A simplified extension of the conventional theory of arching in soils

A general formulation is presented for the analysis of arching in soils as an extension of the conventional shear plane approach, in which the slip surfaces within the soil mass are considered as vertical planes. Such an assumption results in a low estimate of the design load on the yielding buried structure because of a considerable separation between the assumed vertical slip surfaces and the actual curved slip surfaces. The arching theory presented in this paper overcomes this limitation of the conventional theory by assuming inclined slip surfaces close to the actual slip surfaces. Based on this concept, an analytical expression for the vertical stress on the yielding structure is derived; a special case of this general expression reduces to the conventional expression. The variation of the vertical stress on the yielding structure with depth has been presented graphically along with a comparison with the conventional vertical shear plane approach. It is observed that the amount of arching increases with increase in the ratio of depth to width of the yielding structure as reported in the literature.