Investigating the Collapsible Behavior of Sedimentary Soil in Shallow Foundations

Some unsaturated soils present volumetric instability with moisture variation, under constant stress. This paper presents results of an investigation on the behavior of a soil subjected to wetting, aimed at applying shallow foundations. The investigation occurred through laboratory tests (on natural and compacted samples) and field tests (load tests on plates with diameters of 0.80 m and 0.10 m), for analysis of the load x settlement curve and the behavior of natural soil collapse and compressed. From the results, it is highlighted that both in the laboratory and in the field, the undisturbed soil showed collapse behavior when wet, under stresses > 100 kN/m²; the compacted soil showed a significant reduction of settlement by collapse, indicating that it is a treatment option to support superficial foundations, being important to be careful with the width of the compacted layer; field tests, with different sizes of plates, suggest correlations between them, as well as with edometric tests; the load tests, with a 0.10 m diameter plate, proved to be promising for estimating the admissible stress of fine textured soils and for estimating the potential for collapse in the field, being able to help the projects of small works, supported on shallow foundations.