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In the event of sudden earthquakes, loose sandy soil loses its shear strength tremendously due to the generation of excess pore water pressure causing liquefaction. Due to soil liquefaction, the infrastructures’ foundation becomes unstable, thereby causing threats to its structural stability. Hence the application of suitable ground improvement methods becomes necessary for improving the liquefaction susceptibility of sandy soils. Ground reinforcement using the stone column proves to be an efficient reinforcement technique for improving liquefaction resistance of sandy soils. In this study, the stone column improvement technique was evaluated experimentally under repeated acceleration loading events. The experiments were carried out in a tank of dimension 1.4 m × 1.0 m × 1.0 m, placed over a uniaxial shaking table. A saturated sand bed having 40% relative density was prepared and tested under repeated acceleration loading of 0.3 g and 0.4 g at 5 Hz Frequency sequentially. A comparative analysis between untreated virgin sand bed and stone column treated ground was performed for performance assessment. The liquefaction assessment parameters such as generation and dissipation of pore water pressures, foundation settlement and soil displacement were monitored and compared. The results showed that there is a significant reduction in the excess pore water pressure generation even at repeated acceleration loading for the stone column stabilized bed. The test results concluded that soil densification and drainage are the key features in the liquefaction mitigation system to enhance the safety of foundation structures in seismic-prone areas.

Soil liquefaction and its associated ground failures during earthquake is one of the major hazards causing risk to life and infrastructures. Even though several literatures available using sand compaction pile (SCP) technique, investigations under sequential acceleration conditions for SCP-treated soil deposits were limited. Hence in this study, liquefaction resistance of sand treated with sand compaction pile under sequential acceleration conditions was performed and reported. For experimental studies, an acrylic tank having dimensions of 1.4 m × 1 m × 1 m was selected and mounted on uniaxial shaking table. Soil deposits having 600-mm depth were prepared with 40 and 60% relative density using sand pluviation method. For soil reinforcement, SCP having diameter 110 and 600 mm length was installed inside the soil deposit. Then, shaking table experiments were performed with and without improvement technique under sequential accelerations. For sequential acceleration, the selected accelerations are 0.1, 0.2, 0.3 and 0.4 g with 5 Hz frequency. Initially, the sand deposit was subjected to 0.1 g acceleration amplitude and generation of excess pore water pressure with time was continuously monitored and recorded. After 0.1 g loading, the tank was left undisturbed for 24 h or until complete dissipation of generated pore water pressure whichever earlier. Then, next sequential loading of 0.2 g acceleration amplitude was applied and the same procedure was repeated up to 0.3 and 0.4 g testing conditions. The influence of various parameters affecting the performance of SCP improvement technique under sequential loading was compared and reported.

This paper presents an overview of sustainability approaches followed in ground improvement techniques. A review on research works performed in ground improvement techniques such as solar prefabricated vertical drains and microbial induced partial saturation and the way these techniques promotes the global sustainability. The tools used for evaluating the sustainability applicable to ground improvement are discussed and a comprehensive review is done for the research studies performed in ground improvement which contributes to the sustainable development. Accordingly, multi criteria-based sustainability evaluation framework consisting of Environmental Impact Assessment, Life Cycle Cost and Life Cycle Assessment was reviewed and its contribution towards global sustainability was presented. By estimating sustainability index through detailed sustainable assessment and evaluation, new and innovative ground improvement measures can be developed which enable global sustainability and eco-friendly geotechnical engineering. Also in this paper, the sustainable ground improvement developments in India and abroad are presented through available case studies.

The vertical stress exerted by the vehicles will be high in a populated road and to increase the bearing capacity of subgrade characteristics, geosynthetic material can be used. In the current study different geosynthetic material such as geo-grid, geo-textile and geo-membrane were used to as a subgrade reinforcement member inside the CBR mould for understanding the improvement in subgrade for single, two and three geosynthetic layering in the CBR mould. The results show there was a constant increase in the bearing with the increase in a number of layers and this improvement varied with type of geosynthetic materials also. Among three geosynhteic materials, geogrid shows improved CBR characteristics. Finally, Cost analysis and design of flexible pavement were carried for an optimum number of layers for geogrids. There was reduction of about 6.38% in the cost of construction when using geogrid as subgrade reinforcement member. Resumen La tensión vertical ejercida por los vehículos será alta en una carretera poblada y, para aumentar la capacidad de carga de las características de subrasante, se puede usar material geosintético. En el presente estudio, se usaron diferentes materiales geosintéticos, como geo-rejilla, geo-textil y geo-membrana, como elemento de refuerzo de subrasante dentro del molde CBR para comprender la mejora en subgrado para capas simples, dos y tres geosintéticas en el molde CBR. Los resultados muestran que hubo un aumento constante en el rodamiento con el aumento en varias capas y esta mejora también varió con el tipo de materiales geosintéticos. Entre los tres materiales geosintéticos, la geomalla muestra características CBR mejoradas. Finalmente, el análisis de costos y el diseño de pavimento flexible se llevaron a cabo para un número óptimo de capas para geomallas. Hubo una reducción de alrededor del 6.38% en el costo de construcción al usar la geomalla como miembro de refuerzo de subrasante. Resumo A tensão vertical exercida pelos veículos será alta em uma estrada povoada e, para aumentar a capacidade de carga das características de subleito, pode-se usar material geossintético. No presente estudo, usaram-se diferentes materiais geossintéticos, como geogrelha, geo-têxtil e geo-membrana, como elemento de reforço de subleito dentro do molde CBR para compreender a melhora em subgrau para camadas simples, dois e três geossintéticas no molde CBR. Os resultados mostram que houve um aumento constante no rolamento com o aumento em várias camadas e esta melhora também variou com o tipo de materiais geossintéticos. Entre os três materiais geossintéticos, a geomalha mostra características CBR melhoradas. Finalmente, a análise de custos e o desenho de pavimento flexível foram realizados a um número ótimo de camadas para geomalhas. Houve uma redução de aproximadamente 6.38% no custo de construção ao usar a geomalha como membro de reforço de subleito.

The present paper investigates the effectiveness of using geotextile encased stone column for mitigating the liquefaction phenomenon in saturated sandy deposits. Reduced scale 1-g model tests were conducted using a uniaxial shake table to study the behavior of loose saturated sand reinforced with encased stone columns when subjected to harmonic (sinusoidal) loading. Additionally, the response of saturated sand reinforced with stone column, with and without geotextile encasement is also studied and compared. The test results show that the installation of stone column in the saturated loose sand increases the liquefaction resistance of sand. The presence of geotextile allows quicker dissipation of pore water which results in an improved liquefaction resistance of sand. Moreover, the acceleration amplitude influences the response of both the unreinforced and reinforced sand. The increase in acceleration amplitude increases the magnitude of excess pore water pressure ratio. Furthermore, the presence of stone column also reduces the settlement of the shallow foundation.