scholarly journals THE MECHANISM OF THE EFFECTS OF INCREASING THE LENGTH OF THE PILES UNDER LATERAL LOADS IN SAND

2021 ◽  
Vol 1 (25) ◽  
Author(s):  
Abbas Firouzi Karamjavan ◽  
Hojjat Hashempour
Keyword(s):  
Bending Moment ◽  
Poor Performance ◽  
Pile Group ◽  
Group Behavior ◽  
Offshore Structures ◽  
Deep Foundations ◽  
Lateral Loads ◽  
Adjacent Structures ◽  
Subsurface Layers ◽  
Soil Settlement

In many projects, piles are designed and installed as the ultimate solution in foundation construction, load transition to the resistant subsurface layers, providing lateral resistance, and overcoming the poor performance of surface soils. Pile design should be done with respect to structural consideration, the load-carrying capacity of the surface and surrounding soil, settlement, and constructional, technical and environmental problems. Pile group is a particular type of deep foundations which is mostly and widely utilized in coastal and offshore structures, and sustains vertical and lateral loads. Noting the lateral load exerted on the structure, the effect of loading on the behavior of pile should be analyzed using an appropriate method. In this article, a 4x4 pile group with piles of 100 cm diameter and 10, 15-m in length with center-to-center spacing of 3 times the diameter are modeled using the Plaxis 3D Foundation, which uses the finite element method, and the Mohr-Coulomb model, and the behavior of the piles driven in sand and subjected to loading is studied. Taking the results, the mechanism of the pile group behavior under vertical, lateral, adjacent structures loads and bending moment is calculated, and displacement in the x-direction, y-direction, and along the length, bending moment, and bearing capacity along the length of the pile have been obtained for each pile.

scholarly journals STUDY ABOUT THE EFFECTS OF PILE SPACING ON THE PERFORMANCE OF PILE GROUP UNDER COMPOSITE LOADS, ADJACENT STRUCTURE LOADS, AND BENDING MOMENT IN SAND

2017 ◽  
Vol 1 (16) ◽  
Author(s):  
Abbas Firouzi Karamjavan
Keyword(s):  
Bending Moment ◽  
Poor Performance ◽  
Pile Group ◽  
Offshore Structures ◽  
Deep Foundations ◽  
Lateral Loads ◽  
Adjacent Structure ◽  
Foundation Program ◽  
Subsurface Layers ◽  
Soil Settlement

Pile group is a particular type of deep foundations which is designed and installed as the ultimatesolution to foundation construction, load transition to the resistant subsurface layers, providing lateralresistance, and overcoming the poor performance of surface soils. Pile design should be done withrespect to structural consideration, the load-carrying capacity of the surface and surrounding soil,settlement, and constructional, technical and environmental problems. Piles are mostly and widelyutilized in coastal and offshore structures, and sustain vertical and lateral loads. Considering theimposed loads on structure, the effect of these loads on the pile behavior should be analyzed with anappropriate method. In this study, a 4x4 pile group with piles of 100-cm diameter and center-to-centerspacing of 2, 3, 4 times the diameter is modeled using the Plaxis 3D foundation program, which usesthe finite element method, and the Mohr-Coulomb model, and the behavior of piles subjected toloading, driven in sand, are investigated. Taking the achieved results, the mechanism of the pile groupbehavior under composite loads, adjacent structure loads, and bending moment are calculated, anddisplacement in the x-direction, y-direction and along the length, the bending moment and the axialforce for each pile within a distance of 2, 3, 4 times the diameter are attained.

Some data on long term large screw pile group behavior

ce/papers ◽  
2018 ◽  
Vol 2 (2-3) ◽  
pp. 113-134
Author(s):  
William F. VAN IMPE ◽  
Peter O. VAN IMPE ◽  
Alice MANZOTTI
Keyword(s):  
Pile Group ◽  
Group Behavior ◽  
Screw Pile

Chemoradiotherapy is an Alternative Choice for Patients with Primary Mediastinal Seminoma

2021 ◽  
Author(s):  
Yirui Zhai ◽  
Bo Chen ◽  
Xiaoli Feng ◽  
Kan Liu ◽  
Shulian Wang ◽  
...  
Keyword(s):  
Univariate Analysis ◽  
Progression Free Survival ◽  
Poor Performance ◽  
Rank Test ◽  
Clinicopathologic Characteristics ◽  
Cancer Specific Survival ◽  
Adjacent Structures ◽  
Significant Difference ◽  
Mediastinal Seminoma ◽  
Alternative Choice

Abstract Background: The low incidence of primary mediastinal seminomas has precluded the development of clinical trials on mediastinal seminomas. We investigated the clinicopathologic characteristics, prognosis of patients with primary mediastinal seminomas as well as the efficiency of nonsurgical treatments compared with treatments containing surgery.Methods: We retrospectively collected data on the clinicopathologic characteristics, treatments, toxicities, and survival of 27 patients from a single center between 2000 and 2018. Patients were divided into two groups according to whether they received operation. Survivals were assessed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test.Results: The median age was 28 (13-63) years. The most common symptoms were chest pain (29.6%), cough (25.9%), and dyspnea (22.2%). There were 13 and 14 patients in surgery and non-surgery group. Patients in the non-surgical group were more likely to be with poor performance scores (100% vs.76.9%) and disease invaded to adjacent structures(100% vs.76.9%) especially great vessels(100% vs.46.2%).The median follow-up period was 32.23 (2.7-198.2) months. There was no significant difference of overall survival (5-year 100% vs 100%), cancer-specific survival (5-year 100% vs.100%), local regional survival (5-year 91.7% vs.90.0%, p=0.948) , distant metastasis survival (5-year 100.0% vs. 90.9%, p=0.340) and progression-free survival (82.5% vs.90.0%, p=0.245) between patients with and without surgery. Conclusions: Primary mediastinal seminoma was with favorable prognosis, even though frequently invasion into adjacent structures brings difficulties to surgery administration. Chemoradiotherapy is an alternative treatment with both efficacy and safety.

Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

2021 ◽  
Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding
Keyword(s):  
Seismic Behavior ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Pile Group ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Shaking Table Tests ◽  
Pile Groups ◽  
Acceleration Response ◽  
Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

scholarly journals Lateral Response of a Single Pile under Combined Axial and Lateral Cyclic Loading in Sandy Soil

2018 ◽  
Vol 4 (9) ◽  
pp. 1996 ◽  
Author(s):  
Muqdad Abdallah Kahribt ◽  
Jasim M. Abbas
Keyword(s):  
Lateral Displacement ◽  
Slenderness Ratio ◽  
Offshore Structures ◽  
Lateral Loading ◽  
Loading Conditions ◽  
Lateral Loads ◽  
Dense Sand ◽  
Lateral Response ◽  
Loading System ◽  
Vertical Displacements

According to practical situation, there have been limited investigations on the response of piles subjected to combined loadings especially when subjected to cyclic lateral loads. Those few studies led to contradictory results with regard to the effects of vertical loads on the lateral response of piles. Therefore, a series of experimental investigation into piles in dense sand subjected to combination of static vertical and cyclic lateral loading were conducted with instrumented model piles. The effect of the slenderness ratio (L/D) was also considered in this study (i.e. L/D= 25 and 40). In addition, a variety of two-way cyclic lateral loading conditions were applied to model piles using a mechanical loading system. One hundred cycles were used in each test to represent environmental loading such as offshore structures. It was found that under combined vertical and cyclic lateral loads the lateral displacement of piles decreased with an increase in vertical load whereas it causes large vertical displacements at all slenderness ratios. In addition, for all loading conditions the lateral, vertical (settlement and upward) displacements and bending moments increased as either the magnitude of cyclic load or the number of cycles increases. 

scholarly journals A Numerical Analysis on the Behavior of Single Battered Pile under Pullout Loading

2021 ◽  
Vol 318 ◽  
pp. 01010
Author(s):  
Mais S. Al-Tememy ◽  
Mohammed A. Al-Neami ◽  
Mohammed F. Asswad
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
Offshore Structures ◽  
Pullout Capacity ◽  
Element Analysis ◽  
Dense Sand ◽  
Dimensional Finite Element ◽  
Pullout Load ◽  
Three Dimensional Finite Element ◽  
3D Software

Batter or raker piles are piles driven at an inclination with a vertical to resist large inclined or lateral forces. Many structures like offshore structures and towers are subjected to overturning moments due to wave pressure, wind load, and ship impacts. Therefore in such structures, a combination of the vertical and batter piles is used to transfer overturning moments in compression and tension forces to the foundation. This paper presents a three-dimensional finite element analysis using PLAXIS 3D software to study the battered pile's behavior under the effect of pullout load. Several variables that influence the pile tension capacity embedded in sandy soil are investigated. The pile models are steel piles embedded in the dense sand at different batter angles (0, 10, 20, and 30) degrees with two embedment ratios, L/d (15 and 20). To clarify the pile shape's influence on a pullout capacity, two shapes are used, a circular pile with a diameter equal to 20 mm and a square pile with a section of 15.7×15.7 mm. These dimensions are chosen to achieve an equal perimeter for both shapes. The numerical results pointed that the pile pullout capacity increases with the increasing of the batter angle and embedment ratio, and the maximum values are marked at a batter angle of 20o. The shape of the bending moment profile is a single curvature, and the peak values are located approximately at the midpoint of the battered pile, while a zero value is located at the pile tip and pile head.

A Numerical Study of Deep Foundations Under Lateral Loads

2002 ◽  
Vol 2 (2) ◽  
pp. 273-276
Author(s):  
V.R. Ouhadi . ◽  
A. Ghalandarzadeh .
Keyword(s):  
Numerical Study ◽  
Deep Foundations ◽  
Lateral Loads

scholarly journals An Investigation into the Effect of Cracking on the Response of Drilled and Postgrouted Concrete Pipe Pile under Lateral Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Zhijun Yang ◽  
Qing Fang ◽  
Bu Lv ◽  
Can Mei ◽  
Xudong Fu
Keyword(s):  
Flexural Rigidity ◽  
Bending Moment ◽  
Test Results ◽  
Lateral Loads ◽  
Analysis Method ◽  
Pile Head ◽  
Laterally Loaded Piles ◽  
Pipe Pile ◽  
Concrete Pipe ◽  
Laterally Loaded

The cracks are likely to initiate on a lateral loaded pile and would cause greater deflection at the pile head. However, there is a lack of thorough investigation into the effect of cracking on the response of the lateral loaded pile. In this article, a full-scale field test was carried out to investigate the behavior of Drilled and Postgrouted Concrete Pipe Pile under lateral loads. A novel analysis method for the lateral loaded pile, which can take the cracking effects into consideration, was proposed, and the validity was verified by the test results. With the proposed method, the cracking effects on flexural rigidity, displacement, rotation, and bending moment of the pile were studied. In brief, cracking effect would dramatically reduce the flexural rigidity of the pile, remarkable increase the displacement and rotation of the pile top, and slightly decrease bending moment of the pile. Unambiguously, the results show that the proposed method can excellently predict the response of laterally loaded piles under cracking effects.

Comparative Study of New Airfoils for Small Horizontal Axis Wind Turbines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Thiago Canale ◽  
Kamal A. R. Ismail ◽  
Fatima A. M. Lino ◽  
Ahmad Arabkoohsar
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
High Efficiency ◽  
Twist Angle ◽  
Bending Moment ◽  
Poor Performance ◽  
Numerical Code ◽  
Power Coefficient ◽  
Intermediate Region ◽  
Marginal Improvement

Abstract The high cost and poor performance of small wind turbines make them not widely used. In an attempt to meliorate this situation, the authors propose to investigate alternative airfoils with different chord and pitch angle distributions that permit low manufacturing, installation and maintenance costs, as well as high efficiency. To achieve these goals, two airfoil sections, Gottingen and Joukowski, together with different chord and pitch angle distributions were simulated by using a validated numerical code based on the blade element momentum (BEM) method. The chord geometry includes constant, linear, and elliptic distributions while the twist angle includes constant and linear distributions. The results reveal that the linear pitch distribution reduces the thrust in the intermediate region of the blade and the bending moment at the root and reduces the power coefficient for both rotors. Rotors with elliptic chord distribution show increased forces in the intermediate region. Joukowski based blades with elliptic chord distribution show lower thrust compared with those with linear chord distribution. The linear chord distribution increases the thrust in the intermediate region and reduces it at the tip and root regions. Blades with multiple airfoils show marginal improvement. The Gottingen and Joukowski based rotors have similar annual energy production (AEP). The Joukowski based rotor with linear pitch and linear chord distribution shows better performance at low velocities and easy to manufacture which makes it a good candidate for small power wind turbines.

Sign in / Sign up

Export Citation Format

Share Document