Under contemporary conditions, various soil reinforcement methods are employed, each possessing distinct characteristics and applications. These methods aim to improve the strength characteristics and stability of soil foundations. This study evaluates the effectiveness of combined soil reinforcement using a biopolymer (xanthan gum) and a geosynthetic (non-woven geotextile). The study included preparation of the modified soil, pH determination, and structural analysis using scanning electron microscopy to evaluate the physicochemical properties of soil, particle morphology, and interaction with the biopolymer. Unreinforced soil samples, as well as samples modified with biopolymer and combined reinforcement (biopolymer-geosynthetics), were shear tested to study their strength properties and resistance to deformation. The aim was to examine the effect of different reinforcement methods on the mechanical behavior of the soil. The test results showed that the combined reinforcement with biopolymer and nonwoven geosynthetics improved the shear strength. It was observed particularly at a low shear stress level. At the same time, soil cohesion increased significantly, while the impact on the friction angle was generally negligible. The friction angle of the soil after combined reinforcement increased by 14 %, and soil cohesion increased from 8 kPa to 23 kPa. Discussing the application of the combined reinforcement method, technological features, and advantages of the technique is important for understanding the overall effectiveness of soil stabilization. This method of soil modification has demonstrated effectiveness and represents a promising approach for enhancing soil properties

Distributed fiber-optic sensing (DFOS) with intentionally spaced mechanical fixity points was experimentally evaluated for the structural health monitoring (SHM) of reinforced concrete (RC) members. A full-scale four-point bending test was conducted on a 12 m RC beam (400 × 400 mm) instrumented with a single-mode DFOS cable incorporating internal anchors at 2 m intervals and bonded externally with structural epoxy. Brillouin time-domain analysis (BOTDA) provided distributed strain measurements at approximately 0.5 m spatial resolution, with all cables calibrated to ±15,000 µε. Under stepwise monotonic loading, the system captured smooth, repeatable strain baselines and clearly resolved localized tensile peaks associated with crack initiation and propagation. Long-gauge averages exhibited a near-linear load–strain response (R² ≈ 0.99) consistent with discrete foil and vibrating-wire strain gauges. Even after cracking, the DFOS signal remained continuous, while some discrete sensors showed saturation or scatter. Temperature compensation via a parallel fiber ensured thermally stable interpretation during load holds. The fixed-point configuration mitigated local debonding effects and yielded unbiased long-gauge strain data suitable for assessing serviceability and differential settlement. Overall, the results confirm the suitability of fixed-point DFOS as a durable, SHM-ready sensing approach for RC foundation elements and as a dense data source for emerging digital-twin frameworks.

The study presents the treatment of soil with chitosan and xanthan gum, examines the influence of the pH of base solutions on the solubility and activity of these biopolymers, and investigates the changes in soil properties resulting from their application. The first stage of the study is devoted to the peculiarities of preparing soil reinforcement with biopolymers and their mixing process. The obtained samples were analyzed for their texture, which allowed identifying the optimal conditions for maximum solubility. The second stage of the study is devoted to evaluating the modified soil's behavior under wetting conditions. The moisture level of the soil directly affects its physical and mechanical properties. Understanding these changes makes it possible to predict the behavior of the soil under different service conditions. The study considered 10 soil samples prepared with base solutions of different acidity (pH 4, pH 7, pH 9), among which one sample serves as a control sample without modification with biopolymers. This makes it possible to evaluate the effect of modification on soil properties and to identify optimal conditions for its use. The analysis showed that the solutions' moisture level and acidity significantly affect the samples' structural characteristics. At the same time modified soils show improved performance compared to the control sample, the sample reinforced with chitosan increased density by 16 %. These data are important for the development of effective solutions in geotechnical and construction engineering.

This study examines the thermal regime of multilayer highway subgrades under seasonal freezing conditions in Northern Kazakhstan, with particular attention to differences between soil beneath the pavement and adjacent snow-covered ground. Field monitoring was conducted along the Kosshy highway near Astana using a vertical array of temperature and relative humidity sensors installed within pavement layers and the underlying soil profile. Measured temperature gradients were used to estimate the effective thermal conductivity of pavement layers and frozen subgrade soil through inverse calculations based on Fourier’s law. The results show that the multilayer pavement structure significantly modifies the thermal regime of the soil profile, producing steeper temperature gradients and deeper frost penetration compared with nearby snow-insulated ground. Moisture migration in the vapour phase was evaluated using a diffusion-based formulation derived from Fick’s law. In addition, a simplified energy-balance approach was applied to estimate the potential upper limit of vapour-related ice accumulation by relating conductive heat flux to latent heat associated with vapour deposition. The comparison of the pavement and snow-covered profiles demonstrates that differences in thermal conductivity and thermal boundary conditions strongly influence both temperature distribution and potential moisture redistribution in freezing soils.

The structural monitoring of high-rise building foundations requires measurement systems that can register spatially distributed deformation and temperature effects during construction and at the early stage of service. This paper presents a field case study of a distributed fiber optic sensing (DFOS) system installed in the raft foundation of a high-rise building complex. The study is focused not on general crack detection, but on the practical commissioning of the sensing line, interpretation of initial measurements, and preparation of a reference dataset for subsequent long-term observation.The monitoring object is the raft foundation beneath Block R of Abu Dhabi Plaza in Astana, Kazakhstan. Measurements were obtained along the same horizontal sensing route using Brillouin Optical Time Domain Analysis (BOTDA). Two commissioning stages were compared in order to evaluate the repeatability of the installed system and to separate temporary con-struction-stage influences from the stable response of the foundation slab.The analysis showed that signal variability during the first measurement stage was mainly associated with ongoing construction operations, including concrete casting and related thermal-mechanical disturbances. In the second stage, after the completion of active works on the monitored section, the measured strain and temperature responses became significantly more stable. The proposed approach demonstrates how DFOS data can be converted from raw distributed measurements into a practical monitoring basis for reinforced concrete substructures. The results are relevant for commissio-ning control, baseline formation, diagnostic comparison of future measure-ments.

Frost heave in cold-region pavements is governed by coupled heat and moisture migration, but the specific contribution of vapour transport in multilayer subgrades remains poorly constrained. This study combines field temperature monitoring with analytical modelling to estimate effective thermal conductivities of pavement structural layers and to evaluate vapour-driven moisture fluxes during seasonal freezing. A vertical thermistor array beneath a two-lane highway near Astana (Kazakhstan) and in the adjacent snow-covered ground is used to back-calculate layer-specific conductivities from midwinter temperature gradients by applying Fourier’s law under quasi-steady conditions. Vapour migration is then assessed by two complementary approaches. A diffusion-based formulation, which couples measured vapour-density gradients with air-filled porosity, provides a conservative lower bound and yields very small fluxes, with maximum daily ice deposition of 8.17 × 10⁻⁵ kg·m⁻²·day⁻¹ beneath the pavement and cumulative seasonal masses of order 10⁻² kg·m⁻² (10⁻³ kg·m⁻² under snow). An energy-balance approach, which relates conductive heat flux to latent heat of vapour–ice phase change and introduces an efficiency parameter α, supplies a physically constrained upper envelope. For a central scenario with α = 0.6, daily deposition in the 0.60–1.00 m layer reaches 0.0961 and 0.0330 kg·m⁻²·day⁻¹ beneath pavement and snow, respectively, yielding seasonal totals of 12.1 and 4.1 kg·m⁻². Together, these bounds indicate that vapour migration beneath pavements, although unlikely to be the dominant driver of frost heave, can be substantially more intense than under adjacent snow-covered ground due to steeper temperature gradients in the upper subgrade.