Sudip Basack

Pile foundations transmit structural loads to deeper subsoil strata whenever the soil in the vicinity of the ground surface lacks sufficient strength and stiffness to ensure an adequate factor of safety against ultimate failure or warrant settlements to remain below acceptable limits. In many in situ conditions, piles are embedded in layered subsoil medium. In several circumstances, piles are subjected to tensile loading. Large and high-rise civil infrastructure subjected to wind loading, transport infrastructure under horizontal loading due to moving vehicles, offshore structures withstanding wind and wave loading, underground structures subjected to hydrostatic pressure due to buoyancy, etc., are some examples where tension loads are imparted on the supporting piles. The imparted uplift loads in these tension piles are balanced by the negative skin friction induced at the pile–soil interface. In this paper, an analytical model using systematic application of established upper bound shear stress theory to three-layered soil configurations has been developed to formulate the ultimate uplift capacity of tension piles in three-layered soil. The model adopted appropriate correlations for upper bound interface shear stresses in different soils as well as tensile failure of pile material itself. The developed solution was validated by comparing with available experimental results. Thereafter, a case study was performed to study the influence of the variation of pile geometries and relative stiffness on ultimate uplift capacities. Important conclusions were drawn from the entire study.

Horizontally buried rectangular hollow pipe barriers are investigated as a potential solution for mitigating ground-borne vibrations in densely built environments. This study combines high-fidelity three-dimensional finite-element analyses, a computationally efficient two-dimensional plane-strain modeling strategy, and a Python-based automated optimization framework to evaluate the effects of barrier geometry and material properties on vibration isolation performance. The results show that vertical vibration attenuation is consistently better than horizontal attenuation. Among the geometric variables, burial depth and barrier width are the dominant factors, with isolation benefits becoming marginal when the burial depth exceeds approximately 3 m and with barrier widths smaller than about 0.5 m leading to poor performance. The material parametric study indicates a threshold behavior for stiffness contrast: the improvement in isolation gradually saturates when the Young’s modulus ratio of barrier to soil exceeds about 5.12, suggesting that reinforced concrete provides a practical balance between structural reliability and engineering applicability. A comparison between the three-dimensional and two-dimensional models shows that the plane-strain approximation can reproduce the three-dimensional results with acceptable accuracy while substantially reducing the computational demand. The automated optimization further identifies high-performing design configurations for practical application. Overall, the study offers numerical insight and computational guidance for the preliminary design and evaluation of rectangular hollow pipe barriers for ground vibration mitigation.

Large civil infrastructures, including high-rise buildings, bridges, offshore platforms, transmission towers, tall chimneys, basements below the water table, etc., are often supported on pile foundations. Apart from the usual dead loads and live loads imposed by superstructures, these piles are often subjected to significant uplift forces due to overturning moments or hydrostatic pressure resulting from the effects of wind and wave loading, traffic movement, buoyancy, etc. Piles that withstand tensile loads are termed tension piles. Since the soil is unable to resist tensile stress, the pullout loads imposed on tension piles are prevented primarily by downward skin friction at the pile–soil interface, as well as by the self-weight of the piles. In this paper, a numerical model was developed using boundary element analysis, wherein piles were assumed to be made of an elastic–perfectly plastic material, and the soil was modeled using a parabolic model. The developed model was validated with available experimental results, and acceptable agreement was found. An in-depth study by detailed parametric analysis revealed that the parabolic soil model yielded satisfactory results. Extensive full-scale case studies were also performed to study the influence of various factors on tension pile performance. A set of important conclusions was drawn from the entire work.

Structural health monitoring has become a critical aspect of engineering, particularly in assessing the integrity of civil infrastructures. Reinforced Cement Concrete (RCC) buildings, which have a specific design lifespan, require periodic structural evaluation to investigate the nature and extent of possible damages caused by prolonged exposure to adverse environmental conditions. Non-Destructive Testing (NDT) techniques offer an effective method for detecting structural damage without compromising the integrity of building components. This study focuses on evaluating the structural health condition of aged RCC residential and commercial buildings in eastern India using a series of in-situ NDTs. The tests results were analyzed and interpreted to detect the extent of structural defects and damage development. Results indicated that most of the buildings exhibited severe degradation, demanding a complete dismantling of structural elements, while few data indicated potential for repair and rehabilitation of the relevant components. These findings hold practical relevance for construction engineers involved in the maintenance and preservation of aging structures.

The demand for sustainable and environmentally friendly soil stabilization methods for subgrade improvement for pavements has led to exploring techniques that minimize ecological impact while optimizing engineering properties. Traditional stabilizers like cement and lime, though effective, have significant environmental drawbacks, including a high carbon footprint, disruption of vegetation, and health risks to workers. This study investigates the efficiency of biopolymers and eggshell powder as eco-friendly, sustainable soil stabilization agents. Parameters such as compaction characteristics, California Bearing Ratio (CBR), and micro-structural analysis were assessed. The research evaluates soil samples treated with varying concentrations of biopolymer (1%, 2%, and 3%) and eggshell powder (4%, 6%, and 8%). Results indicated that biopolymer addition slightly decreased the maximum dry density (MDD) and increased the optimum moisture content (OMC), while eggshell powder slightly increased MDD and decreased OMC. The optimal mix, soil + 1% xantham gum + 6% eggshell powder, enhanced CBR by 225.6% and 323.8% for soaked and unsoaked conditions, respectively. The scanning electron microscope revealed that treated soil samples transformed into a hard solid matrix, demonstrating improved stability. EDX analysis revealed the mineralogical composition of the mixes. Overall, the use of biopolymers and eggshell powder not only enhances soil strength but also promotes environmental sustainability.

Rivers play a critical role in sustaining human civilization by supporting domestic, agricultural, and industrial water needs. They also function as pathways for conveying treated and untreated wastes toward downstream environments. The Hooghly, a major distributary of the Ganges, flows through densely populated and industrialized regions of eastern India and is subject to complex interactions among tidal forcing, urban effluents, and sediment dynamics. This study presents a post-monsoon (September 2021) assessment of water quality at seven strategically selected sites, focusing on key physicochemical and bacteriological parameters: total solids (TS), pH, alkalinity, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total coliforms. DO ranged from 6.0-7.0 mg/L, COD from 3.0-28.1 mg/L, and total coliforms peaked at 74.63 × 105 MPN/L at Garden Reach, indicating localized organic loading and significant fecal contamination. Spatial trends showed heterogeneous conditions influenced by population density, sewage discharge, and tidal hydrodynamics, rather than a uniform upstream-to-downstream gradient. As this represents a single-season snapshot (n = 7 sites), interpretations are conservative and avoid broad generalization. The findings highlight the need for enhanced wastewater management, targeted monitoring of pollution hotspots, and improved treatment strategies to support safe water abstraction and ecological resilience.

This study explores the integration of wind power generation into urban infrastructure via a rooftop vertical-axis wind turbine. A rigorous experimental framework was established by installing a small-scale turbine on an urban building for performance assessment under controlled conditions. Simulated environmental conditions were created using a pedestal fan and blower to evaluate mechanical interactions between the components and electrical output efficiency of the turbine. Extensive numerical modeling was conducted to analyze turbine performance, by computational fluid dynamics using ANSYS FLUENT. The results reveal that the turbine operates efficiently even at low to moderate wind speeds (0.5–6 m/s), demonstrating its feasibility for urban deployment. Performance tests indicated that, as the shaft rotational speed increased from 55 rpm to 115 rpm, the output voltage, current and power varied nonlinearly in the ranges of 3–11.9 V, 20–130 mA and 0.05–2.7 W, respectively. Vibration measurement at specified turbine locations revealed nonlinear variation in displacement, velocity, acceleration and frequency without fixed patterns. Good agreement was observed between the experimental and numerical results. The numerical model yielded interesting profiles related to velocity and turbulence distributions, apart from torque, mechanical power and electrical voltage. Important conclusions were drawn from the entire work.