Experimental and analytical Study on Three-dimensional Bearing Capacity of Soft Rock Ground.

为了研究软岩的承载力特性，在人工软岩上进行了模型圆形基础的加载试验。本文研究了软岩试验装置的制备方法。进行了单调加载试验、循环加载试验和开挖加载试验。对基础和地基的观测表明，在单调荷载作用下，软岩地基的破坏形式为冲剪破坏。在单调加载试验中不能识别屈服应力。在开挖试验中，软岩地基表现出明显的屈服特征，并识别出典型的一般剪切破坏。通过对软岩地基纵断面的观测，得出以下结论：对其屈服变形特性和破坏机理进行了研究。局部压缩致密区产生于地基边缘，并在地基下方合并；致密区向下延伸。同时，裂缝从基础边缘产生。在开挖荷载中，由于消除了基础上方质量的约束，显示出普遍的剪切破坏。在软岩台阶圆形基础的加载试验中，也观察到典型的一般剪切破坏。

In order to investigate the bearing capacity characteristics of soft rock, loading test of model circular footing was carried on the artificial soft rock. In this study, Preparation method of Soft Rock test Ppparatus were developed.Three types of loading tests were performed : monotonic loading test, cyclic loading test and excavation loading test. The observed behavior of the footing and the ground showed that the soft rock ground failed in punching shear type under the monotonic loading. The yielding stress is not recognized in the monotonic loading test. In the excavation test the soft rock ground showed the clear yielding feature, and the typical general shear failure was recognized.From the observation of the vertical section of soft rock ground, the follouings were revealed. The yielding-deformation characteristics and the failure mechanics were investigated.The local compressed densified zones generate at the verge of the footing and merge at the beneath the footing ; the densified zone extends downward. At the same time the crack generates from the verge of the footing. In the excavation loading the general shear failure was shown due to the elimination of the confinement by the mass over the footing base. In the loading test of the circular footing on the step of the soft rock ground, also the typical general shear failure was observed.