Solved: 2. (a) When calculating the drained bearing capacity of a shallow foun

Question

2. (a) When calculating the drained bearing capacity of a shallow foundation, it is important to know the highest level to which groundwater could rise during the design life. Using diagrams to illustrate your answer, explain why this is so. [5] (b) A pad footing with the dimensions shown in Figure Q2.1 is to carry a dead load Gk of (1290+Y) kN and a live load Qk of (410+Y) kN at existing ground level. The footing is founded in stiff saturated clay that extends to a depth of 20 m, underlain by very dense gravel. The undrained shear strength is (35+X) kPa at ground level, increasing linearly with depth at a rate of 5 kPa/m. The saturated unit weight of the clay is (19+Z) kN/m3, and Eu/cu is estimated to be about 400. The combined weight of the concrete footing and backfill can be assumed to be equal to that of the excavated soil. The variables X, Y and Z are defined on the cover page. Pad footing (L = 4.4 m) Soil strength profile (GK + QK) KN V GL > 35+X Cụ (kPa) 1.5 m 5 clay 1 backfill 2.2 m z (m) (NOT TO SCALE) Figure Q2.1 i) Calculate the degree of utilisation using Eurocode 7 Design Approach 1, Combination 2 (DA1-2) and comment on the value obtained. Why would it be unnecessary to check the long term degree of utilisation in this case? [13] ii) Using Butler's (1975) charts, estimate the immediate settlement at one corner of the footing, stating any assumptions made. [8]