An Investigation on the Behaviour of Geosynthetic Reinforced Quarry Waste Bases (QWB) Under Vertical loading.

The strength and rigidity of base course can significantly affect the performance of pavements. The rigidity of roadways relies on the infill material used in base layers which is interdependent on its thickness and quality. With the increase in the base thickness, the performance of the base course improves but the cost associated with it also increases. Since the natural aggregates are not adequately available, use of waste materials in road construction can prove economical and environmental friendly. In this study, efficacy of geosynthetic (geocells and non-woven geotextile) reinforced quarry waste as an alternative base course materials (BCM) were investigated under static loading conditions (plate load test-PLT). By increasing the geocell height from 100 to 150 mm, the bearing capacity (BC) increased from 450 to 840 kPa. Similarly due to combined use of geocell and geotextile, BC increased from 500 to 890 kPa. The experimental results depict that the geosynthetic reinforcement increases the load bearing capacity of QWB's by 85%. Moreover, the artificial neural network analysis (ANN) was performed to predict the deformation on top of footing while considering different influential parameters. The results obtained from the ANN analysis were in good fit.

Plate load tests to analyze the load-settlement response of shallow foundations on sand beds reinforced with micropiles.

Micropiles can act as structural support for a new foundation and sustainable solution for existing foundations with advantages such as high load-carrying capacity and use in in situ conditions. Installing micropiles around the footing at some distance from the footing edge could turn out to be extremely helpful for existing distressed foundations where improvement is needed. An experimental investigation is carried out on a laboratory model square footing in the ongoing study, placed on sand, with micropiles driven around the footing. A parametric study focusing on the effect of the slenderness ratio of the micropiles, the state of sand beds, the micropile spacing ratio (S/b), and the micropile edge distance ratio (ED/d) are analyzed. The results demonstrate that the micropiles can appreciably improve the footing's settlement characteristics and load-bearing capacity when placed around it. The load-carrying capacity shows some appreciable increase by increasing the slenderness ratio of micropiles, but increasing the slenderness ratio beyond 20 is insignificant. For unreinforced footing, a denser form of sand was found more advantageous in terms of bearing capacity, while as for reinforced footing, micropiles provided maximum improvement for medium-density sand. The improvement in bearing capacity is approximately 22.2% when the spacing ratio is reduced from 0.5 to 0.3. Also, for an edge distance ratio of 3, the improvement in the bearing capacity ratio is 76% higher than that of unreinforced footing. Multivariate linear regression showed a strong correlation between the experimental and predicted bearing capacity ratio.

Influence of micropile parameters on bearing capacity of footings.

Micropiles, on account of their versatility, can serve as both a new foundation and a long-term option for prevailing foundations without disturbing the subgrade underneath. They can improve highway facilities, historically significant structures, or distressed structures. The present laboratory model study is conducted on a square footing installed with micropiles all around it and subjected to vertical concentric loading. A parametric analysis based on the impact of five micropile parameters is also performed. The results obtained from this study reveal that the inclination of micropiles has little effect on ultimate vertical load but can profoundly impact the horizontal load. As the diameter of micropiles is progressively increased from 10 to 20 mm, the bearing capacity improves by around 27%. As the micropile spacing decreases from five times diameter (5d) to three times diameter (3d), the footing system's bearing capacity increases nearly by 22.2%. The bearing capacity ratio shows a reduction beyond the value of L/b = 2. Installing micropiles nearer to the footing edge (ED/b = 0.3) provided approximately 76% improvement with respect to the unreinforced footing. The optimum value of the different parameters is equal to L/b = 2, d = 20 mm, ED/b = 0.3, and S/d = 3. There is a 98% improvement in bearing capacity at the optimum values for 30° inclined micropiles.