Estudo de caso: análise de projeto de fundações não convencionais em solo arenoso com a presença de rocha calcária

Abstract

This work presents the analysis of a foundation project partially divided between injected rotary piles with bulbs and footings based on improved limestone rock with mortared columns, located in the beach region of the city of Maceió, Alagoas, located in the Northeast region of Brazil. The surveys carried out indicated that 47.5% and 52.5% of the land area was made up of sandy soil and limestone, respectively. Making the use of continuous helix piles, the most used in the region, unfeasible, in addition, due to the high cost of mobilization, the Root piles were discarded. For the section in sandy soil, Injected Rotary Piles with a diameter of 0.40 m, 10 m in length and 2 shaft extensions (bulbs) were adopted, located 3.25 m and 7.75 m from the top of the pile. For the section in limestone rock, footings placed directly on limestone rock were adopted, to fill the possible caves in the rock, a 700 x 700 mm mesh was created with mortared columns of 0.1 m in diameter and 4.50 m in length in the entire base of the shoe. To analyze the performance of the foundation, two slow static load tests were carried out, one test with the footing supported on rock (PC-1) and the other test with the pile supported on soil (PC-2). In the PC-1 test, a final load of 204 tf/m² was applied, with a maximum settlement of 17.70 mm and a working load settlement of 6.46 mm. In the PC-2 test, a final load of 180 tf was applied, with a maximum settlement of 36.47 mm and a working load settlement of 5.07 mm. As the allowable stress of the limestone rock and the design load of the piles were set at 100 tf/m² and 60 tf, respectively, and the difference in settlement in the working load was insignificant, the analysis of the results of the load tests showed that the design assumptions met both the rupture and allowable settlement criteria.