Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100151
Wenqiang Xia , Chun Liu , Hui Liu , Tao Zhao , Yao Zhu
Pore-scale particle migration in piping is the main reason of the suffusion-induced damage, which poses a significant threat to earth-rock dams. In order to investigate the micro-mechanism of piping seepage process, an improved fluid-solid coupling discrete element method is proposed in this paper. In this method, particles in a packed model are divided into coarse- and fine particle groups. Pores can be defined based on the coordinates of the coarse particles and the Delaunay triangulation algorithm. A pore density flow method is introduced to calculate the overall fluid pressure of each pore and the fluid flow via pore throats. Further, the drag force on fine particles inside a pore can be calculated according to the fluid velocities of the neighboring four pore throats. The proposed method was implemented in the discrete element software MatDEM, and was successfully used to simulate fine particle migration of piping, the particle loss process, and the related variation of permeability coefficient. The pore-jamming phenomenon during the fine particle migration is observed. The model provides an effective way for the numerical analysis and mechanism study of piping seepage process at the pore scale.
{"title":"Modeling of particle migration in piping based on an improved discrete element method","authors":"Wenqiang Xia , Chun Liu , Hui Liu , Tao Zhao , Yao Zhu","doi":"10.1016/j.rockmb.2024.100151","DOIUrl":"10.1016/j.rockmb.2024.100151","url":null,"abstract":"<div><div>Pore-scale particle migration in piping is the main reason of the suffusion-induced damage, which poses a significant threat to earth-rock dams. In order to investigate the micro-mechanism of piping seepage process, an improved fluid-solid coupling discrete element method is proposed in this paper. In this method, particles in a packed model are divided into coarse- and fine particle groups. Pores can be defined based on the coordinates of the coarse particles and the Delaunay triangulation algorithm. A pore density flow method is introduced to calculate the overall fluid pressure of each pore and the fluid flow via pore throats. Further, the drag force on fine particles inside a pore can be calculated according to the fluid velocities of the neighboring four pore throats. The proposed method was implemented in the discrete element software MatDEM, and was successfully used to simulate fine particle migration of piping, the particle loss process, and the related variation of permeability coefficient. The pore-jamming phenomenon during the fine particle migration is observed. The model provides an effective way for the numerical analysis and mechanism study of piping seepage process at the pore scale.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100151"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100153
Zhong-jian Zhang , Zhongqi Quentin Yue , Biao Li , Zhi-fa Yang
This paper presents a directional large-area rock fracturing method. The method had distinctive features compared with other common fracturing methods. The area of the fracturing surface could reach 10–500 m2. The fractured rock was sheet-like in shape, with a thickness of 6–8 cm. The main fracturing tools and procedures used were described in the paper. This paper analyzed the reason for controllable and directional (also mode-I) rupturing in rock from the view of fracture mechanics. Counter-intuitively, the fracturing surface of the rock sheet had an angle (approximately 25°) to the loading direction (i.e., the orientation of the maximum principal compressive stress). The rupture behavior was controlled by the relationship between the load and the geometric boundary of the rock. It is found that the fracturing surface can suddenly and rapidly propagate after a certain strike by calculating the energies of the rock sheet. The striking energy could be converted into elastic strain energy, which accumulates in a very-slightly bent rock sheet step by step until exceeds the bearing limit of rock sheet. Most of the stored elastic strain energy was subsequently released in the form of splitting energy, leading to rock fracturing. This study provides insights into the occurrence of tectonic earthquakes.
{"title":"Manually directional splitting of in-situ intact igneous rocks into large sheets","authors":"Zhong-jian Zhang , Zhongqi Quentin Yue , Biao Li , Zhi-fa Yang","doi":"10.1016/j.rockmb.2024.100153","DOIUrl":"10.1016/j.rockmb.2024.100153","url":null,"abstract":"<div><div>This paper presents a directional large-area rock fracturing method. The method had distinctive features compared with other common fracturing methods. The area of the fracturing surface could reach 10–500 m<sup>2</sup>. The fractured rock was sheet-like in shape, with a thickness of 6–8 cm. The main fracturing tools and procedures used were described in the paper. This paper analyzed the reason for controllable and directional (also mode-I) rupturing in rock from the view of fracture mechanics. Counter-intuitively, the fracturing surface of the rock sheet had an angle (approximately 25°) to the loading direction (i.e., the orientation of the maximum principal compressive stress). The rupture behavior was controlled by the relationship between the load and the geometric boundary of the rock. It is found that the fracturing surface can suddenly and rapidly propagate after a certain strike by calculating the energies of the rock sheet. The striking energy could be converted into elastic strain energy, which accumulates in a very-slightly bent rock sheet step by step until exceeds the bearing limit of rock sheet. Most of the stored elastic strain energy was subsequently released in the form of splitting energy, leading to rock fracturing. This study provides insights into the occurrence of tectonic earthquakes.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100153"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100170
Saeed Vadiee , Biao Li , Jasmin Raymond , Mafalda M. Miranda
This study numerically investigates the thermo-poromechanical effects in a Canadian geothermal reservoir caused by long-term fluid production and injection. Using finite element modeling, it explores pore pressure diffusion and thermal dynamics, incorporating both the geological structure of the rock mass and faults. The simulations utilize the IAPWS (International Association for the Properties of Water and Steam) equations to model fluid density and viscosity, ensuring realistic representations of heterogeneous pressure fields. The system replicates a doublet configuration within a faulted zone, featuring two hydraulically stimulated fractures. The primary aim is to assess the likelihood of fault reactivation under varying in-situ stress conditions over a 100-year geothermal operation. Results show that stress distribution is largely influenced by thermal stresses along the fluid circulation pathway, with fluid velocity and temperature gradients affecting reservoir stability. Minimal pore pressure changes highlight the dominant role of thermal stresses in controlling fault behavior. The analysis indicates no potential for fault reactivation, as slip tendency values remain below the critical threshold, even when accounting for reduced mechanical properties using the Hoek-Brown criterion. Thermal effects continue to influence the surrounding rock throughout the operational period, suggesting that the reservoir maintains mechanical stability conducive to sustained geothermal production and injection. These findings provide valuable insights into the long-term safety and behavior of geothermal reservoirs, offering important implications for future geothermal energy development and management strategies.
{"title":"Numerical modeling of the long-term poromechanical performance of a deep enhanced geothermal system in northern Québec","authors":"Saeed Vadiee , Biao Li , Jasmin Raymond , Mafalda M. Miranda","doi":"10.1016/j.rockmb.2024.100170","DOIUrl":"10.1016/j.rockmb.2024.100170","url":null,"abstract":"<div><div>This study numerically investigates the thermo-poromechanical effects in a Canadian geothermal reservoir caused by long-term fluid production and injection. Using finite element modeling, it explores pore pressure diffusion and thermal dynamics, incorporating both the geological structure of the rock mass and faults. The simulations utilize the IAPWS (International Association for the Properties of Water and Steam) equations to model fluid density and viscosity, ensuring realistic representations of heterogeneous pressure fields. The system replicates a doublet configuration within a faulted zone, featuring two hydraulically stimulated fractures. The primary aim is to assess the likelihood of fault reactivation under varying in-situ stress conditions over a 100-year geothermal operation. Results show that stress distribution is largely influenced by thermal stresses along the fluid circulation pathway, with fluid velocity and temperature gradients affecting reservoir stability. Minimal pore pressure changes highlight the dominant role of thermal stresses in controlling fault behavior. The analysis indicates no potential for fault reactivation, as slip tendency values remain below the critical threshold, even when accounting for reduced mechanical properties using the Hoek-Brown criterion. Thermal effects continue to influence the surrounding rock throughout the operational period, suggesting that the reservoir maintains mechanical stability conducive to sustained geothermal production and injection. These findings provide valuable insights into the long-term safety and behavior of geothermal reservoirs, offering important implications for future geothermal energy development and management strategies.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100170"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100155
Yanting Liu , Yuan Liang , Yueqiang Ma , Jingyi Liu , Derek Elsworth , Quan Gan
Retasking existing subsurface abandoned mines as infrastructure for solar energy storage could be a feasible approach in overcoming the low thermal gradient present in shallow formations. In this work, the potential for thermal storage in the high permeability goaf of abandoned mines through diurnal cyclic injection-then-extraction using coupled thermo-hydro-mechanical modeling was explored by coupling FLAC3D with TOUGH2. The temperature sensibility of reservoir during 30 days of cyclic injection-then-production was examined at various injection temperatures (ranging from 50 °C to 250 °C) and rates (ranging from 1 kg/s to 10 kg/s) and for representative reservoir physical and thermal properties, including variable thermal expansion coefficients. The simulation results reveal that: The principal mechanisms driving reservoir deformation result from the combined influence of thermal poroelastic and thermal effects. With the change of reservoir temperature, the reservoir is perturbed by pressure and thermal stresses causing permeability evolution. Permeability reduces ∼10% for a maximum injection temperature of 250 °C – although effects are reduced the lower injection temperatures. The pore pressure fluctuations for an injection rate of 10 kg/s is ∼6.5 times that for a rate of 1 kg/s. The pressure perturbation of the reservoir during the injection process decreases with the injection rate, and the reservoir is relatively more stable. When the thermal stress becomes predominant, the reservoir volume expands. Uplift displacements 220 m above the hot injection well are trivial an of the order of ∼1.5 mm at a mean temperature of 163 °C.
{"title":"Dynamic evolution of reservoir permeability and deformation in geothermal battery energy storage using abandoned mines","authors":"Yanting Liu , Yuan Liang , Yueqiang Ma , Jingyi Liu , Derek Elsworth , Quan Gan","doi":"10.1016/j.rockmb.2024.100155","DOIUrl":"10.1016/j.rockmb.2024.100155","url":null,"abstract":"<div><div>Retasking existing subsurface abandoned mines as infrastructure for solar energy storage could be a feasible approach in overcoming the low thermal gradient present in shallow formations. In this work, the potential for thermal storage in the high permeability goaf of abandoned mines through diurnal cyclic injection-then-extraction using coupled thermo-hydro-mechanical modeling was explored by coupling FLAC<sup>3D</sup> with TOUGH2. The temperature sensibility of reservoir during 30 days of cyclic injection-then-production was examined at various injection temperatures (ranging from 50 °C to 250 °C) and rates (ranging from 1 kg/s to 10 kg/s) and for representative reservoir physical and thermal properties, including variable thermal expansion coefficients. The simulation results reveal that: The principal mechanisms driving reservoir deformation result from the combined influence of thermal poroelastic and thermal effects. With the change of reservoir temperature, the reservoir is perturbed by pressure and thermal stresses causing permeability evolution. Permeability reduces ∼10% for a maximum injection temperature of 250 °C – although effects are reduced the lower injection temperatures. The pore pressure fluctuations for an injection rate of 10 kg/s is ∼6.5 times that for a rate of 1 kg/s. The pressure perturbation of the reservoir during the injection process decreases with the injection rate, and the reservoir is relatively more stable. When the thermal stress becomes predominant, the reservoir volume expands. Uplift displacements 220 m above the hot injection well are trivial an of the order of ∼1.5 mm at a mean temperature of 163 °C.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100155"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vibrations generated by rock blasting are a serious and hazardous outcome of these activities, causing harmful effects on the surrounding environment as well as the nearby residents. Both the local ecology and human communities suffer from the consequences of these vibrations. Assessing the severity of blasting vibrations necessitates a thorough evaluation of Peak Particle Velocity (PPV) and frequency, which are essential parameters for measuring vibration velocity. Accurate prediction of vibration occurrence is critically important. Therefore, this study employs five machine learning models for predicting the PPV and frequency resulting from quarry blasting. This work compares five machine learning models (XGBoost, Catboost, Bagging, Gradient Boosting, and Random Forest Regression) to choose the most efficient performance model. The performance evaluation of each five machine learning models demonstrates each model achieved a performance of more than 0.90 during the testing phase, there was a strong correlation observed between the actual and the predicted ones. The analysis of performance metrics shows Catboost regression model demonstrate better performance prediction comparing with the other models with R2 = 0.983, MSE = 0.000078, RMSE = 0.008, NRMSE = 0.019, MAD = 0.004, MAPE = 35.197 in the PPV prediction, and R2 = 0.975, MSE = 0.000243, RMSE = 0.015, NRMSE = 0.031, MAD = 0.008, MAPE = 37.281 for the frequency prediction. This study will help mining engineers and blasting experts to select the best machine learning model and its hyperparameters in estimating ground vibration, and frequency. In the context of the mining and civil industry, the application of this study offers significant potential for enhancing safety protocols and optimizing operational efficiency. By employing machine learning models, this research aims to accurately predict and assess ground vibrations with frequency resulting from rock blasting.
{"title":"Data-driven machine learning approaches for simultaneous prediction of peak particle velocity and frequency induced by rock blasting in mining","authors":"Yewuhalashet Fissha , Prashanth Ragam , Hajime Ikeda , N. Kushal Kumar , Tsuyoshi Adachi , P.S. Paul , Youhei Kawamura","doi":"10.1016/j.rockmb.2024.100166","DOIUrl":"10.1016/j.rockmb.2024.100166","url":null,"abstract":"<div><div>The vibrations generated by rock blasting are a serious and hazardous outcome of these activities, causing harmful effects on the surrounding environment as well as the nearby residents. Both the local ecology and human communities suffer from the consequences of these vibrations. Assessing the severity of blasting vibrations necessitates a thorough evaluation of Peak Particle Velocity (<em>PPV</em>) and frequency, which are essential parameters for measuring vibration velocity. Accurate prediction of vibration occurrence is critically important. Therefore, this study employs five machine learning models for predicting the <em>PPV</em> and frequency resulting from quarry blasting. This work compares five machine learning models (XGBoost, Catboost, Bagging, Gradient Boosting, and Random Forest Regression) to choose the most efficient performance model. The performance evaluation of each five machine learning models demonstrates each model achieved a performance of more than 0.90 during the testing phase, there was a strong correlation observed between the actual and the predicted ones. The analysis of performance metrics shows Catboost regression model demonstrate better performance prediction comparing with the other models with <em>R</em><sup>2</sup> = 0.983, <em>MSE</em> = 0.000078, <em>RMSE</em> = 0.008, <em>NRMSE</em> = 0.019, <em>MAD</em> = 0.004, <em>MAPE</em> = 35.197 in the <em>PPV</em> prediction, and <em>R</em><sup>2</sup> = 0.975, <em>MSE</em> = 0.000243, <em>RMSE</em> = 0.015, <em>NRMSE</em> = 0.031, <em>MAD</em> = 0.008, <em>MAPE</em> = 37.281 for the frequency prediction. This study will help mining engineers and blasting experts to select the best machine learning model and its hyperparameters in estimating ground vibration, and frequency. In the context of the mining and civil industry, the application of this study offers significant potential for enhancing safety protocols and optimizing operational efficiency. By employing machine learning models, this research aims to accurately predict and assess ground vibrations with frequency resulting from rock blasting.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100166"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100168
Rouhollah Basirat
This paper employs analytical and pseudo-static approaches to analyze the tunnel response under the compression (P) and shear (S) waves. In the first step, Einstein and Schwartz’s method is revised for calculating Tunnel Lining Internal Forces (TLIFs) under P-wave. Next, a comprehensive comparison is performed between TLIFs under S and P-waves in two extreme contact interfaces of no-slip (NS) and full-slip (FS) conditions. Lastly, the effect of the intermediate layer was investigated by quasi-static finite element numerical modeling. The results showed that the maximum value of the axial force under the P-wave exceeds that of the S-wave in both the NS and FS conditions. Also, the amount of bending moment and shear force in both the NS and FS conditions under the S-wave is almost twice the P-wave. In general, the weak interlayer causes a decrease in the maximum axial force and the axial force values in the range of placement of the weak interlayer with the tunnel. Besides, it increases the maximum bending moment and shear force compared to the homogeneous medium. It was also observed that the weak interlayer with low thickness causes unpredictable behavior under S and P-waves. Overall, the presence of a layer with different stiffness led to a significant effect on the TLIFs under S and P-waves and increased the complexity of the dynamic analysis of tunnel lining. Therefore, it should be simulated separately under NS and FS conditions.
{"title":"Analysis of tunnel lining internal forces under the influence of S and P-waves: An analytical solution and quasi-static numerical method","authors":"Rouhollah Basirat","doi":"10.1016/j.rockmb.2024.100168","DOIUrl":"10.1016/j.rockmb.2024.100168","url":null,"abstract":"<div><div>This paper employs analytical and pseudo-static approaches to analyze the tunnel response under the compression (P) and shear (S) waves. In the first step, Einstein and Schwartz’s method is revised for calculating Tunnel Lining Internal Forces (TLIFs) under P-wave. Next, a comprehensive comparison is performed between TLIFs under S and P-waves in two extreme contact interfaces of no-slip (NS) and full-slip (FS) conditions. Lastly, the effect of the intermediate layer was investigated by quasi-static finite element numerical modeling. The results showed that the maximum value of the axial force under the P-wave exceeds that of the S-wave in both the NS and FS conditions. Also, the amount of bending moment and shear force in both the NS and FS conditions under the S-wave is almost twice the P-wave. In general, the weak interlayer causes a decrease in the maximum axial force and the axial force values in the range of placement of the weak interlayer with the tunnel. Besides, it increases the maximum bending moment and shear force compared to the homogeneous medium. It was also observed that the weak interlayer with low thickness causes unpredictable behavior under S and P-waves. Overall, the presence of a layer with different stiffness led to a significant effect on the TLIFs under S and P-waves and increased the complexity of the dynamic analysis of tunnel lining. Therefore, it should be simulated separately under NS and FS conditions.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100168"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100169
S. Dumoulin , A. Kane , T. Coudert , N. Morin , L. Gerbaud , N. Velmurugan , E. Jahangir , H. Sellami , J.-P. Latham , S. Naderi , J. Xiang
The EU H2020 ORCHYD project seeks to enhance drilling efficiency in hard rock environments, particularly for deep geothermal wells, by integrating innovative rock weakening techniques. In this context, 3D finite element simulations of bit-rock interactions were performed to assess how combining high pressure water jetting (HPWJ)-induced groove and bottom-hole geometry can contribute to improve the down-hole percussive drilling performance. A Red Bohus granite rock was modelled using a continuum, elasto-visco-plastic, and damage-based model calibrated using Brazilian, uniaxial compression, and triaxial material tests as well as single insert impact tests. Bit-rock interaction with an HPWJ groove was studied through modelling of twelve different groove depths and bottom-hole configurations. Results demonstrate that deeper grooves significantly reduce impact loads by up to 35% and increase penetration up to 40%, leading to higher material removal (up to 240%). Groove depth also influences damage propagation between adjacent indents, with grooves facilitating a broader zone of fractured rock, particularly near the groove itself. Notably, the drilling efficiency benefits from HPWJ slotting are highly dependent on bit design: flat and concave bit profiles exhibit 70% greater improvement in drilling performance compared to other profiles.
{"title":"Three-dimensional numerical study of DTH bit-rock interaction with HPWJ downhole slotting: Influence of bit design and bottom hole geometric conditions on rock breaking efficiency in percussive drilling","authors":"S. Dumoulin , A. Kane , T. Coudert , N. Morin , L. Gerbaud , N. Velmurugan , E. Jahangir , H. Sellami , J.-P. Latham , S. Naderi , J. Xiang","doi":"10.1016/j.rockmb.2024.100169","DOIUrl":"10.1016/j.rockmb.2024.100169","url":null,"abstract":"<div><div>The EU H2020 ORCHYD project seeks to enhance drilling efficiency in hard rock environments, particularly for deep geothermal wells, by integrating innovative rock weakening techniques. In this context, 3D finite element simulations of bit-rock interactions were performed to assess how combining high pressure water jetting (HPWJ)-induced groove and bottom-hole geometry can contribute to improve the down-hole percussive drilling performance. A Red Bohus granite rock was modelled using a continuum, elasto-visco-plastic, and damage-based model calibrated using Brazilian, uniaxial compression, and triaxial material tests as well as single insert impact tests. Bit-rock interaction with an HPWJ groove was studied through modelling of twelve different groove depths and bottom-hole configurations. Results demonstrate that deeper grooves significantly reduce impact loads by up to 35% and increase penetration up to 40%, leading to higher material removal (up to 240%). Groove depth also influences damage propagation between adjacent indents, with grooves facilitating a broader zone of fractured rock, particularly near the groove itself. Notably, the drilling efficiency benefits from HPWJ slotting are highly dependent on bit design: flat and concave bit profiles exhibit 70% greater improvement in drilling performance compared to other profiles.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100169"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100154
Argha Biswas, Aditya Singh, Mahendra Singh
Extensive research is available on excavation walls in soils. However, very few studies address their performance in rocks and jointed rock masses. This study aimed to investigate the effect of staggered and non-staggered joints on ultimate bearing capacity, load settlement behavior, failure mechanism, and lateral wall displacement for a jointed rock mass supported by an excavation wall. The present study has been conducted on scaled 2D physical laboratory model tests. Tests were performed on artificial jointed rock masses comprising orthogonal joint sets and an excavation wall supporting a nearby foundation. Two sets of rock masses were prepared, one with continuous joints and another with slightly staggered joints. Three different excavation depths were used in this study. The results revealed that minor staggering significantly enhanced bearing capacity by two to three times compared to continuous joints. Furthermore, the presence of minor staggering reduced both vertical settlement of the footing and lateral movement of the excavation wall, thereby altering the failure patterns. Additionally, a discrete element model (DEM) was developed using the Universal Distinct Element Code (UDEC) to compare numerical simulation results with the physical model test results. The discrepancies between the numerical and physical model results were attributed to the difficulty in accurately representing the physical position of individual blocks in the UDEC model. This issue was addressed by introducing the concept of “apparent cohesion” and aligning DEM results closely with experimental outcomes, confirming the effectiveness of this approach in reconciling numerical and physical model differences.
{"title":"The effects of staggered and non-staggered joints on the ultimate bearing capacity, load settlement behavior, and failure mechanism with the change of excavation depths","authors":"Argha Biswas, Aditya Singh, Mahendra Singh","doi":"10.1016/j.rockmb.2024.100154","DOIUrl":"10.1016/j.rockmb.2024.100154","url":null,"abstract":"<div><div>Extensive research is available on excavation walls in soils. However, very few studies address their performance in rocks and jointed rock masses. This study aimed to investigate the effect of staggered and non-staggered joints on ultimate bearing capacity, load settlement behavior, failure mechanism, and lateral wall displacement for a jointed rock mass supported by an excavation wall. The present study has been conducted on scaled 2D physical laboratory model tests. Tests were performed on artificial jointed rock masses comprising orthogonal joint sets and an excavation wall supporting a nearby foundation. Two sets of rock masses were prepared, one with continuous joints and another with slightly staggered joints. Three different excavation depths were used in this study. The results revealed that minor staggering significantly enhanced bearing capacity by two to three times compared to continuous joints. Furthermore, the presence of minor staggering reduced both vertical settlement of the footing and lateral movement of the excavation wall, thereby altering the failure patterns. Additionally, a discrete element model (DEM) was developed using the Universal Distinct Element Code (UDEC) to compare numerical simulation results with the physical model test results. The discrepancies between the numerical and physical model results were attributed to the difficulty in accurately representing the physical position of individual blocks in the UDEC model. This issue was addressed by introducing the concept of “apparent cohesion” and aligning DEM results closely with experimental outcomes, confirming the effectiveness of this approach in reconciling numerical and physical model differences.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100154"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.rockmb.2024.100156
Cexuan Liu , Fengshou Zhang , Emmanuel Detournay
In this work, we present a domain-based algorithm to simulate the propagation of a plane-strain hydraulic fracture in a zero-toughness permeable elastic medium. The algorithm utilizes a domain-based method to solve the elasticity equation and integrates a multi-scale tip asymptote, which is particular to hydraulic fractures, into this framework. This integration is key to accurately model the energy dissipation and the fluid leak-off in the fracture tip region. The algorithm combines a 2D finite volume method (FVM) for solving the elasticity equation with a 1D FVM for solving the nonlinear lubrication equation. Incorporating the far-field asymptotics and using a moving-mesh scheme reduces the computational burden while improving the accuracy of the scheme. The paper concludes with an analysis of the numerical results. This study demonstrates the potential of this domain-based approach for modeling hydraulic fractures in poroelastic media.
{"title":"Finite domain solution of a hydraulic fracture in a permeable rock","authors":"Cexuan Liu , Fengshou Zhang , Emmanuel Detournay","doi":"10.1016/j.rockmb.2024.100156","DOIUrl":"10.1016/j.rockmb.2024.100156","url":null,"abstract":"<div><div>In this work, we present a domain-based algorithm to simulate the propagation of a plane-strain hydraulic fracture in a zero-toughness permeable elastic medium. The algorithm utilizes a domain-based method to solve the elasticity equation and integrates a multi-scale tip asymptote, which is particular to hydraulic fractures, into this framework. This integration is key to accurately model the energy dissipation and the fluid leak-off in the fracture tip region. The algorithm combines a 2D finite volume method (FVM) for solving the elasticity equation with a 1D FVM for solving the nonlinear lubrication equation. Incorporating the far-field asymptotics and using a moving-mesh scheme reduces the computational burden while improving the accuracy of the scheme. The paper concludes with an analysis of the numerical results. This study demonstrates the potential of this domain-based approach for modeling hydraulic fractures in poroelastic media.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 1","pages":"Article 100156"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-30DOI: 10.1016/j.rockmb.2024.100171
Chongyang Wang , Sijiang Wei , Dongming Zhang , Beichen Yu , Yisha Pan , Xunjian Hu
To investigate the deterioration of mechanical properties in engineering rock masses subjected to fatigue stress, this study conducted laboratory tests, theoretical analysis, and model building to analyze the evolution of mechanical and rockburst characteristics in gypsum-like rock before and after fatigue loading. The results showed that the effects of cyclic stress and loading frequency on fatigue damage characteristics of the samples are interrelated. The effect of fatigue cyclic stress on the mechanical parameters and rockburst parameters of the samples after fatigue loading is relatively straightforward, while the impact of frequency on the mechanical properties of samples after fatigue loading is more complex. The impact of frequency on mechanical properties and rockburst parameters varies distinctly under different cyclic stress conditions. A deterioration index model () was established for the samples after fatigue loading, and the real part, imaginary part, and of the model were calculated to plot the function in the complex plane. This model provided insight into the evolution of mechanical properties and rockburst characteristics in gypsum-like rock before and after fatigue loading with different stress levels and frequencies. By examining the λ curve’s position within the complex plane, the overall variation in mechanical properties was assessed. Finally, neural network methods were employed to extend and test the complex plane model, expanding the input factors from discrete data points to continuous definition fields on the number line, thereby increasing the model's practicality and applicability.
{"title":"Evolution of mechanical and rockburst parameters of gypsum-like rock under fatigue stress disturbance","authors":"Chongyang Wang , Sijiang Wei , Dongming Zhang , Beichen Yu , Yisha Pan , Xunjian Hu","doi":"10.1016/j.rockmb.2024.100171","DOIUrl":"10.1016/j.rockmb.2024.100171","url":null,"abstract":"<div><div>To investigate the deterioration of mechanical properties in engineering rock masses subjected to fatigue stress, this study conducted laboratory tests, theoretical analysis, and model building to analyze the evolution of mechanical and rockburst characteristics in gypsum-like rock before and after fatigue loading. The results showed that the effects of cyclic stress and loading frequency on fatigue damage characteristics of the samples are interrelated. The effect of fatigue cyclic stress on the mechanical parameters and rockburst parameters of the samples after fatigue loading is relatively straightforward, while the impact of frequency on the mechanical properties of samples after fatigue loading is more complex. The impact of frequency on mechanical properties and rockburst parameters varies distinctly under different cyclic stress conditions. A deterioration index model (<span><math><mrow><mi>λ</mi><mo>=</mo><mi>p</mi><mo>+</mo><mi>j</mi><mi>q</mi></mrow></math></span>) was established for the samples after fatigue loading, and the real part, imaginary part, and <span><math><mrow><mo>|</mo><mi>λ</mi><mo>|</mo></mrow></math></span> of the model were calculated to plot the function in the complex plane. This model provided insight into the evolution of mechanical properties and rockburst characteristics in gypsum-like rock before and after fatigue loading with different stress levels and frequencies. By examining the <em>λ</em> curve’s position within the complex plane, the overall variation in mechanical properties was assessed. Finally, neural network methods were employed to extend and test the complex plane model, expanding the input factors from discrete data points to continuous definition fields on the number line, thereby increasing the model's practicality and applicability.</div></div>","PeriodicalId":101137,"journal":{"name":"Rock Mechanics Bulletin","volume":"4 2","pages":"Article 100171"},"PeriodicalIF":0.0,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143163314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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