In this study, a new ecological slope protection method—Anchor Reinforced Vegetation System (ARVS) was applied to the newly excavated expansive soil slope. To explore the effect and mechanism of ARVS protection of newly excavated expansive soil slopes, expansive soil slopes with three different protection methods (bare slopes, grassed slopes, and ARVS slopes) were built. The continuous natural rainfall test and artificial rainfall tests were carried out. The results show that: compared with the bare slope and the grassed slope, ARVS could effectively adjust the moisture and heat balance of newly excavated expansive soil slopes and achieve a satisfactory soil and water conservation performance. Under different rainfall intensities, the runoff and soil loss rates of the ARVS-protected slope were smallest. Under the combined action of vegetation, high-performance turf reinforcement mats (HPTRMs) and anchors, the ARVS provided a superior erosion resistance. The higher the rainfall intensity is, the more significant the anti-erosion effect of the ARVS compared to that of grass protection technology. The ARVS could also effectively limit vertical and horizontal deformation of newly excavated expansive soil slopes. Therefore, the ARVS could effectively reduce the negative influences of the atmospheric environment on newly excavated expansive soil slopes and provide a new solution for shallow protection of newly excavated expansive soil slopes.
{"title":"Ecological flexible protection method of expansive soil slope under rainfall","authors":"Yingzi Xu, Chunyan Yang, Chao Su, Zhen Huang, Xuhang Liao, Linqiang Tang","doi":"10.1680/jenge.22.00185","DOIUrl":"https://doi.org/10.1680/jenge.22.00185","url":null,"abstract":"In this study, a new ecological slope protection method—Anchor Reinforced Vegetation System (ARVS) was applied to the newly excavated expansive soil slope. To explore the effect and mechanism of ARVS protection of newly excavated expansive soil slopes, expansive soil slopes with three different protection methods (bare slopes, grassed slopes, and ARVS slopes) were built. The continuous natural rainfall test and artificial rainfall tests were carried out. The results show that: compared with the bare slope and the grassed slope, ARVS could effectively adjust the moisture and heat balance of newly excavated expansive soil slopes and achieve a satisfactory soil and water conservation performance. Under different rainfall intensities, the runoff and soil loss rates of the ARVS-protected slope were smallest. Under the combined action of vegetation, high-performance turf reinforcement mats (HPTRMs) and anchors, the ARVS provided a superior erosion resistance. The higher the rainfall intensity is, the more significant the anti-erosion effect of the ARVS compared to that of grass protection technology. The ARVS could also effectively limit vertical and horizontal deformation of newly excavated expansive soil slopes. Therefore, the ARVS could effectively reduce the negative influences of the atmospheric environment on newly excavated expansive soil slopes and provide a new solution for shallow protection of newly excavated expansive soil slopes.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"51 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140579091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This briefing presents an overview of inland aquaculture scenario that focuses on challenges of aquaculture farming, contaminant transport and the future of aqua farming in a broader perspective of environmental geotechnics. Un-engineered aquaculture practices are a cause of concern, and special attention is necessary in waste water management, cross-contamination with the adjacent environment, sludge–subsoil interaction, pond embankment slope failure, leachate migration into the vadose zone, geoenvironmental remediation strategies and geotechnical engineering aspects of engineered pond construction.
{"title":"Briefing: Intensive inland aquaculture ponds: challenges and research opportunities","authors":"T Vamsi Nagaraju, B M Sunil","doi":"10.1680/jenge.23.00090","DOIUrl":"https://doi.org/10.1680/jenge.23.00090","url":null,"abstract":"This briefing presents an overview of inland aquaculture scenario that focuses on challenges of aquaculture farming, contaminant transport and the future of aqua farming in a broader perspective of environmental geotechnics. Un-engineered aquaculture practices are a cause of concern, and special attention is necessary in waste water management, cross-contamination with the adjacent environment, sludge–subsoil interaction, pond embankment slope failure, leachate migration into the vadose zone, geoenvironmental remediation strategies and geotechnical engineering aspects of engineered pond construction.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"744 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140197620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Na Li, Wei-ying Xu, Ping Jiang, Shao-wei Lv, Xian-wen Huang
With the vigorous development of industrial economy, the production capacity and level have been significantly improved, but at the same time, a large number of iron tailings, fly ash and a series of bulk solid waste materials have been accumulated. These industrial wastes have caused serious impact on the ecological environment. How to deal with them effectively is an urgent problem to be solved. The aim of this study was to investigate the effect of cement and fly ash compound admixtures on the mechanical properties of iron tailings powder (ITP). Hence, different mixing ratios of cement and fly ash were used to prepare two kinds of ITP-based materials. A range of uniaxial compressive strength (UCS), resonance column (RC), scanning electron microscopy (SEM), and X-ray diffraction tests were conducted to investigate the roles of cement, fly ash, and curing age on ITP solidification. A random 1D damage model was imported to study the damage evolution of ITP materials using the UCS and RC test results, which showed that cement and fly ash enhanced the unconfined compression strength and small strain stiffness of iron tailings powder. When 5–10% fly ash content was a substitute for 10% cement, the unconfined compressive strength and small strain modulus of the cement–fly ash–iron tailings powder increased with curing age. The microstructure and mineralogy analysis confirmed that fly ash enhanced the strength of the material. Overall, the damage constitutive model effectively represented the randomness of the compressive strength and stress–strain relationship of ITP materials under unconfined conditions.
{"title":"1D Damage constitutive model and small strain characteristics of fly ash–cementitious iron tailings powder under static and dynamic loading","authors":"Na Li, Wei-ying Xu, Ping Jiang, Shao-wei Lv, Xian-wen Huang","doi":"10.1680/jenge.23.00033","DOIUrl":"https://doi.org/10.1680/jenge.23.00033","url":null,"abstract":"With the vigorous development of industrial economy, the production capacity and level have been significantly improved, but at the same time, a large number of iron tailings, fly ash and a series of bulk solid waste materials have been accumulated. These industrial wastes have caused serious impact on the ecological environment. How to deal with them effectively is an urgent problem to be solved. The aim of this study was to investigate the effect of cement and fly ash compound admixtures on the mechanical properties of iron tailings powder (ITP). Hence, different mixing ratios of cement and fly ash were used to prepare two kinds of ITP-based materials. A range of uniaxial compressive strength (UCS), resonance column (RC), scanning electron microscopy (SEM), and X-ray diffraction tests were conducted to investigate the roles of cement, fly ash, and curing age on ITP solidification. A random 1D damage model was imported to study the damage evolution of ITP materials using the UCS and RC test results, which showed that cement and fly ash enhanced the unconfined compression strength and small strain stiffness of iron tailings powder. When 5–10% fly ash content was a substitute for 10% cement, the unconfined compressive strength and small strain modulus of the cement–fly ash–iron tailings powder increased with curing age. The microstructure and mineralogy analysis confirmed that fly ash enhanced the strength of the material. Overall, the damage constitutive model effectively represented the randomness of the compressive strength and stress–strain relationship of ITP materials under unconfined conditions.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"467 ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138506383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yangyang Cai, Yong Wan, Xingxing He, Zhixiang Chen, Lei Liu, Jiangshan Li
Biopolymers efficiently improve the anti-seepage function of compacted clay layers, but research concerning the permeability stability of biopolymer-modified clay during cyclic wetting and drying is scarce. In this paper, the macro–microstructures and the permeability coefficients of biopolymer-modified clay and conventional bentonite-modified clay under dry–wet cycles are comparatively studied. The bentonite modifier is found to increase macro–microscopic cracks under dry–wet cycles, while the xanthan modifier decreases the macro–microscopic fracture rate of the clay. The physical properties of 2% by dry weight xanthan-modified clay are similar to those of 10% by dry weight bentonite-modified clay, but the permeability coefficient of the former is lower by approximately one order of magnitude. After the dry–wet cycles, xanthan-modified clay performed better in leakage prevention than bentonite-modified clay. For low-liquid-limit clay, the recommended mass percentage of xanthan gum was 1.5% considering the seepage resistance safety during dry–wet cycles.
{"title":"Dry shrinkage cracking and permeability of biopolymer-modified clay under dry-wet cycles","authors":"Yangyang Cai, Yong Wan, Xingxing He, Zhixiang Chen, Lei Liu, Jiangshan Li","doi":"10.1680/jenge.22.00113","DOIUrl":"https://doi.org/10.1680/jenge.22.00113","url":null,"abstract":"Biopolymers efficiently improve the anti-seepage function of compacted clay layers, but research concerning the permeability stability of biopolymer-modified clay during cyclic wetting and drying is scarce. In this paper, the macro–microstructures and the permeability coefficients of biopolymer-modified clay and conventional bentonite-modified clay under dry–wet cycles are comparatively studied. The bentonite modifier is found to increase macro–microscopic cracks under dry–wet cycles, while the xanthan modifier decreases the macro–microscopic fracture rate of the clay. The physical properties of 2% by dry weight xanthan-modified clay are similar to those of 10% by dry weight bentonite-modified clay, but the permeability coefficient of the former is lower by approximately one order of magnitude. After the dry–wet cycles, xanthan-modified clay performed better in leakage prevention than bentonite-modified clay. For low-liquid-limit clay, the recommended mass percentage of xanthan gum was 1.5% considering the seepage resistance safety during dry–wet cycles.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135293387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kangjian Zhang, Zhiqiang Zhang, Yuxi Li, Zhechuan Hu
Understanding gas migration behaviours in unsaturated sand–clay mixtures is of great importance to design and construction involving applications of shield-cutting-tool replacement using pressure. A gas permeability test apparatus for unsaturated soil was upgraded to investigate gas migration behaviours further. A series of gas, liquid and solid three-phase coupling gas injection tests were performed on unsaturated clay under different moisture contents and sand–clay ratios. There are three stages of gas migration in unsaturated sand–clay: steep drop stage, transition stage and stability stage. In unsaturated sand–clay with low moisture contents and gas pressures, gas migration is affected primarily by the slippage effect. When the gas pressure is greater than 300 kPa, the permeability remains nearly unchanged. In this case, the gas permeability of the soil sample is affected primarily by the internal structural characteristics of the unsaturated soil sample and those of the shrinkage film. The ideal gas permeability of the soil used in actual engineering and the empirical formula for calculating the pressure of the shield pressure-holding system are summarised.
{"title":"Experimental investigation on gas migration behaviour in unsaturated sand-clay mixture","authors":"Kangjian Zhang, Zhiqiang Zhang, Yuxi Li, Zhechuan Hu","doi":"10.1680/jenge.22.00156","DOIUrl":"https://doi.org/10.1680/jenge.22.00156","url":null,"abstract":"Understanding gas migration behaviours in unsaturated sand–clay mixtures is of great importance to design and construction involving applications of shield-cutting-tool replacement using pressure. A gas permeability test apparatus for unsaturated soil was upgraded to investigate gas migration behaviours further. A series of gas, liquid and solid three-phase coupling gas injection tests were performed on unsaturated clay under different moisture contents and sand–clay ratios. There are three stages of gas migration in unsaturated sand–clay: steep drop stage, transition stage and stability stage. In unsaturated sand–clay with low moisture contents and gas pressures, gas migration is affected primarily by the slippage effect. When the gas pressure is greater than 300 kPa, the permeability remains nearly unchanged. In this case, the gas permeability of the soil sample is affected primarily by the internal structural characteristics of the unsaturated soil sample and those of the shrinkage film. The ideal gas permeability of the soil used in actual engineering and the empirical formula for calculating the pressure of the shield pressure-holding system are summarised.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":" 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135293106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-07DOI: 10.3390/geotechnics3040067
Gisèle A. Rudderham, Jennifer J. Day
Geotechnical rockmass characterization is a key task for design of underground and open pit excavations. Hydrothermal veins influence excavation performance by contributing to stress-driven rockmass failure. This study investigates the effects of vein orientation and thickness on stiffness and peak strength of laboratory scale specimens under uniaxial and triaxial compression using finite element numerical experiments of sulfide veined mafic igneous complex (CMET) rocks from El Teniente mine, Chile. The initial numerical models are calibrated to and validated against physical laboratory test data using a multi-step calibration procedure, first of the unveined Lac du Bonnet granite to define the model configuration, and second of unveined and veined CMET. Once calibrated, the numerical experiment involves varying the vein geometry in the veined CMET models by orientation (5 to 85°) and thickness (1, 4, 8 mm). This approach enables systematic investigation of any vein geometry without limitations of physical specimen availability or complexity of physical materials. This methodology greatly improves the value of physical laboratory test data with a limited scope of vein characteristics by using calibrated numerical models to investigate the effects of any other vein geometry. In this study, vein orientation and thickness were both found to have a significant impact on the specimen stiffness and peak strength.
岩土岩体特征是地下和露天开挖设计的关键任务。热液脉通过引起应力驱动的岩体破坏而影响开挖性能。通过对智利El Teniente矿硫化物脉状基性火成岩杂岩(CMET)的有限元数值实验，研究了脉状方向和厚度对实验室尺度试样在单轴和三轴压缩下刚度和峰值强度的影响。初始数值模型使用多步骤校准程序，根据物理实验室测试数据进行校准和验证，首先对未抛光的Lac du Bonnet花岗岩进行校准，以定义模型配置，然后对未抛光和脉状CMET进行校准。一旦校准，数值实验涉及改变脉状CMET模型中的脉状几何形状，通过方向(5至85°)和厚度(1,4,8 mm)。这种方法可以系统地研究任何静脉几何形状，而不受物理标本可用性或物理材料复杂性的限制。该方法通过使用校准的数值模型来研究任何其他静脉几何形状的影响，极大地提高了物理实验室测试数据的价值，这些数据具有有限的静脉特征范围。在本研究中，我们发现静脉的方向和厚度对试件刚度和峰值强度都有显著的影响。
{"title":"Veined Rock Performance under Uniaxial and Triaxial Compression Using Calibrated Finite Element Numerical Models","authors":"Gisèle A. Rudderham, Jennifer J. Day","doi":"10.3390/geotechnics3040067","DOIUrl":"https://doi.org/10.3390/geotechnics3040067","url":null,"abstract":"Geotechnical rockmass characterization is a key task for design of underground and open pit excavations. Hydrothermal veins influence excavation performance by contributing to stress-driven rockmass failure. This study investigates the effects of vein orientation and thickness on stiffness and peak strength of laboratory scale specimens under uniaxial and triaxial compression using finite element numerical experiments of sulfide veined mafic igneous complex (CMET) rocks from El Teniente mine, Chile. The initial numerical models are calibrated to and validated against physical laboratory test data using a multi-step calibration procedure, first of the unveined Lac du Bonnet granite to define the model configuration, and second of unveined and veined CMET. Once calibrated, the numerical experiment involves varying the vein geometry in the veined CMET models by orientation (5 to 85°) and thickness (1, 4, 8 mm). This approach enables systematic investigation of any vein geometry without limitations of physical specimen availability or complexity of physical materials. This methodology greatly improves the value of physical laboratory test data with a limited scope of vein characteristics by using calibrated numerical models to investigate the effects of any other vein geometry. In this study, vein orientation and thickness were both found to have a significant impact on the specimen stiffness and peak strength.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"92 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135539677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-04DOI: 10.3390/geotechnics3040066
Alison McQuillan, Amichai Mitelman, Davide Elmo
Over the past decades, numerical modelling has become a powerful tool for rock mechanics applications. However, the accurate estimation of rock mass input parameters remains a significant challenge. Machine learning (ML) tools have recently been integrated to enhance and accelerate numerical modelling processes. In this paper, we demonstrate the novel use of ML tools for calibrating a state-of-the-art three-dimensional (3D) finite-element (FE) model of a kinematic structurally controlled failure event in an open-pit mine. The failure event involves the detachment of a large wedge, thus allowing for the accurate identification of the geometry of the rock joints. FE models are automatically generated according to estimated ranges of joint input parameters. Subsequently, ML tools are used to analyze the synthetic data and calibrate the strength parameters of the rock joints. Our findings reveal that a relatively small number of models are needed for this purpose, rendering ML a highly useful tool even for computationally demanding FE models.
{"title":"Back-Analysis of Structurally Controlled Failure in an Open-Pit Mine with Machine Learning Tools","authors":"Alison McQuillan, Amichai Mitelman, Davide Elmo","doi":"10.3390/geotechnics3040066","DOIUrl":"https://doi.org/10.3390/geotechnics3040066","url":null,"abstract":"Over the past decades, numerical modelling has become a powerful tool for rock mechanics applications. However, the accurate estimation of rock mass input parameters remains a significant challenge. Machine learning (ML) tools have recently been integrated to enhance and accelerate numerical modelling processes. In this paper, we demonstrate the novel use of ML tools for calibrating a state-of-the-art three-dimensional (3D) finite-element (FE) model of a kinematic structurally controlled failure event in an open-pit mine. The failure event involves the detachment of a large wedge, thus allowing for the accurate identification of the geometry of the rock joints. FE models are automatically generated according to estimated ranges of joint input parameters. Subsequently, ML tools are used to analyze the synthetic data and calibrate the strength parameters of the rock joints. Our findings reveal that a relatively small number of models are needed for this purpose, rendering ML a highly useful tool even for computationally demanding FE models.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"38 20","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135773493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.3390/geotechnics3040065
Mrityunjay Singh, Saeed Mahmoodpour, Kristian Bär, Ingo Sass
The fracture network largely determines the efficiency of heat extraction from fractured geothermal reservoirs. Fracture openings are influenced by thermo-poroelastic stresses during cold fluid flow, with the interplay between fracture length and fracture opening regulating heat transfer. The lack of field data concerning fluctuating fracture openings underscores the necessity for computational models. This work emphasizes the impact of such gaps in the literature. Factors such as temperature, pressure, stress, thermal breakthrough time, and cumulative energy are evaluated to analyze the system’s behavior. A sensitivity analysis is employed to ascertain the significance of stress on fracture opening, compared with thermo-hydraulic behavior. The results show that stress field alterations, due to intersections with minor fractures, can cause up to a 15% variation in the largest fracture’s opening. The impact of thermoelastic stress outweighs the impact of poroelastic stress approximately threefold. Such stress-induced variations in fracture openings can lead to an up to 30% increase in cumulative heat extraction, while the drop in production temperature is limited to around 50%.
{"title":"Heat Extraction in Geothermal Systems with Variable Thermo-Poroelastic Fracture Apertures","authors":"Mrityunjay Singh, Saeed Mahmoodpour, Kristian Bär, Ingo Sass","doi":"10.3390/geotechnics3040065","DOIUrl":"https://doi.org/10.3390/geotechnics3040065","url":null,"abstract":"The fracture network largely determines the efficiency of heat extraction from fractured geothermal reservoirs. Fracture openings are influenced by thermo-poroelastic stresses during cold fluid flow, with the interplay between fracture length and fracture opening regulating heat transfer. The lack of field data concerning fluctuating fracture openings underscores the necessity for computational models. This work emphasizes the impact of such gaps in the literature. Factors such as temperature, pressure, stress, thermal breakthrough time, and cumulative energy are evaluated to analyze the system’s behavior. A sensitivity analysis is employed to ascertain the significance of stress on fracture opening, compared with thermo-hydraulic behavior. The results show that stress field alterations, due to intersections with minor fractures, can cause up to a 15% variation in the largest fracture’s opening. The impact of thermoelastic stress outweighs the impact of poroelastic stress approximately threefold. Such stress-induced variations in fracture openings can lead to an up to 30% increase in cumulative heat extraction, while the drop in production temperature is limited to around 50%.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"24 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135868523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-02DOI: 10.3390/geotechnics3040064
Louis Katele Kabwe, Ward Gordon Wilson
Accurate measurements and predictions of near-surface soil drying and evaporation following heavy rainfall events are often needed for research in agriculture and hydrology. However, such measurements and predictions at mine waste pile and tailing settings are limited. The prediction of evaporation at mine waste piles is essential for many problems in geotechnical engineering, including the design of soil cover systems for the long-term closure of hazardous waste sites, and thus mitigates, for example, the generation of acid mine drainage (AMD) and metal leaching. AMD is one of mining’s most serious threats to the environment. This study investigated the short-term (8 days) and medium-term (27 days) drying rates and evaporative fluxes at the surface and near-surface of the Deilmann South waste-rock (DSWR) pile at the Key Lake uranium mine, northern Saskatchewan, using the gravimetric (GV) method and SoilCover (SC) model, respectively, during and following heavy rainfall events for the environment. The SC simulation results showed that during the weather-controlled stage (Stage I) of the first 5-day period of rainfall events, while the surface was wet, the potential evaporation (PE) was equal to the actual evaporation (AE) (i.e., AE/PE = 1). As the surface became drier on Day 6, the cumulative PE began to separate from the cumulative AE and the surface’s drying rate rapidly diverged from those at the deeper depths. This occurrence signaled the onset of the soil profile property-controlled stage (Stage II). As the drying continued, the surface became desiccated and the slow-rate drying stage (Stage III) was established from Day 7 onward. The SC-simulated AE results were compared to those measured using the eddy covariance (EC) method for the same test period at the DSWR pile in a different study. The comparison showed that the two methods yielded similar AE results, with 18% relative errors. The results of this study provided the opportunity to validate the SC model using actual data gathered under field conditions and to ascertain its ability to accurately predict the PE and AE at the surfaces of mine waste piles.
{"title":"Short-Term Predictions of Evaporation Using SoilCover at the Near-Surface of a Mine Waste Pile following Heavy Rainfall Events","authors":"Louis Katele Kabwe, Ward Gordon Wilson","doi":"10.3390/geotechnics3040064","DOIUrl":"https://doi.org/10.3390/geotechnics3040064","url":null,"abstract":"Accurate measurements and predictions of near-surface soil drying and evaporation following heavy rainfall events are often needed for research in agriculture and hydrology. However, such measurements and predictions at mine waste pile and tailing settings are limited. The prediction of evaporation at mine waste piles is essential for many problems in geotechnical engineering, including the design of soil cover systems for the long-term closure of hazardous waste sites, and thus mitigates, for example, the generation of acid mine drainage (AMD) and metal leaching. AMD is one of mining’s most serious threats to the environment. This study investigated the short-term (8 days) and medium-term (27 days) drying rates and evaporative fluxes at the surface and near-surface of the Deilmann South waste-rock (DSWR) pile at the Key Lake uranium mine, northern Saskatchewan, using the gravimetric (GV) method and SoilCover (SC) model, respectively, during and following heavy rainfall events for the environment. The SC simulation results showed that during the weather-controlled stage (Stage I) of the first 5-day period of rainfall events, while the surface was wet, the potential evaporation (PE) was equal to the actual evaporation (AE) (i.e., AE/PE = 1). As the surface became drier on Day 6, the cumulative PE began to separate from the cumulative AE and the surface’s drying rate rapidly diverged from those at the deeper depths. This occurrence signaled the onset of the soil profile property-controlled stage (Stage II). As the drying continued, the surface became desiccated and the slow-rate drying stage (Stage III) was established from Day 7 onward. The SC-simulated AE results were compared to those measured using the eddy covariance (EC) method for the same test period at the DSWR pile in a different study. The comparison showed that the two methods yielded similar AE results, with 18% relative errors. The results of this study provided the opportunity to validate the SC model using actual data gathered under field conditions and to ascertain its ability to accurately predict the PE and AE at the surfaces of mine waste piles.","PeriodicalId":11823,"journal":{"name":"Environmental geotechnics","volume":"56 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135933142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3390/geotechnics3040063
Yang Cao, Hoang Bao Khoi Nguyen, Derrick Aikins, Md. Rajibul Karim, Md. Mizanur Rahman
In some cases, the water content in granular soil increases to the extent that it becomes saturated, which noticeably alters its responses. For example, the pore water pressure within saturated granular soil would increase rapidly under sudden external loading, which is equivalent to undrained or constant volume conditions. This reduces the effective stress in soil dramatically and may result in catastrophic failure. There have been different numerical approaches to analyse such a failure mechanism of soil to provide a deeper understanding of soil behaviour at the microscopic level. One of the most common numerical tools for such analysis is the discrete element method (DEM) due to its advantage in obtaining microscopic properties (e.g., statistics on particle contacts and fabric), reproducibility and simple feedback control. However, most DEM studies ignore the fluid phase and merely consider the solid particles while the fluid pressure is indirectly calculated by mimicking undrained condition to a constant volume condition. Note that fluid’s influence does not limit to the change of pore water pressure. For example, the external loading would induce the movement of fluid, and the fluid-solid interaction could subsequently drag the solid particles to shift within the system. In addition, the state of soil could change from solid to suspension under an excess hydraulic gradient. Therefore, the study of the fluid-solid mixture is essential as it is a typical scenario in geotechnical practice, and the simulations of saturated sand should be conducted in numerical forms in which both the solid and fluid phases can be modelled.
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