The interface between geotextile and geomaterials plays a crucial role in the performance of various geotechnical structures. Soil-geotextile interfaces often suffer reduced performance under environmental stressors such as rainfall and cyclic loading, limiting the reliability of geotechnical structures. This study examines the influence of gravel content (Gc), compaction degree (Cd), and rainfall duration (Rd) on the mobilized shear strength at the silty clay-gravel mixture (SCGM)- geotextile interface through a comprehensive series of direct shear tests under both static and cyclic loadings. A novel approach using Polyurethane Foam Adhesive (PFA) injection is introduced to enhance the interface behavior. The results reveal that increasing Gc from 0 % to 70 % leads to a 35-70 % improvement in mobilized shear strength and friction angle, while cohesion decreases by 15 %-60 %, depending on Cd. A higher Cd further boosts shear strength by 6 %- 70 %, influenced by Gc and normal stress levels. Under cyclic loading, increasing displacement amplitude reduces shear stiffness (K), while having minimal impact on the damping ratio (D); K and D appear unaffected by the number of cycles in non-injected samples. Rainfall reduces mobilized shear strength by 8 %-25 %, depending on the normal stress, with a 47 % drop in friction angle and a 24 % increase in cohesion after 120 minutes of rainfall exposure. In contrast, PFA-injected samples exhibit a marked increase in mobilized shear strength under both dry and wet conditions, primarily attributed to enhanced cohesion. Notably, PFA treatment proves particularly effective in maintaining higher shear strength and stiffness in rainfall-affected interfaces, demonstrating its potential in improving geotextile-soil interaction under challenging environmental conditions.

Phenolic foam (PF) produces much PF waste during processing because of its friability and tendency to pulverize. Currently, commonly used disposal methods like incineration and landfill cause air and soil pollution. Moreover, protective polyurethane foam (PUF) requires both excellent acoustic insulation and mechanical strength in scenarios, such as factories and roads, to enhance environmental comfort and safety. In this study, PF waste was recycled via a mechanical method, and compounding the recycled PF powder as a functional filler with PUF significantly improved its mechanical and acoustic properties. The sample (PUFB-2.5) with 2.5 g PF powder added achieved a compressive strength of 372.19 kPa, 99.03% higher than the standard foam sample (PUFB-0). Additionally, the sample (PUFB-10) with 10.0 g PF powder added achieved an optimal average sound absorption coefficient (alpha) of 0.59, 63.89% higher than PUFB-0. In the 400-2400 Hz frequency range, sample PUFB-2.5 displayed superior sound absorption properties, with alpha reaching 0.78. This study not only achieves the recyclable and circular utilization of PF waste but also enhances the mechanical and acoustic properties of PUF and offers new paths for the convergence of material science and environmental engineering industries.

While traditional methods of soil stabilization using cement or lime have been extensively researched, there is a notable gap in understanding the mechanical behavior of soil stabilized with innovative materials. This study aims to investigate the mechanical properties of soil stabilized with polyurethane (PU) foam, nanosilica, and basalt fiber. Unconfined compressive strength (UCS) and direct shear tests were conducted on reconstituted silica and calcareous samples treated with various combinations of these additives. Various parameters, including additive content, curing time, and freeze-thaw cycles, were thoroughly examined. The findings demonstrate a significant increase in UCS and shear strength parameters (c and phi) with the addition of PU foam, nanosilica, or their combination with fiber. Notably, the combination of PU and basalt fiber exhibits the most promising performance in improving the mechanical behavior and freeze-thaw durability of silica and calcareous sand, especially for short curing times. Additionally, calcareous samples consistently exhibit higher UCS, and shear strength compared to silica samples. Furthermore, the analysis of failure patterns and the microstructure of the samples using scanning electron microscopy provides insights into the effectiveness of these stabilizing agents and their influence on the mechanical properties of the soil.

The mechanical properties and envelope curve predictions of polyurethane-improved calcareous sand are significantly influenced by the magnitude and direction of principal stress. This study conducted a series of directional shearing tests with varying polyurethane contents (c = 2.5%, 5%, and 7.5%), stress Lode angles (theta sigma = -19.1 degrees, 0 degrees, 19.1 degrees, and 30 degrees), and major principal stress angles (alpha = 0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) to investigate the strength and non-coaxial characteristics of calcareous sand improved by polyurethane foam adhesive (PFA). Key findings revealed that failure strength varied significantly with the major principal stress axis direction, initially decreasing to a minimum at alpha = 45 degrees before increasing, with a 30% decrease and 25% increase observed at c = 5%. Non-coaxial characteristics between strain increment and stress directions became more pronounced, with angles varying up to 15 degrees. Increasing polyurethane content from 2.5% to 7.5% enhanced sample strength by 20% at theta sigma = -19.1 degrees and alpha = 60 degrees. A generalized linear strength theory in the pi-plane accurately described strength envelope variations, while a modified Lade criterion, incorporating polymer content, effectively predicted multiaxial strength characteristics with less than 10% deviation from experimental results. These contributions provide quantitative insights into failure strength and non-coaxial behavior, introduce a robust strength prediction framework, and enhance multiaxial strength prediction accuracy, advancing the understanding of polyurethane-improved calcareous sand for engineering applications.

The polyurethane foam (PU) compressible layer is a viable solution to the problem of damage to the secondary lining in squeezing tunnels. Nevertheless, the mechanical behaviour of the multi-layer yielding supports has not been thoroughly investigated. To fill this gap, large-scale model tests were conducted in this study. The synergistic load-bearing mechanics were analyzed using the convergenceconfinement method. Two types of multi-layer yielding supports with different thicknesses (2.5 cm, 3.75 cm and 5 cm) of PU compressible layers were investigated respectively. Digital image correlation (DIC) analysis and acoustic emission (AE) techniques were used for detecting the deformation fields and damage evolution of the multi-layer yielding supports in real-time. Results indicated that the loaddisplacement relationship of the multi-layer yielding supports could be divided into the crack initiation, crack propagation, strain-hardening, and failure stages. Compared with those of the stiff support, the toughness, deformability and ultimate load of the yielding supports were increased by an average of 225%, 61% and 32%, respectively. Additionally, the PU compressible layer is positioned between two primary linings to allow the yielding support to have greater mechanical properties. The analysis of the synergistic bearing effect suggested that the thickness of PU compressible layer and its location significantly affect the mechanical properties of the yielding supports. The use of yielding supports with a compressible layer positioned between the primary and secondary linings is recommended to mitigate the effects of high geo-stress in squeezing tunnels. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Road infrastructure plays an important role in strengthening transportation and driving the economic advancement of countries. However, the increasing traffic volume has accelerated road deterioration, particularly at critical points like bridge-road junctions. Traditional repair methods involving demolition and reconstruction lead to extended closures and high costs. This study explores the polyurethane (PU) foam injection technique as an alternative solution, which can reduce both repair time and costs. The research evaluates the application of PU foam in various road projects across Thailand, highlighting its ability to repair pavement surfaces and structures, even in severely damaged areas. Despite its advantages, the use of PU foam faces challenges due to a lack of standardized quality control. This paper proposes a set of working guidelines for PU foam injection, aimed at key stakeholders such as the Department of Highways, the Department of Rural Roads, and the Department of Local Administration. The findings underline the importance of establishing standardized methods to ensure the long-term effectiveness of PU foam in road maintenance. Future research should focus on refining these guidelines for diverse road conditions to support the sustainable development of national transportation infrastructure.

Earthquake is one of the most critical hazard that damage buildings all over the world. Earthquake can result in ground shaking, soil liquefaction, damages, or even leads to complete collapse of buildings. So, buildings must be built to withstand the effect of earthquake so as to secure living conditions. Isolation method emerged as one of the efficient techniques for reducing the severe effects of earthquake. This project proposes a promising seismic isolation method by analysing different isolation method. A variety of isolation materials are available in order to reduce the seismic impact on buildings. This study investigated the efficiency of isolation materials such as polyurethane (PU) foam, coir fibre polyester composite, and geomembrane on seismic effect. In order to study the effectiveness of different isolation materials, seismic responses such as maximum roof acceleration, storey displacement, drift, and base shear of G+4 building was analysed using linear analysis by ANSYS software. Thus, this work aimed to propose the best suitable position of the most effective isolation material that reduces the seismic energy transferred. On other hand the use of this isolation method can provide an economic way to reduce the seismic energy transferred.