Numerical Study of Spudcan Penetration in Clay-Sand-Clay Soil

2016 ◽  
Author(s):  
Qilin Yin ◽  
Sheng Dong ◽  
Jinjin Zhai
Keyword(s):  
Finite Element ◽  
Yellow River ◽  
Numerical Study ◽  
Soft Clay ◽  
River Estuary ◽  
Small Strain ◽  
Penetration Resistance ◽  
Sand Layer ◽  
Clay Layer ◽  
Set Up

Aiming at simulating the preloading process of jack-up rig at drilling locations with typical stratum combination near the Yellow River estuary, FE models of interaction between spudcan and sub-soil are set up based on a large deformation finite element method known as Remeshing and Interpolation Technique with Small Strain (RITSS). The ABAQUS finite element package is used to calculate small strain solutions following each step. The seabed can be simplified as a three-layer deposits with soft clay layer, sand layer and soft clay layer from surface to bottom according to geological data. The backfill phenomenon during preloading is described. The results show that the surface soft clay falls onto the upper surface of spudcan very soon after the preloading process begins, afterwards the backfill tendency occurs in the middle sand layer. SNAME recommends two sets of formulas for calculating penetration resistance respectively for backfill penetration and penetration with no backfill. In this study the model with no backfill is realized by condition control in program codes and the penetration resistance is compared with the results of practical backfill model. The variance proves the shortcomings of the method given by SNAME.

Effect of Large Deformation Analysis for Site Investigation Tool - CPT in Layered Soils

2020 ◽  
Author(s):  
Qiang Xie ◽  
Yuxia Hu ◽  
Mark J. Cassidy
Keyword(s):  
Large Deformation ◽  
Strain Analysis ◽  
Small Strain ◽  
Deformation Analysis ◽  
Large Strains ◽  
Embedment Depth ◽  
Sand Layer ◽  
Clay Layer ◽  
Layered Soils ◽  
Soil Response

Abstract Cone penetration test (CPT) is regularly used during offshore site investigations to interpret soil stratification and soil characteristics due to its continuous penetration resistance profile. However, its use could be improved if better numerical methods to simulate its penetration could be developed. Finite element (FE) analysis, for instance, has the potential to provide insightful information on soil response and soil flow mechanisms. However, it is challenging to simulate CPT in layered soils, as the soil experiences extremely large strains around the cone and the simulation costs are high. In this study, the efficiency of using a partial large deformation FE (LDFE) approach was explored to examine the pre-embedment depth allowed for saving LDFE analysis cost. The LDFE analysis was conducted using the remeshing and interpolation technical with small strain (RITSS) method to model the large strain problem. Both soft-stiff-soft clays and clay-sand-clay soil were considered to study the thin stiff layer effect when it was sandwiched in soft clay. The LDFE/RITSS analysis compared a CPT penetrating from the soil surface with penetrations from a pre-embedded depth above the stiff layer. Pre-embedded small strain analysis was also conducted for comparison. The results show that the small strain analysis underestimated the resistance in both clay and sand. For the partial LDFE analysis with pre-embedment in the top clay layer, the CPT response in the middle stiff clay layer could be well captured regardless of the initial pre-embedment depth. However, for the middle medium dense sand layer (ID = 60%), the pre-embedment depth needs to have sufficient distance above it (10D, D is cone diameter) to capture the soil response in the sand layer correctly.

scholarly journals A Simplified Finite Element Approach for Modeling of Multilayer Plates

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Taiyou Liu ◽  
Xinbo Ma ◽  
Pak Kin Wong ◽  
Jing Zhao ◽  
Zhengchao Xie ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Reference Value ◽  
Fe Model ◽  
Practical Applications ◽  
Aerospace Applications ◽  
Equivalent Bending Stiffness ◽  
Element Approach ◽  
Set Up ◽  
Transverse Response

The multilayer plate has a great potential for automotive and aerospace applications. However, the complexity in structure and calculation of the response impede the practical applications of multilayer plates. To solve this problem, this work proposes a new plate finite element and a simplified finite element (FE) model for multilayer plates. The proposed new plate finite element consists of the shear and extension strains in all layers. The multilayer structure with the proposed new plate finite element is regarded as a reference to calculate the reference value of the transverse response. The simplified FE model of multilayer plates is proposed based on the equivalent bending stiffness by curve fitting of the reference value of the transverse response. Numerical study shows that this approach can be used to set up the simplified FE model of multilayer plates.

scholarly journals Behavior of Foundations on Reinforced Sabkha Soil: A Numerical Study

2020 ◽  
pp. 15-23
Author(s):  
Lamia Sadek ◽  
Khaled M. M. Bahloul
Keyword(s):  
Finite Element ◽  
Computer Program ◽  
Bearing Capacity ◽  
Numerical Study ◽  
Sand Layer ◽  
Fiber Reinforced ◽  
Reinforced Sand ◽  
Strip Footings

The aim of this research is to investigate numerically the behavior of strip footings resting on Sabkha soil reinforced using two methods. Firstly, using a layer of compacted sand reinforced with random distributed fibers beneath footing. Secondly, using a layer of compacted sand reinforced with geogrids. The benefit of mentioned two methods on the improvement of strip footings bearing capacity and decreasing the settlement was investigated using a finite element computer program Plaxis 2D ver. 8.6. It was found that using two methods increases bearing capacity of strip footings significantly specially using first method (fiber reinforced sand layer). It was observed also that the settlement decreased for the same stress values.

Numerical study of ultimate bearing capacity of rectangular footing on layered sand

2020 ◽  
Vol 1 (101) ◽  
pp. 15-26
Author(s):  
V. Panwar ◽  
R.K. Dutta
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bearing Capacity ◽  
Numerical Study ◽  
Friction Angle ◽  
Ultimate Bearing Capacity ◽  
Loose Sand ◽  
Sand Layer ◽  
Element Analysis ◽  
Dense Sand

Purpose: The purpose of this study is to investigate the ultimate bearing capacity of the rectangular footing resting over layered sand using finite element method. Design/methodology/approach: Finite element analysis was used to investigate the dimensionless ultimate bearing capacity of the rectangular footing resting on a limited thickness of upper dense sand layer overlying limitless thickness of lower loose sand layer. The friction angle of the upper dense sand layer was varied from 41° to 46° whereas for the lower loose sand layer it was varied from 31° to 36°. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to increase up to an H/W ratio of about 1.75 beyond which the increase was marginal. The results further reveal that the dimensionless ultimate bearing capacity was the maximum for the upper dense and lower loose sand friction angles of 46° and 36°, while it was the lowest for the upper dense and lower loose sands corresponding to the friction angle of 41° and 31°. For H/W = 0.5 and 2, the dimensionless bearing capacity decreases with the increase in the L/W ratio from 0.5 to 6 beyond which the dimensionless ultimate bearing capacity remains constant for all combinations of parameters. The results were presented in nondimensional manner and compared with the previous studies available in literature. Research limitations/implications: The analysis is performed using a ABAQUS 2017 software. The limitation of this study is that only finite element analysis is performed without conducting any experiments in the laboratory. Further the study is conducted only for the vertical loading. Practical implications: This proposed numerical study can be used to predict the ultimate bearing capacity of the rectangular footing resting on layered sand. Originality/value: The present study gives idea about the ultimate bearing capacity of rectangular footing when placed on layered sand (dense sand over loose sand) as well as the effect of thickness of top dense sand layer on the ultimate bearing capacity. The findings could be used to calculate the ultimate bearing capacity of the rectangular footing on layered sand.

Based on the Technology of Shaped Charge Numerical Simulation Research of the Ice Model's Combination Blasting

2013 ◽  
Vol 753-755 ◽  
pp. 1002-1006 ◽  
Author(s):  
Wen Yuan Meng ◽  
Jun Qiang Hu ◽  
Xin Liu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Large Scale ◽  
Peak Pressure ◽  
Yellow River ◽  
Underwater Explosion ◽  
Shaped Charge ◽  
Simulation Research ◽  
Finite Element Software ◽  
Set Up

Combination of ice blasting model is set up with the program of blasting with technology of shaped charge, numerical calculation is carried out, and the shockwave peak pressure in ice medium is obtained based on the large-scale finite element software ANSYS/LS-DYNA . This paper analyzes the stress distribution of ice in the combination of underwater explosion loads, and studies the process of the underwater explosion. The article aims to promote the application and research of underwater explosion in Yellow River and Hei Long Jiang River ice blasting, etc.

Numerical Study of Spudcan Foundation Penetrating Into Layered Soils

2005 ◽  
Author(s):  
Zarnaz Mehryar ◽  
Yuxia Hu
Keyword(s):  
Numerical Study ◽  
Strain Analysis ◽  
Small Strain ◽  
Soil Strength ◽  
Critical Distance ◽  
Adaptive Finite Element Method ◽  
Potential Hazard ◽  
Strength Ratio ◽  
Clay Layer ◽  
Layer Boundary

Spudcan foundation, penetrating into stratified soils is studied using H-adaptive finite element method (FE) together with Remeshing and Interpolation Technique with Small Strain model (RITSS). This is to investigate the potential hazard of punch-through failure in layered soil profiles. There are two series of analysis conducted. Firstly, for a pre-embedded spudcan foundation, a series of parametric studies has been undertaken in order to find the critical distance between the spudcan and the layer boundary, within which a punch-through failure is likely to occur. Soil profile is a uniform stiff clay layer overlaying a uniform soft clay layer with soil strength ratio (upper layer soil strength to lower layer strength) varying from 1 to 10. Secondly, continuous analysis has been undertaken for 2 cases with shear strength ratio of 2 and 3 and thickness of the upper stiff layer of one spudcan diameter. It is found that, in small strain analysis, the critical distance to the layer boundary is increasing with increasing the strength ratio. It reaches at a limit of 1.0 ∼ 1.25 D (D is the spudcan diameter) when the strength ratio is 5 or larger. In large deformation analysis, the critical distance is much lower than the one from small strain analysis. This is due to the trapped top layer soil underneath the spudcan, which cannot be simulated in small strain analysis.

scholarly journals Development of a Luminal Esophageal Temperature Monitoring Device for Use During Treatment for Atrial Fibrillation

2018 ◽  
Author(s):  
Scott Garner ◽  
Karcher Morris ◽  
Raul Pegan ◽  
Thomas Savides ◽  
Frank E. Talke
Keyword(s):  
Finite Element ◽  
Ex Vivo ◽  
Numerical Study ◽  
Temperature Monitoring ◽  
Esophageal Wall ◽  
Esophageal Temperature ◽  
Element Analysis ◽  
Flow Through ◽  
Set Up ◽  
Potential Use

Luminal esophageal temperature monitoring is of high importance during catheter ablation surgeries of the left atrium. A device is currently under development to accurately measure temperature of the inner esophageal wall. Ex vivo tests using porcine esophageal and left atrial tissue have been set up and performed to better understand heat flow through the biomaterials in contact. To compliment ex vivo experiments, a numerical analysis using thermal finite element analysis has been implemented to compliment ex vivo experiments with a numerical study of the temperature distribution across tissue layers as a function of tissue thickness, as well as heat source contact size and time. Both the ex vivo experiments and finite element simulations aid in development of a practical prototyped device for potential use during catheter ablations.

scholarly journals Analysis of the application results of the traditional vacuum preloading method: A case study

2020 ◽  
Vol 198 ◽  
pp. 01032
Author(s):  
Wenbin Liu
Keyword(s):  
Soft Clay ◽  
Sand Layer ◽  
Clay Layer ◽  
Site Testing ◽  
Vacuum Preloading ◽  
Bearing Strength ◽  
Testing Data ◽  
Lateral Drainage ◽  
Preloading Method

The traditional vacuum preloading method is a common way for enhancing the bearing strength of the soft clay layer. In general, a serious of plastic drainage boards are plugged into the soft clay foundation, and a sand layer is covered above the soft clay layer to establish a space for lateral drainage of the clay before applicating vacuum load. This paper analysed the application results of the traditional vacuum preloading method with the help of the data from an engineering case. The in-site testing data of the variation of the pore pressure in clay layer and the settlement are collected to evaluate the benefit of traditional vacuum preloading method.

Spudcan Penetration in Clay-Sand-Clay Soils

2011 ◽  
Author(s):  
Long Yu ◽  
Hui Zhou ◽  
Wen Gao ◽  
Jun Liu ◽  
Yuxia Hu
Keyword(s):  
Yield Criterion ◽  
Soft Clay ◽  
Friction Angle ◽  
Small Strain ◽  
Clay Soils ◽  
Soil Conditions ◽  
Sand Layer ◽  
Element Analysis ◽  
Dense Sand ◽  
Flow Mechanisms

Multi-layered soil conditions often exist in offshore practice. In some sites a thin layer of medium dense sand lays between firm to stiff clay layers. In these cases the ultimate bearing capacity of foundations can be increased due to the strong sand layer by comparing with foundations in uniform clay. However, there is also a potential of reduction in foundation capacity when the foundation punches through the sand layer. The punch-through failure can occur during either pre-loading or storm loading. In this study, the continuous penetration of spudcan foundations on clay-sand-clay soils was investigated by large deformation finite element analysis. The numerical simulation was carried out using Remeshing and Interpolation Technique with Small Strain (RITSS) model. The clays obey Tresca failure criterion for undrained analysis and the sands obey Mohr-Coulomb yield criterion for drained analysis. The friction angle of the sand was taken as φ = 32° and 40° with its dilation angle ψ = 2° and 10° respectively. The effects of the relative height of the top soft clay and the relative thickness of the middle sand layer on the load-displacement responses were investigated. The soil flow mechanisms at various penetration depths were also discussed.

scholarly journals Analisis Perkuatan Timbunan Di Atas Tanah Lunak Menggunakan Dinding Turap dengan Pendekatan Model Numerik

2019 ◽  
Vol 25 (1) ◽  
pp. 48
Author(s):  
Indra Noer Hamdhan ◽  
Fauziah Fitriani Iskandar
Keyword(s):  
Soft Clay ◽  
Vertical Deformation ◽  
Sand Layer ◽  
Clay Layer ◽  
Lateral Deformation ◽  
Sheet Pile ◽  
The Finite Element Method ◽  
Soil Layers ◽  
Wall Position ◽  
Sheet Pile Wall

Embankment on soft clay may be affect settlement at subgrade, causing lateral deformation and vertical deformation around embankment. Therefore, reinforcement is needed to overcome the effects caused of the embankment. This research was conducted to find out the influence of sheet pile wall of embankment using PLAXIS 2D program based the finite element method. The analysis was done by varying of two condition, they are installation of sheet pile wall under the embankment and the sheet pile wall outside embankment. Sheet pile wall installation is carried out before embankment construction and length of sheet pile wall in this model is 15 m. The soil layers beneath the embankment consist of 10 m layer of soft clay layer and 5 m of sand layer. The height of embankment in this analysis is 8 m, where the constructing of the embankment was done in stages. The distance of sheet pile wall position under embankment from toe of embankment are -9 m, -6 m, -3 m, 0 m, 3 m dan 6 m. The results of analysis show the effective position for displacement are toe of embankment. The Installation of sheet pile walls below the embankment will reducing deformation up to 78% and the safety factor will increase up to 10%.

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