# Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai

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## Abstract

**:**

## 1. Introduction

## 2. Engineering Geological Conditions

## 3. Parameter Calibration and Model Setting

#### 3.1. Model Analysis

^{−4}–10

^{−6}) [27,28,29]. The main model parameters include the dynamic shear modulus, triaxial drainage test secant modulus, and shear strain level. In order to accurately obtain the required HSS parameters, laboratory experiments under various loading conditions were carried out using resonance columns, triaxial consolidation drainage shearing, and triaxial consolidation drainage loading and unloading tests. This paper takes the resonant column test results as an example calibration of the dynamic shear modulus in the HSS model. Saturated silt samples under different confining pressures are selected for the resonance column test. The dynamic shear modulus of the samples in the small strain range was measured as a function of the strain amplitude, as shown in Figure 3.

_{d}—γ

_{d}) characteristic curve can be described by a hyperbolic model, that is, 1/G

_{d}= a + b × γ

_{d}. The obtained relationship curve is shown in Figure 3b. a and b are test constants whose values can be obtained through regression statistical analysis of the test data. When γ

_{d}tends to zero, 1/G

_{d}tends to a and G

_{d}is represented by G

_{0}, that is, G

_{0}= 1/a, where G

_{0}is the initial shear modulus. The reference dynamic shear modulus, ${G}_{0}^{ref}$, of each sample under the reference confining pressure, P

^{ref}= 100 kPa, can be calculated by:

#### 3.2. Simulation of the Complex Hydraulic Load Process

- (1)
- Balance the ground stress, select gravity loading for the calculation type, and select the phreatic level for the pore pressure calculation type;
- (2)
- Activate the plain concrete piles, select the plasticity calculation for the calculation type and the phreatic water level for the pore pressure calculation type;
- (3)
- Activate the subgrade and pavement, select the plastic calculation for the calculation type, and select the phreatic level for the pore pressure calculation type;
- (4)
- Eliminate excess pore pressure generated by pile formation, choose the consolidation calculation for the calculation type, and use the previous stage pressure for the pore pressure calculation type. This fourth step aims to eliminate the influence of self-settlement of the pile and soil in the subsequent simulation process. After this calculation, the displacement is cleared to zero; that is, the subsequent excess pore pressure, displacement, and deformation are the net excess pore pressure, net displacement, and net deformation caused by changes in external conditions, respectively;
- (5)
- Apply tidal water-level changes (tidal action, maintained level after the water level rises sharply, and maintain level after the water level falls sharply). Select fluid–solid coupling for calculation type to analyze the simultaneous development of deformation and pore pressure in the soil. The method takes the vertical boundary of the land area on the left side of the model as a fixed water head that is consistent with the mean sea level (0.5 m). The right side of the model is the initial water level of 0.5 m, and three groups of time-related variable head groundwater seepage boundaries are considered.

## 4. Results and Discussion

#### 4.1. Model Validation

#### 4.2. Deformation Law of Foundation Soft Soil

#### 4.3. Pile Axial Force and Bending Moment

#### 4.4. Pore Water Pressure and Mean Effective Stress

## 5. Conclusions

- (1)
- Based on the resonance column, triaxial consolidation drainage shear, triaxial consolidation drainage loading and unloading shear, and basic physical property tests, the HSS model parameters of typical silt and silty soil layers in the construction area were calibrated. Reliable parameters of the Zhuhai soft soil HSS model were determined. Compared with the soft soil in coastal areas, such as the Yangtze River Delta and Bohai Bay, Zhuhai soft soil exhibits worse engineering properties, including smaller dynamic shear modulus, cohesion, and internal friction angle.
- (2)
- Through numerical simulations, the deformation laws of the composite foundation under three cases of cyclic tidal action, water-level maintenance after sudden rise and drop are explored. Since the sea level rises the most under the condition of a sudden water-level rise and the rightmost side of the composite foundation is closest to the dike, the deformation of the pile foundation near the sea of the composite foundation is the largest, which is the most unfavorable condition among the three cases.
- (3)
- Under the three cases, the relative displacement of the No. 1 pile on the offshore side and the No. 21 pile on the far seaside in the composite foundation is small. The risk of problems, such as inclination, extrusion, and cracking of the composite foundation superstructure, is relatively small. The maximum deformation of the pile occurs at the No. 1 pile on the offshore side and its upper part passes through the dredger fill layer with a large permeability coefficient. Under the influence of groundwater seepage, the pile may cause a large horizontal displacement and tilt. After checking the calculation, deformation and force are less than the standard design value, so no additional protective measures were taken in the construction process.
- (4)
- The hydraulic load increases the axial force and bending moment of the pile, which needs to be considered for actual engineering. The average effective stress in the composite foundation corresponds to the changing trend in the pore water pressure, showing a changing law of ebb and flow.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- Lin, D.F.; Lin, K.L.; Hung, M.J.; Luo, H.L. Sludge Ash/Hydrated Lime on the Geotechnical Properties of Soft Soil. J. Hazard. Mater.
**2007**, 145, 58–64. [Google Scholar] [CrossRef] - Burland, J.B. On the Compressibility and Shear Strength of Natural Clays. Geotechnique
**1990**, 40, 329–378. [Google Scholar] [CrossRef] - Tavenas, F.; Leroueil, S. The Behaviour of Embankments on Clay Foundations. Can. Geotech. J.
**1980**, 17, 236–260. [Google Scholar] [CrossRef] - Jean, P.; Leblond, P. The Permeability of Natural Soft Clays. Part Ⅱ: Permeability Characteristics. Can. Geotech. J.
**1983**, 20, 645–660. [Google Scholar] - Lin, Y.; Ai, K.; Huang, L. Issues of Engineering Characteristics and Engineering Construction of Soft Clay in Zhuhai Region. Chinese J. Rock Mech. Eng.
**2006**, 25, 3372–3376. [Google Scholar] - Peng, L.C.; Lin, Y.X.; Huang, L.J. Analysis and Treatment of Quality Accident of Pipe Piles in Soft Clay Area of Zhuhai. Chinese J. Geotech. Eng.
**2011**, 33, 169–173. [Google Scholar] - Wang, Y.; Chen, Y.; Qiao, W.; Zuo, D.; Hu, Z.; Feng, Q. Road Engineering Field Tests on an Artificial Crust Layer Combined with Pre-Stressed Pipe Piles over Soft Ground. Soil Mech. Found. Eng.
**2018**, 54, 402–408. [Google Scholar] [CrossRef] - Chen, K.; Gan, G. Flexural Test and Numerical Simulation of a New Combination Splice for Prestressed, Precast Concrete Piles Using High-Strength Steel Strands. Buildings
**2022**, 12, 1371. [Google Scholar] [CrossRef] - Wang, Y.; Sang, S.; Zhang, M.; Bai, X.; Su, L. Investigation on In-Situ Test of Penetration Characteristics of Open and Closed PHC Pipe Piles. Soils Found.
**2021**, 61, 960–973. [Google Scholar] [CrossRef] - Umravia, N.B.; Solanki, C.H. Comparative Study of Existing Cement Fly Ash Gravel Pile and Encased Stone Column Composite Foundation. IOP Conf. Ser. Mater. Sci. Eng.
**2021**, 1197, 1–9. [Google Scholar] [CrossRef] - Zou, X.J.; Zhao, Z.M.; Xu, D.B. Consolidation Analysis of Composite Foundation with Partially Penetrated Cement Fly-Ash Gravel (CFG) Piles under Changing Permeable Boundary Conditions. J. Cent. South Univ.
**2015**, 22, 4019–4026. [Google Scholar] [CrossRef] - Wang, D.F.; Wang, X.Q.; Zhang, N.T.; Chen, Y. Numerical Simulation of Reinforcement Effect and Settlement of Concrete Pile Composite Foundation. Adv. Mater. Res.
**2013**, 779, 434–438. [Google Scholar] [CrossRef] - Wang, L.; Zhao, Q.; Mao, J.; Wu, J.; Guo, F. Bearing Capacity and Simplified Calculation Approach for Large-Diameter Plain-Concrete Piles. Arab. J. Geosci.
**2021**, 14, 1–13. [Google Scholar] [CrossRef] - Zhu, Q.; Zuo, W.; Xu, P.; Wang, H. Research and Application of Stress and Strain Testing Method for Plain Concrete Pile. E3S Web Conf.
**2021**, 233, 3–6. [Google Scholar] [CrossRef] - Li, S.C.; Xie, C.; Liang, Y.H.; Yan, Q. Seepage Flow Model and Deformation Properties of Coastal Deep Foundation Pit under Tidal Influence. Math. Probl. Eng.
**2018**, 2018, 1–11. [Google Scholar] [CrossRef] [Green Version] - Zhang, L.; Wei, X. Responses of Excavation Base under Influences of Confined Aquifer: An Analytical Approach. Mar. Georesources Geotechnol.
**2021**, 39, 241–254. [Google Scholar] [CrossRef] - Ying, H.W.; Sun, W.; Zhu, C.W. Experiment Research on Response of Excess Pore Pressure to Wave around Near-Sea Excavation. Rock Soil Mech.
**2016**, 37, 187–194. [Google Scholar] - Hong, Y.; Ng, C.W.W. Base Stability of Multi-Propped Excavations in Soft Clay Subjected to Hydraulic Uplift. Can. Geotech. J.
**2013**, 50, 153–164. [Google Scholar] [CrossRef] - Xiang, X.C.; Hou, J.S.; Zhu, C.Q. Consolidation Deformation Properties of Silt Roadbed under Effect of Tide. Rock Soil Mech.
**2009**, 7598, 1142–1146. [Google Scholar] - Ying, H.W.; Nie, W.F.; Huang, D.Z. Semi-Analytical Solution of Pore Pressure Response around Excavations to Groundwater Level Fluctuation. Chinese J. Geotech. Eng.
**2014**, 36, 1012–1019. [Google Scholar] - Ying, H.; Nie, W.; Huang, D. Influences of Groundwater Level Fluctuation on the Stability of Gravity Retaining Wall of Pits. Chinese J. Rock Mech. Eng.
**2014**, 33, 2370–2376. [Google Scholar] - Li, L.; Barry, D.A.; Pattiaratchi, C.B. Numerical Modelling of Tide-Induced Beach Water Table Fluctuations. Coast. Eng.
**1997**, 30, 105–123. [Google Scholar] [CrossRef] - Liu, R.; Yuan, Y.; Fu, D.; Sun, G. Numerical Investigation to the Cyclic Loading Effect on Capacities of the Offshore Embedded Circular Foundation in Clay. Appl. Ocean Res.
**2022**, 119, 103022. [Google Scholar] [CrossRef] - Chen, J.; Lin, C.; Liu, S.; Mo, H. Study on Supporting Structure Performance of Deep Soft Soil Foundation Pit near Sea under Waves, Tides, Vibration, and Unbalanced Loads. Adv. Civ. Eng.
**2020**, 2020, 1–18. [Google Scholar] [CrossRef] - Hsieh, P.G.; Ou, C.Y. Shape of Ground Surface Settlement Profiles Caused by Excavation. Can. Geotech. J.
**1998**, 35, 1004–1017. [Google Scholar] [CrossRef] - Samanta, M.; Bhowmik, R. 3D Numerical Analysis of Piled Raft Foundation in Stone Column Improved Soft Soil. Int. J. Geotech. Eng.
**2019**, 13, 474–483. [Google Scholar] [CrossRef] - Gu, X.Q.; Wu, R.T.; Liang, F.Y.; Gao, G.Y. On HSS Model Parameters for Shanghai Soils with Engineering Verification. Rock Soil Mech.
**2021**, 42, 833–845. [Google Scholar] - Cudny, M.; Truty, A. Refinement of the Hardening Soil Model within the Small Strain Range. Acta Geotech.
**2020**, 15, 2031–2051. [Google Scholar] [CrossRef] [Green Version] - Clayton, C.R.I. Stiffness at Small Strain: Research and Practice. Geotechnique
**2011**, 61, 5–37. [Google Scholar] [CrossRef] [Green Version] - Huang, X.; Schweiger, H.F.; Huang, H. Influence of Deep Excavations on Nearby Existing Tunnels. Int. J. Geomech.
**2013**, 13, 170–180. [Google Scholar] [CrossRef] - Yin, J. Application of Hardening Soil Model with Small Strain Stiffness in Deep Foundation Pits in Shanghai. J. Geotech. Eng.
**2010**, 32, 166–172. [Google Scholar] - Liu, R.; Basu, P.; Xiong, H. Laboratory Tests and Thermal Buckling Analysis for Pipes Buried in Bohai Soft Clay. Mar. Struct.
**2015**, 43, 44–60. [Google Scholar] [CrossRef] - Liu, R.; Yan, S.; Wu, X. Model Test Studies on Soil Restraint to Pipeline Buriedin Bohai Soft Clay. J. Pipeline Syst. Eng. Pract.
**2013**, 4, 49–56. [Google Scholar] [CrossRef]

**Figure 2.**Top view of the standard section of the foundation. (

**a**) Plum blossom pile (

**b**) Square pile.

**Figure 3.**(

**a**) Dynamic shear modulus–dynamic strain amplitude relationship curve under different confining pressure, (

**b**) Reciprocal of dynamic shear modulus–dynamic strain amplitude relationship curve under different confining pressure.

**Figure 6.**Contours of horizontal displacement and vertical displacement of foundation soil under three cases.

**Figure 8.**Horizontal displacement of the No. 1 pile under three cases: (

**a**) Horizontal displacement of No. 1 pile in one tidal action period. (

**b**) Horizontal displacement of No. 1 pile when the water level suddenly rises and drops.

**Figure 9.**Time-history curves of the horizontal displacement of three characteristic points (indicated in Figure 8) of the No. 1 pile under three cases: (

**a**) Horizontal displacement of feature points in 3 d due to tidal action. (

**b**) Horizontal displacement of feature points when the water level rises and drops suddenly.

**Figure 10.**Axial force distribution of the No. 1 pile body under three cases: (

**a**) Axial force distribution of the No. 1 pile body under tidal action. (

**b**) Axial force distribution of the No. 1 pile body under sudden water level rise and drop.

**Figure 11.**Bending moment distribution of pile No. 1 under three cases: (

**a**) Bending moment distribution of the No. 1 pile body under tidal action. (

**b**) Bending moment distribution of the No. 1 pile body when the water level rises and falls suddenly.

**Figure 12.**Time-history curves of maximum axial force and bending moment of the No. 1 pile under three cases: (

**a**) Time-history curve of maximum axial force. (

**b**) Time-history curve of maximum bending moment.

**Figure 13.**Contours of pore water pressure in the initial state and at the end of moment of the three cases.

**Figure 14.**Fluctuation at feature point D under three cases:(

**a**) Pore water pressure fluctuation. (

**b**) Average effective stress fluctuation.

Structure Type | Material Model | Elastic Modulus/MPa | Poisson’s Ratio | Permeability Coefficient m/d |
---|---|---|---|---|

Dike | Linear elasticity | $30\times $ 10^{3} | 0.1 | 0 |

Dike stone | Linear elasticity | $28\times $10^{3} | 0.15 | 100 |

Dry block stone | Linear elasticity | $26\times $10^{3} | 0.2 | 100 |

Two pieces of stone | Linear elasticity | $20\times $ 10^{3} | 0.2 | 100 |

Filter layer | Linear elasticity | $15\times $ 10^{3} | 0.25 | 50 |

Fence board | Linear elasticity | $15\times $ 10^{3} | 0.25 | 100 |

Masonry stone | Linear elasticity | $23\times $10^{3} | 0.18 | $2.6\times $ 10^{−3} |

C30 concrete | Linear elasticity | $30\times $10^{3} | 0.2 | 0.026 $\times $ 10^{−3} |

Confining Pressure /kPa | a /MPa^{−1} | ${\mathit{G}}_{0}$/MPa | ${\mathit{G}}_{0}^{\mathit{r}\mathit{e}\mathit{f}}$/MPa | ${\mathit{G}}_{0\mathit{a}\mathit{v}\mathit{e}}^{\mathit{r}\mathit{e}\mathit{f}}$/MPa | |
---|---|---|---|---|---|

1 | 50 | 0.10 | 9.33 | 13.32 | 15.5 |

2 | 100 | 0.068 | 14.78 | 14.78 | |

3 | 150 | 0.047 | 21.32 | 16.40 | |

4 | 200 | 0.036 | 27.79 | 17.37 |

Soil Type | Material Model | ${\mathit{\gamma}}_{\mathit{u}\mathit{n}\mathit{s}\mathit{a}\mathit{t}}$ | ${\mathit{\gamma}}_{\mathit{s}\mathit{a}\mathit{t}}$ | ${\mathit{E}}_{50}^{\mathit{r}\mathit{e}\mathit{f}}$ | ${\mathit{E}}_{\mathit{e}\mathit{o}\mathit{d}}^{\mathit{r}\mathit{e}\mathit{f}}$ | ${\mathit{E}}_{\mathit{u}\mathit{r}}^{\mathit{r}\mathit{e}\mathit{f}}$ | m | ${\mathit{c}}^{\prime}$ | ${\mathit{\phi}}^{\prime}$ | k | ${\mathit{G}}_{0}^{\mathit{r}\mathit{e}\mathit{f}}$ | ${\mathit{\gamma}}_{0.7}$ | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|

/(kN/m^{3}) | /(kN/m^{3}) | /MPa | /MPa | /MPa | /kPa | /° | /(m/d) | /MPa | |||||

Dredging Fill | M–C | 18 | 20 | 50 | 2 | 32 | 0.3 | ||||||

Silt | HSS | 15 | 15.4 | 3 | 3 | 10 | 0.75 | 11 | 9 | 0.8$\times $10^{−3} | 16 | 2$\times $10^{−4} | |

Muddy soil | HSS | 16.5 | 16.8 | 3.5 | 3.5 | 14 | 0.7 | 16.4 | 10 | 3.3$\times $10^{−3} | 20 | $1.5\times $10^{−4} |

Soft Soil HSS Model Parameters |
${\mathit{c}}^{\prime}$ /Kpa | ${\mathit{\phi}}^{\prime}$ /° | ${\mathit{E}}_{50}^{\mathit{r}\mathit{e}\mathit{f}}$ /MPa | ${\mathit{G}}_{0}^{\mathit{r}\mathit{e}\mathit{f}}$ /MPa | ${\mathit{\gamma}}_{0.7}$ |
---|---|---|---|---|---|

Zhuhai area (this test) | 11 | 9 | 3 | 16 | 2 × 10^{−4} |

Yangtze River Delta Region (Shanghai) | 12 | 23.3 | 3.3 | 38.8 | 3.2 × 10^{−4} |

Bohai rim (Tianjin) | 20 | 25 | 6 | 50 | 3.6 × 10^{−4} |

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## Share and Cite

**MDPI and ACS Style**

Fu, X.; Li, J.; Liu, J.; Hu, Z.; Tang, C.
Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai. *Buildings* **2023**, *13*, 563.
https://doi.org/10.3390/buildings13020563

**AMA Style**

Fu X, Li J, Liu J, Hu Z, Tang C.
Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai. *Buildings*. 2023; 13(2):563.
https://doi.org/10.3390/buildings13020563

**Chicago/Turabian Style**

Fu, Xiaohai, Jinze Li, Jiankun Liu, Zheng Hu, and Changyi Tang.
2023. "Influence of Complex Hydraulic Environments on the Mechanical Properties of Pile-Soil Composite Foundation in the Coastal Soft Soil Area of Zhuhai" *Buildings* 13, no. 2: 563.
https://doi.org/10.3390/buildings13020563