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The role of locking segments on an earthquake-resistant segmented ductile iron water pipeline joint behavior under tension and bending
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-23 DOI: 10.1016/j.tust.2025.106378
Qinglai Zhang , Shih-Hung Chiu , Shakhzod Takhirov , Jeff Mason , David Katzev , Kenichi Soga , Zili Li
Ground displacements by fault movements or landslides can cause significant damage and failure of buried water pipelines. This is particularly concerning for urban water distribution networks with segmented water pipelines connected by vulnerable joints. The objective of this study is to assess the deformation and failure mechanism of a ‘restrained’ axial joint integrated into a segmented ductile iron pipeline to enable it to tolerate significant ground movements. This joint type employs locking segments to restrain the relative axial movements of the two pipe sections after some free movement. The hypothesis of this study is that the joint structure and locking segment orientation influence the joint’s performance. A series of full-scale axial and bending tests were conducted on an 8-inch (203-mm) diameter jointed ductile iron pipeline with various orientations of the locking segments at the joint. Distributed fiber optic sensor (DFOS) was utilized to capture the development of spatially continuous strain profiles of the joint section and the pipes with increasing loads. Three-dimensional (3D) finite element (FE) models of the jointed pipeline are developed and validated against the DFOS measurements. Combined results from the laboratory tests and FE analyses show that the behavior of joint opening under increasing tension has three stages, depending on the interaction between the spigot and the locking segments. In particular, the axial force builds up significantly when the weld bead starts to engage with the locking segments until it breaks. A crack initiates at the interface between the locking segment and single slot. The joint behavior observed by the four-point bending tests can be also divided into three distinctive stages, and each of them influenced by the orientations of the locking segments in terms of deflection flexibility, capacity, and the initiation deflection points for potential joint failure and water leakage. The effect of the initial positioning of the bell-spigot joint on the joint’s overall bending stiffness is investigated. In addition, a novel joint bushing connector model is proposed as a surrogate model of the continuum contact model of the bell-spigot joint. This bushing connector model is capable of capturing the essential characteristics of the joint while simultaneously mitigating computational time for future modelling of pipeline system in system level.
{"title":"The role of locking segments on an earthquake-resistant segmented ductile iron water pipeline joint behavior under tension and bending","authors":"Qinglai Zhang ,&nbsp;Shih-Hung Chiu ,&nbsp;Shakhzod Takhirov ,&nbsp;Jeff Mason ,&nbsp;David Katzev ,&nbsp;Kenichi Soga ,&nbsp;Zili Li","doi":"10.1016/j.tust.2025.106378","DOIUrl":"10.1016/j.tust.2025.106378","url":null,"abstract":"<div><div>Ground displacements by fault movements or landslides can cause significant damage and failure of buried water pipelines. This is particularly concerning for urban water distribution networks with segmented water pipelines connected by vulnerable joints. The objective of this study is to assess the deformation and failure mechanism of a ‘restrained’ axial joint integrated into a segmented ductile iron pipeline to enable it to tolerate significant ground movements. This joint type employs locking segments to restrain the relative axial movements of the two pipe sections after some free movement. The hypothesis of this study is that the joint structure and locking segment orientation influence the joint’s performance. A series of full-scale axial and bending tests were conducted on an 8-inch (203-mm) diameter jointed ductile iron pipeline with various orientations of the locking segments at the joint. Distributed fiber optic sensor (DFOS) was utilized to capture the development of spatially continuous strain profiles of the joint section and the pipes with increasing loads. Three-dimensional (3D) finite element (FE) models of the jointed pipeline are developed and validated against the DFOS measurements. Combined results from the laboratory tests and FE analyses show that the behavior of joint opening under increasing tension has three stages, depending on the interaction between the spigot and the locking segments. In particular, the axial force builds up significantly when the weld bead starts to engage with the locking segments until it breaks. A crack initiates at the interface between the locking segment and single slot. The joint behavior observed by the four-point bending tests can be also divided into three distinctive stages, and each of them influenced by the orientations of the locking segments in terms of deflection flexibility, capacity, and the initiation deflection points for potential joint failure and water leakage. The effect of the initial positioning of the bell-spigot joint on the joint’s overall bending stiffness is investigated. In addition, a novel joint bushing connector model is proposed as a surrogate model of the continuum contact model of the bell-spigot joint. This bushing connector model is capable of capturing the essential characteristics of the joint while simultaneously mitigating computational time for future modelling of pipeline system in system level.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106378"},"PeriodicalIF":6.7,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Optimization study of cooling parameters of the high-temperature working face in underground engineering
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-22 DOI: 10.1016/j.tust.2025.106420
Song Xin , Yiwen Hu , Shangxiao Liu , Zhen Zhang
To address the escalating thermal risks and suboptimal cooling capacity distribution of centralized refrigeration systems in large-width faces, this study developed a specialized “high-efficiency air cooler for working faces” and introduced an innovative cooperative cooling strategy integrating air coolers, dust suppression water, and emulsion (A-D-E system). Numerical simulations and field measurements were conducted to evaluate the thermal environment under both traditional cooling methods and the A-D-E synergistic approach. The analysis revealed that, for a 250 m-wide mining face, optimal cooling performance was achieved by strategically placing five air coolers along a gradient. Employing the A-D-E system reduced the average face temperature by 8 K and expanded the comfort zone to cover 96 % of the working area. This approach effectively mitigates excessive heat challenges in large-width faces, enhances the utilization of coolant resources in centralized refrigeration units, and provides a forward-looking framework for advancing cooling strategies in deep mining operations.
{"title":"Optimization study of cooling parameters of the high-temperature working face in underground engineering","authors":"Song Xin ,&nbsp;Yiwen Hu ,&nbsp;Shangxiao Liu ,&nbsp;Zhen Zhang","doi":"10.1016/j.tust.2025.106420","DOIUrl":"10.1016/j.tust.2025.106420","url":null,"abstract":"<div><div>To address the escalating thermal risks and suboptimal cooling capacity distribution of centralized refrigeration systems in large-width faces, this study developed a specialized “high-efficiency air cooler for working faces” and introduced an innovative cooperative cooling strategy integrating air coolers, dust suppression water, and emulsion (A-D-E system). Numerical simulations and field measurements were conducted to evaluate the thermal environment under both traditional cooling methods and the A-D-E synergistic approach. The analysis revealed that, for a 250 m-wide mining face, optimal cooling performance was achieved by strategically placing five air coolers along a gradient. Employing the A-D-E system reduced the average face temperature by 8 K and expanded the comfort zone to cover 96 % of the working area. This approach effectively mitigates excessive heat challenges in large-width faces, enhances the utilization of coolant resources in centralized refrigeration units, and provides a forward-looking framework for advancing cooling strategies in deep mining operations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106420"},"PeriodicalIF":6.7,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Full-scale experimental study on the smoke and thermal insulation of a water mist fire extinguishing system in a short road tunnel with natural ventilation
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-22 DOI: 10.1016/j.tust.2025.106414
Deyuan Kan , Shouzhong Feng , Zhiguo Yan , Long Zhou , Hehua Zhu
Tunnel fires have become a huge threat to human life and property, and the large amount of smoke and thermal produced by the fire is the principal cause of human casualties. The water mist system is considered a highly promising fire extinguishing technology. However, the research on the water mist system which could simultaneously extinguish fire and block smoke is rare. The objective of this study is to propose a new water mist fire extinguishing system, which can achieve effects of fire suppression, smoke suppression and thermal insulation concurrently. Two full-scale fire tests were conducted: one involving free combustion without the activation of the water mist system and another where the water mist was activated after ignition. The fire extinction mechanism of the proposed water mist system was discussed via the analysis of heat release rate and flame characteristics. Moreover, the smoke and thermal insulation capabilities were qualitatively investigated by observing the longitudinal temperature variation below the tunnel ceiling and the temperature distribution within the tunnel. Additionally, the smoke insulation performance was quantitatively analyzed based on the concentration of particulate matter and the concentration of carbon monoxide. The results revealed that with the activation of water mist system, the fire source was continuously suppressed until it was extinguished. The water mist fire extinguishing system proposed in this research can effectively block the heat and smoke generated by combustion. Notably, the system exhibited an excellent barrier effect on smoke particles, ensuring that the tunnel space beyond the mist spray segment remained visibly clear during the fire. Thanks to the inhibitory effect of water mist onto the fire source, the concentration of carbon monoxide inside the tunnel was reduced by over 30%, and the presence time of carbon monoxide inside the tunnel was shortened by over 58%. However, the water mist fire extinguishing system failed to effectively block the spread of carbon monoxide.
{"title":"Full-scale experimental study on the smoke and thermal insulation of a water mist fire extinguishing system in a short road tunnel with natural ventilation","authors":"Deyuan Kan ,&nbsp;Shouzhong Feng ,&nbsp;Zhiguo Yan ,&nbsp;Long Zhou ,&nbsp;Hehua Zhu","doi":"10.1016/j.tust.2025.106414","DOIUrl":"10.1016/j.tust.2025.106414","url":null,"abstract":"<div><div>Tunnel fires have become a huge threat to human life and property, and the large amount of smoke and thermal produced by the fire is the principal cause of human casualties. The water mist system is considered a highly promising fire extinguishing technology. However, the research on the water mist system which could simultaneously extinguish fire and block smoke is rare. The objective of this study is to propose a new water mist fire extinguishing system, which can achieve effects of fire suppression, smoke suppression and thermal insulation concurrently. Two full-scale fire tests were conducted: one involving free combustion without the activation of the water mist system and another where the water mist was activated after ignition. The fire extinction mechanism of the proposed water mist system was discussed via the analysis of heat release rate and flame characteristics. Moreover, the smoke and thermal insulation capabilities were qualitatively investigated by observing the longitudinal temperature variation below the tunnel ceiling and the temperature distribution within the tunnel. Additionally, the smoke insulation performance was quantitatively analyzed based on the concentration of particulate matter and the concentration of carbon monoxide. The results revealed that with the activation of water mist system, the fire source was continuously suppressed until it was extinguished. The water mist fire extinguishing system proposed in this research can effectively block the heat and smoke generated by combustion. Notably, the system exhibited an excellent barrier effect on smoke particles, ensuring that the tunnel space beyond the mist spray segment remained visibly clear during the fire. Thanks to the inhibitory effect of water mist onto the fire source, the concentration of carbon monoxide inside the tunnel was reduced by over 30%, and the presence time of carbon monoxide inside the tunnel was shortened by over 58%. However, the water mist fire extinguishing system failed to effectively block the spread of carbon monoxide.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106414"},"PeriodicalIF":6.7,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Characterization of particle size distribution of rock chips and evaluation of rock breaking efficiency of TBM based on multifractal theory: A case study
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-21 DOI: 10.1016/j.tust.2025.106418
Jianping Liu , Zhijia Zhou , Yucong Pan , Quansheng Liu
In the process of rock breaking by a TBM (Tunnel boring machine), the particle size distribution of rock chips is affected by both rock lithology and TBM operational parameters, showing typical variability and inhomogeneity. Multifractal theory can describe the variability and inhomogeneity of the particle size distribution of rock chips more comprehensively. Therefore, this study attempts to quantitatively analyze the particle size distribution of rock chips by using multifractal parameters based on multifractal theory. Based on the TBM tunnel project in Jiajin Mountain, a method of calculating the volume of rock chips sampled in the field is proposed, and field sieving tests are carried out. The multifractal behaviors of rock chips of sandstone and slate are verified, and the correlations between the multifractal parameters and TBM performance parameters are analyzed. The results show that: under the two lithological conditions, the particle size distribution of rock chips both meets the three conditions of multifractal theory, confirming that the multifractal behavior of the particle size distribution of rock chips is objective. It is further observed that the inhomogeneity of small-sized rock chip intervals is higher than that of large-sized rock chip intervals. In addition, lithology is shown to have a significant impact on the heterogeneity of the particle size distribution of rock chips. Under the two lithological conditions, the information dimension D(1) is positively correlated with the coarseness index (CI) and negatively correlated with the specific energy (SE), while the Hölder index of zero order α(0) is negatively correlated with CI and positively correlated with SE. The use of multifractal parameters D(1) and α(0) can provide a new method for characterizing the particle size distribution of rock chips and evaluating rock breaking efficiency. When D(1) reaches its maximum value and α(0) reaches its minimum value, the corresponding SE is the lowest, and TBM is in an “optimal” rock breaking state. A new method can be provided for optimizing rock breaking state of TBM using multifractal parameters.
{"title":"Characterization of particle size distribution of rock chips and evaluation of rock breaking efficiency of TBM based on multifractal theory: A case study","authors":"Jianping Liu ,&nbsp;Zhijia Zhou ,&nbsp;Yucong Pan ,&nbsp;Quansheng Liu","doi":"10.1016/j.tust.2025.106418","DOIUrl":"10.1016/j.tust.2025.106418","url":null,"abstract":"<div><div>In the process of rock breaking by a TBM (Tunnel boring machine), the particle size distribution of rock chips is affected by both rock lithology and TBM operational parameters, showing typical variability and inhomogeneity. Multifractal theory can describe the variability and inhomogeneity of the particle size distribution of rock chips more comprehensively. Therefore, this study attempts to quantitatively analyze the particle size distribution of rock chips by using multifractal parameters based on multifractal theory. Based on the TBM tunnel project in Jiajin Mountain, a method of calculating the volume of rock chips sampled in the field is proposed, and field sieving tests are carried out. The multifractal behaviors of rock chips of sandstone and slate are verified, and the correlations between the multifractal parameters and TBM performance parameters are analyzed. The results show that: under the two lithological conditions, the particle size distribution of rock chips both meets the three conditions of multifractal theory, confirming that the multifractal behavior of the particle size distribution of rock chips is objective. It is further observed that the inhomogeneity of small-sized rock chip intervals is higher than that of large-sized rock chip intervals. In addition, lithology is shown to have a significant impact on the heterogeneity of the particle size distribution of rock chips. Under the two lithological conditions, the information dimension <em>D</em>(1) is positively correlated with the coarseness index (<em>CI</em>) and negatively correlated with the specific energy (<em>SE</em>), while the Hölder index of zero order <em>α</em>(0) is negatively correlated with <em>CI</em> and positively correlated with <em>SE</em>. The use of multifractal parameters <em>D</em>(1) and <em>α</em>(0) can provide a new method for characterizing the particle size distribution of rock chips and evaluating rock breaking efficiency. When <em>D</em>(1) reaches its maximum value and <em>α</em>(0) reaches its minimum value, the corresponding <em>SE</em> is the lowest, and TBM is in an “optimal” rock breaking state. A new method can be provided for optimizing rock breaking state of TBM using multifractal parameters.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106418"},"PeriodicalIF":6.7,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Simulation of screening characterization of double-deck vibrating screen of slurry TBM tunnelling using integrated CFD-DEM-FEM
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-21 DOI: 10.1016/j.tust.2025.106399
Yidong Guo , Yingran Fang , Xinggao Li , Dalong Jin , Hongzhi Liu
To evaluate and optimize the screening characterization of double-deck vibrating screen of slurry TBM tunnelling, a three-dimensional (3D) coupled model of vibrating screen was established based on an integrated CFD-DEM-FEM method in this paper. The transport characteristics of particles and the fluidity of slurry were revealed, and the kinetic response of the screen surfaces was comprehensively analyzed. The results indicated that the particles were evenly distributed on the screen surface, and the velocity of the particles shows a trend of a steady increase in velocity from 0 m/s to 5 m/s. The coarse screen experienced impact forces up to 90 times greater than those on the fine screen, influenced by particle bed formation and collision dynamics, which reduced direct loads on the screen surface. Screening efficiencies of coarse and fine screens stabilized at approximately 61 % and 73 %, with coarse screens exhibiting greater efficiency fluctuations due to the particle size distribution and collisions. The stress and deformation primairly concentrate in the middle position of the screen surface near the feed and discharge ends, highlighting the need for structural reinforcements to enhance strength and stiffness. Lastly, the optimization schemes for each parameters were proposed, and applied to the slurry TBM tunnelling of Qingdao Jiaozhou Bay Second Undersea Tunnel. The findings in this work provide references and suggestions on the efficient operation of double-deck vibrating screen for slurry TBM tunnelling.
{"title":"Simulation of screening characterization of double-deck vibrating screen of slurry TBM tunnelling using integrated CFD-DEM-FEM","authors":"Yidong Guo ,&nbsp;Yingran Fang ,&nbsp;Xinggao Li ,&nbsp;Dalong Jin ,&nbsp;Hongzhi Liu","doi":"10.1016/j.tust.2025.106399","DOIUrl":"10.1016/j.tust.2025.106399","url":null,"abstract":"<div><div>To evaluate and optimize the screening characterization of double-deck vibrating screen of slurry TBM tunnelling, a three-dimensional (3D) coupled model of vibrating screen was established based on an integrated CFD-DEM-FEM method in this paper. The transport characteristics of particles and the fluidity of slurry were revealed, and the kinetic response of the screen surfaces was comprehensively analyzed. The results indicated that the particles were evenly distributed on the screen surface, and the velocity of the particles shows a trend of a steady increase in velocity from 0 m/s to 5 m/s. The coarse screen experienced impact forces up to 90 times greater than those on the fine screen, influenced by particle bed formation and collision dynamics, which reduced direct loads on the screen surface. Screening efficiencies of coarse and fine screens stabilized at approximately 61 % and 73 %, with coarse screens exhibiting greater efficiency fluctuations due to the particle size distribution and collisions. The stress and deformation primairly concentrate in the middle position of the screen surface near the feed and discharge ends, highlighting the need for structural reinforcements to enhance strength and stiffness. Lastly, the optimization schemes for each parameters were proposed, and applied to the slurry TBM tunnelling of Qingdao Jiaozhou Bay Second Undersea Tunnel. The findings in this work provide references and suggestions on the efficient operation of double-deck vibrating screen for slurry TBM tunnelling.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106399"},"PeriodicalIF":6.7,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Application and mechanism of a novel flocculation reagent for mechanical dewatering: A case study on slurry separation in a large-diameter slurry shield
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-21 DOI: 10.1016/j.tust.2025.106413
Jian Zhang , Guoping Ren , Tugen Feng , Yu Liang , Yihao Yin
A novel C-type flocculation reagent was developed to address the high water content of sludge and the environmental pollution caused by wastewater discharge during mechanical dewatering in the Zhanjiang Bay undersea tunnel. Microscopic parameters, such as particle size and zeta potential, were analyzed to elucidate the flocculation and dewatering mechanisms of the C-type reagent. The applicability of the C-type reagent was further validated in a field test and compared to that of conventional reagents. The results showed that the C-type reagent reduced the water content of the sludge by approximately 20 % and decreased the turbidity of the supernatant by approximately 79 %. The C-type reagent demonstrated enhanced bridging and charge neutralization activity, which facilitated the aggregation of fine particles (<10 μm) into larger particles (>50 μm), ultimately enhancing the efficiency of flocculation. The C-type reagent also facilitated the formation of a calcium drainage channel skeleton with enhanced water permeability and reduced the slurry viscosity to improve the efficiency of mechanical dewatering. These effects enhanced the pore size distribution of the slurry to a range of 346 to 8656 nm, which was approximately 15 % to 41 % greater than the overall pore size of the original slurry. Onsite utilization of 0.5 % C-type reagent enhanced the solid content of the sludge by 35.7 % compared with that obtained with the original reagent, resulting in a 20 % reduction in cost. Moreover, the sludge meets the sewage standards for indicators such as pH and thus qualifies for direct discharge. The findings of this study offer valuable insights for the selection of environmentally friendly and efficient reagents in the context of combined flocculation–mechanical dewatering.
{"title":"Application and mechanism of a novel flocculation reagent for mechanical dewatering: A case study on slurry separation in a large-diameter slurry shield","authors":"Jian Zhang ,&nbsp;Guoping Ren ,&nbsp;Tugen Feng ,&nbsp;Yu Liang ,&nbsp;Yihao Yin","doi":"10.1016/j.tust.2025.106413","DOIUrl":"10.1016/j.tust.2025.106413","url":null,"abstract":"<div><div>A novel C-type flocculation reagent was developed to address the high water content of sludge and the environmental pollution caused by wastewater discharge during mechanical dewatering in the Zhanjiang Bay undersea tunnel. Microscopic parameters, such as particle size and zeta potential, were analyzed to elucidate the flocculation and dewatering mechanisms of the C-type reagent. The applicability of the C-type reagent was further validated in a field test and compared to that of conventional reagents. The results showed that the C-type reagent reduced the water content of the sludge by approximately 20 % and decreased the turbidity of the supernatant by approximately 79 %. The C-type reagent demonstrated enhanced bridging and charge neutralization activity, which facilitated the aggregation of fine particles (&lt;10 μm) into larger particles (&gt;50 μm), ultimately enhancing the efficiency of flocculation. The C-type reagent also facilitated the formation of a calcium drainage channel skeleton with enhanced water permeability and reduced the slurry viscosity to improve the efficiency of mechanical dewatering. These effects enhanced the pore size distribution of the slurry to a range of 346 to 8656 nm, which was approximately 15 % to 41 % greater than the overall pore size of the original slurry. Onsite utilization of 0.5 % C-type reagent enhanced the solid content of the sludge by 35.7 % compared with that obtained with the original reagent, resulting in a 20 % reduction in cost. Moreover, the sludge meets the sewage standards for indicators such as pH and thus qualifies for direct discharge. The findings of this study offer valuable insights for the selection of environmentally friendly and efficient reagents in the context of combined flocculation–mechanical dewatering.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106413"},"PeriodicalIF":6.7,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Creep-slip behaviors of surrounding rocks in a water diversion tunnel considering strike-slip and dip-slip scenarios
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-21 DOI: 10.1016/j.tust.2025.106405
Chengwei Zhao , Hui Zhou , Chuanqing Zhang , Wenbo Liu , Lingyu Li , Zhongbo Liu , Zhengyang Huo
A 3D numerical model of distributed fault is established in this paper. Considering both strike-slip and dip-slip, the stress evolution and spatial–temporal migration characteristics of surrounding rock at different creep-slip times and depths are analyzed during creep-slip. The failure approach index (FAI) was employed to assess the failure degree. The results show that the shearing and squeezing behaviors of the surrounding rock are obvious during creep-slip. The stress direction rotates sharply in the hanging wall and influence zone. Several obvious stress concentration areas (bottom and right) and unloading areas (top and left) are formed in the hanging wall near the slip surface. From the FAI values, the shear failure generates near the slip surface and extends to the hanging wall, especially in the surrounding rock at the top and left. The failure has experienced a rapid growth stage (0–5 years), a slow growth stage (5–40 years), and an accelerated growth stage (40–100 years) during the creep-slip. The maximum FAI values in the surrounding rock at the top and left are 6.5 and 8.4, respectively, and little failure occurs in the surrounding rock at the bottom and right. More attention should be paid to the failure range and failure degree in the axial direction of the tunnel when the stress ratios are of 0.5:1 and 2:1. The dip angle and dip direction only affect the failure mode and failure degree in the tunnel section. These should all be considered when designing the protection measures. The peak position of displacement gradient is inconsistent with the peak position of maximum principal stress and peak position of FAI, which may be affected by the model parameters. This study may provide a basis for the prevention and control of fault slip in tunnels crossing faults under similar geological conditions.
{"title":"Creep-slip behaviors of surrounding rocks in a water diversion tunnel considering strike-slip and dip-slip scenarios","authors":"Chengwei Zhao ,&nbsp;Hui Zhou ,&nbsp;Chuanqing Zhang ,&nbsp;Wenbo Liu ,&nbsp;Lingyu Li ,&nbsp;Zhongbo Liu ,&nbsp;Zhengyang Huo","doi":"10.1016/j.tust.2025.106405","DOIUrl":"10.1016/j.tust.2025.106405","url":null,"abstract":"<div><div>A 3D numerical model of distributed fault is established in this paper. Considering both strike-slip and dip-slip, the stress evolution and spatial–temporal migration characteristics of surrounding rock at different creep-slip times and depths are analyzed during creep-slip. The failure approach index (FAI) was employed to assess the failure degree. The results show that the shearing and squeezing behaviors of the surrounding rock are obvious during creep-slip. The stress direction rotates sharply in the hanging wall and influence zone. Several obvious stress concentration areas (bottom and right) and unloading areas (top and left) are formed in the hanging wall near the slip surface. From the FAI values, the shear failure generates near the slip surface and extends to the hanging wall, especially in the surrounding rock at the top and left. The failure has experienced a rapid growth stage (0–5 years), a slow growth stage (5–40 years), and an accelerated growth stage (40–100 years) during the creep-slip. The maximum FAI values in the surrounding rock at the top and left are 6.5 and 8.4, respectively, and little failure occurs in the surrounding rock at the bottom and right. More attention should be paid to the failure range and failure degree in the axial direction of the tunnel when the stress ratios are of 0.5:1 and 2:1. The dip angle and dip direction only affect the failure mode and failure degree in the tunnel section. These should all be considered when designing the protection measures. The peak position of displacement gradient is inconsistent with the peak position of maximum principal stress and peak position of FAI, which may be affected by the model parameters. This study may provide a basis for the prevention and control of fault slip in tunnels crossing faults under similar geological conditions.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106405"},"PeriodicalIF":6.7,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Study on construction mechanical characteristics and pinch rocks reinforcement schemes of honeycomb tunnel clusters in Mountainous City
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-21 DOI: 10.1016/j.tust.2025.106397
Hai Chen , Xiaohan Zhou , Xinrong Liu , Suliman Lojain , Qiang Xu , Lijun Ren
Due to the growing need for underground space and the acceleration of urbanization, narrow clearance tunnel clusters are being created, making construction more challenging. This paper investigated tunnel clusters consisting of five parallel tunnels at Hongyan Village in Chongqing as a background project. The mechanical behaviour of the clusters has been studied by using three main methods as the following: model test, theoretical analysis, and numerical simulation. The induced forces characteristics in the pinch rock based on the stress correlation theory have been accomplished, with establishing a pinch-rock yielding reserve (YR) model for different pinch-rock reinforcement schemes to be compared with the other ones. The results can be introduced as the following: (1) During the stage of temporary support removal, the incremental displacement of the crown of each tunnel accounted for 6.25 %∼60.53 % of the total displacement. Moreover, it seems that the temporary support has a significant influence on the stability of the surrounding rock. (2) The value of YR depends on the position of the shear and tensile damage line, the “centre” and the “radius” of the Mohr’s circle. A smaller value indicates a higher tendency towards instability. (3) For the left pinch rock that has been disturbed many times during the construction of the tunnel clusters, the combination of prestressed tie-back anchors- grouting is preferred, which raises the maximum value of the YR to 1,324.62 kN/m.
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引用次数: 0
Study on the deformation of existing tunnel under the combined effect of pit excavation and dewatering based on the Kerr foundation model
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-20 DOI: 10.1016/j.tust.2025.106382
Meng Fei, Qiao Shifan
There is a significant progression towards the trend of significant depth and extensive scale in foundation pit construction, where the excavation range is large and dewatering measures are usually required. To overcome the shortcomings associated with the complexity of the 3D numerical analysis model and the long period of on-site measurement in existing studies, a two-stage analysis method is proposed to consider the impacts on existing tunnels under the combined effects of pit excavation and dewatering. The first step involves calculating the additional stress imposed on the existing tunnel under the construction of pit bottom, pit side, and dewatering. Secondly, a differential equation describing the deformation effects on the existing tunnel is established based on the Kerr foundation model. Finally, the control equation is solved using the Galerkin method. Three engineering cases with different locations and tunnel parameters are selected to validate the proposed method. The effects of various factors on the deformation of the existing tunnel under the influence of pit excavation and dewatering are analyzed. Subsequently, an orthogonal experiment is designed to analyze the significant factors influencing the deformation of the existing tunnel and their prioritization, and an optimal parameter combination for controlling the existing tunnel deformation is obtained.
{"title":"Study on the deformation of existing tunnel under the combined effect of pit excavation and dewatering based on the Kerr foundation model","authors":"Meng Fei,&nbsp;Qiao Shifan","doi":"10.1016/j.tust.2025.106382","DOIUrl":"10.1016/j.tust.2025.106382","url":null,"abstract":"<div><div>There is a significant progression towards the trend of significant depth and extensive scale in foundation pit construction, where the excavation range is large and dewatering measures are usually required. To overcome the shortcomings associated with the complexity of the 3D numerical analysis model and the long period of on-site measurement in existing studies, a two-stage analysis method is proposed to consider the impacts on existing tunnels under the combined effects of pit excavation and dewatering. The first step involves calculating the additional stress imposed on the existing tunnel under the construction of pit bottom, pit side, and dewatering. Secondly, a differential equation describing the deformation effects on the existing tunnel is established based on the Kerr foundation model. Finally, the control equation is solved using the Galerkin method. Three engineering cases with different locations and tunnel parameters are selected to validate the proposed method. The effects of various factors on the deformation of the existing tunnel under the influence of pit excavation and dewatering are analyzed. Subsequently, an orthogonal experiment is designed to analyze the significant factors influencing the deformation of the existing tunnel and their prioritization, and an optimal parameter combination for controlling the existing tunnel deformation is obtained.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106382"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Intelligent monitoring-based resilience assessment system for prefabricated underground structures based on restorability
IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2025-01-20 DOI: 10.1016/j.tust.2025.106411
Tong Qiu, Xiangsheng Chen, Wei Rao, Dong Su, Xiaohua Bao, Chengyu Hong
In the context of low-carbon strategies, China has joined the global leadership series of prefabricated underground structures (PUS). However, PUS faces significant challenges in construction, maintenance, and restoration subjected to multi-hazard impacts, particularly at the assembled joints. Addressing this research gap, this study focuses on the PUS life-cycle resilience based on joint restorability. The full-scale experimental studies were conducted on typical assembled joint of PUS and its restored specimen. Integrating experimental results with intelligent monitoring techniques, a resilience assessment framework for the PUS was proposed. The effectiveness of this framework was validated through a case study. Key findings include: (1) Even with minor restoration level undetected rotations, the assembled joint can rapidly reach major restoration thresholds after cumulative operational impacts. (2) Intelligent monitoring techniques enable rapid and accurate responses to restoration needs. It reduces recovery time and cost by more than 10 times, with a 52 % resilience enhancement compared to traditional techniques. (3) The proposed joint restoration technology enhances the yield and ultimate load-bearing capacities by 11.8 % and 7.9 %, respectively, primarily owing to the enhancement of interface bond strength. (4) Restored joints exhibit higher resilience under subsequent daily operations and extreme conditions. Compared to original assembled joints, restored joints show 29 % improvements in rotation tolerance at minor restoration thresholds. Along with 22 % resilience enhancement, the restored joint significantly reduces more than 90 % restoration costs. This study not only provides key restoration technologies and intelligent resilience management methods for the life-cycle resilience of PUS, but also has significant practical application value and resilience enhancement implications.
{"title":"Intelligent monitoring-based resilience assessment system for prefabricated underground structures based on restorability","authors":"Tong Qiu,&nbsp;Xiangsheng Chen,&nbsp;Wei Rao,&nbsp;Dong Su,&nbsp;Xiaohua Bao,&nbsp;Chengyu Hong","doi":"10.1016/j.tust.2025.106411","DOIUrl":"10.1016/j.tust.2025.106411","url":null,"abstract":"<div><div>In the context of low-carbon strategies, China has joined the global leadership series of prefabricated underground structures (PUS). However, PUS faces significant challenges in construction, maintenance, and restoration subjected to multi-hazard impacts, particularly at the assembled joints. Addressing this research gap, this study focuses on the PUS life-cycle resilience based on joint restorability. The full-scale experimental studies were conducted on typical assembled joint of PUS and its restored specimen. Integrating experimental results with intelligent monitoring techniques, a resilience assessment framework for the PUS was proposed. The effectiveness of this framework was validated through a case study. Key findings include: (1) Even with minor restoration level undetected rotations, the assembled joint can rapidly reach major restoration thresholds after cumulative operational impacts. (2) Intelligent monitoring techniques enable rapid and accurate responses to restoration needs. It reduces recovery time and cost by more than 10 times, with a 52 % resilience enhancement compared to traditional techniques. (3) The proposed joint restoration technology enhances the yield and ultimate load-bearing capacities by 11.8 % and 7.9 %, respectively, primarily owing to the enhancement of interface bond strength. (4) Restored joints exhibit higher resilience under subsequent daily operations and extreme conditions. Compared to original assembled joints, restored joints show 29 % improvements in rotation tolerance at minor restoration thresholds. Along with 22 % resilience enhancement, the restored joint significantly reduces more than 90 % restoration costs. This study not only provides key restoration technologies and intelligent resilience management methods for the life-cycle resilience of PUS, but also has significant practical application value and resilience enhancement implications.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106411"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
期刊
Tunnelling and Underground Space Technology
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