Study on Pile-Soil Interaction Mechanism and Failure Modes of CFG Rigid Pile Composite Foundation in the Fluid-Plastic Soft Soil of High-Speed Railway

Composite foundation is commonly used to control the soft soil subgrade settlement. Considering that post-construction settlement of high speed railway is strictly controlled, it’s supposed to use jet grouting pile to strengthen the existed composite foundation and it’s necessary to analyse the effectiveness. Take a line as an example, analyse embankment settlement regularity of the original design mixing pile reinforcement and jet grouting pile reinforcement, evaluate the effect of the jet grouting pile reinforcement. The results show that the jet grouting pile reinforcement on the basis of original design does not have obvious effect on the embankment surface and ground surface settlement control, but effectively controls horizontal displacement at toe of slope and improves the foundation stability.

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Comparative Analysis on Neutral Point Distribution in Rigid Pile Composite Foundation on Collapsible Loess in High Speed Railway

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.90-93.471 ◽

2011 ◽

Vol 90-93 ◽

pp. 471-476

Author(s):

Chang Dan Wang ◽

Hui Su ◽

Chun Hua Zou

Keyword(s):

High Speed ◽

Neutral Point ◽

Composite Foundation ◽

Stable Range ◽

Point Distribution ◽

Pile Spacing ◽

Rigid Pile ◽

Collapsible Loess ◽

Pile Cap ◽

Rigid Pile Composite Foundation

To research and analyze the neutral point distribution of rigid pile composite foundation on collapsible loess ground in high speed railway, the centrifuge model tests are used to imitate pile raft composite foundation and pile net composite foundation in different pile spacing based on the experimental study at home and abroad. The research results show that the movement of negative skin friction and the position of neutral point which is drop conspicuously with larger pile spacing are a continuous changing process in composite foundation. In the pile spacing 2D,4D,6D of pile raft composite foundation, the stable range of neutral point position are 0.25(the pile length ratio), 0.59,0.63 separately in post-construction stage. In the pile spacing 2D(no pile-cap),4D(no pile-cap),4D(pile-cap),6D(pile-cap) of pile net composite foundation, the stable range of neutral point position are 0.37to0.43(the pile length ratio),0.50,0.80,0.81separately in post-construction stage. The pile-cap setting has more influence on Neutral point distribution. Suggestions are given that the waterproof and drainage measures in foundation must be considered when setting up composite foundation on collapsible loess.

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The Dynamic Analysis of Soft Soil Subgrade in High-Speed Railway Strengthened by PHC Pile

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1030-1032.908 ◽

2014 ◽

Vol 1030-1032 ◽

pp. 908-911 ◽

Cited By ~ 3

Author(s):

Zhen Hua Pan ◽

Kong Ming Yan ◽

Jin Biao Wu ◽

Zhe Wang ◽

Wei Ming Liao

Keyword(s):

Prestressed Concrete ◽

High Speed ◽

Dynamic Stress ◽

Soft Soil ◽

Time History ◽

Composite Foundation ◽

High Speed Train ◽

High Speed Railway ◽

Soft Soil Area ◽

Soil Area

The combination of PHC pile (prestressed concrete pile) with geogrid to reinforce the foundation has been widely used in high-speed railway, and the response of dynamic stress under the high-speed train is worth studying. By using Midas/GTS NX software to establish a 3-D model of pile-net composite foundation in one section of Hangzhou - Shenzhen line, the influence of pile-net composite foundation generated by high-speed train is studied. Moreover, this paper also studies the distribution and propagation of dynamic stress generated by train load in soft soil area. The results show that the dynamic stress reducing quickly in the embankment structure and the time –history curve of the dynamic stress behaves differently along the depth. With the depth increasing, there is phenomenon of peak superposition in the time-history curve of the vertical dynamic stress. In the meanwhile, the PHC pile is the main structure to propagate and sustain the dynamic stress in soft soil area, and with the tendency of ‘large in the middle, small on both ends’.

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An Analysis on Failure Pattern of CFG Pile-Net Composite Foundation of High-Speed Railway

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.594-597.1357 ◽

2012 ◽

Vol 594-597 ◽

pp. 1357-1362

Author(s):

Dan Ping Jiang ◽

Bing Long Wang

Keyword(s):

High Speed ◽

Shear Failure ◽

Soft Soil ◽

Composite Foundation ◽

Failure Pattern ◽

Lagrangian Analysis ◽

High Speed Railway ◽

Foundation Treatment ◽

Sliding Soil ◽

Cfg Pile

CFG pile-net composite foundation has the advantages of small post construction settlement and uneven settlement, easy control of construction quality and fast construction speed. It`s widely used in subgrade engineering of high-speed railway. However, in coastal soft soil area, phenomena like breaking pile, collapsed embankment, cracking in embankment surface, undue settlement or convergence appeared in many places where railway CFG pile was improved during the foundation treatment, filling and preloading. Four numerical calculations were performed to investigate the failure pattern of CFG pile-net composite foundation with FLAC3D ( Fast Lagrangian Analysis of Continua, 3 dimensions) software. The paper describes four failure pattern, they are slip circle shear failure, pile tilt failure, roadbed sliding, soil sliding at pile end respectively through the analysis of the embankment and pile displacement as well as embankment deformation.

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Character Analysis of Balance and Imbalance of Varying Rigidity of Rigid Pile Composite Foundation under Seismic Load

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1065-1069.19 ◽

2014 ◽

Vol 1065-1069 ◽

pp. 19-22

Author(s):

Zhen Feng Wang ◽

Ke Sheng Ma

Keyword(s):

Finite Element ◽

Bending Moment ◽

Horizontal Displacement ◽

Element Model ◽

Composite Foundation ◽

Seismic Load ◽

Seismic Loads ◽

Element Analysis ◽

Rigid Pile ◽

Rigid Pile Composite Foundation

Based on ABAQUS finite element analysis software simulation, the finite element model for dynamic analysis of rigid pile composite foundation and superstructure interaction system is established, which selects the two kinds of models, by simulating the soil dynamic constitutive model, selecting appropriate artificial boundary.The influence of rigid pile composite foundation on balance and imbalance of varying rigidity is analyzed under seismic loads. The result shows that the maximum bending moment and the horizontal displacement of the long pile is much greater than that of the short pile under seismic loads, the long pile of bending moment is larger in the position of stiffness change. By constrast, under the same economic condition, the aseismic performance of of rigid pile composite foundation on balance of varying rigidity is better than that of rigid pile composite foundation on imbalance of varying rigidity.

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