Recently,the use of deep foundations has increased as a result of the expansion in the construction of high-rise buildings,train tracks,and port berths.As a result of this expansion,it was necessary to use deep founda...Recently,the use of deep foundations has increased as a result of the expansion in the construction of high-rise buildings,train tracks,and port berths.As a result of this expansion,it was necessary to use deep foundations that have low cost,high bearing loads,low settlement,and construction time,and such foundations are subjected to different types of loads such as lateral,vertical compression,and tension loads.This research paper will present one of the most important types of deep foundations that are aptly used in such structures and the most important factors affecting their bearing capacity and settlement in stiff clay.This type of deep foundation is called an under-reamed pile.The factors used in this study are pile length to diameter ratio L/D=30,bulb diameter ratio(Du/D=1.5,2,2.25,and 2.5),number of bulbs(N=1,2,and 3),and spacing ratio(S/D=2 to 8).To investigate the effects of these parameters and obtain optimal results,the PLAXIS 3D was used.The analysis shows that the increase in bulb diameter increases the bearing load by 43%.Bulb spacing controls the failure mechanisms,whether cylindrical shear failure or individual failure and increases the capacity by 66%and 99%,respectively,for two and three bulbs when the bulb spacing becomes S/D=8.When the number of bulbs increases to three,the capacity increases by 90%.If each bulb works individually,the bearing capacity doubles.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
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
深挖掘的一个完全的盒子被探索。根据实际工作条件, 3D 非线性的有限元素过程被用来模仿合成土壤支持的深挖掘有在软土壤的无聊的堆积的钉的墙。修改凸轮泥土模特儿在数字模拟作为土壤的组成的关系被雇用。从数字分析的结果与领域数据...深挖掘的一个完全的盒子被探索。根据实际工作条件, 3D 非线性的有限元素过程被用来模仿合成土壤支持的深挖掘有在软土壤的无聊的堆积的钉的墙。修改凸轮泥土模特儿在数字模拟作为土壤的组成的关系被雇用。从数字分析的结果与领域数据被适合很好,它显示使用的研究途径是可靠的。基于数据和钉的合成土壤的四个不同模式支持的深挖掘的数字结果围的地,重要角落效果深在 3D 被成立挖掘。如果无聊的堆积或土壤锚在钉的合成土壤被认为墙,他们对减少的变丑和在深挖掘附近的无聊的堆积,混合堆积的水泥,土壤锚,土壤钉和土壤的内部力量有益。而且,效果由于无聊的堆积比从土壤锚推出的那些更重要。上面提及的所有证明合成土壤与无聊的堆积钉了墙在深挖掘是可行的。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
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
The precise prediction of maximum load carrying capacity of bored piles is a complex problem because the load is a function of a large number of factors. These factors include method of boring, method of concreting, q...The precise prediction of maximum load carrying capacity of bored piles is a complex problem because the load is a function of a large number of factors. These factors include method of boring, method of concreting, quality of concrete, expertise of the construction staff, the ground conditions and the pile geometry. To ascertain the field performance and estimate load carrying capacities of piles, in-situ pile load tests are conducted. Due to practical and time constraints, it is not possible to load the pile up-to failure. In this study, field pile load test data is analyzed to estimate the ultimate load for friction piles. The analysis is based on three pile load test results. The tests are conducted at the site of The Cultural and Recreational Complex project in Port Said, Egypt. Three pile load tests are performed on bored piles of 900 mm diameter and 50 m length. Geotechnical investigations at the site are carried out to a maximum depth of 60 m. Ultimate capacities of piles are determined according to different methods including Egyptian Code of practice (2005), Tan-gent-tangent, Hansen (1963), Chin (1970), Ahmed and Pise (1997) and Decourt (1999). It was concluded that approxi- mately 8% of the ultimate load is resisted by bearing at the base of the pile, and that up to 92% of the load is resisted by friction along the shaft. Based on a comparison of pile capacity predictions using different method, recommendations are made. A new method is proposed to calculate the ultimate capacity of the pile from pile load test data. The ultimate capacity of the bored piles predicted using the proposed method appears to be reliable and compares well to different available methods.展开更多
文摘Recently,the use of deep foundations has increased as a result of the expansion in the construction of high-rise buildings,train tracks,and port berths.As a result of this expansion,it was necessary to use deep foundations that have low cost,high bearing loads,low settlement,and construction time,and such foundations are subjected to different types of loads such as lateral,vertical compression,and tension loads.This research paper will present one of the most important types of deep foundations that are aptly used in such structures and the most important factors affecting their bearing capacity and settlement in stiff clay.This type of deep foundation is called an under-reamed pile.The factors used in this study are pile length to diameter ratio L/D=30,bulb diameter ratio(Du/D=1.5,2,2.25,and 2.5),number of bulbs(N=1,2,and 3),and spacing ratio(S/D=2 to 8).To investigate the effects of these parameters and obtain optimal results,the PLAXIS 3D was used.The analysis shows that the increase in bulb diameter increases the bearing load by 43%.Bulb spacing controls the failure mechanisms,whether cylindrical shear failure or individual failure and increases the capacity by 66%and 99%,respectively,for two and three bulbs when the bulb spacing becomes S/D=8.When the number of bulbs increases to three,the capacity increases by 90%.If each bulb works individually,the bearing capacity doubles.
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Foundation item: Project(2009-K3-2) supported by the Ministry of Housing and Urban-Rural Development of China
文摘深挖掘的一个完全的盒子被探索。根据实际工作条件, 3D 非线性的有限元素过程被用来模仿合成土壤支持的深挖掘有在软土壤的无聊的堆积的钉的墙。修改凸轮泥土模特儿在数字模拟作为土壤的组成的关系被雇用。从数字分析的结果与领域数据被适合很好,它显示使用的研究途径是可靠的。基于数据和钉的合成土壤的四个不同模式支持的深挖掘的数字结果围的地,重要角落效果深在 3D 被成立挖掘。如果无聊的堆积或土壤锚在钉的合成土壤被认为墙,他们对减少的变丑和在深挖掘附近的无聊的堆积,混合堆积的水泥,土壤锚,土壤钉和土壤的内部力量有益。而且,效果由于无聊的堆积比从土壤锚推出的那些更重要。上面提及的所有证明合成土壤与无聊的堆积钉了墙在深挖掘是可行的。
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.
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The precise prediction of maximum load carrying capacity of bored piles is a complex problem because the load is a function of a large number of factors. These factors include method of boring, method of concreting, quality of concrete, expertise of the construction staff, the ground conditions and the pile geometry. To ascertain the field performance and estimate load carrying capacities of piles, in-situ pile load tests are conducted. Due to practical and time constraints, it is not possible to load the pile up-to failure. In this study, field pile load test data is analyzed to estimate the ultimate load for friction piles. The analysis is based on three pile load test results. The tests are conducted at the site of The Cultural and Recreational Complex project in Port Said, Egypt. Three pile load tests are performed on bored piles of 900 mm diameter and 50 m length. Geotechnical investigations at the site are carried out to a maximum depth of 60 m. Ultimate capacities of piles are determined according to different methods including Egyptian Code of practice (2005), Tan-gent-tangent, Hansen (1963), Chin (1970), Ahmed and Pise (1997) and Decourt (1999). It was concluded that approxi- mately 8% of the ultimate load is resisted by bearing at the base of the pile, and that up to 92% of the load is resisted by friction along the shaft. Based on a comparison of pile capacity predictions using different method, recommendations are made. A new method is proposed to calculate the ultimate capacity of the pile from pile load test data. The ultimate capacity of the bored piles predicted using the proposed method appears to be reliable and compares well to different available methods.