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Bearing behavior of pile foundation in karst region: Physical model test and finite element analysis Cover

Bearing behavior of pile foundation in karst region: Physical model test and finite element analysis

Applied Rheology
Volume 34 (2024): Issue 1 (January 2024)
By: Minghong Sheng,  Fangqing Lu,  Nan Jiang,  Panpan Guo,  Xian Li,  Ran An and  Yixian Wang  
Open Access
|Feb 2024

Figures & Tables

Figure 1

Distribution of karst in China and types and subtypes of karst danger: subtype A1 – collapse sinkholes; subtype A2 – the karst hazard resulting from local subsidence; subtype A3 – a karst hazard caused by an old sinkhole on construction; subtype A4 – threat of differential foundation settlement; subtype A5 – karst hazard created by slow subsidence; and subtype A6 – hazards related to karst (karst-suffosion) soil slumps.
Distribution of karst in China and types and subtypes of karst danger: subtype A1 – collapse sinkholes; subtype A2 – the karst hazard resulting from local subsidence; subtype A3 – a karst hazard caused by an old sinkhole on construction; subtype A4 – threat of differential foundation settlement; subtype A5 – karst hazard created by slow subsidence; and subtype A6 – hazards related to karst (karst-suffosion) soil slumps.

Figure 2

Experimental system: (a) model system, (b) monitoring system; (c) data processing system, and (d) device connection field diagram.
Experimental system: (a) model system, (b) monitoring system; (c) data processing system, and (d) device connection field diagram.

Figure 3

Experimental arrangement: (a) model of variable height of cave and (b) model of variable span of cave.
Experimental arrangement: (a) model of variable height of cave and (b) model of variable span of cave.

Figure 4

Laboratory equipment: (a) strain-measuring instrument, (b) strain gauge, (c) dial indicators, (d) soil pressure box, (e) model box, and (f) jack reaction loading device.
Laboratory equipment: (a) strain-measuring instrument, (b) strain gauge, (c) dial indicators, (d) soil pressure box, (e) model box, and (f) jack reaction loading device.

Figure 5

Pile lateral resistance calculation diagram.
Pile lateral resistance calculation diagram.

Figure 6

Arrangement of strain gauges and earth pressure box.
Arrangement of strain gauges and earth pressure box.

Figure 7

Weight loading.
Weight loading.

Figure 8

Q–s curve of monopile pile top: (a) different cave heights and (b) different cave spans.
Q–s curve of monopile pile top: (a) different cave heights and (b) different cave spans.

Figure 9

P b –s curve of monopile pile tip: (a) different cave heights and (b) different cave spans.
P b –s curve of monopile pile tip: (a) different cave heights and (b) different cave spans.

Figure 10

Axial force distribution curve of pile body (h × D = 3 m × 6 m).
Axial force distribution curve of pile body (h × D = 3 m × 6 m).

Figure 11

Finite element analysis model: (a) meshing and (b) central profile.
Finite element analysis model: (a) meshing and (b) central profile.

Figure 12

Gradual damage process of pile foundation under vertical graded loading (Unit: Pa, h × D = 3 m × 6 m): (a) 2,500 kN, (b) 5,000 kN, (c) 7,500 kN, and (d) 10,000 kN.
Gradual damage process of pile foundation under vertical graded loading (Unit: Pa, h × D = 3 m × 6 m): (a) 2,500 kN, (b) 5,000 kN, (c) 7,500 kN, and (d) 10,000 kN.

Figure 13

Pile axial force distribution curve along the pile length.
Pile axial force distribution curve along the pile length.

Figure 14

Distribution of pile lateral frictional resistance along the pile length (h × D = 3 m × 6 m).
Distribution of pile lateral frictional resistance along the pile length (h × D = 3 m × 6 m).

Figure 15

Q–s curves of monopile tops at different cavity heights.
Q–s curves of monopile tops at different cavity heights.

Figure 16

Q–s curves of monopile tops at different cavity spans.
Q–s curves of monopile tops at different cavity spans.

Figure 17

Ultimate bearing capacity of pile foundation for different: (a) cave height; (b) cave span.
Ultimate bearing capacity of pile foundation for different: (a) cave height; (b) cave span.

Program of numerical simulation

Height of cave (h/m)Cave span (D/m)Pile diameter (d/m)Distance from the bottom of the cavity to the bottom of the pile (m)
133, 4, 61.03
22, 3, 461.03

Mechanical parameters of the prototype limestone material and pile

Material ρ (g/cm3) σ c (MPa) E (MPa) c (kPa) φ (°)
Strongly weathered limestone2.4828.33,00080032
Moderately weathered limestone2.78814,0001,20038
Pile2.48—24,0002,060—

Mechanical parameters of similar materials

Mix proportion ρ (g/cm3) σ c (MPa) E (MPa) c (kPa) φ (°)
Q:G:C:R:D:L = 66:10:10:4:4:61.7881.93328.9332.38 35.50
Q:G:C:R:D:L = 80:3:3:6:6:21.763 0.6242.0719.9132.03
Q:G:C:R:D:L = 66:12:12:4:4:21.7272.57448.5338.2136.01

Loading load-level design

Tag (times)012345678910
Load class (kN)02468101214161820

Program of physical model test simulation

Height of cave (h/cm)Cave span (D/cm)Pile diameter (d/cm)Distance from the bottom of the cavity to the bottom of the pile/cm
11010, 13.3, 203.310
26.7, 1, 13.3203.310

Material parameters

Similar material γ (kN/m3) E (MPa) υ c (kPa) φ (°)
Strongly weathered limestone24.82,0000.33032
Moderately weathered limestone2714,0000.2530038
Pile2524,0000.2——

Targeted parameters of the similar materials obtained using the corresponding ratio of similitude

Similar material ρ (g/cm3) σ c (MPa) E (MPa) c (kPa) φ (°)
Strongly weathered limestone1.670.6366.6717.7732
Moderately weathered limestone1.81.95311.1126.6738
Pile1.67—533.3345.7—
DOI: https://doi.org/10.1515/arh-2023-0115 | Journal eISSN: 1617-8106
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Language: English
Submitted on: Oct 7, 2023
Accepted on: Jan 19, 2024
Published on: Feb 23, 2024
Published by: Sciendo
In partnership with: Paradigm Publishing Services
Keywords:
pile bearing capacity,
physical model tests,
karst,
numerical analyses
Related subjects:
Physics,
Mechanics and fluid dynamics,
Materials sciences,
Polymers,
Industrial chemistry,
Polymer science and technology,
Chemistry,
Macromolecular chemistry

© 2024 Minghong Sheng, Fangqing Lu, Nan Jiang, Panpan Guo, Xian Li, Ran An, Yixian Wang, published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 License.

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