In this study, th e least sq u are su p p o rt v ecto r m achine （LSSVM） alg o rith m w as applied to predicting th ebearing capacity o f b ored piles e m b ed d ed in sand an d m ixed soils. Pile g eo m etry an d c...In this study, th e least sq u are su p p o rt v ecto r m achine （LSSVM） alg o rith m w as applied to predicting th ebearing capacity o f b ored piles e m b ed d ed in sand an d m ixed soils. Pile g eo m etry an d cone p e n e tra tio nte s t （CPT） resu lts w ere used as in p u t variables for pred ictio n o f pile bearin g capacity. The d ata u se d w erecollected from th e existing litera tu re an d consisted o f 50 case records. The application o f LSSVM w ascarried o u t by dividing th e d ata into th re e se ts： a train in g se t for learning th e pro b lem an d obtain in g arelationship b e tw e e n in p u t variables an d pile bearin g capacity, and testin g an d validation sets forevaluation o f th e predictive an d g en eralization ability o f th e o b tain ed relationship. The predictions o f pilebearing capacity by LSSVM w ere evaluated by com paring w ith ex p erim en tal d ata an d w ith th o se bytrad itio n al CPT-based m eth o d s and th e gene ex pression pro g ram m in g （GEP） m odel. It w as found th a t th eLSSVM perform s w ell w ith coefficient o f d eterm in atio n , m ean, an d sta n d ard dev iatio n equivalent to 0.99,1.03, an d 0.08, respectively, for th e testin g set, an d 1, 1.04, an d 0.11, respectively, for th e v alidation set. Thelow values o f th e calculated m ean squared e rro r an d m ean ab so lu te e rro r indicated th a t th e LSSVM w asaccurate in p redicting th e pile bearing capacity. The results o f com parison also show ed th a t th e p roposedalg o rith m p red icted th e pile bearin g capacity m ore accurately th a n th e trad itio n al m eth o d s including th eGEP m odel.展开更多
A systematic method was proposed to estimate the occurrence probability of defective piles(OPDP) from a site according to quality assurance inspection. The OPDP was firstly suggested as the criterion to weight the per...A systematic method was proposed to estimate the occurrence probability of defective piles(OPDP) from a site according to quality assurance inspection. The OPDP was firstly suggested as the criterion to weight the performance of a pile foundation. Its prior distribution and updating distribution were deduced to follow Beta distributions. To calibrate the OPDP, a dynamic estimation model was established according to the relationships between prior mean and variance and updating mean and variance. Finally, a reliability-control method dealing with uncertainties arising from quality assurance inspection was formalized to judge whether all the bored piles from a site can be accepted. It is exemplified that the OPDP can be substantially improved when more definite prior information and sampling formation become available. For the example studied herein, the Bayesian estimator of updating variance for OPDP is reduced from 0.0037 to 0.0014 for the first inspection, from 0.0014 to 0.0009 for the second inspection, and with less uncertainty by incorporating experience information.展开更多
A complete case of a deep excavation was explored. According to the practical working conditions, a 3D non-linear finite element procedure is used to simulate a deep excavation supported by the composite soil nailed w...A complete case of a deep excavation was explored. According to the practical working conditions, a 3D non-linear finite element procedure is used to simulate a deep excavation supported by the composite soil nailed wall with bored piles in soft soil. The modified cam clay model is employed as the constitutive relationship of the soil in the numerical simulation. Results from the numerical analysis are fitted well with the field data, which indicate that the research approach used is reliable. Based on the field data and numerical results of the deep excavation supported by four different patterns of the composite soil nailed wall, the significant corner effect is founded in the 3D deep excavation. If bored piles or soil anchors are considered in the composite soil nailed wall, they are beneficial to decreasing deformations and internal forces of bored piles, cement mixing piles, soil anchors, soil nailings and soil around the deep excavation. Besides, the effects due to bored piles are more significant than those deduced from soil anchors. All mentioned above prove that the composite soil nailed wall with bored piles is feasible in the deep excavation.展开更多
The methodology of predicting pile shaft skin ultimate friction has been studied in a systematic way. In the light of that, the analysis of the pile shaft resistance for bored and cast in situ piles in cohesive soil...The methodology of predicting pile shaft skin ultimate friction has been studied in a systematic way. In the light of that, the analysis of the pile shaft resistance for bored and cast in situ piles in cohesive soils was carried out thoroughly in the basis of field performance data of 10 fully instrumented large diameter bored piles (LDBPs) used as the bridge foundation. The undrained strength index μ in term of cohesive soils was brought forward in allusion to the cohesive soils in the consistence plastic state, and can effectively combine the friction angle and the cohesion of cohesive soils in undrained condition. And that the classical ' α method' was modified much in effect to predict the pile shaft skin friction of LDBPs in cohesive soils. Furthermore, the approach of standard penetration test (SPT) N value used to estimate the pile shaft skin ultimate friction was analyzed, and the calculating formulae were established for LDBPs in clay and silt clay respectively.展开更多
A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypi...A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypical materials are simulated using different indicators in the centrifuge model.The silver sand,the shaft and the pile cap are simulated according to the natural density,the compressive stiffness and the bending stiffness,respectively.The finite element method（FEM）is implemented and analyzed in ANSYS,in which the stress field during the undisturbed soil stage,the boring stage,the concrete-casting stage and the curing stage are discussed in detail.Comparisons in terms of load-settlement,shaft axial force distribution and lateral friction between the numerical results and the test data are carried out to investigate the bearing behaviors of super-long rock-socketed bored pile groups under loading and unloading conditions.Results show that there is a good agreement between the centrifuge modeling tests and the FEM.In addition,the load distribution at the pile top is complicated,which is related to the stiffness of the cap,the corresponding assumptions and the analysis method.The shaft axial force first increases slightly with depth then decreases sharply,and the rate of decrease in rock is greater than that in sand and soil.展开更多
Due to the increasing number of large and heavy transportation vehicles, the road and bridge are facing great pressure. In order to better deal with and solve such pressure, the construction quality problem of bored p...Due to the increasing number of large and heavy transportation vehicles, the road and bridge are facing great pressure. In order to better deal with and solve such pressure, the construction quality problem of bored piles should be properly solved, which is beneficial to control the adverse factors in the construction and provide basic guarantee for the quality of roads and bridges. Common quality problems in the construction of bored piles for urban road bridges include: hole collapse, borehole deviation, cage floating, pile breaking, warp shrinkage, etc. Therefore, the quality problems of the cast-in-place pile and the solutions should be discussed in depth, the causes of the problems should be analyzed, and prevention suggestions should be provided.展开更多
In water conservancy projects, the technology of cast-in-place bored pile in water conservancy construction is also an important content. The quality of the project will directly affect the speed and benefit of the wh...In water conservancy projects, the technology of cast-in-place bored pile in water conservancy construction is also an important content. The quality of the project will directly affect the speed and benefit of the whole construction. However, in the actual construction of water conservancy projects, more stringent measures are still needed to manage them to ensure that they can work more smoothly. This article mainly analyzes the current construction technology of cast-in-place bored piles in water conservancy projects, and at the same time gives some suggestions, hoping to bring some reference significance to relevant engineers.展开更多
Bridge plays an important role in highway engineering. Among them, the pile foundation is the foundation structure of the bridge, which is not conducive to the smooth progress of the construction in case of special ge...Bridge plays an important role in highway engineering. Among them, the pile foundation is the foundation structure of the bridge, which is not conducive to the smooth progress of the construction in case of special geological conditions such as karst caves. If there is no effective treatment measures, it is easy to have problems such as drilling loss, hammer sticking and hole collapse, which seriously threaten the stability of the pile foundation and even the whole bridge. In order to ensure that the bored piles meet the requirements of the quality standards, the construction procedures of pile position measurement, casing embedding, mud preparation, drilling, hole cleaning and concrete pouring should be done well, so that the bridge foundation can be completed according to the quality, quantity and time.展开更多
Combined with the engineering example of cast-in-place bored pile in the area of deep miscellaneous fill, according to the single variable factor analysis method, the key factors of hole collapse of cast-in-place bore...Combined with the engineering example of cast-in-place bored pile in the area of deep miscellaneous fill, according to the single variable factor analysis method, the key factors of hole collapse of cast-in-place bored pile are determined. The results show that the main factors of hole collapse are loose structure of miscellaneous fill layer, insufficient settlement consolidation and low slurry viscosity of retaining wall. In order to improve the compactness of miscellaneous fill and the low viscosity of mud, the foundation dynamic compaction was adopted to accelerate the self-weight settlement and consolidation of miscellaneous fill, and the mud viscosity was tested. According to the effect of mud under different viscosities, the optimal viscosity ratio was selected. The verification test of cast-in-place bored piles is carried out after the improvement of the two factors. The results show that, under the conditions of improving the compactness of miscellaneous fill and improving the viscosity of mud, the effect of improving the qualified rate of one-time hole formation of cast-in-place bored piles is obvious. In an engineering example, the hole collapse rate can be reduced to less than 10%, which has reference significance for practical engineering application.展开更多
Subgrade is the main infrastructure of pavement, and the overall quality of the path determines the performance and service life of the pavement. Highway bridge bored pile combined with the change of bearing layer to ...Subgrade is the main infrastructure of pavement, and the overall quality of the path determines the performance and service life of the pavement. Highway bridge bored pile combined with the change of bearing layer to configure the reinforcement combination, which uses less reinforcement, construction is simple and practical. At the same time, the cost of the technology itself is not very high, the applicability is strong, and the operation is more convenient. Based on the actual project, aiming at the application of bored pile in highway bridge, this paper studies the problems that may be encountered in the process of highway bridge drilling construction, so as to study the construction technology of bored pile.展开更多
Bored cast-in-place pile technology is the most widely used foundation bearing method in major projects in China. However, due to its special working environment, the application of cast-in-place bored pile technology...Bored cast-in-place pile technology is the most widely used foundation bearing method in major projects in China. However, due to its special working environment, the application of cast-in-place bored pile technology in bridge engineering is easy to cause various malignant consequences, such as broken pile, broken hole, steel cage floating box, etc. In this paper, the most common quality problems of cast-in-place bored pile technology in bridge engineering and the corresponding effective solutions are analyzed and explained in detail.展开更多
Road and bridge engineering requires subgrade to have high stability and firmness. Therefore, the subgrade needs to have strong load performance. At present, the construction technology of bored piles for highway brid...Road and bridge engineering requires subgrade to have high stability and firmness. Therefore, the subgrade needs to have strong load performance. At present, the construction technology of bored piles for highway bridges is well developed and widely used in various industries. The application of this technology in the construction of bored piles for highway bridge construction can greatly improve the physical properties of the subgrade, strengthen the stability of the subgrade and avoid the occurrence of uneven settlement. Therefore, relevant technical personnel need to be familiar with the construction technology of cast-in-place bored piles, and enterprises need to attach great importance to the construction management work, which is beneficial to maximize the use of cast-in-place bored piles construction technology.展开更多
In order to improve the quality of bored piles in bridge construction and ensure the overall quality of the bridge,we analyzed a series of problems in the construction process of bored piles,then propose corresponding...In order to improve the quality of bored piles in bridge construction and ensure the overall quality of the bridge,we analyzed a series of problems in the construction process of bored piles,then propose corresponding quality control measures,in hopes of improving quality control of bored piles in bridge construction in our country.展开更多
Cast-in-place bored pile construction technology is one of the commonly used technologies in water conservancy projects. The mechanical equipment used in the construction is not expensive and does not need to occupy a...Cast-in-place bored pile construction technology is one of the commonly used technologies in water conservancy projects. The mechanical equipment used in the construction is not expensive and does not need to occupy a large construction site. It can obtain local materials, and the construction management is safe and convenient. The technology can be applied to various geological conditions, and the underground water is not required to be discharged during drilling, and the environment is not greatly affected, thus having good economic applicability. Based on this, the paper discusses the construction technology of cast-in-place bored piles in water conservancy projects.展开更多
Time to enter the 21st century, our country gradually moving towards modernization power, along with our country's economic strength, science and technology development, such as the country's many industry get...Time to enter the 21st century, our country gradually moving towards modernization power, along with our country's economic strength, science and technology development, such as the country's many industry get the progress by leaps and bounds, road engineering in China traditional architectural engineering, road engineering has always been about the development of China's people's daily life level and the development of the economy, but in the road engineering construction, Often face a variety of construction challenges, in actual engineering construction, due to loose soil, settlement or some other reasons, if the relevant staff careless operation, it is easy to lead to a lot of potential problems in the use of road engineering, and even bring a certain threat to people's daily use experience. In the face of these problems, it is necessary for relevant personnel to analyze the problems existing in the construction process and operate in strict accordance with the operation plan of drilling perfusion technology in road construction.展开更多
The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the p...The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.展开更多
In the construction of modern highway and bridge engineering, bored cast-in-place pile is used in many cases. Bored cast-in-place pile can penetrate various complicated soil layers, has strong bearing capacity, and th...In the construction of modern highway and bridge engineering, bored cast-in-place pile is used in many cases. Bored cast-in-place pile can penetrate various complicated soil layers, has strong bearing capacity, and the construction machinery involved in it is relatively simple. Moreover, the noise produced in the construction process is relatively small, and the construction safety is relatively high, so it has been widely used in construction enterprises. But bored pile in essence belongs to the hidden works, will be affected by other parts of the construction technology application effect, such as highway bridge engineering drilling process, wall protection and concrete configuration may affect the application level of bored pile technology, and technical personnel must strictly regulate the use of bored pile technology, to avoid quality accidents in the construction process. This paper analyzes the advantages of bored pile technology in bridge construction, studies the working principle and application principles of bored pile, explores the possible problems in highway bridge engineering, and puts forward effective solutions and quality control measures for reference.展开更多
The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the differ...The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the different distributions of pile shaft resistance. Primarily, this paper summarizes the conceptualized mode of pile shaft resistance under the circum- stance that the soil surrounding the piles presents different layer distributions. Secondly, based on Mindlin＇s displacement solution and in consideration of the effect of pile diam- eter, the calculation equation is optimized with the assumption that the pile shaft resis- tance has a parabolic distribution. The influencing factors are analyzed according to the calculation result of effective pile length. Finally, combined with an engineering example, the calculation equation deduced in this paper is analyzed and verified. The result shows that both the Poisson ratio of soil and pile diameter have impacted the effective pile length. Compared with the Poisson ratio of soil, the effect of pile diameter is more significant. If the pile diameter remains the same, the effect of the Poisson ratio of soil to the effective pile length decreases as the ratio of pile elastic modulus and soil share modulus increases. If the Poisson ratio of soil remains the same, the effect of the pile diameter to the effective pile length increases as the ratio of pile elastic modulus and soil share modulus increases. Thus the optimized calculation result of pile effective length under the consideration of pile diameter effect is more close to the actual situation of engineering and reasonably practicable.展开更多
文摘In this study, th e least sq u are su p p o rt v ecto r m achine （LSSVM） alg o rith m w as applied to predicting th ebearing capacity o f b ored piles e m b ed d ed in sand an d m ixed soils. Pile g eo m etry an d cone p e n e tra tio nte s t （CPT） resu lts w ere used as in p u t variables for pred ictio n o f pile bearin g capacity. The d ata u se d w erecollected from th e existing litera tu re an d consisted o f 50 case records. The application o f LSSVM w ascarried o u t by dividing th e d ata into th re e se ts： a train in g se t for learning th e pro b lem an d obtain in g arelationship b e tw e e n in p u t variables an d pile bearin g capacity, and testin g an d validation sets forevaluation o f th e predictive an d g en eralization ability o f th e o b tain ed relationship. The predictions o f pilebearing capacity by LSSVM w ere evaluated by com paring w ith ex p erim en tal d ata an d w ith th o se bytrad itio n al CPT-based m eth o d s and th e gene ex pression pro g ram m in g （GEP） m odel. It w as found th a t th eLSSVM perform s w ell w ith coefficient o f d eterm in atio n , m ean, an d sta n d ard dev iatio n equivalent to 0.99,1.03, an d 0.08, respectively, for th e testin g set, an d 1, 1.04, an d 0.11, respectively, for th e v alidation set. Thelow values o f th e calculated m ean squared e rro r an d m ean ab so lu te e rro r indicated th a t th e LSSVM w asaccurate in p redicting th e pile bearing capacity. The results o f com parison also show ed th a t th e p roposedalg o rith m p red icted th e pile bearin g capacity m ore accurately th a n th e trad itio n al m eth o d s including th eGEP m odel.
基金Project(51278216) supported by the National Natural Science Foundation of ChinaProject(2013BS010) supported by Henan University of Technology Fund for High-level Talent,China
文摘A systematic method was proposed to estimate the occurrence probability of defective piles(OPDP) from a site according to quality assurance inspection. The OPDP was firstly suggested as the criterion to weight the performance of a pile foundation. Its prior distribution and updating distribution were deduced to follow Beta distributions. To calibrate the OPDP, a dynamic estimation model was established according to the relationships between prior mean and variance and updating mean and variance. Finally, a reliability-control method dealing with uncertainties arising from quality assurance inspection was formalized to judge whether all the bored piles from a site can be accepted. It is exemplified that the OPDP can be substantially improved when more definite prior information and sampling formation become available. For the example studied herein, the Bayesian estimator of updating variance for OPDP is reduced from 0.0037 to 0.0014 for the first inspection, from 0.0014 to 0.0009 for the second inspection, and with less uncertainty by incorporating experience information.
基金Foundation item： Project（2009-K3-2） supported by the Ministry of Housing and Urban-Rural Development of China
文摘A complete case of a deep excavation was explored. According to the practical working conditions, a 3D non-linear finite element procedure is used to simulate a deep excavation supported by the composite soil nailed wall with bored piles in soft soil. The modified cam clay model is employed as the constitutive relationship of the soil in the numerical simulation. Results from the numerical analysis are fitted well with the field data, which indicate that the research approach used is reliable. Based on the field data and numerical results of the deep excavation supported by four different patterns of the composite soil nailed wall, the significant corner effect is founded in the 3D deep excavation. If bored piles or soil anchors are considered in the composite soil nailed wall, they are beneficial to decreasing deformations and internal forces of bored piles, cement mixing piles, soil anchors, soil nailings and soil around the deep excavation. Besides, the effects due to bored piles are more significant than those deduced from soil anchors. All mentioned above prove that the composite soil nailed wall with bored piles is feasible in the deep excavation.
文摘The methodology of predicting pile shaft skin ultimate friction has been studied in a systematic way. In the light of that, the analysis of the pile shaft resistance for bored and cast in situ piles in cohesive soils was carried out thoroughly in the basis of field performance data of 10 fully instrumented large diameter bored piles (LDBPs) used as the bridge foundation. The undrained strength index μ in term of cohesive soils was brought forward in allusion to the cohesive soils in the consistence plastic state, and can effectively combine the friction angle and the cohesion of cohesive soils in undrained condition. And that the classical ' α method' was modified much in effect to predict the pile shaft skin friction of LDBPs in cohesive soils. Furthermore, the approach of standard penetration test (SPT) N value used to estimate the pile shaft skin ultimate friction was analyzed, and the calculating formulae were established for LDBPs in clay and silt clay respectively.
基金The Natural Science Foundation of Hubei Province(No.2007ABA094)
文摘A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypical materials are simulated using different indicators in the centrifuge model.The silver sand,the shaft and the pile cap are simulated according to the natural density,the compressive stiffness and the bending stiffness,respectively.The finite element method（FEM）is implemented and analyzed in ANSYS,in which the stress field during the undisturbed soil stage,the boring stage,the concrete-casting stage and the curing stage are discussed in detail.Comparisons in terms of load-settlement,shaft axial force distribution and lateral friction between the numerical results and the test data are carried out to investigate the bearing behaviors of super-long rock-socketed bored pile groups under loading and unloading conditions.Results show that there is a good agreement between the centrifuge modeling tests and the FEM.In addition,the load distribution at the pile top is complicated,which is related to the stiffness of the cap,the corresponding assumptions and the analysis method.The shaft axial force first increases slightly with depth then decreases sharply,and the rate of decrease in rock is greater than that in sand and soil.
文摘Due to the increasing number of large and heavy transportation vehicles, the road and bridge are facing great pressure. In order to better deal with and solve such pressure, the construction quality problem of bored piles should be properly solved, which is beneficial to control the adverse factors in the construction and provide basic guarantee for the quality of roads and bridges. Common quality problems in the construction of bored piles for urban road bridges include: hole collapse, borehole deviation, cage floating, pile breaking, warp shrinkage, etc. Therefore, the quality problems of the cast-in-place pile and the solutions should be discussed in depth, the causes of the problems should be analyzed, and prevention suggestions should be provided.
文摘In water conservancy projects, the technology of cast-in-place bored pile in water conservancy construction is also an important content. The quality of the project will directly affect the speed and benefit of the whole construction. However, in the actual construction of water conservancy projects, more stringent measures are still needed to manage them to ensure that they can work more smoothly. This article mainly analyzes the current construction technology of cast-in-place bored piles in water conservancy projects, and at the same time gives some suggestions, hoping to bring some reference significance to relevant engineers.
文摘Bridge plays an important role in highway engineering. Among them, the pile foundation is the foundation structure of the bridge, which is not conducive to the smooth progress of the construction in case of special geological conditions such as karst caves. If there is no effective treatment measures, it is easy to have problems such as drilling loss, hammer sticking and hole collapse, which seriously threaten the stability of the pile foundation and even the whole bridge. In order to ensure that the bored piles meet the requirements of the quality standards, the construction procedures of pile position measurement, casing embedding, mud preparation, drilling, hole cleaning and concrete pouring should be done well, so that the bridge foundation can be completed according to the quality, quantity and time.
文摘Combined with the engineering example of cast-in-place bored pile in the area of deep miscellaneous fill, according to the single variable factor analysis method, the key factors of hole collapse of cast-in-place bored pile are determined. The results show that the main factors of hole collapse are loose structure of miscellaneous fill layer, insufficient settlement consolidation and low slurry viscosity of retaining wall. In order to improve the compactness of miscellaneous fill and the low viscosity of mud, the foundation dynamic compaction was adopted to accelerate the self-weight settlement and consolidation of miscellaneous fill, and the mud viscosity was tested. According to the effect of mud under different viscosities, the optimal viscosity ratio was selected. The verification test of cast-in-place bored piles is carried out after the improvement of the two factors. The results show that, under the conditions of improving the compactness of miscellaneous fill and improving the viscosity of mud, the effect of improving the qualified rate of one-time hole formation of cast-in-place bored piles is obvious. In an engineering example, the hole collapse rate can be reduced to less than 10%, which has reference significance for practical engineering application.
文摘Subgrade is the main infrastructure of pavement, and the overall quality of the path determines the performance and service life of the pavement. Highway bridge bored pile combined with the change of bearing layer to configure the reinforcement combination, which uses less reinforcement, construction is simple and practical. At the same time, the cost of the technology itself is not very high, the applicability is strong, and the operation is more convenient. Based on the actual project, aiming at the application of bored pile in highway bridge, this paper studies the problems that may be encountered in the process of highway bridge drilling construction, so as to study the construction technology of bored pile.
文摘Bored cast-in-place pile technology is the most widely used foundation bearing method in major projects in China. However, due to its special working environment, the application of cast-in-place bored pile technology in bridge engineering is easy to cause various malignant consequences, such as broken pile, broken hole, steel cage floating box, etc. In this paper, the most common quality problems of cast-in-place bored pile technology in bridge engineering and the corresponding effective solutions are analyzed and explained in detail.
文摘Road and bridge engineering requires subgrade to have high stability and firmness. Therefore, the subgrade needs to have strong load performance. At present, the construction technology of bored piles for highway bridges is well developed and widely used in various industries. The application of this technology in the construction of bored piles for highway bridge construction can greatly improve the physical properties of the subgrade, strengthen the stability of the subgrade and avoid the occurrence of uneven settlement. Therefore, relevant technical personnel need to be familiar with the construction technology of cast-in-place bored piles, and enterprises need to attach great importance to the construction management work, which is beneficial to maximize the use of cast-in-place bored piles construction technology.
文摘In order to improve the quality of bored piles in bridge construction and ensure the overall quality of the bridge,we analyzed a series of problems in the construction process of bored piles,then propose corresponding quality control measures,in hopes of improving quality control of bored piles in bridge construction in our country.
文摘Cast-in-place bored pile construction technology is one of the commonly used technologies in water conservancy projects. The mechanical equipment used in the construction is not expensive and does not need to occupy a large construction site. It can obtain local materials, and the construction management is safe and convenient. The technology can be applied to various geological conditions, and the underground water is not required to be discharged during drilling, and the environment is not greatly affected, thus having good economic applicability. Based on this, the paper discusses the construction technology of cast-in-place bored piles in water conservancy projects.
文摘Time to enter the 21st century, our country gradually moving towards modernization power, along with our country's economic strength, science and technology development, such as the country's many industry get the progress by leaps and bounds, road engineering in China traditional architectural engineering, road engineering has always been about the development of China's people's daily life level and the development of the economy, but in the road engineering construction, Often face a variety of construction challenges, in actual engineering construction, due to loose soil, settlement or some other reasons, if the relevant staff careless operation, it is easy to lead to a lot of potential problems in the use of road engineering, and even bring a certain threat to people's daily use experience. In the face of these problems, it is necessary for relevant personnel to analyze the problems existing in the construction process and operate in strict accordance with the operation plan of drilling perfusion technology in road construction.
文摘The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.
文摘In the construction of modern highway and bridge engineering, bored cast-in-place pile is used in many cases. Bored cast-in-place pile can penetrate various complicated soil layers, has strong bearing capacity, and the construction machinery involved in it is relatively simple. Moreover, the noise produced in the construction process is relatively small, and the construction safety is relatively high, so it has been widely used in construction enterprises. But bored pile in essence belongs to the hidden works, will be affected by other parts of the construction technology application effect, such as highway bridge engineering drilling process, wall protection and concrete configuration may affect the application level of bored pile technology, and technical personnel must strictly regulate the use of bored pile technology, to avoid quality accidents in the construction process. This paper analyzes the advantages of bored pile technology in bridge construction, studies the working principle and application principles of bored pile, explores the possible problems in highway bridge engineering, and puts forward effective solutions and quality control measures for reference.
基金supported by the National Natural Science Foundation of China(51208047)
文摘The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the different distributions of pile shaft resistance. Primarily, this paper summarizes the conceptualized mode of pile shaft resistance under the circum- stance that the soil surrounding the piles presents different layer distributions. Secondly, based on Mindlin＇s displacement solution and in consideration of the effect of pile diam- eter, the calculation equation is optimized with the assumption that the pile shaft resis- tance has a parabolic distribution. The influencing factors are analyzed according to the calculation result of effective pile length. Finally, combined with an engineering example, the calculation equation deduced in this paper is analyzed and verified. The result shows that both the Poisson ratio of soil and pile diameter have impacted the effective pile length. Compared with the Poisson ratio of soil, the effect of pile diameter is more significant. If the pile diameter remains the same, the effect of the Poisson ratio of soil to the effective pile length decreases as the ratio of pile elastic modulus and soil share modulus increases. If the Poisson ratio of soil remains the same, the effect of the pile diameter to the effective pile length increases as the ratio of pile elastic modulus and soil share modulus increases. Thus the optimized calculation result of pile effective length under the consideration of pile diameter effect is more close to the actual situation of engineering and reasonably practicable.
