نتیجه نشست فونداسیون سطحی بر روی خاک گرانولار Load–settlement response of shallow foundations resting on granular soil

Introduction Foundations are essential for engineered structures, transmitting and distributing the supported loads into the underlying soil structure. Engineers typically aim for designs where soil pressures at all depths are maintained within acceptable levels, preventing soil shear failure and limiting soil settlements within tolerable levels. Foundation settlement starts as early as during construction, and increases gradually as the load is increased. This loadsettlement response, if permitted, continues up to the point where the load per unit area equals ultimate pressure, at which the soil supporting the foundation fails, referred to as the ultimate bearing capacity (qult). The classical solution for Ultimate Bearing Capacity of soil with cohesion, c, and friction angle, /, is typically assessed based on a bearing capacity equation composed of three terms, as a function of the pressure generated by the foundation width, B, embedment depth, Df, and c; as in Terzaghi, Meyerhof, Hansen and Vesic models. Each term is multiplied by a bearing capacity factor; these factors are a function of /. These models are thoroughly reported in the literature. For instance, The Army Corps of Engineers (republished by ASCE [1]) provides a comprehensive listing of Terzaghi, Meyerhof, Hansen, and Vesic equations and factors. While there is an agreement on the basic bearing capacity equation, differences regarding the form of the factors exist between them. However, the equations for bearing capacity factors are largely theoretical utilizing multiple correction factors that are semi-empirical in nature, based on lab scale model tests, where B is usually less than 12 inches. Only a few field tests with more realistic values of B have been documented in the literature. Then again, most field tests are usually terminated as some arbitrarily predetermined failure criterion based on settlement, rather than carrying out the test to the ultimate soil failure where no additional load carrying capacity is observed, regardless of the settlement. Hence, these solutions provide an ultimate bearing capacity value without regard to the progression of the load response (up to failure), then this load response is decoupled from the corresponding settlement response.