation occurs at the early stages of undrained simple shear, and the final direction near the peak strength is always a few degrees below 45°. The small strain behavior indicates that there exists a very small elastic zone of the order of 2 × 10−5 shear strain, and that the behavior beyond this region is highly nonlinear. The trend in the variation of the peak strength with OCR obtained in this system is similar to that obtained in the conventional simple shear apparatus as reported in the literature.