Bearing behavior and failure mechanism of a shallow foundation located on/behind the crest of a poorly cemented artificial sandstone

Abstract

Shallow footing located on/behind the crest of a slope is encountered frequently. To reduce the cost and to improve the performance of structure supports, structures are usually placed on the slope crest or at a setback distance from the slope crest. However, the bearing capacity of such foundations may be reduced because of the influence of the slope. The understanding of the bearing behavior and failure mechanism of the geo-material under a footing foundation under such conditions is essential. In general, the bearing-failure mode of a foundation on soil depends on soil compressibility and loading type. These types of failure mechanisms are essentially plastic in nature. On the other hand, the bearing-failure mode of a footing foundation on rock can be attributed to the discontinuities or the intact rock properties in a rock mass [1]. Landanyi [2] studied the punching failure of a nonporous brittle rock; he observed various fracturing stages as the bearing pressure approached the ultimate bearing capacity. These fracturing stages included initiation, growing, and finally coalesce forming, which resulted in the areas of crushed rock. Unlike foundations on soil, the feature of the failure mechanism of rock is essentially brittle. For many young and poorly cemented rocks, the function of lithification with particle cementation and perfect lock-up cannot be achieved due to short period of lithification age [3]. The poorly cemented rock commonly observed in the northern and western foothills of Taiwan is a typical example of this type of geo-material. It usually displays distinctive engineering characteristics including