Search

Tunnel deformation is hard to predict since the complicated geological conditions and lack of understanding of soil-structure interactions. This paper proposes basement excavation influence zones for the deformation of the adjacent tunnel, providing a way for tunnel deformation prediction. An excavation project in Cangshan District, Fuzhou, was used as a base case to generate artificial data on tunnel response at different locations. All simulations are done in the condition when the maximum horizontal displacement of the supporting structure reaches 40 mm. Given the control requirements of tunnel deformation in several codes, 5, 10, and 20 mm tunnel deformation is selected as zone boundaries. Excavation influence zones for adjacent existing side tunnel under typical soil conditions were then proposed with the boundaries. These boundaries of influence zones are simplified into a three-segment polyline and therefore divided influence zones into four parts: strong influence zone, secondary influence zone, moderate influence zone, and weakly influence zone. Three coordinate values are introduced to quantify the boundary of the influence zone, including top width Li1, the turning point depth Vi, and the bottom width Li2 of the influence zone. The application results showed the proposed excavation influence zones could provide support for tunnel deformation prediction. [ABSTRACT FROM AUTHOR]

This paper aims to discuss the recent development in rock hardness testing methods and their applications in rock engineering and geological studies. Hardness is one of the essential physical characteristics of minerals and rocks, with dominant effects on rock mechanics and excavatability. In this paper, all available rock hardness testing methods are classified into main categories: static and dynamic methods. After that, standards and testing procedures have been briefly discussed using various literature. The review clarifies the dominant factors that affect the rock hardness as well as physicomechanical characteristics, which affect the hardness. The correlations between different hardness testing methods are analyzed using regression analysis, and their interconnections between them are presented. Also, the applications of hardness scales in the assessment of rock excavatability and machinability have been investigated. In total, it could be concluded that dynamic hardness testing methods have been widely applied in rock engineering. However, the relative standards and field measurement procedures have not been developed well. Future research must incredibly be focused on this lack of past studies and should try to develop reliable models for the prediction of physicomechanical rock parameters. [ABSTRACT FROM AUTHOR]

Mine water disaster has always been one of the major disasters restricting coal mine safety production. The thin bedrock area threatened by Quaternary unconsolidated aquifer may be affected by mining; on the one hand, it may cause the roof water disaster accident of working face, and on the other hand, it will cause the loss of groundwater resources. Therefore, it is of great practical significance to evaluate the risk of water inrush in thin bedrock area and analyze the feasibility of water conservation mining, which provides a reference basis for ensuring mine safety production and sustainable development of groundwater resources. In this paper, Zhuanlongwan coal mine is taken as an example to comprehensively determine the development height and shape of the water-conducting fracture zone through discrete element numerical simulation, empirical formula calculation, and field measurement, and finally determine the maximum development height of the water-conducting fracture zone. According to the analysis of lithologic structure characteristics of the study area, it is concluded that the bottom of the Quaternary system has a good plastic mudstone layer, which can effectively block water inrush of Quaternary roof. In this paper, the risk of water inrush of Quaternary loose aquifer in the thin bedrock area is evaluated by the height of safe coal pillar and the distance between coal roof and Quaternary aquifer, and it is divided into three grades: dangerous zone, relatively dangerous zone, and safe zone. The study shows that the dangerous areas and relatively dangerous areas are mainly distributed in the east and south of the first mining area, which are basically in a gully, and the other areas are safe areas. Taking measures of mining height limit, speed limit, and constant speed to push through the thin bedrock area directly can reduce the disturbance to the roof aquifer as much as possible and ensure the dual effects of water resource protection and water disaster prevention. [ABSTRACT FROM AUTHOR]

For the project in this paper, the maximum slope of the large-diameter shield tunneling is 27.4‰. A refined numerical model that takes into account the construction loads and the hardening of synchronous grout during the shield tunneling with a large slope was established. The influence of tunneling on the ground settlement and the force characteristics of the segmental lining has been achieved, the results of which have been compared with those of the on-site monitoring. Based on the three-dimensional image theory, the analytical formulae for calculating ground settlement have been proposed and revised. The variation of the ground surface settlement obtained from the numerical simulation in this paper is in good agreement with that obtained from the field measurement. The proposed analytical formula is applicable for the ground settlement prediction, especially for the Pearl River Delta stratum. Based on the numerical simulation, it is found that the positions of the maximum principal stress of the segment are close to the measured positions of the crack and dilapidation. The maximum compressive stress and maximum tensile stress at these locations are both increased compared with those when the segment is newly assembled. Affected by the radial restraint force of the hard rock formation on the segment, the horizontal convergence of the segment at the tunnel springline is very small, and the phenomenon of upward floating of the segment under the strong slurry pressure is consistent with the monitoring results. [ABSTRACT FROM AUTHOR]

Rapid urban development and modernization in Makkah have led to an increase in urban infrastructure needs. The city of Makkah is a main destination for the global Islamic pilgrimage and is highly utilized for major infrastructure and building expansion including processes of densification. As a consequence of Hajj and Umrah activities, the city experiences a major annual upward trajectory of public space usage and solid waste production which caters to the needs of temporary activities targeted to foreign visitors. These circumstances lead to issues of inefficiencies in the management of public services in the city, particularly in the provision of public space and solid waste management for residents. Within this context, the aim of this paper is to understand the development of public space in Makkah and the level of services delivered to local residents based on residents' perspectives on services provided in formal and informal settlements in Makkah. The study contributes to the gap in research on public space and waste handling in Makkah. Interviews addressing resident characteristics and public space with the quality of solid waste provision in Makkah are presented. An explanation of residents' preferences for public space was also presented. At different times of the day, in the year 2018, the observations were carried out to identify usage patterns by the residents. The paper accomplishes this by presenting significant points for developments in community space and solid waste management. [ABSTRACT FROM AUTHOR]

During a landfill's service, a large amount of methane will be produced and released attributable to microbial degradation of organic matter; this methane escapes into the atmosphere even with gas traps in place. Methane is a flammable and explosive greenhouse gas. When the concentration of methane in the landfill reaches a certain limit, it can cause explosions, fires, and other accidents, and its potential global greenhouse effect is approximately 25 times higher than that of carbon dioxide. Therefore, because the emission of methane from landfills into the atmosphere aggravates the greenhouse effect, for the sake of safety and environmental protection, it is urgent to take measures to reduce the ability of methane to escape through the landfill cover. Methanotrophs are microorganisms that use methane as their sole carbon and energy source and have a strong ability to oxidize methane biologically. In this paper, methanotrophs' methane removal efficiency in an inorganic salt culture medium was studied. It was found that the methane removal efficiency in the inorganic salt culture medium increased first and then decreased as the pH or initial methane concentration increased. Methanotrophs' methane removal efficiency in this study was highest when the pH was equal to 7, or the initial methane concentration was equal to 2%. Biochar is an economic and environment-friendly "green material" with a porous structure, high specific surface area, and high ion exchange capacity. It can adsorb escaped methane and can provide a good habitat for methanotrophs. In this paper, biochar-methanotroph-amended clay was taken as the research target, and the effects of the presence or absence of methanotrophs, the amount of biochar, and the compactness of soil on the removal of methane were analyzed, and the methane removal efficiency of biochar-clay mixture with methanotrophs was studied. The above experiments were conducted under laboratory-scale conditions, and the methane concentration, pH, and dry density were set with reference to the measured data in the cover of the landfill in order to expect the closest possible approximation to the actual landfill cover experimental environment. The results showed that the efficiency of methane removal increased first and then decreased as the biochar content and compaction increase. Furthermore, the efficiency of methane removal was strongest when the biochar content was 15% or the dry density was 1.2 g/cm3. [ABSTRACT FROM AUTHOR]

In the existing standards, there are still some insufficient considerations of the pile end soil and the mutual reinforcing effect between piles when computing the settlement of long-short-pile composite foundation. For fully considering the mutual reinforcing effect, the thin-ring cylinder shear model and the shear displacement method are adopted in this paper. Besides, the relationship between the settlement and axial force of the solid pile and the virtual soil pile is obtained in process by applying the virtual soil-pile model to considering the stress and deformation of pile end soil. It proposes an improvement of the interaction coefficient between the long and short piles and is applied to the analytical solution for the settlement of long-short-pile composite foundation. Compared with experiments, the error between results of two methods is only 4.65%, which indicates that the proposed method can accurately calculate the settlement of long-short-pile composite foundation. Meanwhile, the measured values are compared with the analytical and simulated values, and the results of three methods have good consistency, which further verifies the correctness and applicability of the analytical method in this paper. [ABSTRACT FROM AUTHOR]

During the excavation of shallow-buried large-span metro tunnel, the surrounding rock is easily affected by the excavation disturbance, using the common passive support system which often leads to the problem of increasing the deformation of the surrounding rock. In this paper, a shallow-buried large-span metro tunnel station under construction in China is used as the engineering background, We here firstly introduce the supporting application effect of the new negative Poisson's ratio (NPR) bolt based on the research and development of micro-materials, and we optimized the bolt element according to the test results. The results show that the use of NPR bolt significantly reduces the tensile stress zone and effectively avoids the problems of support structure damage and lining cracking and deformation caused by the passive support method. The active support system is more effective than the passive support system in suppressing the surrounding rock deformation, with the surface settlement, vault displacement, and horizontal convergence accounting for 47%, 29%, and 50% of the passive support in the same period, respectively. Meanwhile, based on simulations of the deformation of the surrounding rock and the structure stress, as well as the field monitoring results, the characteristic curves of the deformation of the surrounding rock and the support stress under the active support system with the excavation of the pilot tunnel are obtained, and the mechanism of the active support system of the NPR bolt in the shallow-buried large-span metro tunnel is revealed. The results of this paper can provide a practical reference for the construction and support of similar shallow-buried large-span metro tunnel. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive investigation into pore pressure prediction methodologies, specifically addressing challenges in the upper zones of a field in southwestern Iran characterized by intricate geological complexities. Our analysis centers on the application of the drilling exponent (D-exponent) methodology, utilizing drilling parameters for accurate pore pressure estimation. Three methodologies are scrutinized: a section-specific approach, a site-specific analysis establishing unique normal compaction trend lines, and a novel method refining the normal compaction trend line mathematically. The Zamora method stands out as superior, especially in geologically complex regions like the Gachsaran formation, where overburden pressure may not be the primary stress. Implementing the Zamora method yields a substantial reduction in mean absolute percentage error (MAPE), enhancing pore pressure prediction accuracy by up to 9%. Additionally, a newly proposed method enhances accuracy by 7%. These findings underscore the importance of customizing pore pressure prediction techniques to the distinct geological conditions of specific regions. The outcomes not only advance our understanding of pore pressure prediction but also offer practical guidance for similar geological settings. [ABSTRACT FROM AUTHOR]

This paper presents the findings regarding the displacement-load behavior of both plane strain model experiments' ultimate load and numerical analyses conducted on unreinforced and reinforced sand slopes loaded with strip footing. The investigated parameters include the impact of the reinforcement and varying eccentricity on the ultimate load and displacement of the strip footing. A group of finite element analyses was performed with the 3D plane strain model and the computer code ANSYS software to validate the results of the model experiments on a slope. The results from both the numerical analyses and model experiments suggested that the use of reinforcement could enhance the load–displacement behavior of the central and eccentrically loaded footings. The load–displacement curves demonstrated that a higher load eccentricity leads to a reduction in the ultimate load of the strip footing. The concordance between the computed and observed results was reasonably satisfactory for the load displacement and the overall behavioral trend. [ABSTRACT FROM AUTHOR]

Microwave treatment is one of the research topics to solve cutting problems of hard rocks such as low cutting rate and high tool wear. Microwave irradiation creates fractures in the rock body and decreases its strength. Numerous studies have been conducted to ascertain how microwaves affect the strength of rocks. Ten carbonate rocks are examined in this paper to see how microwaving affects their strength. First, unconfined compression and tensile strength tests were conducted on unirradiated dry and saturated core specimens. Following that, the two tests were performed again on samples that had been exposed to radiation for varying amounts of time—between 2 and 6 min—at a microwave power of 6 kW. The results showed that the uniaxial compressive strength loss due to microwave irradiation was between 9.0 and 90.0% and 7.3 and 92.0% for the dry and saturated samples, respectively. Tensile strength loss was between 15.6 and 62.7% and 23.2 and 63.1% for the dry and saturated samples, respectively. The efficiency of treating carbonate rocks with microwaves is significantly impacted by density, porosity, and impurities. Multiple regression equations were derived to estimate the strength losses. Concluding remark is that the strength reductions due to microwaves are significant for carbonate rocks. [ABSTRACT FROM AUTHOR]

This paper presents an integrated approach involving geophysical and remote sensing datasets in the identification of regions that have undergone hydrothermal alteration in the gold-hosted site of the Ife–Ilesa schist belt. Geophysical methods employed include the aeromagnetic and aeroradiometric data, while the remote sensing involved Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Derivatives such as analytic signal, total horizontal derivative, tilt derivative of the total horizontal derivative, and 3-D Euler deconvolution were applied on the aeromagnetic data for the mapping and delineation of structures guiding migration of hydrothermal and mineralizing fluids in the study area. Radiometric analyses involving K/eTh, Ideal K anomalies deviation (Kd), and F-parameter, including principal component analyses on ASTER to isolate Potassic, Argillic, Propylitic, and Phyllic alteration zones were performed to delineate hydrothermally altered zones. The lineament map showed that the study area is geodynamically active as evident by the presence of deep-seated intersecting structures with depths ranging from 189 to 899 m, principally trending NE–SW, which is an impression of the Pan–African orogeny. The fuzzy gamma operator 0.9 was thereafter used in the integration of aeroradiometric and ASTER data for the hydrothermal alteration map production. Subsequently, five classes ranging from background to very high alteration anomalies were derived using the concentration–area (C–A) fractal model from the hydrothermal alteration map. These classes reveal the pervasive styles of alteration in the study area. The study further revealed the close association of structures, granitoids, hydrothermal alteration, and orogenic gold deposits. Also, the flurry of mining activities in the southern flank of the study coincides with most of the hydrothermally mapped areas with the Prediction–area (P–A) plot showing 78% occurrence of orogenic gold deposits in 22% of the total area explored. This translates to high potential of orogenic gold mineralization in the study area. The study therefore concluded based on the validation result that hydrothermal alteration mapping is important in the mapping of orogenic gold deposit. Hence, unexplored areas particularly in the western and eastern flank of the study area where there are strong indications of hydrothermal alteration have good prospect for gold mineralization. [ABSTRACT FROM AUTHOR]

Rock material, such as sandstone, frequently shows a wide range of fracture characteristics and mechanical responses due to variations in weathering grades and the existence of natural fractures. These natural fractures in sandstone are regularly cemented by different minerals or cementation removed by weathering and/or stained with iron, which can affect the stress-induced fracture pattern and rock strength. These effects, along with fracture orientation and location on mechanical behavior and failure modes resulting from quasi-static loading, are poorly understood. The focus of this paper is to assess the effects of cemented and stained natural fractures on stress-induced sandstone failure mechanism and mechanical behavior, with a focus on natural fracture angle and location. To investigate sandstone mechanical behavior and failure mechanism, six unconfined compressive tests were conducted on specimens with pre-existing natural fractures at different angles (∅) to estimate unconfined compressive strength (UCS) and failure modes. ANSYS was also utilized for finite-element modeling and simulation to analyze comprehensive 3D fractured models. The results revealed that UCS of sandstone decreased with increasing fracture angles of 0°, 20°, 30°, 45°, 50°, to 60°, respectively. Sandstone with a 90° fracture angle exhibits higher UCS than samples with a 0° fracture angle. The findings indicated that sandstone with 0° and 20° fracture angles had multiple fracturing, while specimens with 90° fracture angles provided axial splitting. On the other hand, the shear failure in sandstone specimens occurred as the fracture angle superseded 50°. The simulation results demonstrate that fracture location affects only the UCS of sandstone. [ABSTRACT FROM AUTHOR]

The German TanDEM-X mission's primary goal is to create a highly accurate and global digital elevation model (DEM) with global accuracies of at least 10 m absolute height error (linear 90% error). This paper provides one-of-a-kind accuracy assessment of the TanDEM-X global DEM. The assessment of the TanDEM-X DEMs over Nallamala Area, Andhra Pradesh is presented through a comparison with SRTM and TanDEM-X DEMs. TanDEM-X has a finer effective spatial (i.e., horizontal) resolution than SRTM, according to analysis, visualization, and elevation scatterplots. As a first step, digital elevation models are compared to the conventional method of GCP (ground control point) elevation. Then, any two DEMs are compared using a computational method such as R programing, which is a statistical technique that selects point locations with equal distance. TanDEM-X lower elevations indicate that the radar signal penetrates deeper. DEMs with differences allowed the identification of issues related to the production methods of the DEMs. A systematic difference in elevations between TanDEM-X 12 and 30 m, and SRTM was observed. The results show a high level of detail and consistency for TanDEM-X data, indicate that the effective horizontal resolution of SRTM is coarser than the nominal 12 and 30 m. These DEMs are then delineated in QSWAT model for stream network generation. QSWAT is a tool used for the validation of digital elevation models (DEMs) in hydrological modeling. It allows for the comparison of the topographic features of the DEM with field survey data to identify discrepancies and improve model accuracy. [ABSTRACT FROM AUTHOR]

The P-Y curves-based methods are nowadays powerful tools of design of laterally loaded piles. Semi-empirical methods based on correlation of the P-Y curves parameters with the in situ tests data are increasingly gaining interest among the geotechnical engineers. The aim of this paper is to present a new method of construction of the P-Y curves for a single pile embedded in a clayey soil, based on the pre-bored pressuremeter test (PBPMT) data. Detailed interpretation of full-scale lateral loading tests on 10 instrumented piles driven into 2 saturated clays served as a framework to develop this method. It was shown that the lateral reaction modulus and the lateral soil resistance may be formulated respectively as power and linear functions of the lateral pile/soil stiffness ratio. The predictive capability of the proposed method was demonstrated through a validation process by comparing the predicted load–deflection curves to the ones obtained from a database of full-scale piles. It was found the proposed method slightly overpredicts the pile deflections, which is in the safe side. [ABSTRACT FROM AUTHOR]

Flooding is a prevalent natural disaster in major cities throughout Indonesia. Over the past decade, Makassar City has experienced a severe increase in flood risk due to rapid and poorly controlled urbanization, as well as significant environmental degradation. The lack of reliable country-level flood hazard mapping at the sub-district level, coupled with limited local information and inadequate urban flood mitigation planning, further exacerbates the risk for residents. This paper aims to evaluate the vulnerability of social, physical, economic, and environmental aspects in the impacted areas of Makassar City to floods. The study employs a local methodological framework and geographic information system (GIS) to discern differences in flood risk levels across various areas. Leveraging available statistical and spatial data from the major flood that occurred in 2013, the research utilizes GIS spatial and temporal analysis to generate individual indicators and scores them using relevant parameters for vulnerability assessment in the local context. By combining the spatial parameters of the vulnerability index and flood hazard index, the study analyzes each component of the risk index and creates an overall risk index map. The distribution forms of specific risk levels and the percentage of risk areas for each sub-district are then examined. This analysis provides valuable insights to the local government, enabling better urban risk mitigation planning and accurate prioritization of necessary actions for each zone in Makassar City. [ABSTRACT FROM AUTHOR]

The Xihu Sag is the largest subunit of the East China Sea shelf Basin. The discovery of several large gas fields in the Xihu Sag shows excellent oil and gas storage potential. This paper focuses on the braided river in the Huagang Formation (HF) central axial channel in Xihu Sag. The seismic data, drilling data to establish sand prediction models under the HF's high-resolution sequence stratigraphic framework. Further combining seismic attributes, constrained sparse pulse inversion, and post-stack geostatistical inversion methods under the model to research the braided river's characterization finely. From the perspectives of paleo-geomorphic terrace morphology, sand development stage, external structure, and internal depositional composition, the sizeable axial sand of the HF in the north-central study area of the Xihu Sag are researched and established the sands evolution model in the north-central Xihu Sag. There are large-scale canyon erosion landforms with multiple terraces spreading in the northeast. The channel width is small in the braided channel's upper reaches, the sand has a limited cross-spread range and evident down-cutting erosion, and the sand is thicker, with the characteristics of "narrow and wide." The braided channel center is dominated by thick sand with good lateral continuity. The delta front was the main sedimentary facies in the study area, and the underwater distributary channel was the most critical sedimentary microfacies, which provides reliable data for finding favorable reservoir areas in Xihu Sag to provide evidence support for oil and gas exploration in the East China Sea. [ABSTRACT FROM AUTHOR]

The dynamic performance of floating piles under coupled vibration is of significant importance and the studies extended in this area are scant due to its complexity in analysis. Therefore, this paper made an attempt to investigate the characteristics of floating piles under rotating machine-induced coupled vibration using both experimental and numerical approach. A MATLAB program has been developed based on continuum approach to analyze the response of single floating piles using two different soil models, namely linear and an equivalent linear model. By indulging a decent choice of boundary zone parameters, variation in complex soil stiffness parameters with frequency has been studied. The efficacy of developed numerical approach is validated using field experimental investigations on single pile by replicating floating tip condition. The experimental response has been manifesting nonlinear behavior and it is further compared with numerical responses of both models. The study showcased that equivalent linear model has been able to portend the nonlinear response of floating pile to a great extent with precise estimation of boundary zone parameters, whereas linear model failed to simulate the responses by underestimating amplitude. This study is also extended to demonstrate the effect of various input soil parameters on the stiffness and damping of the soil-pile system. These studies will be beneficial in determining the influencing parameters responsible for the nonlinear response of floating piles under harmonic-coupled vibration. [ABSTRACT FROM AUTHOR]

The present study reveals the geological fracture line of the earth surface of the Mula catchment area with the help of remote sensing and GIS techniques. In this paper, a comparative analysis of lineament extraction is carried out by using different DEM data like Cartosat, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array L-band Synthetic Aperture Radar), JAXA's (Japan Aerospace Exploration Agency), and Shuttle Radar Topographic Mission (SRTM). Lineaments were extracted from each DEM data, to recognize which DEM data is accurately showcasing the extracted lineaments. From the analysis, it is found that the highest number of lineaments can be extracted from ALOS PALSAR DEM data having a resolution of 12.5 m, whereas comparing the other four datasets having a resolution of 30 m, it is found that the lineament features extracted using Cartosat DEM are more accurate. The results of this study recommend that ALOS PALSAR and Cartosat DEM data should be used for the extraction of lineaments and can be used for the Indian region as it layouts definite geological information. The result is analyzed with the help of a rosette diagram showing flow direction and azimuth angle for all DEM from 0 to 315° at an interval of 45°. The study area shows major direction is NW–SE. More lineaments are seen in the source region and formed as rills and gullies. The geological analysis of lineament is helpful to study the groundwater permeability tectonic evolution etc. [ABSTRACT FROM AUTHOR]

This research evaluates the potentials of argillite quarry waste (AQW) as raw material in ceramics and other industrial applications based on traditional firing techniques. In this context, the AQW samples were first characterized by mineralogical (X-ray diffraction, XRD), chemical (X-ray fluorescence) and physical (grain size distribution and Atterberg limits) analysis. From the results, AQWs composed predominately of clayey-silt with medium to high plasticity. The XRD revealed predominance of clay minerals (illite-chlorite-vermiculite) with high contents of quartz and variable percentages of carbonate and feldspar. The oxides were dominated by SiO2 and Al2O3, low contents of ferromagnesian elements with considerable amounts of alkali and alkali earth elements. The CaO concentrations are high and relate to carbonate contents. The feldspar contents and proportions of alkali and alkali earth elements revealed their potential as stating materials for earthenware production. Empirical assessments using compositional ternary and Winkler diagrams revealed their acceptable level in ceramic applications. To evaluate firing behaviors, the AQW samples were prepared and fired in the range of 800 to 1000°C and technological properties (linear shrinkage LS, weight loss WL, water absorption WA, bulk density and flexural strength FS) were determined. Statistical approach was employed with focus on accuracy and reliability of the data. At 800°C and above, results revealed an increase in LS, WL and FS with decrease in WA. The levels of performance of technological properties of the AQW are considered marginal except with SiO2 contents reduction by 5–10% and with the addition of degreasers. The AQW met the most requirements for grade I, II and III ceramic raw material and other industrial applications such as filler for paper, rubber, plastic and paint industries as described in Indian standard specification. To achieve excellent performance in ceramics and other industrial applications, AQW requires beneficiations. [ABSTRACT FROM AUTHOR]

Nowadays, the only source of water in the Algerian Sahara is groundwater. This source, unique and fossil, knows overexploitation and anarchic management of the wells carried out in these aquifers for needs like drinking water, irrigation, and industrial. Therefore, its management in Algeria represents a crucial problem because of its impact on the environment and human life. This paper presents an extensible, scalable, agile, and incremental decision support system allowing the management of this groundwater in Algeria based on data lake, a new concept of big data. The developed system comprises three parts: data collection, data processing, and storage in the data lake and restitution of this data in a dashboard and mapping. To conclude, this system can help to provide better visibility to Algerian decision-makers allowing optimal management of this vital source with the ultimate goal of improving the life of Algerian citizens. [ABSTRACT FROM AUTHOR]

The key factors to the success of shale gas play are complex fracture network and stimulated reservoir volume (SRV) after the treatment of massive hydraulic fracturing. These two factors jointly determine the total contact area between the matrix system and the fracture system and therefore the productivity. To accurately model shale gas flow, researchers have been engaged in different ways to introduce complex fracture networks. The pattern of the main hydraulic fractures is mostly assumed to be separate, planar, and bi-wing, which forms a regular fracture network together with numerous secondary fractures. However, the main fractures are more likely to be bent, multi-branched, and intersected arbitrarily according to the micro-seismic data analysis and the fracture network propagation simulation and could be a complex and explicit fracture network themselves. The analytical methods are hard to analyze the complex irregular fracture network, and many numerical methods require the mesh to be aligned with the fractures. In addition, the stimulated reservoir volume is often overestimated to cover the whole shale reservoir which may be not as large as expected. To better simulate gas flow in the fractured shale, in this paper, the extended finite element method (XFEM) and the multi-branched enrichment scheme are adopted to address the influence of complex hydraulic fractures. The mass transfer equations were derived to describe the fluid exchange between complex hydraulic fractures and micro-scale fracture networks, so a separate pressure system can be used in the complex macro-scale fractures. Dual permeability model was used to simulate gas flow in the SRV and combines several mechanisms including gas adsorption/desorption, the Knudson flow, and the Darcy flow. In addition, a stress-sensitive formula was introduced to describe the effect of pressure changes of the fractures on permeability. By comparing with the results of the CMG simulator, the validity of this model is verified. The results show that the proposed model can better evaluate the impact of complex hydraulic fractures. The coverage area of SRV, the productivity, the Langmuir gas volume, and the pressure-dependent permeability of fractures all influence the bottom-hole pressure behavior greatly. [ABSTRACT FROM AUTHOR]

This paper examined the efficiency of artificial neural network (ANN) and multivariate linear regression (MLR) models in the prediction of groundwater quality parameters such as ecological risk index (ERI), pollution load index (PLI), metal pollution index (MPI), Nemerow pollution index (NPI), and geoaccumulation index (Igeo). Forty groundwater samples were collected systematically and analyzed for mainly heavy metals. Results revealed that adopting measured parameters is effective in modeling the parameters with a high level of accuracy. Contamination factor results reveal that Ni, Zn, Pb, Cd, and Cu have relatively low values < 1 within the region while the iron values ranged from low contamination to very high contamination (> 6). PLI, MPI, and ERI results indicated low pollution. NPI results indicated that the majority of the samples were heavily polluted. Quantification of contamination results revealed that most of the sample's quality was geogenically influenced. Igeo results revealed that most of the samples had extreme pollution. The health risk assessment results revealed that children are substantially prone to more health risk more than adults. The ANN and MLR models showed a high effective tendency in the prediction of ERI, PLI, MPI, NPI, and Igeo. Principal component analysis results showed appreciable variable loadings while the correlation matrix results reveal that there exists weak and positive correlation among elements. Based on the outcome of this study, this research recommends the use of ANN and MLR models in the prediction of groundwater quality parameters as they yielded positive, reliable, acceptable, and appropriate accuracy performances. [ABSTRACT FROM AUTHOR]

While desalination-installed capacity is growing continuously, the number of membrane elements being discarded from such facilities is growing at the equivalent rate due to the limited lifespan of reverse osmosis (RO) membranes. It will be an attractive option to use the materials from the waste membrane element in the geotechnical engineering industry owing to their higher tensile strength and puncture resistance rather than landfill and incineration. The current study provides a simple yet effective approach for the use of discarded RO module components (i.e. discarded membrane sheet, permeate spacer and feed spacer) as reinforcement material for soil strength enhancement. A series of laboratory-scale experiments were conducted to quantify the beneficial effect of the soil reinforcement system (i.e. single, double and triple layers). The California bearing ratio (CBR) tests and triaxial compression tests were conducted on the soil reinforced. In addition to this, the effect of the number of reinforcement layers on the load-settlement behaviour of the soil was also studied. When compared to unreinforced soil, the compressibility of the soil was significantly decreased and there was a corresponding increase in the load-bearing capacity of the soil. The CBR value of soil was increased 3.14 times when reinforced with three layers of permeate spacer. In this way, this paper presents the end-of-life solution of reverse osmosis membranes for a novel application to create a circular economy in the membrane market. [ABSTRACT FROM AUTHOR]

The behavior of rock under different loading conditions is very important for the stability analysis and safety measures taken in mining engineering. Rocks are generally inhomogeneous in nature and contain different minerals, cracks, and pores. This inhomogeneity in rock causes departure in their behavior from known theories of rock failure based on homogeneous assumption of rock. In the research presented in this paper, inhomogeneity present due to different mineral constituents is taken into account for their mechanical strength analysis. Digital image processing techniques are utilized to capture this inhomogeneous nature. Region segmentation method and edge detection method are two popular image processing techniques used for this purpose. The obtained image data is then vectorized and transformed so as to feed it into numerical and structural analysis software. Brazilian indirect test is used for stress analysis of rock specimen. The results obtained from numerical modelling software and from laboratory tests show that the weakest mineral present in rock specimen generally controls the overall failure phenomenon for Brazilian tensile test. [ABSTRACT FROM AUTHOR]

Flyrock is known as one of the main problems in open pit mining operations. This phenomenon can threaten the safety of mine personnel, equipment and buildings around the mine area. One way to reduce the risk of accidents due to flyrock is to accurately predict that the safe area can be identified and also with proper design of the explosion pattern, the amount of flyrock can be greatly reduced. For this purpose, 14 effective parameters on flyrock have been selected in this paper i.e. burden, blasthole diameter, sub-drilling, number of blastholes, spacing, total length, amount of explosives and a number of other effective parameters, predicting the amount of flyrock in a case study, Songun mine, using linear multivariate regression (LMR) and artificial intelligence algorithms such as Gray Wolf Optimization algorithm (GWO), Moth-Flame Optimization algorithm (MFO), Whale Optimization Algorithm (WOA), Ant Lion Optimizer (ALO) and Multi-Verse Optimizer (MVO). Results showed that intelligent algorithms have better capabilities than linear regression method and finally method MVO showed the best performance for predicting flyrock. Moreover, the results of the sensitivity analysis show that the burden, ANFO, total rock blasted, total length and blast hole diameter are the most significant factors to determine flyrock, respectively, while dynamite has the lowest impact on flyrock generation. [ABSTRACT FROM AUTHOR]

The swelling water demand due to population rise and inefficient water management has caused water scarcity in Pakistan's Sindh Province. The Sindh province almost entirely relies on the Indus River supply to meet its demand to irrigate 6Mha of culturable area. Many studies have predicted a shortfall of water in the coming years. It is also anticipated that Pakistan may become water scarce until 2025, which will cause food security issues. This study, funded by the Sindh Water Sector Improvement Project (WSIP), aimed to understand the current water availability trends to develop sustainable water budgeting for the province. The agricultural activities in Sindh are usually carried out in two seasons—Rabi and Kharif. In this study, agricultural water use was estimated in terms of actual evapotranspiration (ET) for14 canal command areas (CCAs) of Sindh during the Rabi (Oct to Mar) and Kharif (Apr to Sept) seasons during 2017–2019. Landsat satellite data product—Earth Engine Evapotranspiration Flux (EEflux)—is used for analysis. This study assessed agriculture water balance for three scenarios: 1) Rabi and Kharif seasons, 2) a water year, and 3) overall growing seasons. The result shows that when flows are low in the Rabi seasons, the consumptive water use exceeds the combined canal flows and rainwater. The deficits were supposedly met through groundwater abstraction. However, during the Kharif season, water availability was in surplus of the need indicating a possible recharge of aquifers. This study proposes that the disparity of the supplies and demands can be balanced by reallocating the canal water supply based on the actual need. Furthermore, the spatial distribution of consumptive water use through GIS maps is also represented in this study. The water balance of all 14 CCAs in Sindh is illustrated in this paper, discussing possible guidelines on when, where, and how future allocations should be made. [ABSTRACT FROM AUTHOR]

The past few decades have been marked by a rapid acceleration in Municipal Solid Waste (MSW) generation because of industrialization, urbanization, and economic growth combined with a high population growth rate. Thus, the most economically effective alternative to developing new landfills is the construction of reinforced soil walls (RSW) in existing MSW landfills to allow for their vertical expansion. This paper presents a structure for the system reliability-based seismic design optimization (SRBSDO) approach for landfills by incorporating the variability associated with design parameters under seismic conditions. The formulation considers a three-part wedge mechanism based on the pseudo-static limit equilibrium method. The influence of the horizontal seismic acceleration coefficient (kh) on the stability against external and internal modes of failure is studied. A target reliability index of not less than 3.0 is adopted to obtain the optimum dimensions of RSW required to achieve stability against three modes of failure (bearing capacity, sliding, and eccentricity). The dimensions of RSW are presented with respect to vertically expanded heights in the form of design charts. The results of the internal stability analysis of an RSW are provided to obtain the optimum number of geosynthetic reinforcement layers required for the stability of RSW under seismic loading. It is reported that kh has a substantial influence on the reliability of RSW, and higher values of mean and coefficient of variations of kh may cause instability. It is observed that the total length of the reinforcement (B2) should not be less than 0.67 and 0.91 times the height of the RSW (H2) for kh = 0.1 and 0.2, respectively. The minimum required number of reinforcement layers to maintain overall stability are 13 for kh = 0.10 with minimum B2/H2 of 0.66 and 19 for kh = 0.20 with minimum B2/H2 of 0.83. [ABSTRACT FROM AUTHOR]

The Ogaden Basin is one of the largest sedimentary basins which covers an area of 350,000 km2 in Ethiopia. Since the middle of the last century, hydrocarbon exploration research has been conducted in the basin of the Calub Formation, and the Adigrat sandstone is identified to be the reservoir rocks of most Calub wells. Although enough studies have not been conducted on the reservoir rocks, to assess the potentiality of the reservoir rocks, this paper is focused on the determination of the observable porosity using petrographic methods and the estimation of the permeability and the hydrocarbon saturations using well-logging data. The used core samples were taken from Calub wells and a total of 24 core-cutting samples (Calub-4 six samples, Calub-5 six samples, Calub-7 six samples, and Calub-9 six samples) were carefully chosen, and the same number of thin sections were prepared from the core-cutting samples. The whole thin section samples collected from the laboratory were subjected to petrographic analysis and it was later interpreted. The maximum porosity and permeability observed in the reservoir Adigrat sandstone of Calub-4, Calub-5, Calub-7, and Calub-9 were 12.6% and 97.2×10−3m2 respectively while the minimum porosity and permeability observed were 3.5% and 0.1×10−3m2 respectively. The maximum porosity and permeability observed in the reservoir Calub sandstone of Calub-4, Calub-5, Calub-7, and Calub-9 were 11.3% and 18.5×10−3m2 respectively as the minimum porosity and permeability observed were 2.2% and 0.1×10−3m2 respectively. In conclusion, it can be said that the Adigrat and Calub Formations are highly hydrocarbon potential reservoirs. [ABSTRACT FROM AUTHOR]

The Khurmala Dome is the northernmost of three domes forming the Kirkuk anticline which houses the giant Kirkuk oil field. It stretches some 100 km in length with an average width of 4 to 5 km, it has been discovered in the 1930s, and it ties together with the southward ensuing Avana and Baba domes. Khurmala Cretaceous reservoirs have been recently discovered for extracting the natural hydrocarbons available in the Lower Kometan, Upper Qmachuqa, and Lower Qmachuqa reservoirs. The Kometan Formation at the time being with the available limited data is not considered to be a potential reservoir over the Khurmala area compare with the other existing reservoirs. The analysis of the log data indicates that the formation has poor reservoir properties and very low or negligible hydrocarbon saturation. This paper aimed to develop a methodology for the application of discrete fracture network (DFN) to the characterisation of fracture and modelling in the Lower Kometan Formation for Khurmala Field in Kurdistan Region-Iraq. Consequently, bore-hole image logging (BHI) fracture characterisation and processed similarity attributed to that purpose. For this reason, geological, seismic, and bore hole image (BHI) data from five wells that penetrated the Lower Kometan Formation were used to characterise the fractures and construct a reliable discrete fracture network (DFN). According to the BHI and seismic analyses, Lower Kometan is fractured, with a strike direction of NW–SE and higher intensities on the middle part of the formation. In addition, the modelling result indicated that the Lower Kometan fracture network and its matrix have relatively little potential for storing hydrocarbons. Low fracture intensities on the bottom half of the Lower Kometan Formation along with the resulting low hydrocarbon quantities in the matrix and fractures clearly imply that there will be no or very little exchange with the underlying Upper Qmachuqa reservoir. To summarise, the potential of hydrocarbon storage in the Lower Kometan fracture network and its matrix is very limited around one billion standard cubic feet of gas (≈ 1BSCF). The resulting low hydrocarbon volumes in both matrix and fractures in the Lower KOMETAN Fm are between 1 and 3 million barrels of oil with the additional storage from the fracture contribution with the matrix. [ABSTRACT FROM AUTHOR]

Groundwater is an important source of drinking water and irrigation. However, due to increased anthropogenic activities, its quantity and quality are gradually deteriorating over time. The current paper focuses on the evaluation of groundwater quality and its variability for drinking purpose in Gurugram district of Haryana. Geographical Information System based groundwater quality index (GWQI) is a cost-effective tool for the assessment of groundwater quality and its variability. Nine water quality parameters, i.e., sodium, potassium, magnesium, calcium, chloride, sulfate, nitrate, fluoride, and total dissolved solvent have been considered for quality assessment of pre-monsoonal season. Two GIS-based groundwater quality index maps GWQI-9 (for all the above mentioned parameters) and GWQI-4 (for the critical parameters whose concentrations exceeded the permissible limit) were produced. Subsequently, correlation analysis and factor analysis were performed to determine the degree of correlation and to identify the principal factor of contamination among all nine water quality parameters, respectively. Interpolated maps, concentration maps, and rank maps were developed for each parameter. Furthermore, the rank map was used to assign weight to each parameter. Based on rank and weight, the final GIS-based GWQI-9 and GWQI-4 were developed. Higher GWQI values reflect higher water quality. Overall, the north-eastern parts of the district have high water quality, while the western and northwestern periphery of Gurugram has low water quality. Except northern and north western region, most of region of Gurugram have poor water quality in terms of GWQI-4. It is possible to conclude that GIS-based GWQI could become a comprehensive approach for assessing surface or groundwater quality. [ABSTRACT FROM AUTHOR]

Anti-seismic devices are employed to implement the best performance of the structures under earthquakes. In this paper, semi-active tuned mass dampers (SA-TMDs) are studied by considering several combinations of variable friction forces and external disturbances. The variable damping model is used, where the goal consists in estimating the external actions to find the best friction force for system dampening. In particular, general, sinusoidal, and Gaussian dynamic loadings are considered. To obtain the response of the structure and dampers, several numerical solutions have been implemented. Probabilistic and determines analyses have been also developed to study different damper characteristics. Results show that a SA-TMD can reduce the structure displacements up to ~ 70.0% indicating a good performance in controlling different oscillations. This technology not only preserves the integrity of a structure mitigating its vibrations but also improves the life of occupants and their safety and comfort. This is beneficial from the perspective of practical application, and it is an advancement with respect to this theme. [ABSTRACT FROM AUTHOR]

Relative permeability is one of the dynamic properties in reservoir fluid flow that is essential in characterizing the simultaneous flow of fluids in the reservoir and plays a vital role in reservoir production studies and EOR processes. The relative permeability ratio is used to describe better and employ relative permeability data presented in individual curves. The simultaneous flow of reservoir fluids is well described by the coefficients a and b, which are obtained from the linear part of the ratio curve. These coefficients, considered critical parameters of the relative permeability curve, are complex. Factors and concepts affecting the a and b coeffecients are not well defined. The corresponding values of a and b were obtained from the experimental relative permeability data for carbonate rocks. Factors affecting these coefficients were studied and evaluated in this paper. The results indicate that coefficient b is mainly affected by the pore size heterogeneity and fluid saturation distribution. In contrast, the coefficient a is influenced by residual water saturation and fine pores. Another notable result of this study was using experimental relationships to determine the relative permeability parameters, including coefficients a and b and residual saturation values using mercury injection data. [ABSTRACT FROM AUTHOR]

Khaf Al Laasif is a small (about 100-m long) old mine in the vicinity of Muscat, Oman, with traces of copper and lead. On the contrary to most of the copper mines in Oman developing in ophiolites, Khaf Al Laasif developed in Neoproterozoic metamorphosed dolomite of the Saih Hatat Dome. The copper and lead mineralization was plausibly formed during hydrothermal events that followed major tectonic events in the area. The mine was dug using fire-set mining and that crushing of the mined material was on the spot. The survey of the mine volume has made it possible to estimate the corresponding volume of woody fuel and the minimum forest area necessary for its excavation, which is considerable. Beyond the interest of a site allowing the study of fire-set mining techniques, this paper argues that the main limiting factor to the mine exploitation was the supply of woody fuel, wood or charcoal. It raises questions that could lead to future research on subjects that have been curiously little addressed until now: where did the woody fuel come from and what was the huge paleo-environmental impact of its massive exploitation, at what time does this exploitation go back and in what circuits and socio-economic contexts does it correspond? The main objective of this preliminary study is to reveal the interest of this site and the multidisciplinary issues associated with it. [ABSTRACT FROM AUTHOR]

Bentonite is widely used in industrial wastewater treatment due to its large reserves and excellent physicochemical properties. In order to further improve the properties of bentonite, natural bentonite needs to be modified before application. The common modification methods of bentonite include thermal activation, acid activation, and microwave activation. In recent years, bentonite composite has been applied to the treatment of the mine wastewater including all kinds of waters influenced by mining activity. In this paper, the main modification methods of bentonite, the preparation methods of bentonite composite materials, and the application of bentonite composite materials in the treatment of the mine wastewater including toxic metals are summarized. Also, these technologies are compared and discussed in depth. All kinds of bentonite calcined at 400 ~ 450 ℃ can better improve the surface area. The structure of bentonite is not damaged, and have enough activity to facilitate the adsorption of organic matter at 400 ~ 450 ℃. The acid concentration of Ca-bentonite acidification process is higher than that of Na-bentonite acidification. The microwave activation method of bentonite has faster reaction rate and better modification effect. The combination of microwave activation and other bentonite activation technologies will significantly improve the activation efficiency. The interlayer spacing of organic bentonite generally increases with the increase of modifier concentration, but it will not increase when the added surfactant dose exceeds the cation exchange capacity of the original bentonite. When the concentration of modifier used in modification is the same, the longer the carbon chain of modifier, the greater the layer spacing of organic bentonite. The magnetic bentonite can adsorb Cu2+, Cd2+, Mn2+, and Cr6+ and can be separated and recovered. The composite of graphene/graphene oxide bentonite can significantly increase the spacing between the bentonite layers, improve the pore structure of the composite obviously, and avoid agglomeration. But the price of graphene is much higher than other adsorption materials, which limits the industrial application of the technology. Investigation and research show that bentonite composites have high removal potential for pollutants in mine wastewater. This paper aims to scientifically summarize and analyze the treatment of mine wastewater with bentonite, and discusses some influencing factors. [ABSTRACT FROM AUTHOR]

Pile integrity is a comprehensive qualitative indicator reflecting the relative change of pile section size, the compactness, and continuity of pile material. The evaluation of pile integrity is a systematic and comprehensive evaluation. However, manual detection has some defects, such as cost high, low efficiency, and strong subjectivity. In order to realize the automatic classification of pile integrity, this paper proposes a method of pile integrity classification and recognition based on convolutional neural network (CNN), including one input layer, four convolutional layers, four pooling layers, two fully connected layers, and an output layer. The stochastic gradient descent algorithm and overfitting prevention technology are used to improve the model. The experimental results show that the proposed model can effectively achieve the classification of pile integrity, with an average accuracy of 98.58% on the test set, and has good robustness and generalization performance, which overcomes the shortcomings of complex operation, high cost, and strong subjectivity of artificial extraction feature. [ABSTRACT FROM AUTHOR]

A key issue for controlling surface deformation is to understand the failure mechanism of rectangular shield pipe jacking tunnel. Therefore, based on the assumption of the plane strain and undrained conditions, the stability of shallow rectangular shield pipe jacking tunnels in cohesive and cohesive-friction soils was studied. The results show that using MATLAB programming optimization, the optimal failure mechanism, which is the most realistic failure mechanism, can be obtained based on the upper bound theorem of limit analysis. In addition, the height-span ratio and soil parameters of pipe jacking tunnels have a large impact on the soil stability coefficient. Simultaneously, the improved three-dimensional wedge failure mechanism presented in this paper considers the failure range on both sides of the tunnel face. Compared with the traditional wedge failure mechanism, the failure mechanism presented in this paper is closer to actual conditions. The research results could help the engineering design of shallow rectangular shield pipe jacking tunnels. [ABSTRACT FROM AUTHOR]

Due to its huge production potential, tight sandstone oil reservoir is the most promising exploration target in the Upper Triassic Yanchang Formation, Ordos Basin. Although tight sandstone reservoirs have received much attention in recent years, their strong internal heterogeneity makes the identification of superior sandbodies a great challenge in the industrial community. In this paper, we describe the detailed sedimentary structural characteristics of the Chang 81 sub-member sampled by 52 coring wells in the Longdong area at the Ordos Basin, present well logging data to establish the standards for the identification of superior sandbodies, aiming to investigate the planar distribution regularities and the deposit mode of shallow-water delta superior sandbodies. Five typical sandbody types were identified using samples description: homogeneously and heterogeneously bedded distributary channels, mouth bars, respectively, and levee sandbodies. Among in them, homogeneously bedded distributary channels and mouth bars are of a superior type, developed mainly in the middle of the respective microfacies; other sandbody types are mainly located at the edge of them. The use of sedimentary structures to assess the quality of sandbody reservoirs provides a new method for the identification of superior sandbodies in tight sandstone. The workflow proposed in this paper, based on a step-by-step analysis of beddings and microfacies, can be applied in the Ordos Basin and other similar shallow-water delta systems to improve the accuracy and reduce the economic cost of hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

There are many interactions between hydraulic fractures (HFs) and nature fractures (NFs) during the use of hydraulic fracturing. At present, many scholars have studied hydraulic fracture morphology in hydro-mechanical (HM) coupling. In this paper, thermal-hydro-mechanical (THM) coupling is adopted to investigate the propagation of HFs in NFs. With the purpose of exploring the effects of approach angle, friction angle, NF cohesion, and injection rates on the HF-NF interaction process, the code XSite is used to establish a new THM coupling calculation model in this paper. In addition, we calculated the tensile strength and the toughness of the rock, and the accuracy of the model was verified by tri-axial experiment. Natural fractures and hydraulic fracturing fractures mainly exhibit three different forms: they have not penetrated natural fractures, they are penetrating natural fractures, and they have penetrated NFs. The results indicate that the direction and properties of fractures have a significant influence on the interaction between HFs and NFs. Furthermore, HFs tend to penetrate NFs with large approach angle, friction angle, fracture cohesion, and injection rate, suggesting that large approach angles, friction angles, NF cohesion, and injection rates will prevent NFs from opening and thus prevent cracks from expanding in NFs. With the propagation of fractures, the pressure in the injection well increases while that in the production well decreases. As the injected fluid flows through the rock mass, the low-temperature zone of rock mass diffuses in the same direction, eventually making the temperature of the production fluid and the injection fluid basically the same. [ABSTRACT FROM AUTHOR]

Nanotechnology has been with us as a science since the first nanoscale features were observed under a microscope. Nanotechnology is an emerging technology and one of the key components of the technological advances of the present century. The use of materials with nanometer-based structures has led human knowledge to develop and provide solutions to produce superior products in the future. With the advent of modern nanotechnology and the study of the unique properties of nanoparticles, the field of their use was provided in many branches of engineering, of which geotechnical engineering is no exception. In this paper, while introducing colloidal silica nanoparticles and their gelation, study on the important characteristics and effect of this type of nanoparticles on sandy soils properties will be discussed. In fact, we discussed previous studies on the use of colloidal nano silica in sandy soil, their properties, their effects on soil, and the equipment used in nanotechnology. The current review is an attempt to summarize the applications of nanotechnology in geotechnical engineering. Furthermore, this paper plans a comprehensive review on characteristics of colloidal nano silica, its effect on curing approaches and aging, its behavior upon the addition with sandy soil in terms of strength improvement, liquefaction potential, cyclic properties, hydraulic conductivity, and compressibility. Lastly, the optimal percentage of nano silica for various purposes was presented. [ABSTRACT FROM AUTHOR]

Floods are natural disasters that cause serious loss of life and property, especially in highly urbanized regions. Studies based on the numerical modeling and evaluations regarding the legal statute are required to prevent or mitigate adverse effects of flood. This paper focuses on the assessment of flood regulations from the point of stream flood due to insufficient stream section. The entire process was illustrated by using a case study of a stream flood event in Istanbul, Turkey. For this purpose, initially, the hydrologic-hydraulic models of the Eşkinoz Stream Watershed, where the flood occurred on September 8–9, 2009, were created and the flood map was obtained by using Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) and Hydrologic Engineering Center-River Analysis System (HEC-RAS), respectively. The causes of the flood were determined using the maps via the Watershed Modeling System (WMS). In the second part, the public institutions and organizations that have responsibility for the flood damage of the buildings in a private school campus located on the streamside were determined. The current paper presents a comprehensive legislative assessment and an effective approach for flood events in Turkey that may affect both public and private buildings by evaluating the regulations and developing flood models using various methods. [ABSTRACT FROM AUTHOR]

Maintaining face stability of tunnels during tunnel excavation is essential. Studies on face stability of shield tunnels are generally conducted in completely dry or saturated sandy soils, and there are few studies on face stability in sandy ground with different low moisture contents. However, most practical conditions involve unsaturated sandy ground. In this regard, to investigate the tunnel face stability in sandy ground with different low moisture contents, a series of 1-g large-scale earth pressure balance (EPB) shield model tests were conducted. Variation of face support pressure, ground settlement, vertical stress, and soil arching effect in sand during the construction of shield tunnel was revealed. Furthermore, three kinds of failure mechanisms were proposed considering the soil arching effect and the range of ground settlement. The results show that the moisture content has a significant impact on the limit support pressure, the evolution of soil arching, and failure mechanisms. With the increasing moisture content, the ground settlement trough is wider, but the settlement value is smaller. And higher moisture content corresponds more significant soil arching effect. Moreover, the existence of soil arching makes limit face support pressure much smaller than the initial support pressure. Furthermore, based on three kinds of failure mechanisms constructed in this paper, theoretic approaches to estimate the limit support pressure and analyze face stability in sand with different moisture contents are proposed. Compared with the existing research results, failure mechanisms and empirical approaches proposed in this paper are more applicable to analyze tunnel face stability in sand with different low moisture contents, which is also closer to engineering practice. [ABSTRACT FROM AUTHOR]

In this paper, the spatiotemporal distribution and evolution of Mw ≥ 5 earthquakes that occurred during 1989–2018 are characterized by using both USGS seismic catalogue data and the PB2002 global plate tectonic model. Specifically, the activities of these earthquakes are analyzed from three different viewpoints, i.e., the global strong earthquake activity level, distribution of strong earthquake hot zones, and global plate accumulated strain. The results show the following. (1) The hot zones of global strong earthquakes are mainly located at the junctions of the giant shear faults at the oblique equator and the deep subduction system surrounding the Pacific Ocean (10°S ~ 30°S, 165°E ~ 170°W; 5°S ~ 30°N, 70°W ~ 115°W). (2) The hot zones of strong earthquakes have gradually migrated from the New Hebrides Trench to the Tonga Trench and from the northwest to the southeast along the Central American Trench to the Peru–Chile Trench. (3) Although the global tectonic activity level has risen over the past 30 years, energy is gradually being released from the crust in a relatively gentle way. [ABSTRACT FROM AUTHOR]

Comprehensive land carrying capacity (CLCC) is an important criterion for regional coordinated development and optimization of land use spatial structure. With the continuous acceleration of China's rapid urbanization process, how to scientifically evaluate the CLCC in the urban–rural interlaced zone has become an urgent need for quantitative research on the coordinated development of human-land relationship and effectively solves the conflict between urban and rural development. To this end, this paper takes Chenggong, a rapid development area in the urban–rural interlaced zone, as the research object and constructs a set of analytical methods for the spatiotemporal evolution characteristics of the CLCC of the urban–rural interlaced zone. Firstly, 17 index factors are selected from the three dimensions of social carrying capacity, economic carrying capacity, and ecological carrying capacity to construct an evaluation index system, and the mean square deviation decision weighting method is used to determine the index weight. Secondly, use the comprehensive index method based on the mean square decision weighting to construct the CLCC evaluation model. Finally, integrate Markov model and Geographical Information System (GIS) spatial analysis method to carry out the analysis of CLCC's spatiotemporal evolution characteristics. The results show that this method can reproduce the spatial and temporal evolution of CLCC spatial classification characteristics and spatial transition changes in the study area. The above results are reflected in the following aspects: (1) from the perspective of spatiotemporal evolution trends, Wujiaying's CLCC evolutionary trend continued to rise. In addition, the evolutionary trend of CLCC in other regions has relatively large fluctuations. This result is more consistent with the actual situation. (2) From the perspective of spatial classification characteristics, the CLCC in the study area has a large spatial differentiation. Among them, areas below the medium carrying capacity are distributed in Luoyang, Qidian, and Dayu. However, areas with medium carrying capacity or above are distributed in Longcheng, Dounan, Wujiaying, and Majingpu. (3) From the perspective of spatial transfer changes, the CLCC levels in any two periods are in a state of transfer and change, especially the spatial transfer between low-capacity areas is more intense, which also shows that urban expansion has a greater impact on the changes in CLCC in the urban–rural interlaced zone. [ABSTRACT FROM AUTHOR]

Based on the summary and analysis of previous research works, this paper expounds the research status and significance of landscape planning of stone mine park, elaborates the development background, current status, and future challenges of ecological environment restoration, introduces the methods and principles of ecological environment capacity and landscape design integration, conducts the aesthetic expression of ecological art design, analyzes the functional positioning of ecological environment restoration, constructs the landscape planning mode of stone mine park under the concept of ecological environment restoration, performs the systematic integration of reused resources, explores the spatial sequence optimization of landscape planning, proposes the landscape planning strategy of stone mine park under the concept of ecological environment restoration, and finally discusses the organic combination of natural and human landscape and the intrinsic relationship between landscape and industrial ecology. The results show that the landscape planning of stone mine park under the concept of ecological environment restoration can use old stone mining institutions and elements to rebuild and upgrade the mine park for landscape renewal, so that the function and site of a stone mine park can be transformed into the leading mode of mine park design; moreover, it is of great practical significance to repair the mine environment, protect and utilize the mineral relics, and develop the mine tourism. The results of this paper provide a reference for the follow-up study of landscape planning of stone mine park under the concept of ecological environment restoration. [ABSTRACT FROM AUTHOR]

Grouting has been proposed as an effective reinforcement method for fractured rock. The paper proposed a new prestressed anchor-grouting reinforcement method for underground broken rock with engineering background of anchor net failed to control the track haulage roadway of Daxing Mine. It combines prestressed anchor and self-stressing grouting reinforced material for broken rock. The self-stressing grouting material was first proposed by us. The paper investigated the mechanism and method of the new prestressed anchor-grouting reinforcement. The effect of the new prestressed anchor-grouting reinforcement was verified by numerical simulation and engineering application. The results showed that the new prestressed anchor-grouting reinforcement could restore the loose surrounding rock to the approximately three-dimensional stress state. It had higher strength and better effect than the anchor net. The new self-stressing grouting materials developed included Superfine Portland Cement of 92%, expansion agent content of 8%, early strength agent content of 2%, water reducer content of 1.5%. The deformations of the surrounding rock controlled by the prestressed anchor-grouting were obviously smaller than those controlled by anchor net, indicating that the prestressed anchor-grouting support had a significant effect on controlling the roadway surrounding rock. [ABSTRACT FROM AUTHOR]

Dynamic compressive properties of rock material under cyclic freeze–thaw weathering are the basis of engineering construction in cold regions, while the effect of crack angles and freeze–thaw cycles on dynamic compressive properties has not been figured out yet. This paper adopted rock-like specimens containing crack with different angles as objects, and conducted cyclic freeze–thaw treatment, nuclear magnetic resonance test, and dynamic impact test on specimens. The influence of freeze–thaw cycles and crack angles on pore structures, dynamic mechanical properties, energy evolutions, and fractal dimension were obtained and analyzed. Results show that spectrum areas of all pores and macro-pores present accelerating growth trends with freeze–thaw cycles. With the increase of freeze–thaw cycles, dynamic peak strains and the ratio of reflect energy to incident energy increase nonlinearly, and fractal dimension of fragments increases linearly. Dynamic peak stress and the ratio of dissipate energy to incident energy decrease nonlinearly, and dynamic elastic modulus and the ratio of transmit energy to incident energy decrease linearly. With the increase of crack angle, dynamic peak stress, dynamic elastic modulus, the ratio of transmit energy to incident energy, and the ratio of dissipate energy to incident energy show a V-type variation trend. While dynamic peak strain and the ratio of reflect energy to incident energy show a reverse V-type variation trend, the fractal dimension of fragment shows an M-type variation trend. This study is of importance to engineering construction in cold regions. [ABSTRACT FROM AUTHOR]

Mechanical properties abruptly change of the coal around small geological structures can easily induce dynamic disasters such as coal and gas outbursts. Some research show that the variation of coal and rock mechanical properties impact the drill bit torque during drilling. However, the influence mechanism is not clear, and the drill bit torque is also affected by the drilling parameters. In this paper, an experimental platform for drill bit torque measurement was set up. Through preparing cement specimens with different mechanical properties, the influence of their mechanical properties and drilling parameters on the drill bit torque were studied. The results show that torque increases with feed force and bit diameter while rotation speed has no significant influence. Feed force exerts the greatest impact and diameter has less effect than the former does. However, if the diameter is too small, discharging drill cuttings will be more difficult, which will result in a sky-high torque. The mechanical properties have a significant influence on drill bit torque, the greater the compressive strength, tensile strength and elastic modulus of the specimens, the smaller the torque, these results are well verified when drilling in composite specimen. This shows that during the drilling process, the variations of the torque-on-bit can reflect mechanical property change of the coal-rock. The results in this paper have a guiding significance for back analysis of mechanical property variations of the coal-rock masses through the drill bit torque, which is beneficial to detect small structures. [ABSTRACT FROM AUTHOR]