[논문]Investigation of Spudcan Penetration Resistance in Layered Soil Deposits

Jan, Muhammad Asad; Nizamani, Zubair Ahmed; Park, Duhee

doi:10.14481/jkges.2021.22.1.13

Investigation of Spudcan Penetration Resistance in Layered Soil Deposits 원문보기

한국지반환경공학회논문집 = Journal of the Korean Geoenvironmental Society, v.22 no.1, 2021년, pp.13 - 20

Jan, Muhammad Asad (Department of Civil and Environment Engineering, Hanyang University) , Nizamani, Zubair Ahmed (Department of Civil and Environment Engineering, Hanyang University) , Park, Duhee (Department of Civil and Environment Engineering, Hanyang University)

Abstract ▼ AI-Helper

A suite of 3D large deformation finite element (FE) analyses was performed to investigate the load transfer mechanism and penetration resistance of spudcan foundations in heterogeneous soil profile consisting of sand and clay. The Elasto-Plastic models following Mohr-Coulomb and Tresca failure criteria were adopted for sand and clay, respectively. The accuracy of the numerical model was validated against centrifuge test measurements. The dense sand behavior with dilation is modeled using the non-associated flow rule. An investigation study consisting of key parameters, which includes variation in soil stratigraphy (sand-clay, sand-clay-sand), strength parameters of sand and clay (��' and su) and normalized height ratio of the sand layer (Hs/D) was conducted to assess the penetration behavior of spudcan. Based on calculated outputs, it was demonstrated that these parameters have a significant influence on the penetration resistance of spudcan. The calculated penetration resistance profiles are compared with the published (sand overlying clay) analytical model. It is confirmed that for the case of two-layer soil, the available theoretical model provides an accurate estimate of peak penetration resistance (qpeak). In the case of three-layer soil, the presence of a third stiff layer affects the penetration resistance profile due to the squeezing of the soil.

주제어

표/그림 (14)

그림 Fig. 1. SPT profile: (a) BH-1; (b) BH-2; (c) BH-3
그림 Fig. 2. Spudcan geometry
그림 Fig. 3. Computational model of spudcan in sand-clay-sand
표 Table 1. Spudcan geometry
그림 Fig. 4. Validation of calculated results with centrifuge measurements (Test L1SP1)
표 Table 2. Summary of parameters used for the validation of centrifuge model tests
그림 Fig. 5. Sizes of spudcan in the numerical model
그림 Fig. 6. Friction angle ϕ', and undrained strength s_u calculated from the triaxial test
그림 Fig. 7. Penetration resistance profile (Two-Layer) for D = 8 m, (a, b) H_s/D = 1; (c, d) H_s/D = 0.5
표 Table 3. Numerical simulation case matrix (two-layer)
그림 Fig. 8. Penetration resistance profile (Two-Layer) for D = 6.0 m, (a, b) H_s/D = 1.0; (c, d) H_s/D = 0.67
그림 Fig. 9. Comparison of calculated and estimated peak resistance results for s_u = 10 & 20 kPa
표 Table 4. Engineering properties of sand and clay (Korean site data)
그림 Fig. 10. Penetration profiles of spudcan in sand-clay-sand (BH-2, 3, 4, and 5)

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문제 정의

multi-layer soil deposits. The study focused on the distri- bution of clay soil interbedded with the sand layer. Based on centrifuge observations, the recommendations were provided for limiting squeezing depth and formation of the soil plug due to punch-through penetration of spudcan in subsequent layers.

제안 방법

The study focused on the distri- bution of clay soil interbedded with the sand layer. Based on centrifuge observations, the recommendations were provided for limiting squeezing depth and formation of the soil plug due to punch-through penetration of spudcan in subsequent layers. Ullah et al.
For the evaluation of the bearing capacity of spudcan in the sand over clay using theoretical models, a parametric study was performed. Two spudcan sizes, D = 6 & 8 m, were used in the numerical simulations as shown in Fig.
(2014b). For the selection of penetration rate, a sensitivity study was performed. Based on the comparison, the convergence was achieved at rates lower than 0.
Hence, the study was further extended to investigate the representative site profiles of four bore-logs (BH # 2, 3, 4 & 5). The bore-logs data shows the presence of sand deposits interbedded with a various thickness clay layer.
In this study, the penetration resistance of spudcan in sand overlying clay and sand-clay-sand deposits were calculated using 3D large deformation finite element analysis. The numerical results were used to investigate the influence of strength parameters of soil and variation in the soil layers on the resistance profile of spudcan.
A brief comparison of calculated results is made with the analytical model and field data. The calculated results are used to investigate the potential failure mechanism in the case of a multi-layered soil profile.
Linear elastic-perfectly plastic models following the Mohr-Coulomb and Tresca failure criteria were used for sands and clays, respectively. The model was validated against published centrifuge measurements of two and three-layer soil profiles. The range of parameters for sand overlying clay soil profile simulated in this study demonstrated the accuracy of the calculated and analytical model.
The numerical results were used to investigate the influence of strength parameters of soil and variation in the soil layers on the resistance profile of spudcan. A brief comparison of calculated results is made with the analytical model and field data.
The model was validated against published centrifuge measurements of two and three-layer soil profiles. The range of parameters for sand overlying clay soil profile simulated in this study demonstrated the accuracy of the calculated and analytical model. The increase in the H_s/D, ϕ՛, and s_u causes an increase in the penetration resistance of spudcan.
The comparison with the two-layer analytical model clearly indicated that the resistance profile of the three-layer model has a unique trend in the interbedded clay layer. The study will be further extended to account for the parameters that influence the resistance profile of sand-clay-sand.

대상 데이터

0. The centrifuge experiments were performed at the University of Western Australia using silica sand and kaolin clay. In the numerical simulations, the properties of the soil were assigned to those provided in Hu et al.

데이터처리

For the accuracy of the numerical model, a validation study was performed using the experimental penetration resistance- depth outputs. Hu et al.

이론/모형

The experimental penetration resistance-depth outputs (L1SP1 from Hu et al. (2014a)) measured from centrifuge experiments performed on sand overlying clay was used to validate the numerical model. The H_s/D ratio for test L1SP1 was 1.
(2013), Teh (2007) performed centrifuge experiments for the investigation of the penetration resistance profile of spudcan. The measurements were used to develop the mechanism- based estimation model for the prediction of q_peak of spudcan in the sand over clay.
The simulation of continuous penetration of spudcan was conducted using the Coupled Eulerian-Lagrangian (CEL) approach. The geometry and dimensions of spudcan are shown in Fig.

참고문헌 (18)

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상세보기
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상세보기
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상세보기
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상세보기
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상세보기
Hu, P., Stanier, S. A., Cassidy, M. J. and Wang, D. (2014a), Predicting peak resistance of spudcan penetrating sand overlying clay, Journal of Geotechnical and Geoenvironmental Engineering, 140(2), 04013009.

상세보기
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상세보기
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상세보기
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Ullah, S. N., Stanier, S., Hu, Y. and White, D. (2017), Foundation punch-through in clay with sand: centrifuge modelling, Geotechnique, 67(10), 870-889.
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