https://jeg.khu.ac.ir/ Engineering Geology en daily 1 Sun, 26 Jul 2026 00:00:00 +0330 Sun, 26 Jul 2026 00:00:00 +0330 https://jeg.khu.ac.ir/article_11647.html Land subsidence is one of the major geomorphological hazards in arid and semi-arid regions. It is primarily caused by excessive groundwater extraction. In such areas, a decline in groundwater levels can lead to the irreversible compaction of fine-grained layers, a reduction in storage capacity, and damage to critical infrastructure. This study aims to monitor the rate of land subsidence in the Damghan aquifer and analyse its relationship with groundwater decline, using satellite data, piezometric information and field evidence. The study area covers part of the Damghan aquifer in Semnan Province, spanning approximately 1,522 km². It contains an unconfined aquifer within heterogeneous alluvial deposits. The dataset includes Sentinel-1A images from 2017 to 2021, records from 38 observation wells from 2017 to 2022, and drilling logs from 13 exploitation boreholes. The results indicated that the decline in groundwater levels in the central and south-eastern parts of the aquifer reached 5 metres, with an average annual rate of approximately 0.33 metres. Radar interferometry maps confirmed an average Analysis of soil texture and saturated thickness revealed that zones with higher percentages of clay and silt are more sensitive to groundwater decline. Even small drawdowns in boreholes containing fine-grained sediments resulted in noticeable subsidence, whereas boreholes containing coarse-grained sediments showed limited deformation. Field evidence, including casing protrusion in piezometer wells of up to 27 cm, the formation of initial sinkholes and changes in natural drainage patterns, highlights the practical implications of this phenomenon. The findings of this study demonstrate that, in interaction with geological characteristics and soil texture, groundwater decline is the main driver of subsidence in the Damghan aquifer. Therefore, continuous groundwater monitoring and targeted management of exploitation are essential to mitigate risks and ensure the region's environmental and economic sustainability. https://jeg.khu.ac.ir/article_11638.html Accurate estimation of hydrodynamic parameters in heterogeneous alluvial aquifers remains a major challenge in sustainable groundwater management, as different methods often yield inconsistent results across spatial scales. In this study, hydraulic conductivity, storage coefficient, and specific yield were estimated using pumping tests, geophysical surveys, and grain-size analysis. The results were integrated through a systematic framework based on the Analytical Hierarchy Process (AHP). Uncertainty was quantitatively assessed using the coefficient of variation (CV). Pumping test results indicated that hydraulic conductivity varies within a narrow range of 0.416–0.524 m/day, with a mean value of 0.475 m/day and a CV of approximately 8%, reflecting the high reliability and stability of this method. In contrast, the geophysical approach yielded a mean hydraulic conductivity of about 3.9 m/day with a CV of nearly 41%, highlighting the effects of spatial heterogeneity and uncertainties inherent in indirect estimation techniques. Grain-size analysis exhibited the highest variability, with hydraulic conductivity ranging from approximately 0.7 to 8 m/day and a CV exceeding 50%, indicating strong sensitivity to local-scale sedimentary characteristics. Integration of the three methods using AHP, assigning higher weight to pumping tests, moderate weight to grain-size analysis, and lower weight to geophysical data, effectively reduced method-dependent bias and produced spatially and physically consistent hydrodynamic parameter maps. The highest hydraulic conductivity and specific yield values were identified in the eastern and northeastern parts of the plain, while the lowest values occurred in the western and northwestern areas. The final integrated results indicate hydraulic conductivity and specific yield ranges of 0.49–1.01 m/day and 0.0039–0.045, respectively. The proposed integrative approach provides a practical and transferable framework for uncertainty management and informed decision-making in heterogeneous alluvial aquifers, particularly in arid and semi-arid regions. https://jeg.khu.ac.ir/article_11043.html Land subsidence represents a multifaceted geotechnical hazard that exerts profound impacts on environmental stability, infrastructure resilience, and socio-economic security. This research presents a systematic field-based assessment of subsidence manifestations across the Hashtgerd, Eshtehard, and Karaj plains in Alborz Province, derived from extensive surveys conducted during the spring and summer of 2025. Diagnostic indicators—including extensional and compressional ground fissures, localized structural deformations, wellhead displacements, large-scale surface cracks, and variations in groundwater levels—were systematically documented. The Hashtgerd plain, particularly the Saeidabad, Sepehr, and Najmabad areas, exhibited the highest density of subsidence evidence, encompassing progressive surface settlements, widespread fissuring, and instability of near-surface strata. In the Eshtehard plain, structural cracking in school buildings, ground ruptures adjacent to transmission towers, and failures in retaining walls were frequently observed. Deep surface fissures were also identified in the Fathabad region, situated between Eshtehard and Buin Zahra. Conversely, despite significant groundwater withdrawal, field surveys in parts of the Karaj plain revealed no pronounced subsidence indicators. The findings highlight a strong spatial correlation between the severity of subsidence and geological heterogeneity, unregulated groundwater exploitation, and the absence of smart metering systems in wells. This study underscores the urgent need for integrated monitoring frameworks, adaptive management strategies, and the application of advanced remote sensing technologies to mitigate and control the expansion of land subsidence in Alborz Province. https://jeg.khu.ac.ir/article_11044.html Due to the deepening of open-pit mines and the associated environmental considerations, the current era has been called the "return to underground mining period." One of the fundamental considerations in the transition from open-pit to underground mining is the design of crown pillars based on economic and technical considerations. As result of uncertainties in this research topic, the present study employs three-dimensional numerical simulation to investigate the interactive effects of geometric and geomechanical parameters on crown pillar behavior during the transition to underground mining. The pillar behavior was evaluated based on displacement magnitude and plastic zone volume of the pillar. The results of the numerical simulation showed that geometric parameters play a much more significant role than rock mechanical properties. Among geometric parameters, the pillar dimension index (product of pillar thickness and span) and crown pillar span have a decisive role in controlling pillar behavior. From a geomechanical perspective, within the range of variations considered in this research, rock elastic modulus was identified as the influential parameter on crown pillar behavior, which controls crown pillar behavior with a critical value of 7 GPa. The crown pillar span, as the second most influential parameter, can predict crown pillar displacement with a correlation coefficient of 0.83, and the pillar dimension index can estimate the plastic zone volume in the pillar with 20% accuracy. https://jeg.khu.ac.ir/article_11045.html The present study systematically compares probabilistic slope stability analysis using three widely used geotechnical engineering software packages: PLAXIS LE V21, GeoStudio 2024 (SLOPE/W module), and Slide2. Given the critical importance of risk assessment and the inherent uncertainty in soil parameters, probabilistic analysis has emerged as an essential approach for quantifying uncertainties and calculating key metrics such as probability of failure and reliability index. This research evaluates the capabilities, accuracy, efficiency, and limitations of each software by performing identical analyses on three distinct scenarios (homogeneous soil, three-layered soil, and pseudo-static conditions) while employing ten common limit equilibrium methods. The results demonstrate that all three software packages are capable of conducting probabilistic analyses with acceptable accuracy; however, each offers distinct strengths: Slide2 is ideal for complex risk analyses due to its specialized tools and advanced graphical visualizations; GeoStudio is better suited for routine projects owing to its intuitive user interface and seamless integration with other modules; and PLAXIS LE excels in computationally demanding problems through its high numerical accuracy and hybrid finite element limit equilibrium (FELA) approach. This study provides practical guidance for engineers in selecting the most appropriate software based on project complexity, required accuracy, and available resources. It also emphasizes the advantages of probabilistic approaches over traditional deterministic analyses in effective risk management. https://jeg.khu.ac.ir/article_11046.html Manjil City, situated in northern Iran, faces significant seismic risk due to its proximity to active fault systems and its role as a corridor for critical regional infrastructure. Past catastrophic events have underscored the necessity of robust spatial risk assessment to mitigate human, economic, and infrastructural impacts. This study presents a comprehensive seismic risk assessment and spatial zonation for Manjil using an integrated multi-criteria evaluation approach—coupling Geographic Information Systems (GIS), the Analytic Hierarchy Process (AHP), and fuzzy logic. Risk was modeled as a function of the interaction between seismic hazard potential and spatial vulnerability. Vulnerability indicators, including residential density, land-use patterns, and critical urban lifelines, were standardized and weighted through the AHP framework. Our findings indicate that high-density residential areas are the primary contributors to urban vulnerability, whereas critical infrastructure components are disproportionately vital during emergency response scenarios. For the hazard assessment, a range of proxies were analyzed, including proximity to faults, fault density, peak ground acceleration (PGA), active tectonic indices, topographic slope, and lithological characteristics. These parameters reveal heightened hazard levels in zones adjacent to active faults. By applying fuzzy membership functions and a gamma operator (γ=0.9), we generated an integrated earthquake risk map, classified into five vulnerability tiers ranging from ‘very low’ to ‘very high.’ The spatial analysis delineated four distinct high-risk focal zones within the urban footprint, driven by the convergence of elevated seismic hazards and dense concentrations of residential and critical infrastructure. This research demonstrates the efficacy of the GIS–AHP–Fuzzy integration in providing a reliable, data-driven framework for evidence-based urban planning and proactive seismic risk management in seismically prone regions. https://jeg.khu.ac.ir/article_11047.html Groundwater resources in arid and semi-arid regions are increasingly subjected to intensive exploitation, posing serious challenges to the quantitative sustainability of aquifers. The Mashhad–Chenaran aquifer, one of the most important alluvial aquifers in northeastern Iran and the main source of drinking water for Mashhad city, has experienced increasing stress in recent years. This study evaluates the quantitative sustainability of the Mashhad–Chenaran aquifer based on an integrated analysis of well discharge, aquifer saturated thickness, specific yield (Sy), specific capacity (Q/s), and specific drawdown (s/Q) during the 2015–2016 to 2021–2022 hydrological periods.The results indicate a notable decline in well discharge, particularly in the southeastern and central parts of the aquifer. Concurrently, aquifer saturated thickness decreased, and the specific yield declined from approximately 0.95 to 0.25, corresponding to an approximately 74% reduction in the aquifer storage capacity. In addition, specific capacity decreased from about 0.63 to 0.43 MCM·yr⁻¹·m⁻¹, representing an approximately 32% reduction, while specific drawdown increased from approximately 1.56 to 2.30 m, indicating an increase of about 47% in water-level decline per unit discharge and a reduction in the hydraulic efficiency of groundwater exploitation. Areal sustainability assessment for the 2021–2022 hydrological period shows that approximately 35% of the aquifer area is classified as unstable, 42% as semi-stable, and only 23% as stable. Overall, the findings demonstrate a pronounced intensification of quantitative instability in the Mashhad–Chenaran aquifer and emphasize the need for revising groundwater abstraction practices, controlling pumping rates, and implementing continuous monitoring to ensure sustainable groundwater use. https://jeg.khu.ac.ir/article_11706.html This study aims to propose a novel practical procedure to use demolition waste as recycled concrete. Foam concrete with a density of 960 (kg/m3) was produced using fine-grained demolition waste. Instead of using traditional aggregates, two groups of demolition wastes, with gypsum (WG) and without gypsum (W), have been used in the mixture of the concrete at weight percentages of 30, 70, and 100. The applied experiments were flow table, unconfined compressive strength (UCS), and scanning electron microscope (SEM). Results showed that increasing the percentage of the replaced construction waste decreases the flow rate of the samples due to their high-water absorption. Moreover, the measured wet density of the recycled samples varies from 906 to 1022 (kg/m3). By replacing construction waste with sand by 30%, 70%, and 100%, the 28-day UCS respectively decreases by 36%, 23%, and 19.9%. The highest UCSs were observed in the S0W100 and S0WG100, with the average 28-day UCSs of 2.38 and 2.55 (MPa), respectively. Then, the amount of gypsum waste (6.6%) has no significant effect on reducing the UCS. The SEM results also showed that the average percentage of the pores resulting from the use of foam reagent has decreased by 17.6%, 18.6%, and 21.3% in samples with 100%, 30%, and 70% replacement of recycled materials, respectively. The present study suggests direct use of demolition wastes as produced before disposing of them. https://jeg.khu.ac.ir/article_11707.html One of the major challenges in tunnel engineering is the estimation and prediction of water inflow into tunnels. Although numerous methods have been proposed to evaluate hydraulic behavior and to estimate the permeability of soil and rock masses depending on their geological structures, these methods still lack sufficient accuracy and certainty. Therefore, in this study, the amount of water seepage into different sections of the Sarploe Zahab water transfer tunnel (T4), as part of the Sirvan river water transfer project to the tropical regions of Kermanshah and Ilam provinces, was evaluated using analytical (Goodman, Karlsrud, and El Tani), empirical (SGR and TIC), and numerical (SEEP/W) methods. The tunnel has a total length of 3.4 km, a diameter of 8.6 m, and inlet and outlet elevations of 552.51 m and 549.50 m above sea level, respectively. The results indicate that the water inflow into different tunnel sections varies from https://jeg.khu.ac.ir/article_11708.html Precipitation is one of the most important climatic variables, and due to its direct role in water resources, agriculture, and human livelihoods, its accurate assessment is of great significance. In recent years, gridded precipitation datasets, including station, satellite, and reanalysis data, have found widespread application due to their easy accessibility, lower cost, suitable spatial coverage, absence of missing data, and long temporal duration; however, examining their accuracy and validity is essential for scientific use. In this study, five precipitation datasets, namely APHRODITE and CRU (raingauge-based), PERSIANN-CDR (a combination of satellite and raingauge), and NCEP CFSR and ERA5 (reanalysis-based), were evaluated using the indicators R², NSE, NRMSE, BIAS, POD, FAR, and CSI, in comparison with data from 9 synoptic stations in the Khuzestan province. Since the number of indicators was large, the TOPSIS multi-criteria decision-making method was used for the final ranking of the datasets at each station. The results indicated that APHRODITE, CRU, and NCEP/CFSR provided the best performance, with APHRODITE exhibiting the highest agreement with observations across all stations; its average indicators were POD=0.756, FAR=0.290, and CSI=0.692. It was also found that some datasets may have lower accuracy in estimating precipitation amounts but demonstrate suitable performance in identifying rainy days. Therefore, the selection of a precipitation dataset should be based on the intended application.