scholarly journals Modeling Test and Numerical Simulation of Vertical Bearing Performance for Rigid-Flexible Composite Pouch Piles with Expanded Bottom (RFCPPEB)

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 107
Author(s):  
Xinquan Wang ◽  
Yichen Que ◽  
Kangyu Wang ◽  
Hongguo Diao ◽  
Yunliang Cui ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Bearing Capacity ◽  
Expansion Ratio ◽  
Ultimate Bearing Capacity ◽  
Pipe Pile ◽  
Shaft Resistance ◽  
Cemented Soil ◽  
Distribution Rule ◽  
Tip Resistance ◽  
Vertical Bearing

Rigid-flexible composite pouch piles with expanded bottom (RFCPPEB) are generally considered as new symmetrical piles in practical engineering, but their bearing characteristics and design method are still not completely understood. The objective of this study is to investigate the vertical bearing performance and the optimal design scheme of RFCPPEB. Hence, laboratory modeling tests for this symmetric structure and an ABAQUS three-dimensional (3D) numerical simulation analysis were used to study the vertical bearing characteristics on bottom-expanded piles and rigid-flexible composite piles with expanded bottom. The vertical bearing capacity, shaft resistance, pile tip resistance distribution rule, and load sharing ratio of RFCPPEB were analyzed and verified using different bottom expansion dimensions and cemented soil thicknesses. The results revealed that the optimal bottom expansion ratio of rigid bottom-expanded piles was 1.8 when the ratio of pile body to bottom-expanded pile head was 9:1. When the bottom expansion ratio (D/d) was increased, the bearing capacity of bottom-expanded piles was significantly increased at D/d = 1.4 and D/d = 1.8 compared to that of D/d = 1.0, reaching 1.67 and 2.29 times, respectively, while for D/d = 1.6 and D/d = 2.0, the ultimate bearing capacity remained unchanged. Besides, shaft resistance played an important role in the bearing process of the rigid bottom-expanded piles and RFCPPEB. When the shaft resistance was increased, the ultimate bearing capacity of the pile foundation was significantly improved. The shaft resistance of RFCPPEB was increased with increasing cemented soil thickness. The increases in the shaft resistance and thickness of the cemented soil showed a nonlinear growth, and the maximum shaft resistance was approximately 75 cm from the pile top. When the diameter of the expanded head was 1.8 times the diameter of the pipe pile and slightly larger than the thickness of the cemented soil (0.5 times the diameter of the pipe pile), the optimal amount of concrete 425.5 kN/m3 required for per unit volume around piles was obtained, with the RFCPPEB ultimate bearing capacity of 7.5 kN. For RFCPPEB, the soil pressure at the pile tip was directly proportional to the pile top load under small load and was decreased in the form of a half quadric curve under large load. It reached the most reasonable position where the slope of the quadric curve was the largest when the thickness of the cemented soil was larger than 0.5 times the diameter of the pipe pile.

Analysis of Distribution Characteristics and Reliability for Bearing Capacity of Piles

2014 ◽  
Vol 638-640 ◽  
pp. 365-369
Author(s):  
Shu Jun Zhang ◽  
Zhi Jun Xu ◽  
Kai Wang ◽  
Bo Zhang
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Distribution Characteristics ◽  
Driven Piles ◽  
Performance Function ◽  
Shaft Resistance ◽  
Bored Pile ◽  
Tip Resistance ◽  
Bored Piles ◽  
The Impact

This paper aims to study the distribution characteristics of the ratio of measured value and calculated value for ultimate bearing capacity, shaft resistance and tip resistance, and discuss the impact of shaft resistance and tip resistance on ultimate bearing capacity. A new performance function is proposed in terms of the three types of bearing capacity mentioned ahead. Take bored piles and driven piles for example, and the results from analysis indicate that the ratio of the measured value to calculated value of bored piles ranges from 0.75 to 1.45, and mostly is greater than 1.0; The ratio of the measured to predicted bearing capacity of driven piles lies between 0.8 and 1.5, and is larger than the corresponding ratio of bored piles. In addition, the reliability of tip resistance is lager than that of shaft resistance for bored pile, while the reliability of tip resistance is less than that of shaft resistance for driven piles. Meanwhile, the method presented in this paper can offer references to designers for revising and improving the technical code for pile foundations.

scholarly journals Study on the vertical bearing performance of pile across cave and sensitivity of three parameters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hui Yun Chen ◽  
Zhong Ju Feng ◽  
Tie Li ◽  
Shao Fen Bai ◽  
Cong Zhang
Keyword(s):  
Theoretical Model ◽  
Bearing Capacity ◽  
Axial Force ◽  
Ultimate Bearing Capacity ◽  
The Other ◽  
Karst Cave ◽  
Shaft Resistance ◽  
Karst Caves ◽  
Vertical Bearing ◽  
Centrifugal Model

AbstractA new method was used to study the performance of pile across cave. This paper investigated the vertical bearing characteristics of piles cross caves using centrifugal model tests and a theoretical model of sensitivity. Twelve pile scenarios were selected, the first was a conventional pile, 24 cm long and 2.5 cm in diameter, with no karst cave as a control. In the other eleven scenarios the piles passed through karst caves of four different heights, of four different spans, and three different numbers of caves. The results reveal that increasing the height, span, and number of caves all are negative for vertical ultimate bearing capacity of piles. The axial force and unit shaft resistance of piles are great different. According to the ratios of the tip and shaft resistance, caves change the type of piles. The sensitivity of vertical ultimate bearing capacity to these factors from high to low is height, number, and span of caves. Importantly, the bearing characteristics of piles decrease faster once the height of the prototype karst cave is higher than 9 m, but decreases slowly when the cave’s span is greater than 9 m × 9 m.

Study on Vertical Bearing Capacity and Time Effect of the Jacked-in PHC Pipe Pile in the Cohesive Soil Area

2011 ◽  
Vol 368-373 ◽  
pp. 2706-2710
Author(s):  
Hong Liang Zuo ◽  
Lei Wang ◽  
Hong Ying Gao ◽  
Liang Guo
Keyword(s):  
Bearing Capacity ◽  
Cohesive Soil ◽  
Ultimate Bearing Capacity ◽  
Time Effect ◽  
Load Test ◽  
Static Load Test ◽  
Empirical Coefficient ◽  
Pipe Pile ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

The static load test of 34 jacked-in PHC pipe piles of medium length are performed in the cohesive soil area, the relationship between the vertical ultimate bearing capacity and the final pressure, and the time effect of vertical bearing capacity of the jacked-in PHC pipe pile are studied. The data of static load test is analyzed statistically with software SPSS, the regional empirical coefficient about the vertical ultimate bearing capacity and final pressure, and the time effect formula about vertical bearing capacity of the jacked-in PHC pipe pile in the cohesive area are obtained. According to the regional empirical coefficient, the pile pressing machine and counterweight can be chosen reasonably and the vertical ultimate bearing capacity of single pile can also be estimated rapidly, then we can instruct the design and construction of the jacked-in PHC pipe pile. According to the time effect formula, the vertical bearing capacity at different periods of the jacked-in PHC pipe pile can be obtained, the cost of the foundation engineering can be reduced by considering the time effect influence to the vertical bearing capacity of the jacked-in PHC pipe pile.

scholarly journals Calculation of Ultimate Bearing Capacity of Pile Foundations of Highway Bridges under the Coupling of Steep Slope and Karst

2020 ◽  
Vol 198 ◽  
pp. 02017
Author(s):  
Zhongju Feng ◽  
Shaofen Bai ◽  
Wu Min ◽  
Jingbin He ◽  
Zhouyi Huang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Pile Foundation ◽  
Highway Bridges ◽  
Ultimate Bearing Capacity ◽  
Steep Slope ◽  
Karst Area ◽  
Correction Coefficient ◽  
Finite Element Software ◽  
Calculation Results ◽  
Vertical Bearing

In order to study the influence of steep slope-karst coupling on the vertical bearing characteristics of pile foundation, the orthogonal simulation tests of pile foundation under 4 different roof thickness and 5 different slope are carried out by using Marc finite element software, and the correction coefficient of vertical partial bearing capacity of pile foundation according to roof thickness and slope is put forward. The test results show that when the thickness of the roof is more than 3 times the pile diameter, the ultimate bearing capacity of the pile foundation tends to be stable, and the value is about 19% when the slope is 45°; the ultimate bearing capacity of the pile foundation decreases gradually with the increase of the slope, and the reduction reaches 29.83% when the slope is greater than 45°. According to the calculation results, the variation law of vertical partial bearing capacity of pile foundation is analyzed, and the calculation formula of standard value of vertical ultimate bearing capacity of pile foundation in steep slope karst area considering both roof thickness and slope is put forward, and the correction coefficients αi and β are put forward.

scholarly journals Static Load Test and Numerical Analysis of Influencing Factors of the Ultimate Bearing Capacity of PHC Pipe Piles in Multilayer Soil

2021 ◽  
Vol 13 (23) ◽  
pp. 13166
Author(s):  
Xusen Li ◽  
Jiaqiang Zhang ◽  
Hao Xu ◽  
Zhenwu Shi ◽  
Qingfei Gao
Keyword(s):  
Numerical Analysis ◽  
Bearing Capacity ◽  
Influencing Factors ◽  
Static Load ◽  
Young Modulus ◽  
Ultimate Bearing Capacity ◽  
Load Test ◽  
Freezing Stress ◽  
Static Load Test ◽  
Tip Resistance

Prestressed high-strength concrete (PHC) pipe piles have been widely used in engineering fields in recent years; however, the influencing factors of their ultimate bearing capacity (UBC) in multilayer soil need to be further studied. In this paper, a static load test (SLT) and numerical analysis are performed to obtain the load transfer and key UBC factors of pipe piles. The results show that the UBC of the test pile is mainly provided by the pile shaft resistance (PSR), but the pile tip resistance (PTR) cannot be ignored. Many factors can change the UBC of pipe piles, but their effects are different. The UBC of the pipe pile is linearly related to the friction coefficient and the outer-to-inner diameter ratio. Changes in the pile length make the UBC increase sharply. Low temperatures can produce freezing stress at the pile–soil interface. The effect of changing the Young modulus of pile tip soil is relatively small.

Time Effect of the Pile Bearing Capacity in Dredger Fill

2013 ◽  
Vol 639-640 ◽  
pp. 630-638
Author(s):  
Hua Yang Lei ◽  
Qian Qian Lv
Keyword(s):  
Numerical Simulation ◽  
Bearing Capacity ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ultimate Bearing Capacity ◽  
Time Effect ◽  
Second Phase ◽  
Excess Pore Water Pressure ◽  
Excess Pore

The dissipating of pore water pressure caused by pile sinking is one of the main factors resulting in time effect of ultimate bearing capacity of pile.The pore water pressure is monitored at each observing point during pile sinking and after that. With the pore pressure plan embedded in advance, by means of spot test in the process of pile sinking, under this geological conditions of the pile foundation by referring to the second phase project of the free port logistics processing zone in Dongjiang, Tianjin.The change law of the distribution and dissipation of excess pore water pressure with time, depth, radial distance and permeability coefficient of soil was also discussed. It’s found that the excess pore water pressure attenuates approximately linearly with the increase of the distance from the pile heart and the scope influenced is around 10d. As the numerical simulation accord with the test results effectively, promote the results then get the change rule of pile bearing capacity with time.The formula of pile bearing capacity about time effect in dredge fill was deduced for engineering reference.The effect of soil internal friction angle on the ultimate bearing capacity of pile was discussed. Numerical simulation shows that the ultimate bearing capacity of pipe pile increases over time and keeps stable after 20d.The ultimate limit bearing capacity is 1473kN with increase of 12.3%, the time when it reaches the stable state is in accord with the excess pore water pressure dissipation monitored at each observing point. The larger the internal frictional angle of soil becomes, the more the ultimate bearing capacity is. The angle exceeding 20°,the bearing capacity would not increase as internal frictional angle of soil increases.

Time Effect Research of Prestressed Pipe Pile Based on High Strain Dynamic Test

2012 ◽  
Vol 256-259 ◽  
pp. 531-534
Author(s):  
Jia Tao Wang ◽  
Hong Li Zhao
Keyword(s):  
Bearing Capacity ◽  
High Strain ◽  
Dynamic Test ◽  
Ultimate Bearing Capacity ◽  
Time Effect ◽  
Load Test ◽  
Single Pile ◽  
Dead Load ◽  
Pipe Pile ◽  
Effect Mechanism

More detailed information about the bearing capacity and integrity of the pile can be obtained by high strain dynamic test than by dead-load test [1]. Engineering examples show that the bearing capacity of the prestressed pipe pile gradually increase with the growth of the resting time, and the ultimate bearing capacity of the pile can reach up to 2 times more than the initial bearing capacity. Through the study of the time effect mechanism, it is found that the increment of ultimate bearing capacity of the single pile is mainly caused by side soil resistance. The end resistance has little influence on the time effect of bearing capacity of pile.

Prediction of Ultimate Bearing Capacity of Prestressed Pipe Pile Based on BP Neural Network

2011 ◽  
Vol 101-102 ◽  
pp. 228-231
Author(s):  
Jian Ping Jiang
Keyword(s):  
Neural Network ◽  
Bearing Capacity ◽  
Bp Neural Network ◽  
Ultimate Bearing Capacity ◽  
Pipe Pile ◽  
Absolute Value ◽  
Independent Variables ◽  
Average Value ◽  
Standard Value ◽  
Bp Neural Network Model

Based on BP neural network, this paper had a prediction on ultimate bearing capacity of prestressed pipe pile. Taking pile diameter, effective pile length, ultimate average value of friction standard value, ultimate average value of end resistance standard value as influences factors, the prediction model of pile bearing capacity based on BP neural network was obtained. It was found that, the average value of absolute value for the relative error of fitting value of pile bearing capacity compared with the observed value for 70 groups of independent variables training BP neural network model was 3.1498%; And the average value of absolute value for the relative error of prediction value of pile bearing capacity compared with the observed value for 10 groups of independent variables validating BP neural network model was 3.50126% whose precision was better than ANFIS’5.32293%. The following conclusion can be drawn that, the prediction model of ultimate bearing capacity of prestressed pipe pile based on BP neural network is feasible.

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