Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain anal...Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.展开更多
Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the ...Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the detection of grouting anomalies within connections,enhancing its precision through the integration of wavelet packet energy principles for damage identification purposes.A series of grouting completeness assessments were meticulously conducted,taking into account variables such as the divergent material properties of the sleeves and the configuration of adjacent reinforcement.The findings revealed that:(i)the energy distribution for the highstrength concrete cohort predominantly occupied the frequency bands 42,44,45,and 47,whereas for other groups,it was concentrated within the 37 to 40 frequency band;(ii)the delineation of empty sleeves was effectively discernible by examining the wavelet packet energy ratios across the spectrum of frequencies,albeit distinguishing between sleeves with 50%and full grouting density proved challenging;and(iii)the wavelet packet energy analysis yielded variable detection outcomes contingent on the material attributes of the sleeves,demonstrating heightened sensitivity when applied to ultrahigh-performance concrete matrices and GFRP-reinforced steel bars.展开更多
Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)o...Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)offers a solution for connecting reinforcements in precast components,but their vulnerability to internal defects,such as construction errors and material variability,can significantly impact performance.This article presents a finite element analysis(FEA)to evaluate the impact of internal grouting defects in GSC on the structural performance of precast reinforced concrete columns.Four finite elementmodels representing GSC with varying degrees of defects were used to investigate the effects on mechanical properties,including bearing capacity,stress-deformation behavior,and stiffness degradation.The study highlights the significant impact of internal grouting defects on the mechanical performance of GSC,with findings indicating a decrease in stiffness,increased plastic deformation,and reduced energy dissipation as the proportion of internal defects rises.The analysis reveals that the internal defects in GSC act as stress concentration points,leading to early crack formation and accelerated damage under cyclic loading.By improving construction quality and reducing the prevalence of grouting defects,the adverse effects on the performance of GSC can be mitigated.Compared to defect-free specimens,those with defects of 30%exhibited a 31.23%reduction in horizontal bearing capacity,highlighting the importance of minimizing defects in practical engineering applications.展开更多
Grouted sleeves can effectively connect precast elements,but the effect of grouted sleeves for increased stiffness and assembled seam for weakening stiffness on the precast column’s mechanical properties is unclear.B...Grouted sleeves can effectively connect precast elements,but the effect of grouted sleeves for increased stiffness and assembled seam for weakening stiffness on the precast column’s mechanical properties is unclear.Based on the full-scale test results of precast columns connected with grouted sleeves and the correctness of the numerical models,the influence analysis of the individual and coupling action of the grouted sleeves and assembled seam on the deformation and bearing capacity of the precast column is carried out.The research results show that grouted sleeves significantly affect the deformation and peak bearing capacity of precast columns;when precast columns are subjected to the action of high axial pressure,grouted sleeves significantly affect the bearing capacity.However,the influence of assembled seams on the peaking capacity of the precast column is more obvious when it was tested under low axial compression.It is recommended that the connection position should be 2 times the height of the grouted sleeve from the bottom of the foundation.展开更多
In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance...In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.展开更多
In the Shenzhen region,where strong karst development is widely distributed,karst caves pose significant difficulties and risks to pile foundation construction.This paper,based on the Yanba Expressway Municipalization...In the Shenzhen region,where strong karst development is widely distributed,karst caves pose significant difficulties and risks to pile foundation construction.This paper,based on the Yanba Expressway Municipalization Reconstruction Project and referencing previous engineering experiences,proposes the application of sleeve valve pipe grouting technology for pre-treatment of small-to medium-sized and bead-shaped karst caves.Specific implementation measures and construction precautions are presented.Practical results demonstrate that the pre-treated karst cave areas achieved stable soil conditions,providing favorable prerequisites for subsequent pile foundation construction.The method proves convenient and feasible in operation,substantially reducing safety and quality risks during construction.This successful practice offers valuable experience for similar projects.展开更多
The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connect...The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.展开更多
The precast composite reinforced concrete wall with the advantages of fewer joints,superior impermeability and rapid construction provides an efficient and environmental friendly alternative in the construction of und...The precast composite reinforced concrete wall with the advantages of fewer joints,superior impermeability and rapid construction provides an efficient and environmental friendly alternative in the construction of underground utility tunnels in the last few years.To investigate the seismic performance of precast concrete composite walls of utility tunnels with grouting-sleeve connection under out-ofplane loads,a series of quasi-static cyclic tests were performed on the full-scale sidewall specimens with different axial compression ratios in this study.The experimental results including the failure modes,crack distributions,and the influence of different connections on the out-of-plane seismic performance of precast concrete composite wall were carefully examined and compared with those from the cyclic tests of the cast-in-place sidewalls of the utility tunnel.The test results show that the seismic performance of the precast concrete composite sidewall specimen,such as the hysteresis curves,the ultimate bearing capacity,stiffness degradation pattern and the ductility ratio,is basically the same as that of the cast-in-place specimen,indicating that the seismic performance of the prefabricated structure is equivalent to that of the cast-in-place structure.Moreover,the grouting-sleeves of the joints can effectively transfer the reinforcement stress until the failure of the precast concrete composite sidewall specimens,which exhibits excellent out-of-plane ductility and serviceability.展开更多
基金supported in part by the National Natural Science Foundation of China Grant 11962006the Natural Science Foundation of Jiangxi Province of China Grant 20232BAB204067.
文摘Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.
基金supported by financial support from the National Natural Science Foundation of China(U1904177)the Excellent Youth Natural Science Foundation of Henan Province of China(212300410079)+2 种基金the Subproject of the Key Project of the National Development and Reform Commission of China(202203001)the Project of Young Key Teachers in Henan Province of China(2019GGJS01)Horizontal Research Projects(20230352A).
文摘Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the detection of grouting anomalies within connections,enhancing its precision through the integration of wavelet packet energy principles for damage identification purposes.A series of grouting completeness assessments were meticulously conducted,taking into account variables such as the divergent material properties of the sleeves and the configuration of adjacent reinforcement.The findings revealed that:(i)the energy distribution for the highstrength concrete cohort predominantly occupied the frequency bands 42,44,45,and 47,whereas for other groups,it was concentrated within the 37 to 40 frequency band;(ii)the delineation of empty sleeves was effectively discernible by examining the wavelet packet energy ratios across the spectrum of frequencies,albeit distinguishing between sleeves with 50%and full grouting density proved challenging;and(iii)the wavelet packet energy analysis yielded variable detection outcomes contingent on the material attributes of the sleeves,demonstrating heightened sensitivity when applied to ultrahigh-performance concrete matrices and GFRP-reinforced steel bars.
文摘Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)offers a solution for connecting reinforcements in precast components,but their vulnerability to internal defects,such as construction errors and material variability,can significantly impact performance.This article presents a finite element analysis(FEA)to evaluate the impact of internal grouting defects in GSC on the structural performance of precast reinforced concrete columns.Four finite elementmodels representing GSC with varying degrees of defects were used to investigate the effects on mechanical properties,including bearing capacity,stress-deformation behavior,and stiffness degradation.The study highlights the significant impact of internal grouting defects on the mechanical performance of GSC,with findings indicating a decrease in stiffness,increased plastic deformation,and reduced energy dissipation as the proportion of internal defects rises.The analysis reveals that the internal defects in GSC act as stress concentration points,leading to early crack formation and accelerated damage under cyclic loading.By improving construction quality and reducing the prevalence of grouting defects,the adverse effects on the performance of GSC can be mitigated.Compared to defect-free specimens,those with defects of 30%exhibited a 31.23%reduction in horizontal bearing capacity,highlighting the importance of minimizing defects in practical engineering applications.
基金supported by the National Natural Science Foundation of China(Grant No.51908013)Basic Scientific Research Foundation for Municipal University(X21076)。
文摘Grouted sleeves can effectively connect precast elements,but the effect of grouted sleeves for increased stiffness and assembled seam for weakening stiffness on the precast column’s mechanical properties is unclear.Based on the full-scale test results of precast columns connected with grouted sleeves and the correctness of the numerical models,the influence analysis of the individual and coupling action of the grouted sleeves and assembled seam on the deformation and bearing capacity of the precast column is carried out.The research results show that grouted sleeves significantly affect the deformation and peak bearing capacity of precast columns;when precast columns are subjected to the action of high axial pressure,grouted sleeves significantly affect the bearing capacity.However,the influence of assembled seams on the peaking capacity of the precast column is more obvious when it was tested under low axial compression.It is recommended that the connection position should be 2 times the height of the grouted sleeve from the bottom of the foundation.
基金The authors are grateful for the financial support received from the National Natural Science Foundation of China(No.52078038)Basic Scientific Research Business of Central University(No.FRF-MP-20-20).
文摘In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.
文摘In the Shenzhen region,where strong karst development is widely distributed,karst caves pose significant difficulties and risks to pile foundation construction.This paper,based on the Yanba Expressway Municipalization Reconstruction Project and referencing previous engineering experiences,proposes the application of sleeve valve pipe grouting technology for pre-treatment of small-to medium-sized and bead-shaped karst caves.Specific implementation measures and construction precautions are presented.Practical results demonstrate that the pre-treated karst cave areas achieved stable soil conditions,providing favorable prerequisites for subsequent pile foundation construction.The method proves convenient and feasible in operation,substantially reducing safety and quality risks during construction.This successful practice offers valuable experience for similar projects.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52108428,52178446,51978021,and 51908015)the Fundamental Research Funds for the Central Universities(No.2023MS067).We gratefully acknowledge their support.
文摘The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.
基金supported by the National Natural Science Foundation of China(Grant Nos.51978020,52378470,and 52220105011).
文摘The precast composite reinforced concrete wall with the advantages of fewer joints,superior impermeability and rapid construction provides an efficient and environmental friendly alternative in the construction of underground utility tunnels in the last few years.To investigate the seismic performance of precast concrete composite walls of utility tunnels with grouting-sleeve connection under out-ofplane loads,a series of quasi-static cyclic tests were performed on the full-scale sidewall specimens with different axial compression ratios in this study.The experimental results including the failure modes,crack distributions,and the influence of different connections on the out-of-plane seismic performance of precast concrete composite wall were carefully examined and compared with those from the cyclic tests of the cast-in-place sidewalls of the utility tunnel.The test results show that the seismic performance of the precast concrete composite sidewall specimen,such as the hysteresis curves,the ultimate bearing capacity,stiffness degradation pattern and the ductility ratio,is basically the same as that of the cast-in-place specimen,indicating that the seismic performance of the prefabricated structure is equivalent to that of the cast-in-place structure.Moreover,the grouting-sleeves of the joints can effectively transfer the reinforcement stress until the failure of the precast concrete composite sidewall specimens,which exhibits excellent out-of-plane ductility and serviceability.
