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Extending geotechnical classification using excavation stability data in fine-grained alluvial deposits
Dr Emad Namavar,
Volume 19, Issue 5 (12-2025)
Abstract
Accurate geotechnical classification is essential for designing excavations in urban environments, where soil behavior is  greatly affected by excavation-induced stresses. This study improves the geotechnical characterization of fine-grained alluvial deposits belonging to the youngest sedimentary unit (Unit D) in Rieben’s classification system. A comprehensive investigation was conducted through borehole drilling, Standard Penetration Tests (SPT), pressuremeter testing, and laboratory experiments including triaxial, uniaxial, and direct shear tests. Excavation stability was evaluated using the Morgenstern–Price method under both short-term and long-term conditions. Based on the geotechnical parameters and slope stability simulations, Unit D was subdivided into three distinct zones (D1, D2, and D3) with different excavation behaviors. Zone D1, characterized by lower sand content, allows deeper vertical cuts, whereas the presence of sandy lenses in Zone D3 restricts excavation depth and requires gentler slopes. The findings provide an updated geotechnical classification framework for fine-grained alluvia, offering practical guidelines for safe excavation design and contributing to the broader understanding of alluvial systems in urban geotechnical engineering.

Integration of empirical and systems engineering frameworks in tunnel support design: a comprehensive study of 38 tunnels in Iran
Dr Seyed Mahmoud Fatemi Aghda, Dr Mehdi Talkhablou, Habibolah Heidari,
Volume 19, Issue 5 (12-2025)
Abstract
Reliable assessment methods are required for designing initial support for tunnels in complex geological conditions. This study provides a thorough comparison of the Rock Mass Rating (RMR) and Rock Engineering System (RES) frameworks, examining a substantial dataset comprising 38 tunnels situated in various lithological and tectonic zones across Iran. While the RMR framework offers empirical simplicity, the RES framework provides a systems-based approach that quantifies parameter interdependencies. Analysis of field data, including shotcrete thickness and bolt density, revealed that the RES framework captures hydro-mechanical coupling more effectively, particularly in intermediate rock masses. To reconcile discrepancies between the two systems, we explored an integrated statistical formulation combining normalized RMR ratings with RES stability indices. This approach demonstrated a significantly higher correlation with field performance (R² ≈ 0.99) than the individual methods. The results emphasise the importance of integrating empirical and systems-based approaches to improve the reliability of predictions in tunnel support design and provide a solid foundation for engineering decisions in heterogeneous rock masses.

Determining land subsidence rate and its relationship with groundwater level decline using satellite data in the Damghan aquifer
Akramalsadad Ghadami, Houshang Khairy, Ebrahim Rahimi,
Volume 20, Issue 1 (6-2026)
Abstract
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.

Seismic risk assessment and zoning in urban environments using spatial multi-criteria analysis: a case study of Manjil, Iran
Dr. Manoochehr Mortazavi Chamchali, Dr. Ghazaleh Mohebbi Tafreshi, Dr. Amin Mohebbi Tafreshi,
Volume 20, Issue 1 (6-2026)
Abstract
Situated in northern Iran, Manjil City 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 emphasised the need for robust spatial risk assessment to mitigate the impact on people, the economy and infrastructure. This study presents a comprehensive seismic risk assessment and spatial zonation for Manjil, employing an integrated multi-criteria evaluation approach that couples Geographic Information Systems (GIS), the Analytic Hierarchy Process (AHP) and fuzzy logic. Risk was modelled as a function of the interaction between seismic hazard potential and spatial vulnerability. Vulnerability indicators, including residential density, land use patterns and critical urban infrastructure, were standardized and weighted using the AHP framework. Our findings suggest that high-density residential areas primarily contribute to urban vulnerability, whereas critical infrastructure components play a disproportionately vital role in emergency response scenarios.. In 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’ Spatial analysis revealed 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 areas.   

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