Abstract:
The expand of cities demanded the increase in construction works, and requirement of good construction sites. The accessible sites with problematic geomaterial became a challenge for geotechnical engineers and different methods to increase the use of these sites became priority. Small-scale model tests have been conducted for strip and square footings on soft clay replaced with granular material. Total 10 tests were performed on strip and square footings. 5 tests were performed on each footing, from which one test was performed on soft clay only. While, remaining four tests were performed by changing the width and depth of replacement material. The results were obtained in the form of stress – settlement curve. The ultimate bearing capacity from the tests was calculated using tangent intersection method and 10% footing width method. The extent of replacement was studied by finite element analysis. Total 87 tests were performed on footings in PLAXIS 2D. 41 tests were performed on strip footing by taking four widths of replacement as B, 1.5B, 2B and 2.5B. For each width of replacement, the depth ratio was changed from H/B = 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5. Similarly, 46 tests were performed on square footing with five width of replacements as B, 1.5B, 2B, 2.5B, and 3B with the change of depth ratios of 0.5 to 5B. The plain strain modelling technique, 15 nodal elements and Mohr-Coulomb failure criteria was used in modeling. The direct relation was found between the width of replacement and BCR, the value was significant after the depth ratio of 1.5 and 2.5 for strip and square footings. The increase in BCR was insignificant after a point, that is taken as H/Bcr. The optimum depth of replacement was found to be 4B and 3B for strip and square footings, respectively. While, the most critical and economical width of replacement for square footing was found to be 2B. In strip footing, due to steady increase in bearing capacity no optimum width of replacement was suggested. The small – scale tests were validated and compared with finite element analysis and was found to be in good agreement. It was found that the depth of replacement was more significant factor in improvement of bearing capacity than width of replacement.
