In the present study a Genetic Programing model (GP) proposed for the prediction of relative crest settlement of concrete faced rock fill dams. To this end information of 30 large dams constructed in seven countries a...In the present study a Genetic Programing model (GP) proposed for the prediction of relative crest settlement of concrete faced rock fill dams. To this end information of 30 large dams constructed in seven countries across the world is gathered with their reported settlements. The results showed that the GP model is able to estimate the dam settlement properly based on four properties, void ratio of dam’s body (e), height (H), vertical deformation modulus (Ev) and shape factor (Sc) of the dam. For verification of the model applicability, obtained results compared with other research methods such as Clements’s formula and the finite element model. The comparison showed that in all cases the GP model led to be more accurate than those of performed in literature. Also a proper compatibility between the GP model and the finite element model was perceived.展开更多
Black fungus derived carbonaceous aerogel (BFA) was prepared via a convenient and energy efficient ultrasonic disposal process. The adsorption experiments of atmospheric pollutants demonstrated the superior adsorbabil...Black fungus derived carbonaceous aerogel (BFA) was prepared via a convenient and energy efficient ultrasonic disposal process. The adsorption experiments of atmospheric pollutants demonstrated the superior adsorbability of black fungus aerogel on PM2.5, PM10 and formaldehyde. More importantly, black fungus aerogel (BFA) exhibited intriguing double-faced properties. We explored properties of each side of the black fungus from three aspects: water contact angle measurements, liquid selective absorption capacity and air pollutant adsorption abilities. The subsequent modification of ZnO nanosheets endowed the prepared black fungus aerogel with several valuable properties, including broad-spectrum antibacterial capability and high-efficient adsorption ability. These valuable characters implied the BFA to be a promising bacteriostat and cleaner for air and water pollution treatment.展开更多
Double - faced iso - object embroidery is carried out byusing the uneven intercalated stitch crafts of the parallel- lines stitch as a main body, being accompanied by oth-er stitch crafts and miscellaneous stitches, d...Double - faced iso - object embroidery is carried out byusing the uneven intercalated stitch crafts of the parallel- lines stitch as a main body, being accompanied by oth-er stitch crafts and miscellaneous stitches, done on thesame textile material. This paper deals with the flower -bird double - faced embroidery fan of the Qing Dynasty,from pattern design, stitching formation and techniqueof color arrangement, describes the possible way of mak-ing double - faced embroidery with iso - object effectboth in the front and in the back.展开更多
Since 1980’s,life science has been holding a prominent place in the development ofscience and it is expected to become one of the leading disciplines in the 21 century.Currently the development of life science presen...Since 1980’s,life science has been holding a prominent place in the development ofscience and it is expected to become one of the leading disciplines in the 21 century.Currently the development of life science presents the following characteristics:1.The understanding of life was deepened to the molecule level.展开更多
State-owned enterprises’(SOE) greater independence from government offices as well as property rights reform have optimized SOEs’ shareholding structure. But the reform has to clear several hurdles before it can be ...State-owned enterprises’(SOE) greater independence from government offices as well as property rights reform have optimized SOEs’ shareholding structure. But the reform has to clear several hurdles before it can be fully realized. In 1998, the central government dismantled ministries that had been the direct administrators of large SOEs. Most functions of those ministries were transferred to industry associations. Only a few considered indispensable were taken over by other government offices. The move has pushed forward the SOE reform to some extent. On the other hand, being State-owned, those enterprises have to find new links with the government.展开更多
Under over 50 years' development, Chinese rare earth magnetic industry developed into the global AINiCo, ferrite permanent magnets and NdFeB magnets manufacturing center, and average consumption of magnets per per...Under over 50 years' development, Chinese rare earth magnetic industry developed into the global AINiCo, ferrite permanent magnets and NdFeB magnets manufacturing center, and average consumption of magnets per person in China increased to 1.026 tons in 2003 from 0.217 ton in 1990. Although China has been the large producing country of rare earth permanent magnetic materials, to be the strongest one, there are many problems to solve. Main Problems Faced By Chinese Permanent Magnet展开更多
Owing to the stochastic behavior of earthquakes and complex crustal structure,wave type and incident direction are uncertain when seismic waves arrive at a structure.In addition,because of the different types of the s...Owing to the stochastic behavior of earthquakes and complex crustal structure,wave type and incident direction are uncertain when seismic waves arrive at a structure.In addition,because of the different types of the structures and terrains,the traveling wave effects have different influences on the dynamic response of the structures.For the tall concrete-faced rockfill dam(CFRD),it is not only built in the complex terrain such as river valley,but also its height has reached 300 m level,which puts forward higher requirements for the seismic safety of the anti-seepage system mainly comprising concrete face slabs,especially the accurate location of the weak area in seism.Considering the limitations of the traditional uniform vibration analysis method,we implemented an efficient dynamic interaction analysis between a tall CFRD and its foundation using a non-uniform wave input method with a viscous-spring artificial boundary and equivalent nodal loads.This method was then applied to investigate the dynamic stress distribution on the concrete face slabs for different seismic wave types and incident directions.The results indicate that dam-foundation interactions behave differently at different wave incident angles,and that the traveling wave effect becomes more evident in valley topography.Seismic wave type and incident direction dramatically influenced stress in the face slab,and the extreme stress values and distribution law will vary under oblique wave incidence.The influence of the incident direction on slab stress was particularly apparent when SH-waves arrived from the left bank.Specifically,the extreme stress values in the face slab increased with an increasing incident angle.Interestingly,the locations of the extreme stress values changed mainly along the axis of the dam,and did not exhibit large changes in height.The seismic safety of CFRDs is therefore lower at higher incident angles from an anti-seepage perspective.Therefore,it is necessary to consider both the seismic wave type and incident direction during seismic capacity evaluations of tall CFRDs.展开更多
Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide g...Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide gas sensors.In recent years,a lot of binary ternary compound researches have been carried out.In this paper,five different SnO_(2) samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics.Based on the low temperature nitrogen adsorption tests and the atomic arrangement model,it can be inferred that different exposed surfaces play a key role in TEA sensing properties.In addition,the TEA sensing activity relationship of SnO_(2) exposed crystal faces is proposed as listed:(200)>(101)>(110).展开更多
In recent years, China's economic development has driven the development of the construction industry. The project cost consulting business has developed rapidly, creating a good environment for local economic dev...In recent years, China's economic development has driven the development of the construction industry. The project cost consulting business has developed rapidly, creating a good environment for local economic development. Project cost consulting management can effectively improve the scientificity of project decision-making and maximize economic and social benefits. In the process of this work, we should pay attention to risk prevention and control measures to give full play to its value. Next, the article discusses the risks and preventive countermeasures faced by the project cost consulting management.展开更多
Considering the complex nonlinear relationship between the material parameters of a concrete faced rock-fill dam(CFRD) and its displacements, the harmony search(HS) algorithm is used to optimize the back propagation n...Considering the complex nonlinear relationship between the material parameters of a concrete faced rock-fill dam(CFRD) and its displacements, the harmony search(HS) algorithm is used to optimize the back propagation neural network(BPNN), and the HS-BPNN algorithm is formed and applied for the inversion analysis of the parameters of rock-fill materials. The sensitivity of the parameters in the Duncan and Chang's E-B model is analyzed using the orthogonal test design. The case study shows that the parameters φ0, K, Rf, and Kb are sensitive to the deformation of the rock-fill dam and the inversion analysis for these parameters is performed by the HS-BPNN algorithm. Compared with the traditional BPNN, the HS-BPNN algorithm exhibits the advantages of high convergence precision, fast convergence rate, and strong stability.展开更多
This paper summarizes the main technical points related to 100 m-height-scale concrete faced rock-fill dams and analyzes the main problems and their causes occurring during construction of 200 m-height-scale concrete ...This paper summarizes the main technical points related to 100 m-height-scale concrete faced rock-fill dams and analyzes the main problems and their causes occurring during construction of 200 m-height-scale concrete faced rock-fill dams.This paper has raised the key technical problems which need to study for construction of 300 m-height-scale concrete faced rock-fill dams based on the main experiences on the extra-high concrete faced rock-fill dams built after the year of 2000.展开更多
ESP teachers teaching English for mixed subject -specialist groups meet problems such as selecting teach-ing materials,dealing with the subject matter,and teaching methods.The experience in the ATTSR(Advanced Teacher ...ESP teachers teaching English for mixed subject -specialist groups meet problems such as selecting teach-ing materials,dealing with the subject matter,and teaching methods.The experience in the ATTSR(Advanced Teacher Training in Specialist Reading)project may be a reference point for colleagues whomeet with the same problems.In this paper the author will suggest methods to solve these problems intraining this group:using different subject展开更多
Post-match interview is a medium for athletes to showcase their impressions.This paper focus on the discourse of a post-match interview by Chinese athletes in the sport of table tennis at the 2024 Paris Olympics using...Post-match interview is a medium for athletes to showcase their impressions.This paper focus on the discourse of a post-match interview by Chinese athletes in the sport of table tennis at the 2024 Paris Olympics using the face-saving theory as the main framework introduced by Brown and Levinson(1987).In addition,theoretical extensions(Gu,1990;Mao,1994;Gao,1996)are also used to explain conceptions of face in the Chinese context.This study adopts a qualitative case study approach to investigating how athletes construct and maintain their face.It specifically analyzes the positive face,negative face,and redressive strategies.The findings indicate that Chinese athletes commonly adopt strategies such as emphasizing collective honor,humor,and indirect expressions to address face issues.These strategies are related to the collectivist values that are embedded in Chinese culture.This study extends the application of face theory to the under-explored domain of sports discourse and offers insights for future studies in sports communication and intercultural pragmatics.展开更多
Accurate and rapid recognition of weathering degree(WD)and groundwater condition(GC)is essential for evaluating rock mass quality and conducting stability analyses in underground engineering.Conventional WD and GC rec...Accurate and rapid recognition of weathering degree(WD)and groundwater condition(GC)is essential for evaluating rock mass quality and conducting stability analyses in underground engineering.Conventional WD and GC recognition methods often rely on subjective evaluation by field experts,supplemented by field sampling and laboratory testing.These methods are frequently complex and timeconsuming,making it challenging to meet the rapidly evolving demands of underground engineering.Therefore,this study proposes a rock non-geometric parameter classification network(RNPC-net)to rapidly achieve the recognition and mapping ofWD and GC of tunnel faces.The hybrid feature extraction module(HFEM)in RNPC-net can fully extract,fuse,and utilize multi-scale features of images,enhancing the network's classification performance.Moreover,the designed adaptive weighting auxiliary classifier(AC)helps the network learn features more efficiently.Experimental results show that RNPC-net achieved classification accuracies of 0.8756 and 0.8710 for WD and GC,respectively,representing an improvement of approximately 2%e10%compared to other methods.Both quantitative and qualitative experiments confirm the effectiveness and superiority of RNPC-net.Furthermore,for WD and GC mapping,RNPC-net outperformed other methods by achieving the highest mean intersection over union(mIOU)across most tunnel faces.The mapping results closely align with measurements provided by field experts.The application of WD and GC mapping results to the rock mass rating(RMR)system achieved a transition from conventional qualitative to quantitative evaluation.This advancement enables more accurate and reliable rock mass quality evaluations,particularly under critical conditions of RMR.展开更多
Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoret...Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.展开更多
Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overb...Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.展开更多
文摘In the present study a Genetic Programing model (GP) proposed for the prediction of relative crest settlement of concrete faced rock fill dams. To this end information of 30 large dams constructed in seven countries across the world is gathered with their reported settlements. The results showed that the GP model is able to estimate the dam settlement properly based on four properties, void ratio of dam’s body (e), height (H), vertical deformation modulus (Ev) and shape factor (Sc) of the dam. For verification of the model applicability, obtained results compared with other research methods such as Clements’s formula and the finite element model. The comparison showed that in all cases the GP model led to be more accurate than those of performed in literature. Also a proper compatibility between the GP model and the finite element model was perceived.
基金the National Natural Science Foundation of China(Nos. 21461015, 31860263 to Xiaolei Wang No. 91639106 to Hongbo Xin)+1 种基金Science Foundation of Jiangxi Provincial Department of Education(Nos. KJLD14010, 20153BCB23035, 20161ACB21002, 20165BCB19002 to Xiaolei Wang)Nanchang University Seed Grant for Biomedicine
文摘Black fungus derived carbonaceous aerogel (BFA) was prepared via a convenient and energy efficient ultrasonic disposal process. The adsorption experiments of atmospheric pollutants demonstrated the superior adsorbability of black fungus aerogel on PM2.5, PM10 and formaldehyde. More importantly, black fungus aerogel (BFA) exhibited intriguing double-faced properties. We explored properties of each side of the black fungus from three aspects: water contact angle measurements, liquid selective absorption capacity and air pollutant adsorption abilities. The subsequent modification of ZnO nanosheets endowed the prepared black fungus aerogel with several valuable properties, including broad-spectrum antibacterial capability and high-efficient adsorption ability. These valuable characters implied the BFA to be a promising bacteriostat and cleaner for air and water pollution treatment.
文摘Double - faced iso - object embroidery is carried out byusing the uneven intercalated stitch crafts of the parallel- lines stitch as a main body, being accompanied by oth-er stitch crafts and miscellaneous stitches, done on thesame textile material. This paper deals with the flower -bird double - faced embroidery fan of the Qing Dynasty,from pattern design, stitching formation and techniqueof color arrangement, describes the possible way of mak-ing double - faced embroidery with iso - object effectboth in the front and in the back.
文摘Since 1980’s,life science has been holding a prominent place in the development ofscience and it is expected to become one of the leading disciplines in the 21 century.Currently the development of life science presents the following characteristics:1.The understanding of life was deepened to the molecule level.
文摘State-owned enterprises’(SOE) greater independence from government offices as well as property rights reform have optimized SOEs’ shareholding structure. But the reform has to clear several hurdles before it can be fully realized. In 1998, the central government dismantled ministries that had been the direct administrators of large SOEs. Most functions of those ministries were transferred to industry associations. Only a few considered indispensable were taken over by other government offices. The move has pushed forward the SOE reform to some extent. On the other hand, being State-owned, those enterprises have to find new links with the government.
文摘Under over 50 years' development, Chinese rare earth magnetic industry developed into the global AINiCo, ferrite permanent magnets and NdFeB magnets manufacturing center, and average consumption of magnets per person in China increased to 1.026 tons in 2003 from 0.217 ton in 1990. Although China has been the large producing country of rare earth permanent magnetic materials, to be the strongest one, there are many problems to solve. Main Problems Faced By Chinese Permanent Magnet
基金supported by the National Natural Science Foundation of China(Nos.52192674,U1965206,U2240211)the Fundamental Research Funds for the Central Universities(No.DUT21TD106)。
文摘Owing to the stochastic behavior of earthquakes and complex crustal structure,wave type and incident direction are uncertain when seismic waves arrive at a structure.In addition,because of the different types of the structures and terrains,the traveling wave effects have different influences on the dynamic response of the structures.For the tall concrete-faced rockfill dam(CFRD),it is not only built in the complex terrain such as river valley,but also its height has reached 300 m level,which puts forward higher requirements for the seismic safety of the anti-seepage system mainly comprising concrete face slabs,especially the accurate location of the weak area in seism.Considering the limitations of the traditional uniform vibration analysis method,we implemented an efficient dynamic interaction analysis between a tall CFRD and its foundation using a non-uniform wave input method with a viscous-spring artificial boundary and equivalent nodal loads.This method was then applied to investigate the dynamic stress distribution on the concrete face slabs for different seismic wave types and incident directions.The results indicate that dam-foundation interactions behave differently at different wave incident angles,and that the traveling wave effect becomes more evident in valley topography.Seismic wave type and incident direction dramatically influenced stress in the face slab,and the extreme stress values and distribution law will vary under oblique wave incidence.The influence of the incident direction on slab stress was particularly apparent when SH-waves arrived from the left bank.Specifically,the extreme stress values in the face slab increased with an increasing incident angle.Interestingly,the locations of the extreme stress values changed mainly along the axis of the dam,and did not exhibit large changes in height.The seismic safety of CFRDs is therefore lower at higher incident angles from an anti-seepage perspective.Therefore,it is necessary to consider both the seismic wave type and incident direction during seismic capacity evaluations of tall CFRDs.
基金financially supported by Shandong Provincial Key R&D Plan Program(No.2017GGX10135)Shandong Provincial Science Foundation(No.ZR2018LF013)。
文摘Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide gas sensors.In recent years,a lot of binary ternary compound researches have been carried out.In this paper,five different SnO_(2) samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics.Based on the low temperature nitrogen adsorption tests and the atomic arrangement model,it can be inferred that different exposed surfaces play a key role in TEA sensing properties.In addition,the TEA sensing activity relationship of SnO_(2) exposed crystal faces is proposed as listed:(200)>(101)>(110).
文摘In recent years, China's economic development has driven the development of the construction industry. The project cost consulting business has developed rapidly, creating a good environment for local economic development. Project cost consulting management can effectively improve the scientificity of project decision-making and maximize economic and social benefits. In the process of this work, we should pay attention to risk prevention and control measures to give full play to its value. Next, the article discusses the risks and preventive countermeasures faced by the project cost consulting management.
基金supported by the National Natural Science Foundation of China(Grant Nos.51579086,51479054,51379068&51139001)Jiangsu Natural Science Foundation(Grant No.BK20140039)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant No.YS11001)
文摘Considering the complex nonlinear relationship between the material parameters of a concrete faced rock-fill dam(CFRD) and its displacements, the harmony search(HS) algorithm is used to optimize the back propagation neural network(BPNN), and the HS-BPNN algorithm is formed and applied for the inversion analysis of the parameters of rock-fill materials. The sensitivity of the parameters in the Duncan and Chang's E-B model is analyzed using the orthogonal test design. The case study shows that the parameters φ0, K, Rf, and Kb are sensitive to the deformation of the rock-fill dam and the inversion analysis for these parameters is performed by the HS-BPNN algorithm. Compared with the traditional BPNN, the HS-BPNN algorithm exhibits the advantages of high convergence precision, fast convergence rate, and strong stability.
文摘This paper summarizes the main technical points related to 100 m-height-scale concrete faced rock-fill dams and analyzes the main problems and their causes occurring during construction of 200 m-height-scale concrete faced rock-fill dams.This paper has raised the key technical problems which need to study for construction of 300 m-height-scale concrete faced rock-fill dams based on the main experiences on the extra-high concrete faced rock-fill dams built after the year of 2000.
文摘ESP teachers teaching English for mixed subject -specialist groups meet problems such as selecting teach-ing materials,dealing with the subject matter,and teaching methods.The experience in the ATTSR(Advanced Teacher Training in Specialist Reading)project may be a reference point for colleagues whomeet with the same problems.In this paper the author will suggest methods to solve these problems intraining this group:using different subject
文摘Post-match interview is a medium for athletes to showcase their impressions.This paper focus on the discourse of a post-match interview by Chinese athletes in the sport of table tennis at the 2024 Paris Olympics using the face-saving theory as the main framework introduced by Brown and Levinson(1987).In addition,theoretical extensions(Gu,1990;Mao,1994;Gao,1996)are also used to explain conceptions of face in the Chinese context.This study adopts a qualitative case study approach to investigating how athletes construct and maintain their face.It specifically analyzes the positive face,negative face,and redressive strategies.The findings indicate that Chinese athletes commonly adopt strategies such as emphasizing collective honor,humor,and indirect expressions to address face issues.These strategies are related to the collectivist values that are embedded in Chinese culture.This study extends the application of face theory to the under-explored domain of sports discourse and offers insights for future studies in sports communication and intercultural pragmatics.
基金supported by the National Natural Science Foundation of China(Grant Nos.42077242 and 42171407)the Graduate Innovation Fund of Jilin University.
文摘Accurate and rapid recognition of weathering degree(WD)and groundwater condition(GC)is essential for evaluating rock mass quality and conducting stability analyses in underground engineering.Conventional WD and GC recognition methods often rely on subjective evaluation by field experts,supplemented by field sampling and laboratory testing.These methods are frequently complex and timeconsuming,making it challenging to meet the rapidly evolving demands of underground engineering.Therefore,this study proposes a rock non-geometric parameter classification network(RNPC-net)to rapidly achieve the recognition and mapping ofWD and GC of tunnel faces.The hybrid feature extraction module(HFEM)in RNPC-net can fully extract,fuse,and utilize multi-scale features of images,enhancing the network's classification performance.Moreover,the designed adaptive weighting auxiliary classifier(AC)helps the network learn features more efficiently.Experimental results show that RNPC-net achieved classification accuracies of 0.8756 and 0.8710 for WD and GC,respectively,representing an improvement of approximately 2%e10%compared to other methods.Both quantitative and qualitative experiments confirm the effectiveness and superiority of RNPC-net.Furthermore,for WD and GC mapping,RNPC-net outperformed other methods by achieving the highest mean intersection over union(mIOU)across most tunnel faces.The mapping results closely align with measurements provided by field experts.The application of WD and GC mapping results to the rock mass rating(RMR)system achieved a transition from conventional qualitative to quantitative evaluation.This advancement enables more accurate and reliable rock mass quality evaluations,particularly under critical conditions of RMR.
基金support of the National Natural Science Foundation of China(Grant Nos.52179116 and 51991392)the support of Key Deployment Projects of Chinese Academy of Sciences(Grant No.ZDRW-ZS-2021-3).
文摘Shield tunneling in saturated ground poses challenges due to the potential risk of ground collapse resulting from seepage force and inadequate support pressure.This study employed a laboratory model test and a theoretical validation to elucidate the mechanisms of face failure and subsequent ground collapse in saturated ground during slurry pressure-balanced shield(SPBS)tunneling operations.A slurry circulation system was developed to ensure steady shield tunneling and to replicate the phenomena of ground collapse.Investigations into shield tunneling parameters and ground responses,including soil pressure,pore water pressure,and surface subsidence,were conducted to understand the mechanisms of face failure and subsequent ground collapse.The theoretical solution for the critical collapse pressure of the tunnel face,based on the rotational failure mechanism,was validated through the comparison with the experimentally determined critical collapse pressure.The results indicate that:(1)appropriate adjustments of tunneling parameters are crucial for promoting filtercake formation,maintaining chamber pressure,and minimizing ground subsidence;(2)chamber pressure,soil pressure,pore water pressure,and ground subsidence are closely correlated with shield tunneling parameters and the formation of filter cake;(3)ground collapse follows a continuous failure mode due to the destruction of filtercake and the decrease in chamber pressure;(4)the soil pressure at the cutterhead is more sensitive to disturbances from shield tunneling than chamber pressure;and(5)experimentally determined critical collapse pressures is consistent with the theoretical solution of limit analysis.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.42177143)the National Natural Science Foundation of China(Grant No.U23A2060).
文摘Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.
