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
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
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
At present the bored construction method is one of the main construction methods of metro and tunnel construction in China. The empirical estimated formulas of tunnel ground surface settlement using the bored construc...At present the bored construction method is one of the main construction methods of metro and tunnel construction in China. The empirical estimated formulas of tunnel ground surface settlement using the bored construction method were obtained, combining the mechanical stimulant calculated result of tunnel model of different embedded depth, different cross section and different construction method and the actual measurement data of Beijing metro construction. According to the regressed analysis of calculated data, the calculated equations of ground surface settlement value and settlement range of tunnel section under the condition of different embedded depth, different cross section and different construction method were gained. Among them there are some empirical formulas can apply to the construction design of metro tunnel directly.展开更多
This paper presents some aspects of the load-settlement behavior for large diameter bored piles using four different international codes, namely: ECP 202 [1], DIN 4014 [2], AASHTO [3] and French Code [4]. Ultimate cap...This paper presents some aspects of the load-settlement behavior for large diameter bored piles using four different international codes, namely: ECP 202 [1], DIN 4014 [2], AASHTO [3] and French Code [4]. Ultimate capacities for 38 pile load tests founded in realistic multi-layered soils in Delta and Port Saidareas atEgyptare evaluated using modified Chin (1970) method and compared to ultimate load predictions obtained by the aforementioned codes. Many statistical analyses were conducted on the total pile loads and individual contributions of tip and skin resistances. Based on code predictions of ultimate pile loads, an empirical modified load-settlement model is proposed. This model will simplify to a great extent the analysis of piled-raft systems as it can effortlessly predict pile settlement due to the load on pile itself. Comparisons showed that the pile load test is an irreplaceable process for determining the ultimate capacity of piles.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
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
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
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
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
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
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
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
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
词数:345阅读难度:建议阅读时间:4分钟Well,it used to be fun.It used to be about fun and rest,but now we’re just running across the school to get to the fourth period.We used to go home and see our families but now it’...词数:345阅读难度:建议阅读时间:4分钟Well,it used to be fun.It used to be about fun and rest,but now we’re just running across the school to get to the fourth period.We used to go home and see our families but now it’s being in a dorm with some random doofus who steals your food.It used to be about easy assignments and times tables,but展开更多
The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model...The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model-based boring indexes(derived from rock fragmentation mechanisms)and Euclidean distance analysis to achieve real-time recommendations of TBM operational parameters.Key performance indicators-thrust(F),torque(T),and penetration(p)-were used to calculate three model-based boring indexes(a,b,k),which quantify dynamic rock fragmentation behavior.A dataset of 359 candidate samples,reflecting diverse geological conditions from the Yin-Chao water conveyance project in Inner Mongolia,China,was utilized to validate the framework.The system dynamically recommends parameters by matching real-time data with historical cases through standardized Euclidean distance,achieving high accuracy.Specifically,the mean absolute error(MAE)for rotation speed(n)was 0.10 r/min,corresponding to a mean absolute percentage error(MAPE)of 1.09%.For advance rate(v),the MAE was 3.4 mm/min,with a MAPE of 4.50%.The predicted thrust(F)and torque(T)values exhibited strong agreement with field measurements,with MAEs of 270 kN and 178 kN∙m,respectively.Field applications demonstrated a 30%reduction in parameter adjustment time compared to empirical methods.This work provides a robust solution for real-time TBM control,advancing intelligent tunneling in complex geological environments.展开更多
7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because...7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because of its limited machining space,bad environment and large elongation induced low stiffness.To reduce vibration and improve machined surface quality,a particle damping boring bar,filled with particles in its inside damping block,is designed based on the theory of vibration control.The theoretical damping coefficient is determined,then the boring bar structure is designed and trial-manufactured.Experimental studies through impact testing show that cemented carbide particles with a diameter of 5 mm and a filling rate of 70% achieve a damping ratio of 19.386%,providing excellent vibration reduction capabilities,which may reduce the possibility of boring vibration.Then,experiments are setup to investigate its vibration reduction performance during deep hole boring of 7075 aluminum alloy.To observe more obviously,severe working conditions are adopted and carried out to acquire the time domain vibration signal of the head of the boring bar and the surface morphologies and roughness values of the workpieces.By comparing different experimental results,it is found that the designed boring bar could reduce the maximum vibration amplitude by up to 81.01% and the surface roughness value by up to 47.09% compared with the ordinary boring bar in two sets of experiments,proving that the designed boring bar can effectively reduce vibration.This study can offer certain valuable insights for the machining of this material.展开更多
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.
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.
文摘At present the bored construction method is one of the main construction methods of metro and tunnel construction in China. The empirical estimated formulas of tunnel ground surface settlement using the bored construction method were obtained, combining the mechanical stimulant calculated result of tunnel model of different embedded depth, different cross section and different construction method and the actual measurement data of Beijing metro construction. According to the regressed analysis of calculated data, the calculated equations of ground surface settlement value and settlement range of tunnel section under the condition of different embedded depth, different cross section and different construction method were gained. Among them there are some empirical formulas can apply to the construction design of metro tunnel directly.
文摘This paper presents some aspects of the load-settlement behavior for large diameter bored piles using four different international codes, namely: ECP 202 [1], DIN 4014 [2], AASHTO [3] and French Code [4]. Ultimate capacities for 38 pile load tests founded in realistic multi-layered soils in Delta and Port Saidareas atEgyptare evaluated using modified Chin (1970) method and compared to ultimate load predictions obtained by the aforementioned codes. Many statistical analyses were conducted on the total pile loads and individual contributions of tip and skin resistances. Based on code predictions of ultimate pile loads, an empirical modified load-settlement model is proposed. This model will simplify to a great extent the analysis of piled-raft systems as it can effortlessly predict pile settlement due to the load on pile itself. Comparisons showed that the pile load test is an irreplaceable process for determining the ultimate capacity of piles.
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.
文摘词数:345阅读难度:建议阅读时间:4分钟Well,it used to be fun.It used to be about fun and rest,but now we’re just running across the school to get to the fourth period.We used to go home and see our families but now it’s being in a dorm with some random doofus who steals your food.It used to be about easy assignments and times tables,but
基金supported by the National Key R&D Program of China(2022YFE0200400).
文摘The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model-based boring indexes(derived from rock fragmentation mechanisms)and Euclidean distance analysis to achieve real-time recommendations of TBM operational parameters.Key performance indicators-thrust(F),torque(T),and penetration(p)-were used to calculate three model-based boring indexes(a,b,k),which quantify dynamic rock fragmentation behavior.A dataset of 359 candidate samples,reflecting diverse geological conditions from the Yin-Chao water conveyance project in Inner Mongolia,China,was utilized to validate the framework.The system dynamically recommends parameters by matching real-time data with historical cases through standardized Euclidean distance,achieving high accuracy.Specifically,the mean absolute error(MAE)for rotation speed(n)was 0.10 r/min,corresponding to a mean absolute percentage error(MAPE)of 1.09%.For advance rate(v),the MAE was 3.4 mm/min,with a MAPE of 4.50%.The predicted thrust(F)and torque(T)values exhibited strong agreement with field measurements,with MAEs of 270 kN and 178 kN∙m,respectively.Field applications demonstrated a 30%reduction in parameter adjustment time compared to empirical methods.This work provides a robust solution for real-time TBM control,advancing intelligent tunneling in complex geological environments.
基金supported by the Scientific Research Program of Tianjin Education Committee(No.2022ZD030)。
文摘7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because of its limited machining space,bad environment and large elongation induced low stiffness.To reduce vibration and improve machined surface quality,a particle damping boring bar,filled with particles in its inside damping block,is designed based on the theory of vibration control.The theoretical damping coefficient is determined,then the boring bar structure is designed and trial-manufactured.Experimental studies through impact testing show that cemented carbide particles with a diameter of 5 mm and a filling rate of 70% achieve a damping ratio of 19.386%,providing excellent vibration reduction capabilities,which may reduce the possibility of boring vibration.Then,experiments are setup to investigate its vibration reduction performance during deep hole boring of 7075 aluminum alloy.To observe more obviously,severe working conditions are adopted and carried out to acquire the time domain vibration signal of the head of the boring bar and the surface morphologies and roughness values of the workpieces.By comparing different experimental results,it is found that the designed boring bar could reduce the maximum vibration amplitude by up to 81.01% and the surface roughness value by up to 47.09% compared with the ordinary boring bar in two sets of experiments,proving that the designed boring bar can effectively reduce vibration.This study can offer certain valuable insights for the machining of this material.
