تقييم أداء الأسس المفردة على ترب رملية مفككة مثبتة

ASSESSING THE PERFORMANCE OF ISOLATED FOOTINGS ON STABILIZED LOOSE SAND SOILS

Abstract

Geotechnical engineering aims to improve weak soils for shallow foundations, preventing foundation instability. Soil stabilization techniques, including chemical stabilization and soil fiber reinforcement, are used to enhance soil properties and load-bearing capacity. This study investigates the load-bearing capacity of isolated shallow footings. Chemical stabilization was conducted using two different types of materials: metakaolin (MK) as a pozzolanic material and Conbextra (GP) as a cementitious material. Additionally, glass fiber (GF) was utilized for soil reinforcement. The experimental testing methods utilized in this work include the standard Proctor test, unconfined compressive strength test (UCST), and direct shear test (DST). Additionally, a small testing model was developed to examine the structural behaviour of the different isolated footings (i.e., circle and square) built on stabilized soil. The results of the Proctor test showed an increase in the maximum dry density with the inclusion of GP and MK content in the soil mixtures. The results of the UCST indicate that the optimal dosage of GP and MK used in the soil mixture where 15% and 10%, respectively. It was also found that the use of 0.5% and 1.0% GF provides the optimal soil reinforcement for GP-soil and MK-soil mixtures cured for three days. Moreover, a small testing model was prepared using layers mixed with GP and MK and reinforced with GF at two thicknesses: 1B and 2B (B is with footing). Two types of model footing were evaluated: circular and square. The results of the testing model indicated that the stabilized top layers with GP and MK and reinforced with GF increased the ultimate bearing capacity and decreased the settlement. Square footings perform better than circular footings in terms of bearing capacity and settlement. The bearing capacity increased by 333% and 340% for GP-soil and MK-soil mixtures, and 489% and 430% for GP-soil and MK-soil mixtures when reinforced with GF. The settlement reduction ratio increased by 98% and 36% for GP-soil and MK-soil mixtures, and 89% and 80% for GP-soil and MK-soil mixtures when reinforced with GF. The improvement factor for all GP-soil mixtures ranged from 2.7% to 12%, and the improvement factor for all MK-soil mixtures ranged from 0.5% to 12.4%.