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Showing papers in "Quarterly Journal of Engineering Geology and Hydrogeology in 2020"


Journal ArticleDOI
TL;DR: In this paper, numerical and analytical approaches were applied to the Qomroud water conveyance tunnel (located in Lorestan province, Iran) to assess the impact of tunnelling on the nearby extraction water wells.
Abstract: The decline or drying up of groundwater sources near a tunnel route is damaging to groundwater users. Therefore, forecasting the impact of a tunnel on nearby groundwater sources is a challenging task in tunnel design. In this study, numerical and analytical approaches were applied to the Qomroud water conveyance tunnel (located in Lorestan province, Iran) to assess the impact of tunnelling on the nearby extraction water wells. Using simulation of groundwater-level fluctuation owing to tunnelling, the drawdown at the well locations was determined. From the drawdowns and using Dupuit9s equation, the depletion of well flow rates after tunnelling was estimated. To evaluate the results, observed well flow rates before and after tunnelling were compared with the predicted flow rates. The observed and estimated water well flows (before and after tunnelling) showed a regression factor of 0.64, pointing to satisfactory results

92 citations


Journal ArticleDOI
TL;DR: In this article, a new tunnel squeezing classification tool was proposed to predict tunnel squeezing based on two parameters: Q, the tunnelling quality index; and H, the depth of the tunnel.
Abstract: The characterization of squeezing phenomena as a geological hazard is of great importance because squeezing has a crucial role in the selection of the route and type of tunnels and in the characteristics of the excavation device. Tunnel squeezing is also the basis for the designation and construction of tunnelling-related structures. We present a new tunnel squeezing classification tool to predict tunnel squeezing based on two parameters: Q, the tunnelling quality index; and H, the depth of the tunnel. We used data collected from published papers to train the model; these data included 225 case histories from different countries, including Andorra, India, Iran, Japan, Nepal, Spain, Turkey and Venezuela. Validation of the model indicated that our tunnel squeezing classification tool is more accurate than the speculative and analytical methods currently in use. The proposed model will help tunnelling experts to classify tunnelling media from the point of view of squeezing hazards.

14 citations


Journal ArticleDOI
TL;DR: The Cardiff Geo-Observatory as discussed by the authors measured temperature in a Quaternary aged sand and gravel aquifer in 61 boreholes and at a pilot shallow open-loop ground source heating system.
Abstract: Low-enthalpy ground source heating and cooling is recognized as one strategy that can contribute towards reducing reliance on traditional, increasingly insecure, CO2-intense thermal power generation, as well as helping to address fuel poverty. Development of this technology is applicable in urban areas where high housing density often coincides with the presence of shallow aquifers. In urban areas groundwater temperatures can be elevated owing to the subsurface urban heat island effect. Uptake and development of this technology is often limited by initial investment costs; however, baseline temperature monitoring and characterization of urban aquifers, conducted in partnership with local authorities, can provide a greater degree of certainty around resource and sustainability that can facilitate better planning, regulation and management of subsurface heat. We present a novel high-density, city-scale groundwater temperature observatory and introduce a 3D geological model aimed at addressing the needs of developers, planners, regulators and policy makers. The Cardiff Geo-Observatory measures temperature in a Quaternary aged sand and gravel aquifer in 61 boreholes and at a pilot shallow open-loop ground source heating system. We show that repurposing existing infrastructure can provide a cost-effective method of developing monitoring networks, and make recommendations on establishing similar geo-observatories. Thematic collection: This article is part of the Measurement and monitoring collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring

12 citations


Journal ArticleDOI
TL;DR: In this paper, the authors compare SCAT observations of oil type, surface coverage and pit oiling with collected surface and subsurface sediment samples taken concurrently and analyzed for a suite of hydrocarbon constituents.
Abstract: Trial pitting, borehole drilling, and soil, sediment and groundwater sampling are important components of oil spill response and contaminated land assessment. These investigations provide detailed information on the subsurface geology and contaminant occurrence and transport but have disadvantages including worker safety hazards, cost and time required for completion, and may cause cross-contamination among aquifers. An alternative to such investigations applied in oil spill response is the Shoreline Cleanup Assessment Technique (SCAT) approach, which relies heavily on direct visual observations to assess the severity of oil contamination and guide cleanup efforts. Here, we compare SCAT observations of oil type, surface coverage and pit oiling with collected surface and subsurface sediment samples taken concurrently and analysed for a suite of hydrocarbon constituents. Results indicate that although limited sampling and analysis is required to chemically characterize the contamination, SCAT observations can be calibrated using limited sediment sampling and are sufficient to steer physical cleanup methods. This is particularly evident as even closely spaced chemical samples show high variability. A coarser direct visual observation is fit-for-purpose considering the wide variability in contaminant distribution at even local levels. In this contribution, we discuss the limitations of the different methods. Supplementary material: The modified SCAT data collection form, figures showing subsurface versus ground surface total petroleum hydrocarbons (TPH) and a variogram of TPH measured in the ground surface and subsurface samples, and data tables are available at https://doi.org/10.6084/m9.figshare.c.4534682 Thematic collection: This article is part of the Measurement and monitoring collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring

11 citations


Journal ArticleDOI
TL;DR: In this paper, three alternative backfill mining methods are proposed, for three typical shallow coal mining conditions, using aeolian sand-based backfilling materials, which are readily available in this area.
Abstract: This study addresses the major geo-environmental hazards caused by shallow coal mining in China9s western eco-environment frangible area. These hazards are related to the high overburden pressure, surface subsidence, soil and water losses, and land desertification, with consequent vegetation and wildlife losses. To mitigate these hazards, three alternative backfill mining methods are proposed, for three typical shallow coal mining conditions, using aeolian sand-based backfilling materials, which are readily available in this area. The main influencing factor is the backfill material compaction ratio. Its effect on aquiclude deformation and water-conducting fracture evolution are assessed by numerical and physical simulation methods. The potential application of the proposed backfill coal mining alternatives is evaluated and discussed in detail. The results obtained are considered to be valuable for developing a strategy for the coordinated exploitation of coal resources and environmental protection in China9s western frangible eco-environment area.

10 citations


Journal ArticleDOI
TL;DR: In this paper, the authors use distributed fiber optic sensing for monitoring ground settlements caused by structures, dam integrity and displacements of creeping landslides. But, unlike conventional methods, such as extensometer, geodetical or radar measurements, the distributed sensors offer gapless monitoring over the entire depth of the borehole.
Abstract: Monitoring of ground displacements is critical for reliable geohazard risk assessment, construction and exploration. Recent advances in distributed fibre optic sensing allow for instrumenting boreholes in a wide range of geotechnical applications, such as monitoring of ground settlements caused by structures, dam integrity and displacements of creeping landslides. In contrast to conventional methods, such as extensometer, geodetical or radar measurements, the distributed sensors offer gapless monitoring over the entire depth of the borehole. The paper offers interpretation techniques, shares experiences from settlement- and displacement-monitoring projects, evaluates the results and discusses the limitations of the proposed measurement technology.

10 citations


Journal ArticleDOI
TL;DR: In this article, a logistic regression model and a bivariate statistical analysis were used to evaluate the groundwater recharge susceptibility, based on the assessment of the relationship involving groundwater recharge and parameters that influence this hydrological process.
Abstract: A logistic regression model and a bivariate statistical analysis were used in this paper to evaluate the groundwater recharge susceptibility. The approach is based on the assessment of the relationship involving groundwater recharge and parameters that influence this hydrological process. Surface parameters and aquifer-related parameters were evaluated as thematic map layers using ArcGIS. Then, a weighted-rating method was adopted to categorize each parameter9s map. To assess the role of each parameter in the aquifer recharge, a logistic regression model and a bivariate statistical analysis were applied to the Guenniche phreatic aquifer (Tunisia). Models are explored to establish a map showing the aquifer recharge susceptibility. The code Modflow was used to simulate the consequence of the recharge. The recharge amount was introduced in the model and was tested to verify the recharge effect on the hydraulic head for the two models. The obtained results reveal that the recharge as mapped in the bivariate statistical model has a minor impact on the hydraulic head. Results of the logistic regression model are more significant as the hydraulic head is widely affected. This model provides good results in mapping the spatial distribution of the aquifer recharge susceptibility.

10 citations


Journal ArticleDOI
TL;DR: The results suggest median economic values of 60-160 and mean values of 70-480 US dollars per household per year in the USA followed by Europe, and lowest in Asia.
Abstract: Groundwater is best described as an open access good: as a common pool resource others cannot be excluded from using and as a finite resource, its consumption leaves less for others to enjoy. In addition to its obvious benefits to humans and animals, it contributes in sustaining the hydro-environment and life on the planet. Scarcity causes groundwater to become an economic good and have an economic value. By and large, economic valuations respond to changes in the quantity and quality of groundwater. They are based on willingness to pay for maintaining its benefits or willingness to accept compensation for giving them up. There have been some 50 published groundwater valuation studies worldwide in the last 30 years, mostly focusing on groundwater quality and contamination. There is sparsity of valuations in Africa and Asia. The results suggest median economic values of 60–160 and mean values of 70–480 US dollars per household per year. Generally, values are higher in the USA followed by Europe, and lowest in Asia. People9s income is a major factor affecting values, but this does not mean that they value groundwater less. Economic valuations and cost–benefit analysis are useful in highlighting people9s priorities and choice of options. However, economics alone should not dictate actions for protecting groundwater resources from degradation and depletion.

10 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe results to date of a continuing monitoring study of coastal ‘soft cliff’ recession at the British Geological Survey9s (BGS9s) Coastal Landslide Observatory (CLO) on the east coast of England at Aldbrough, East Riding of Yorkshire.
Abstract: The paper describes results to date of a continuing monitoring study of coastal ‘soft cliff’ recession at the British Geological Survey9s (BGS9s) Coastal Landslide Observatory (CLO) on the east coast of England at Aldbrough, East Riding of Yorkshire. The cliffed site, part of the 50 km long Holderness coast, consists of glacial deposits, and is one of the most rapidly eroding coastlines in Europe. This rapid rate of erosion provides an ideal opportunity for observation and process understanding because it facilitates the collection of data over periods of time encompassing significant new landslide events at the same location. The results of two approaches are reported: first, terrestrial Light Detection and Ranging (LiDAR) surveying (TLS); second, the installation of instrumented boreholes. The aim of the research is to combine these to investigate the role of landslides and their pre-conditioning factors and the influence of geology, geotechnics, topography and environmental factors on cliff recession. To date, an average recession rate of 1.8 m a−1 and a maximum rate of 3.4 m a−1 have been recorded for the site. The establishment of the CLO and its conceptual geological–geotechnical model are described in a related paper.

9 citations


Journal ArticleDOI
TL;DR: In this article, the feasibility of recovering heat energy from mine water contained within an abandoned coal mine in South Wales is assessed for a proposed district heating scheme, where the study area is the village of Caerau, in the Upper Llynfi Valley, Bridgend County Borough, South Wales, UK.
Abstract: The feasibility of recovering heat energy from mine water contained within an abandoned coal mine in South Wales is assessed for a proposed district heating scheme. The study area is the village of Caerau, in the Upper Llynfi Valley, Bridgend County Borough, South Wales, UK, comprising around 750 residential houses, a primary school and 17 commercial properties. This paper describes: an archival geological and mining desk study focussed on Caerau colliery, consideration of regional mine linkages, GIS techniques used to create a 3D initial conceptual geological mine model of Caerau workings, permitting and licencing requirements, community engagement activities undertaken and the findings of a single exploratory borehole. The borehole intersected a void space in flooded mine workings around the horizon of the Six Foot seam at a depth of 224 m below ground level, as predicted by the conceptual mine model. The rest water level within the borehole lies at 92m below ground level and the measured in situ temperature of the mine water at the base of the borehole was 20.3 °C. An unexpectedly high and sustained geothermal gradient of approximately 53 °C/km was calculated from repeated measured temperature profiles.

9 citations


Journal ArticleDOI
TL;DR: The British Geological Survey (BGS) field-based "Coastal Landslide Observatory" as mentioned in this paper was designed for the study of coastal cliff recession on the east coast of England at Aldbrough, East Riding of Yorkshire.
Abstract: The paper describes the establishment of the British Geological Survey (BGS)’s field-based ‘Coastal Landslide Observatory’, designed for the study of coastal ‘soft cliff’ recession on the east coast of England at Aldbrough, East Riding of Yorkshire. The cliffed site is part of the 50 km long Holderness coast which is one of the most rapidly eroding coastlines in Europe. The site features a 16–17 m high sea-cliff formed by Late Devensian (18–13 ka) glacial deposits dominated by tills. The aim of the research is to investigate the role of landslides and their pre-conditioning factors, including geology, geotechnics and topography, in cliff recession with a view to developing coastal landslide forecasting capability. Two research approaches are encompassed in the observatory: firstly, terrestrial LiDAR surveying, from 2001 to present, to create digital elevation models of the cliff and, secondly, installation of instrumented boreholes from 2012. The design, methods, conceptual ground model, implementation of the observatory and geotechnical laboratory test results are described in this article. The interpretation of results and the final ground model are presented in a related article in this volume.

Journal ArticleDOI
TL;DR: In this paper, the authors provide an update on work done and the development of knowledge on Irish compressible soils since Eamon Hanrahan9s book on the topic, which subdivided these soils into three categories; namely, alluvial, estuarine and lake-bed deposits.
Abstract: The objectives of this paper are to provide an update on work done and the development of knowledge on Irish compressible soils since Eamon Hanrahan9s book on the topic. Eamon subdivided these soils into three categories; namely, alluvial, estuarine and lake-bed deposits, and he termed them ‘troublesome soils’. A brief background geology will initially be presented. The complexity of the deposits both on a macro- and micro-scale will be highlighted. Sites that have been well studied will be summarized and the engineering solutions used to construct on these sites will be reviewed. Although work on these sites presents a significant engineering achievement, some important lessons were learned. The remainder of the paper deals with how these lessons might be addressed in the future; for example, how to use modern ground investigation techniques to best characterize these complex deposits and what are the best techniques for examining important detailed aspects of 1D consolidation behaviour such as the identification of the apparent preconsolidation stress, the sometimes rapid rate of consolidation and creep, and also how to characterize the undrained shear strength of the soils. The work will be benchmarked against experience of the behaviour of Scandinavian soft soils.

Journal ArticleDOI
Tim Spink1
TL;DR: In this article, a risk-based approach is adopted that requires an understanding of the likelihood that any of the earthworks may fail, combined with a knowledge of the consequences should they fail.
Abstract: Strategic geotechnical asset management considers the whole of an organization9s earthworks portfolio and is concerned with setting an overall earthworks asset management policy with long-term objectives related to asset performance, safety and condition, and identifying how those objectives can best be met, now and into the future. A risk-based approach is adopted that requires an understanding of the likelihood that any of the earthworks may fail, combined with a knowledge of the consequences should they fail. Procedures are required to identify those earthworks that are most vulnerable to failure under the influence of triggering events, such as extreme weather. The risks are managed through a mix of interventions to reduce the likelihood of failure and mitigations to reduce the impact of failure. Many of the challenges of implementing a strategic earthworks policy have, or are, being met by the main UK transportation infrastructure organizations. Thematic collection: This article is part of the Ground-related risk to transportation infrastructure collection available at https://www.lyellcollection.org/cc/Ground-related-risk-to-transportation-infrastructure

Journal ArticleDOI
TL;DR: In this article, the authors use satellite imagery available on Google Earth, supported by geomorphological field observation, to delineate and assess these notably unstable areas for land use planning and slope management purposes.
Abstract: The Central Cordillera of Luzon in the Philippines is home to some of the most complex geology, active plate margin tectonism, heaviest rainfall and steepest terrain in the world. It also hosts a thriving agricultural community that has developed its agrarian, municipal and transport infrastructure in a landscape of marginal stability and extreme geomorphological sensitivity. The village of Pilando occupies a saddle on a prominent ridge where it is crossed by the Halsema Highway. As a result of landslide displacements, both the highway and the village have been subsiding for several decades and many dwellings have had to be abandoned. From topographical survey and visual observation, average rates of settlement vary between c. 0.1 and 0.4 m a−1. The apparent depth and areal extent of ground movement are such that attempts to stabilize the area would be both impracticable and uneconomic. Realignment and relocation are options that might be considered but many adjacent slopes are unstable or have failed in the past and those that have not are highly sensitive to earthworks and drainage disturbance. Unfortunately, there are many areas of the Central Cordillera that are affected by similar slope instability problems. The interpretation of satellite imagery available on Google Earth, supported by geomorphological field observation, can assist in the delineation and assessment of these notably unstable areas for land use planning and slope management purposes.

Journal ArticleDOI
TL;DR: In this article, the performance of a dewatering scheme comprising of 15 vertical wells in two residential areas in Kuwait is evaluated from pumping tests and preliminary numerical modelling. And the results show that the scheme can keep the water table at the desired levels over a limited area.
Abstract: In heavily populated residential areas lacking adequate subsurface drainage, leakage from urban water supplies and wastewater discharge causes groundwater levels in underlying shallow aquifers to rise. This may have serious consequences for the stability of building foundations, roads and natural landforms. This paper evaluates the performance of a dewatering scheme comprising of 15 vertical wells in two residential areas in Kuwait. The hydraulic effectiveness is evaluated from pumping tests and preliminary numerical modelling. The results show that the scheme can keep the water table at the desired levels over a limited area. The maximum predicted nodal drawdowns after one year of pumping at 16 835 m3d–1 were 4.2 and 5.24 m in the two areas. Further investigations are proposed with the objective of optimizing pumping rates.

Journal ArticleDOI
TL;DR: The concept of an optimum compaction line is introduced in this article, where compaction results for soils in terms of the dry density and degree of saturation and introduce the concept of the optimum line.
Abstract: Soil compaction is an important operation during the construction of road embankments, railway subgrade, earth dams and compacted clay liners for waste disposal. Soil compaction is usually controlled based on the ratio of the dry density of the soil to the soil water content. However, this relationship presents problems in both the laboratory and in the field when using excess compaction energy levels in cohesive soils with a high natural water content, including differences in the compaction energy levels and a reduction in strength as a result of over-compaction. The compaction curve, which considered the compaction energy levels, is usually unknown in the field and the main factors influencing the stiffness and strength of compacted soils are the dry density and the degree of saturation. We show here compaction results for soils in terms of the dry density and degree of saturation and introduce the concept of an optimum compaction line.

Journal ArticleDOI
TL;DR: In 2008, during the construction works in a section of the Madrid-Asturias high-speed railway line (Spain), a large-scale hillside instability affected 460m of the section.
Abstract: The presence of large palaeo-landslides can hinder the construction of railway lines if they cause an alteration of the natural balance of the slope, significantly increasing the cost of the project. During the construction works in a section of the Madrid–Asturias high-speed railway line (Spain), a large-scale hillside instability affected 460 m of the section. The ground movement began 10 months after the start of the excavations and remained active throughout the observation period (2008–2010). Data provided by fieldwork, boreholes and instrumental monitoring have allowed the investigation of the geological units involved, together with the geometry and the kinematics of the mass movement. This landslide involves a Paleozoic basement with an estimated volume of 4 400 000 m3. It shows low displacement rates (

Journal ArticleDOI
TL;DR: In this article, qualitative and quantitative observations from fieldwork and remote sensing are used to describe the materials and geomorphology of the landslides across Langtang Valley, and quantify the extent to which coseismic and monsoon-triggered landslides have affected Langding9s trekking infrastructure.
Abstract: In 2015, the Mw 7.8 Gorkha earthquake struck Nepal, triggering thousands of landslides across the central and eastern Himalayas. These landslides had many adverse effects, including causing widespread damage to low-grade transport routes (e.g. tracks, footpaths) in rural regions that depend on tourism for survival. Langtang Valley is a glacial–periglacial landscape located 60 km north of Kathmandu. It is one of the most popular trekking regions in Nepal and has been severely affected by Gorkha earthquake-triggered and monsoon-triggered landsliding. Here, qualitative and quantitative observations from fieldwork and remote sensing are used to describe the materials and geomorphology of the landslides across Langtang Valley, and to quantify the extent to which coseismic and monsoon-triggered landslides have affected Langtang9s trekking infrastructure. The dominant bedrock materials involved within Langtang landslides are found to be a range of gneisses and intruded leucogranites. In total, 64 landslides are found to have intersected trekking paths across Langtang, with coseismic and monsoon-triggered landslides having an impact on c. 3 km and 0.8 km of path respectively. It is observed that the practice of reconstructing paths through unstable landslide deposits is leaving the trekking infrastructure across Langtang increasingly vulnerable to future failure.

Journal ArticleDOI
TL;DR: In this paper, a scaled model was used to simulate a large cleared-building wall foundation in gravel-fill at a test facility, before multiple 2D electrical resistivity tomography (ERT) profiles were acquired using different array configurations.
Abstract: Electrical resistivity surveys are commonly used to detect and characterize near-surface buried objects in commercial developments of brownfield sites. Two-dimensional electrical resistivity tomography (ERT) profile arrays predominate in such surveys owing to their relatively rapid deployment, good penetration depths and fast data collection rates. However, there is a need to test the optimum array types in such surveys. A scaled model was used to simulate a large cleared-building wall foundation in gravel-fill at a test facility, before multiple 2D ERT profiles were acquired using different array configurations. Results were used to generate 2D resistivity models using both least-squares smoothness-constraint and robust inversion. Two-dimensional profile array comparisons showed that the Wenner and dipole–dipole arrays were the best in detecting the cleared-wall foundation, although dipole–dipole arrays better delineated the top of the wall foundation. This study suggests that both Wenner and dipole–dipole array configurations should be utilized to detect buried wall foundations for 2D resistivity surveys.

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors developed a new technique to control the behavior of the high-located main key stratum (HMKS) to improve mine safety, and they used grouting to add grout between the separated beds during mining.
Abstract: The gob-side entry 150–180 m behind the 14201 working face at Majialiang coal mine is severely deformed. We developed a new technique to control the behaviour of the high-located main key stratum (HMKS) to improve mine safety. The failure type and breaking span of the HMKS were determined based on key stratum theory and the voussoir beam model. By monitoring the deformation of the entry and surface subsidence, we found that the main cause of the large deformation of the gob-side entry was sliding of the HMKS. A new technique is proposed to add grout between the separated beds during mining. Physical simulations indicated that this technique is efficient in controlling sliding of the HMKS and avoiding strong dynamic loading, with the peak abutment stress reduced by 59%. Grouting stations were set up at a spacing of 150 m behind the advancing work face based on the principles and key parameters of the technique and the geological conditions at Majialiang coal mine. Before the HMKS began to slide, we injected high-water content materials with a water to cement ratio of 1.5:1 into the bed separation space to prevent breaking of the key strata.

Journal ArticleDOI
TL;DR: In this article, a 3D finite extended element method was used to calculate the factor of safety (FOS) of the waste dump via the strength reduction technique and the simulation showed the dump to have an FOS of 1.22 and both the position and depth of penetration of cracks in a waste dump have a crucial impact on the stability of the slope.
Abstract: This paper uses a 3D model for stability assessment of Zhujiabaobao waste dump with ground cracks. The study data were gathered via reconnaissance, geomorphological analysis and laboratory experiment. A 3D finite extended element method model that can consider cracks was then used to calculate the factor of safety (FOS) of the waste dump via the strength reduction technique. The simulation shows the dump to have an FOS of 1.22 and both the position and depth of penetration of cracks in the waste dump have a crucial impact on the stability of the slope. Because the study area is located in a seismically active area, simulation and analysis of the dynamic response of the waste dump under different magnitudes of seismic waves (peak acceleration is 0.05, 0.15, 0.25 and 0.45g) were performed via an explicit dynamic model. The simulation shows that high steps in the slope are particularly responsive to earthquakes. The approach used here for analysing stability under static and dynamic loads is useful for hazard prevention and mitigation.

Journal ArticleDOI
TL;DR: The Halsema Highway has been affected by several new typhoons including, most notably, Typhoons Pepeng and Ompong in 2009 and 2018 respectively as discussed by the authors, but very little of the recorded damage has occurred in the locations of earthquake reinstatement.
Abstract: Parts of the Central Cordillera of Luzon are among the most challenging locations on Earth in which to build and maintain transport infrastructure, a situation perhaps most epitomized by the Halsema Highway. Since its original construction in the 1920s, the highway has undergone phased improvement and has become a socio-economic lifeline to the rural communities it serves. Unfortunately, in 1990, continuing road improvement works had to be abandoned owing to the outcome of a 7.8 Ms earthquake and the effects of subsequent typhoon damage. Earthquake reinstatement works were designed in 1998 and constructed between 2001 and 2006. The engineering geological challenge this posed was compounded by the effects of severe typhoon rains during the reconstruction period, requiring continual assessment of changing slope and drainage conditions. Since construction, the road has been affected by several new typhoons including, most notably, Typhoons Pepeng and Ompong in 2009 and 2018 respectively. Field inspections in 2010 and 2018, combined with the interpretation of satellite imagery available in Google Earth, have allowed the performance of the works implemented between 2001 and 2006 to be assessed and the outcome has been largely favourable. Very little of the recorded damage has occurred in the locations of earthquake reinstatement. Instead, several new areas of slope failure and subsequent blockage and damage to the road have developed. Many of these areas can be explained with respect to their underlying engineering geology and geomorphology. However, there are just as many that owe their origin to the pattern of rainfall and runoff arising during the passage of individual and successive typhoons, modified significantly by drainage management practices in the road corridor, where engineering serviceability and land use practices sometimes have conflicting objectives.

Journal ArticleDOI
TL;DR: In this article, electrical resistivity tomography and vertical electrical sounding geophysical methods were used to determine the electrical resistivities structure of the subsurface beneath the rapidly developing Khon Kaen University campus in NE Thailand.
Abstract: Salinization is a growing concern of global proportions. In urban settings effective salinity management strategies must be adopted to ensure environmental sustainability in the face of rapid development. Geophysical methods, particularly electrical methods, can be used to non-invasively map the spatial distribution of subsurface groundwater salinity over wide areas at reasonable cost. In this paper, electrical resistivity tomography and vertical electrical sounding geophysical methods were used to determine the electrical resistivity structure of the subsurface beneath the rapidly developing Khon Kaen University campus in NE Thailand. The geophysical results were combined to generate a contour map of depth to saline groundwater beneath the campus. Saline groundwater was present in shallow strata in the southern part of the campus but is not indicated beneath the northern half, so that drilling for groundwater wells is recommended there. The map can be used by campus planners to inform their salinity management strategies, including the siting of groundwater wells, the design of potential soil reclamation schemes, and the location and design of buried infrastructure according to indications of soil corrosivity. The method can be applied at other urban sites located on salt-affected lands and, in general, provides a valuable supplement to costly traditional geotechnical testing.

Journal ArticleDOI
TL;DR: In this paper, a series of modifications to the New Zealand standard weathering quality index (WQI) method was proposed to improve its effectiveness in evaluating the weatherability of two sources of andesitic UGM aggregates.
Abstract: Despite the fact that the in-service weathering process can cause undesirable changes to unbound granular materials (UGMs), there is no reliable preconstruction laboratory test method to evaluate their weatherability. Most existing durability tests do not take into account either the properties of the parent rock or in-service environmental conditions. This study proposes a series of modifications to the New Zealand standard weathering quality index (WQI) method to improve its effectiveness in evaluating the weatherability of two sources of andesitic UGM aggregates. The modifications proposed include adjusting the gradation of aggregates, the wetting and drying process, and the chemical composition and temperature of the weathering solution, so that they can be more representative of the conditions of the UGMs in the pavement structure. The quality and quantity of produced fines (passing the 75 μm sieve), the physical degradation and the retained abrasion resistance of aggregates were also adopted to assess the weatherability of materials. It can be concluded that the standard WQI fails to evaluate the potential weatherability of andesite road aggregates. The findings also reveal the influence of the modified solution on both physical and chemical weathering of selected aggregates, and, as expected, marginal materials are more significantly affected.

Journal ArticleDOI
TL;DR: Wuxi City is located in the Yangtze River Delta region, China and is underlain by a multi-layered aquifer system in porous Quaternary deposits as discussed by the authors.
Abstract: Wuxi City is located in the Yangtze River Delta region, China and is underlain by a multi-layered aquifer system in porous Quaternary deposits. Groundwater extraction, mainly from the second confined aquifer, has led to severe regional land subsidence. The ground surface started to recover after the restriction and, ultimately, the banning of groundwater pumping. This paper reports the results of long-term surveys, groundwater piezometric head (GPH) measurements and the monitoring of ground surface deformation by levelling and borehole extensometers. The subsidence is attributed to the compression of both the aquifer and aquitards in the porous strata. The spatial characteristics of subsidence are related not only to the distribution of the GPH, but also to the thickness and compressibility of different strata, the distance from the pumped aquifer and the distribution of pumping. There was a temporal lag in subsidence relative to groundwater drawdown. The uplift is related to a period of recovery following the peak pumping period and groundwater recovery subsequent to the restriction and/or banning of groundwater pumping. The uplift was 40% of the previous maximum at the Qianzhou borehole extensometer station.

Journal ArticleDOI
TL;DR: A series of illustrated examples is presented here to demonstrate the capabilities of ground-level monitoring using InSAR (interferometric synthetic aperture radar) and reveal fascinating spatial and temporal patterns of ground motion across London.
Abstract: A series of illustrated examples is presented here to demonstrate the capabilities of ground-level monitoring using InSAR (interferometric synthetic aperture radar). Greater London is an ideal area to demonstrate and validate measurements derived using InSAR; its continuous urban fabric and the regular acquisition of SAR images from high-resolution sensors, such as TerraSAR-X, allows detection and monitoring of over 1.7 million measurement points with millimetre-scale accuracy. The results, some of which are shown here, reveal fascinating spatial and temporal patterns of ground motion across London and demonstrate the benefit of using high-resolution InSAR technologies in engineering applications. Interpreting the motion patterns can be challenging, however, owing to their complex and sometimes mysterious causes; we therefore welcome any assistance in doing so and we hope this photographic feature serves to trigger interest.

Journal ArticleDOI
TL;DR: In this article, a new model considering the change of asperity curvature is proposed to explain the wear behavior of rock joints based on the Greenwood and Williamson (GW) model, and a rough surface model with multi-level curvature radius is proposed.
Abstract: Rock is a material that is affected by wear, and the curvature of the asperities on a rock joint surface increases with the degree of wear after shearing. Based on the Greenwood and Williamson (GW) model, a new model considering the change of asperity curvature is proposed to explain the wear behaviour of rock joints. First, the shear stiffness formula for a joint surface is derived when the asperity curvature is constant, which shows that the shear stiffness increases with increase of asperity curvature. According to the Mohr–Coulomb criterion, the yield position of a single asperity under normal force and tangential friction force is discussed. Then, the critical normal force for a single asperity at a specific friction coefficient is obtained, which shows that the normal force corresponds to the curvature radius of the asperity. A rough surface model with multi-level curvature radius is proposed. With increase of normal force, the higher-order asperities gradually fail and the curvature radius become larger. A specific pressure value excites a specific radius of curvature, and the larger the pressure, the larger the radius of curvature. The relation between the normal force and the curvature radius is proposed and a shear stiffness formula considering the change of curvature radius of the asperity is derived. The proposed model is verified on the basis of the published experimental results. The calculation results of the proposed model can reflect the test results well: for a given joint surface, with increase in normal force the joint surface gradually becomes smooth; for different joint surfaces, with increase in roughness, the joint surface is more easily smoothed.

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TL;DR: In this article, a decision tree is presented, constructed on the basis of hydrogeological characteristics (water table depth, freshwater thickness, surface area required and distance between wells), to choose the optimal groundwater extraction method in the case of a coastal unconfined aquifer.
Abstract: In this paper, a decision tree is presented, constructed on the basis of hydrogeological characteristics (water table depth, freshwater thickness, surface area required and distance between wells), to choose the optimal groundwater extraction method in the case of a coastal unconfined aquifer. A comparison is made of the groundwater extraction methods in a freshwater aquifer of limited thickness occurring in coastal dunes in the eastern region of the Province of Buenos Aires (Argentina). The negative effects brought about by the wrong use of the groundwater extraction methods are analysed, because, as a result of excessive extraction, such methods lead to the dramatic decrease of the freshwater reserves. The decision tree is a useful tool to assist decision-makers as it suggests the most suitable groundwater extraction method options (vertical wells or wellpoints), as well as identifying areas that are unsuitable for sustainable groundwater extraction.

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TL;DR: In this article, the authors used persistent scatterer interferometric (PSI) data derived from TerraSAR-X (TSX) observations for the period from May 2011 to April 2017 were analysed for shrink-swell patterns across three areas of London in Hammersmith, Muswell Hill and Islington.
Abstract: London Clay, which underlies the majority of Greater London, has a high shrink–swell potential that can result in damage to foundations and surface infrastructure due to seasonal expansion and contraction of the clay. Currently, surface movement as a result of shrink–swell is not monitored in London, meaning that the magnitude and cyclicity of these movements is poorly understood. Persistent Scatterer Interferometric (PSI) Synthetic Aperture Radar data provide high-precision line-of-sight displacement measurements at a high point density across urban areas, offering the possibility of routine shrink–swell monitoring across whole cities. To test this, PSI data derived from TerraSAR-X (TSX) observations for the period from May 2011 to April 2017 were analysed for shrink–swell patterns across three areas of London in Hammersmith, Muswell Hill and Islington. A consistent cyclicity and amplitude was detected at all sites and the number of cycles is comparable with those identified in rainfall data. The amplitude of these cycles is smaller than anticipated, most probably because of the resisting effect of roads and pavements. The Cranfield University Leakage Assessment from Corrosivity and Shrinkage (LEACS) database was used to subdivide the PSI data and the average velocity and amplitude of each class statistically tested for significant differences between classes. The results show that it is not possible to statistically isolate possible soil shrink–swell movement in TSX PSI data in London. Thematic collection: This article is part of the ‘Measurement and monitoring’ collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring

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TL;DR: In this paper, the authors demonstrate how geospatial analysis and data management techniques may be applied to this challenge at both strategic (regional or national) and tactical (site-specific) scales for embankments incorporating plastic clay fill.
Abstract: Most British railway embankments were constructed between 120 and 180 years ago without the benefit of modern design and construction methods. This can result in undesirable load-deformation characteristics and consequent disruption to present-day railway operations, for which there is unprecedented demand. Annual rail passenger kilometres have approximately doubled in the last 20 years and freight has increased by 60% over the same period. Whereas elements such as rails or bridges can be refurbished or replaced to meet increasing demand, the same is not usually feasible for embankments. Development of techniques to assess embankment performance risks posed by operational capacity enhancements is therefore of increasing significance to railway geotechnical asset management. The two case studies presented in this paper demonstrate how geospatial analysis and data management techniques may be applied to this challenge at both strategic (regional or national) and tactical (site-specific) scales for embankments incorporating plastic clay fill. The case studies also demonstrate, in a world of ever more abundant data, the growing need for engineering geologists and geotechnical engineers to augment their traditional knowledge with comprehensive data management and geospatial analysis skills, these being essential for modern infrastructure asset management. Thematic collection: This article is part of the ‘Ground-related risk to transportation infrastructure’ collection available at: https://www.lyellcollection.org/cc/Ground-related-risk-to-transportation-infrastructure