Biogrouting, a method to enhance soil properties using microorganisms and mechanical techniques, has shown great potential for soil improvement. Most studies focus on small sand columns in labs, but recent tests used 0.5 m plastic boxes filled with sand stabilized with microorganisms and fly ash. The experiments, conducted over 30 days, applied injection and infusion methods with microbial fluids, maintaining groundwater levels to simulate field conditions. Mechanical properties were analyzed through unconfined compressive strength (UCS) tests on extracted samples. Researchers also assessed calcium carbonate distribution and shear strength. Results showed water saturation significantly influenced vertical stress (qu), while UCS correlated with the permeability of sand containing varying calcium carbonate levels. Bacillus safensis, a resilient bacterium used in this process, can withstand extreme conditions. After completing its task, it enters a dormant state and reactivates when needed. The bacteria produce calcium carbonate by binding calcium with enzymes, which cements soil particles, enhancing strength and stability. center dot Testing enzymes on microbes and natural soil center dot Installation settings for drip tools using infusion center dot Soil resistance testing after stabilization using UCS

Soil liquefaction significantly contributes to inducing catastrophic damage to the infrastructures. Different ground improvement methods were used widely to improve the seismic resistance of liquefiable deposits to mitigate liquefaction. Use of granular column technique is a popular and well-recognized improvement technique due to its drainage, shear reinforcement, and densification characteristics. However, studies relating to seismic resistance of stone column-reinforced ground against multiple shaking events were limited. Recent seismic events also have shown the possibility of liquefaction and reliquefaction due to multiple seismic events. Considering this, the performance assessment of the granular column technique in liquefiable soil under repeated shaking events is addressed in this study. The possibility of re-using construction and demolition waste concrete aggregates as an alternative to natural aggregates is also attempted to propose sustainability in ground improvement. For experimental testing, a saturated ground having 40% density was prepared and subjected to sequential incremental acceleration loading conditions, i.e., 0.1 g, 0.2 g, 0.3 g, and 0.4 g at 5 Hz loading frequency for 40 s shaking duration using a 1 g Uni-axial shake table. The efficiency of selected ground improvement was evaluated and compared with untreated ground. The experimental results showed that ground reinforced with granular columns performs better up to 0.2 g shaking events in minimizing pore water pressure and settlement. Possibility of column clogging, and inadequate area replacement ratio (5%) affects the performance of column during repeated shaking. Also, irrespective of improvement in in-situ ground density; continuous generation of pore water pressure due to absence of drainage posing reliquefaction potential in untreated ground under repeated shaking events.