Ground Improvement Techniques for Sustainable Engineering

Soil compaction is a key technique widely used in pavement and embankment construction. It is crucial to increase soil density and mechanical stability, enhance soil load-bearing capacity, and reduce the void ratio. This chapter delves into soil compaction, beginning with its basic premise as a mechanical method to enhance soil density by decreasing the air voids among soil particles, thus reinforcing the soil structure. The discourse differentiates between static and dynamic compaction, tailored for various soil types and project demands, where static compaction employs gradual pressure, and dynamic compaction involves vigorous impacts or vibrations. The efficacy of these methods is influenced by critical factors, such as soil moisture content and soil type (clay, silt, or sand), which dictate the compaction approach. The analysis extends to factors that impact compaction, highlighting the roles of soil texture, moisture, compaction energy, and equipment in achieving the desired compaction results. The discussion progresses to compaction control mechanisms, underscoring the need for real-time monitoring and adjustments to meet compaction goals while preventing soil overcompaction and damage. By providing an exhaustive understanding of soil compaction, this chapter aims to serve as an invaluable guide, shedding light on its practices, influences, and management strategies to optimize compaction in construction.

Engineered soil is a special type of soil in which the characteristics are altered through the addition of a stabilizing agent, a special type of material that alters the properties. This chapter offers an in-depth exploration of soil stabilization, a crucial technique in enhancing soil properties to meet construction requirements. Mechanical stabilization relies on physical modifications through compaction and soil blending against chemical stabilization, where admixtures are introduced to the soil to improve its characteristics. A detailed examination of various admixtures, including lime, cement, and industrial by-products, is provided in this chapter to give insights into their compatibility with different soil types and their effects on soil strength, durability, and permeability. Emphasis is given for a better understanding of soil conditions such as moisture content, type, and organic matter alongside the choice and proportion of admixture as pivotal factors determining the stabilization outcome. The enhancement of soil properties through chemical and mineral admixtures is highlighted, showcasing their role in augmenting soil strength, enhancing resistance to environmental stresses, and mitigating shrink-swell potential, collectively contributing to the longevity of construction undertakings. Furthermore, the chapter delves into field construction methods for soil stabilization. 

In this chapter, the evolution and application of ground enhancements through lime-soil and cement-soil columns are explored, emphasizing their interaction with native soils, formation mechanisms, installation techniques, load behavior, and effectiveness in soft soil environments. It also presents an in-depth investigation into the chemical dynamics between soil particles and the binder’s lime and cement, revealing how these interactions significantly improve soil strength, elasticity, and longevity. The chapter further dissects the processes of forming these soil columns, presenting a detailed guide on achieving a cohesive and robust load-bearing structure. Installation methodologies are critically analyzed, focusing on disseminating the importance of choosing appropriate methods to attain the desired outcomes in ground support. Additionally, the performance of lime-soil and cement-soil columns under varying loads is scrutinized to demonstrate their capacity to enhance load distribution and bearing capabilities. Special attention is given to their application in soft soil areas, highlighting their role in overcoming settlement challenges and boosting infrastructure stability. Key factors affecting the behavior and efficacy of these columns, such as binder concentration, soil typology, curing duration, and environmental conditions, are thoroughly discussed. This chapter contributes significant insights and empirical evidence to the civil engineering domain, advocating for the expanded use of lime-soil and cement-soil columns to tackle soft soil challenges and promote environmentally sustainable construction methodologies.

This chapter delves into the productive application of preloading techniques and vertical drains, predominantly known as Prefabricated Vertical Drains (PVDs), in ground engineering to enhance the properties of soft soils. A comprehensive overview of various vertical drain systems is provided in this chapter, elucidating their respective advantages and applications in soil improvement projects. Particular emphasis is placed on PVDs, a contemporary practice heralded for its effectiveness in expediting the consolidation process of soft grounds. By facilitating a shorter pathway for pore water expulsion, PVDs significantly augment the strength and stiffness of soft soils over time. Through a detailed exploration of the mechanics behind PVDs, including installation practices, design considerations, and performance evaluation, this chapter aims to thoroughly explain these systems. It highlights the transformative impact of PVDs on soft soil stabilization, underpinning their role in optimizing ground engineering projects for enhanced durability and resilience.

This chapter conveys the utilization of stone columns, a proven method for enhancing the engineering characteristics of soft clayey grounds and loose silt deposits. By facilitating accelerated consolidation through reduced drainage paths and bolstering the load-carrying capacity while curbing settlements by integrating robust, granular materials, stone columns significantly improve soil stability. The discussion encompasses the techniques and construction methodologies of stone columns, elucidating the underlying mechanisms of their behavior under load. It further explores the design principles that guide their application and integrates insights from contemporary research findings, offering a comprehensive overview of stone column utility in reinforcing soft grounds.

This chapter looks into the crucial role of grouting as a soil improvement technique aimed at enhancing construction foundation stability, facilitating open-cut excavations, and supporting tunneling operations. By focusing on the dual objectives of reducing soil permeability and augmenting its strength, the discussion mainly revolves around the traditional use of cement and lime treatments alongside the application of chemical grouts for finer geological textures. Through a critical examination of critically examining various research studies, the aim of this chapter aims to provide practicing engineers with a comprehensive overview of grouting methods, tracing their evolution from historical roots to contemporary practices. It elaborately discusses the spectrum of grouting materials, injection methodologies, pertinent equipment, and the inherent limitations and verification protocols associated with each type of grout. Highlighting the dichotomy between suspension-based permeation grouting and chemical solutions, the narrative underscores the efficiency of suspensions in coarser soils and the suitability of chemical solutions for finer strata. Moreover, it addresses certain chemical solutions' environmental and health concerns, noting the shift toward environmentally benign inorganic suspensions. Ultimately, the chapter serves as a resourceful guide for contractors and consultants, offering valuable insights into designing and implementing grout fluid injection works, thus promoting best practices in soil improvement and substrate strengthening.

This chapter examines the transformative impact of geosynthetics on ground improvement, spotlighting their role in fostering sustainable solutions for various geotechnical and geoenvironmental challenges. By synergizing with traditional and unconventional construction materials, geosynthetics amplify their environmental benefits, aligning with global movements towards sustainable development and a circular economy. The discourse explores various geosynthetic applications, from reinforcing soil structures and enhancing landfill drainage systems to creating practical barriers and stabilizing embankments over soft grounds. Special attention is given to integrating natural materials such as coir and jute, underscoring their potential to further the environmental advantages of geosynthetics. This overview emphasizes the significance of geosynthetics in soil improvement practices, demonstrating their crucial contribution to eco-friendly engineering and the pursuit of global sustainability goals.

This chapter explores the soil nailing technique, which is an innovative approach used for stabilizing slopes, embankments, tunnels, and retaining walls, and presents it as a versatile, cost-effective, and environmentally friendly solution among the various geotechnical stabilization measures. It provides a detailed examination of the favorable ground conditions for soil nailing, detailing its advantages and limitations compared to traditional stabilization methods. The narrative meticulously describes the installation processes crucial for the success of the technique and highlights potential failure modes to equip practitioners with the foresight required to mitigate risks. Emphasizing the response to soil nails pullout as a critical design parameter, the chapter evaluates the effects of grouting pressure, overburden pressure, soil dilation, degree of saturation, nail surface roughness, and borehole conditions on the pullout capacity through a comprehensive review of the literature. By scrutinizing construction parameters and their impact on design methodologies, the chapter advocates an organized and informed approach to soil nailing, emphasizing the importance of a multifaceted consideration of variables to achieve optimal slope stability.

Micropiles, with their slender diameters ranging from 10 to 30 cm, have become a cornerstone of geotechnical engineering, providing high-strength solutions for challenging structural support problems. Initially developed more than 50 years ago for postwar reconstruction complexities, the last two decades have seen a significant evolution in micropile technology, from low-capacity pile networks to the utilization of single, high-capacity elements for substantial structural support. Their effectiveness in enhancing bearing capacity and reducing settlement has been particularly noted in strengthening existing foundations. Whether vertically or in reticulated patterns, micropiles support excavations, slopes, and foundations and are indispensable in the underpinning or retrofitting of structures within confined spaces where traditional methods falter. The recent resurgence of interest in micropile networks, recognized for their technical and economic viability, extends their application to slope stabilization, lateral load accommodation, and seismic retrofitting. This chapter explores the advancements and broadening applications of micropiles technology, underscoring the innovative research and development that continue to expand their potential. It presented a comprehensive view of future advances and envisioned applications, illustrating the pivotal role of micropiles in addressing the intricate challenges of modern geotechnical engineering within a single cohesive narrative.

This chapter delves into using ground anchors in modern construction and civil engineering, highlighting their role in stabilizing and supporting natural and engineered structures. Ground anchors restrain movement by transferring tension to the ground via friction or adhesion at their interfaces. This chapter explains the fundamental design principles of ground anchors and their efficiency in utilizing in situ soil properties to provide vertical or lateral support. Having substantial advantages over traditional methods, such as rigid gravity retaining walls or external bracing systems, including cost reductions and accelerated project timelines, ground anchors have become increasingly prevalent in civil engineering projects over the past few decades. This discussion covers the technical aspects and applications of ground anchors and emphasizes their growing importance in the industry. 

The need for sustainable development is prioritized in all infrastructure projects and frameworks being released by various statutory bodies. The utilization of ground improvement methods assumes a central role in this venture, providing novel approaches to enhance soil stability and functionality in accordance with environmental sustainability principles. This section delves into the correlation between ground improvement techniques and the pursuit of sustainable development goals (SDGs), emphasizing their contribution to a more sustainable and resilient infrastructure environment. Emphasizing the reduction of environmental impact, this discussion investigates the incorporation of sustainable ground improvement approaches that are in line with goals such as carbon emission reduction, advancement of the circular economy, and attainment of cost-effective, high-performance project results. SDG 9 - Industry innovation and infrastructure, SDG 11- Sustainable cities and communities, and SDG 12- Responsible consumption and production are primarily focused on cultivating an environmentally friendly society. Any infrastructure development endeavors must uphold sustainability, and ground improvement activities within these projects should also be evaluated from this perspective. Through the viewpoint of environmental conservation and financial feasibility, we scrutinize diverse ground improvement techniques that utilize both conventional and innovative methodologies, underscoring their capacity to tackle pressing issues like climate change mitigation, resource preservation, and eco-conscious construction practices. By presenting successful case studies and emerging patterns, this section seeks to elucidate the way forward for the integration of ground improvement methods as a fundamental component of sustainable development, ultimately aiding in the realization of the SDGs in an environmentally conscious and economically viable manner.