Development of Ultra Small Shear-box Test Apparatus indeced in the scanning Electron Microscope

为了观察粘土真实的微观剪切变形过程，研制了一种新型的超小型剪切盒试验装置。它的设计目的是能够控制法向应力和剪应力，并观察微观剪切变形和微观剪胀。因此，我们可以很容易地比较细观变形行为和宏观应力-应变特性.用干燥固结的高岭石试样，将所观察到的变形行为记录在录像机上，然后用微机分析其图形，所得结果如下：（1）成功地将微变形行为记录在录像机上。(2)在峰值剪应力出现之前，颗粒变形仅表现为局部变形，弯曲应力发生在裂纹点。(3)在峰值剪应力处，剪切强度达到最大值，主剪切面与微裂纹独立发生。(4)在残余应力作用下，剪切面上的局部变形仍然存在，而不是宏观上的恒定变形。

In order to obsearve the real microscopic shear deformation process of cloay soils, a new type of the Ultra Samll Shear-box Test Apparatus has been developed. It is designed to be able to control the normal and shear strsses and to observe micro shear deformation and micro dilatancy. Therefor, we can easily compare the micro deformation behaviour with the macro stress- strain properties. The observed behaviout was recorded into VTR and then after analyzed their patterns by a microcomputer.The results obtained, using the dried and consolidated kaolinite samples, are summarized as follows;(1) The recording of the micro deformation behaviout into VTR was obtained successfully.(2) Before the peak shear stress, the particle deformation is only observed locally and the bending stree occurs at the crack point.(3) At the peak shear stress, the dilatancy is amounted the maximum values, and then the main shear surfaces take place independently with the micro hair cracks.(4) At the residual stress, the local deformation is still observed in the only shear surface instead of the constant macro dilatancy.