scholarly journals PERANCANGAN TIANG PANCANG DENGAN TAHANAN FRIKSI NEGATIF

2020 ◽  
Vol 3 (3) ◽  
pp. 879
Author(s):  
Vionita Salim ◽  
Aksan Kawanda
Keyword(s):  
Skin Friction ◽  
Carrying Capacity ◽  
Soft Soil ◽  
Neutral Plane ◽  
Initial Size ◽  
Negative Skin Friction ◽  
Hard Soil

Development in Jakarta took place the most, but the condition of the land in Jakarta ehich was dominated by sof soil was becoming an obstacle. Landfill is one way that can be done to strengthen or improve soft soil. But if this landfill causes a settlement in soil around the pile is bigger than the settlement in the pile, there will be negative skin friction which will cause the pile to be pulled down. This study aims to analyze and compare the magnitude of the influence of negative skin friction caused by the pile by using the undrained parameter, drained parameter, Meyerhof empirical, and Vesic empirical to analyze the carrying capacity of the pile and determine the neutral plane and negative skin friction with the Fellenius method and Prakash & Sharma methods. From the results of the analysis,negative skin friction does not accur in the pile that ends hard soil while it occurs in soil that ends soft soil. The location of neutral plane between the Fellenius method and Prakash & Sharma is not too different. But piles that experience negative skin friction need to be redesign. Changes in diameter of this pile can reach 2.5 times the initial size. Pembangunan di Jakarta sangat banyak, tetapi kondisi tanah di Jakarta yang didomisasi oleh tanah lunak mnjdi kendala. Timbunan menjadi salah satu cara yang dapt dilakukan untuk memperkuat atau memperbaiki tanah lunak. Tetapi apabila timbunan ini menyebabkan penurunan tanah di sekitar tiang lebih besar daripada penurunan tiang maka akan timbul gesekan antara selimut tiang dengan tanah ke arah bawah yang akan menyebabkan tiang tertarik ke bawah. Gaya geser ke bawah ini dikenal sebagai gesekan selimt negatif. Studi ini bertujuan untuk menganalisis dan membandingkan besarnya pengaruh gesekan selimut negatif akibat timbunan dengan menggunakan metode undrained parameter, drained parameter, empiris Meyerhoff, dan empiris Vesic untuk menganalisis daya dukung tiang serta penentuan titik netral dan friksi negatif dengan metode Fellenius dan Prakash & Sharma. Dari hasil analisis, gesekan selimut negative tidak terjadi di tiang yang berujung tanah keras sedangkan terjadi di tanah pada tanah yang berujung tanah lunak. Letak tiitk netral antara metode Fellenius dan Prakash & Sharma tidak terlalu berbeda. Tetapi tiang yang mengalami friksi negatif perlu didesain ulang ukurannya. Perubahan diameter tiang ini bisa mencapai 2.5 kali dari ukuran awal.

Negative skin friction and the neutral plane

1994 ◽  
Vol 31 (4) ◽  
pp. 591-597 ◽  
Author(s):  
Elmer L. Matyas ◽  
J. Carlos Santamarina
Keyword(s):  
Closed Form ◽  
Key Words ◽  
Skin Friction ◽  
Closed Form Solution ◽  
Form Solution ◽  
Neutral Plane ◽  
Rigid Plastic ◽  
Negative Skin Friction ◽  
Elastic Plastic ◽  
Drag Forces

Current views indicate that negative skin friction on piles can be mobilized at small relative deformations and should be considered in all designs, primarily for serviceability conditions. An elastic-plastic closed-form solution is presented that permits an estimate of down-drag forces and the location of the neutral plane. It is shown that the conventional rigid-plastic solution may overestimate down-drag forces by as much as 50% and may also overestimate the depth of the neutral plane. Key words : piles, negative skin friction, neutral plane, capacity.

scholarly journals Numerical and Analytical Modeling for Predicting Drag Load Induced on Pile in Collapsible Soil because of Inundation

2017 ◽  
Vol 11 (1) ◽  
pp. 664-675 ◽  
Author(s):  
Sarah Tahsin Noor
Keyword(s):  
Skin Friction ◽  
Experimental Studies ◽  
Numerical Results ◽  
Neutral Plane ◽  
Analytical Models ◽  
Collapsible Soil ◽  
Design Guideline ◽  
Negative Skin Friction ◽  
Pile Shaft ◽  
Pile Diameter

Introduction:Negative skin friction that develops on the pile surface when the soil (adjacent to the pile shaft) settles but the pile is in static condition, causes an additional load (known as drag load) induced on pile. Substantial settlement of collapsible soil occurs only because of inundation. In such a case, the magnitude of drag load is influenced by several parameters, such as the collapse potential, inundation pressure, pile roughness, pile diameter, radius of wetting, depth to the neutral plane, and thickness of collapsible soil subjected to inundation.Methods:A numerical model is developed to simulate the case of a single pile in collapsible soil to predict negative skin friction and drag load by giving consideration to kinetic friction angle between the pile and the settling soil. The comprehensive interdependent relation among the parameters influencing the magnitude of drag load was revealed based on numerical results. Analytical models are developed for predicting the average negative skin friction and depth of neutral plane to quantify drag load because of the inundation of collapsible soil adjacent to the pile shaft.Result and Conclusion:The model coefficients were determined by analyzing the numerical results. The drag loads obtained from the analytical model developed and those from previous experimental studies are found in good agreement. For a given soil profile, the magnitude of drag load is found to vary widely (e.g., between 252 and 925 kN) because of the variations in the pile diameter, pile roughness, and radius of wetting. Thus, this study provides a design guideline for choosing the design pile diameter considering the magnitude of drag load due to inundation of collapsible soil adjacent to the pile shaft.

scholarly journals NEGATIVE SKIN FRICTION EFFECT IN CONSTRUCTION AND SOME METHODS TO REDUCE NEGATIVE SKIN FRICTION EFFECT

2009 ◽  
Vol 12 (6) ◽  
pp. 96-103
Author(s):  
Ngo Van Dau
Keyword(s):  
Skin Friction ◽  
Soft Soil ◽  
Delta Area ◽  
Negative Skin Friction ◽  
Friction Effect ◽  
Practical Experiences

Basing on the researches in negative skin friction effect, especially practical experiences of construction on soft soil at Cuu Long delta area, this article want to show the negative skin friction effect in soft soil and suggest some methods to reduce this affect.

scholarly journals ANALISIS MODEL KEGAGALAN RUMAH 2 LANTAI AKIBAT NEGATIVE SKIN FRICTION DAN CURAH HUJAN YANG TINGGI

2021 ◽  
Vol 4 (3) ◽  
pp. 623
Author(s):  
Jeanfrie Chandra ◽  
Chaidir Anwar Makarim
Keyword(s):  
Skin Friction ◽  
Soft Soil ◽  
Residential Building ◽  
Frictional Resistance ◽  
Slope Instability ◽  
Foundation Design ◽  
Negative Skin Friction ◽  
Soil Subsidence ◽  
Modeling Analysis

ABSTRACTOne of the problems that appear in a project is the presence of soft soil. In projects with soft soil types, it is necessary to manage the soil to increase the bearing capacity of soil. Soil subsidence on soft soil causes friction between the soil and the pile blanket, called the negative skin friction. Negative skin friction should not be neglected because it exerts a large enough force on the load that the pile must support. In addition, in designing an engineer must also pay attention to the optimal rainfall that will occur during the construction of a project and after that has an impact on the quality of the soil and foundation used. The topography of a project also needs to be considered, building a house on the edge of a slope can cause problems with slope instability. Increasing the load on the edge of the slope can reduce the safety factor of a slope. In this study, a modeling analysis will be carried out on a 2-story residential building that causes the house to collapse due to failure of the foundation design, the existence of negative frictional resistance on soft soil, and slope stability. ABSTRAKSalah satu permasalahan yang muncul pada suatu proyek adalah adanya tanah lunak. Pada proyek dengan jenis tanah lunak, perlu dilakukan perbaikan tanah untuk meningkatkan daya dukung tanah. Penurunan tanah pada tanah lunak menyebabkan gesekan antara tanah denan selimut tiang yang disebut fenomena tahanan friksi negatif. Tahanan friksi negatif tidak boleh diabaikan karena memberikan gaya yang cukup besar terhadap beban yang harus ditopang oleh tiang. Oleh karena itu, seorang insinyur harus memperhatikan dan mengetahui mengenai perilaku tanah lunak. Selain itu dalam mendesain, seorang insinyur juga harus memperhatikan mengenai curah hujan optimal yang akan terjadi selama pengerjaan suatu proyek dan setelahnya yang berdampak pada kualitas tanah dan fondasi yang digunakan. Topografi suatu proyek juga perlu diperhatikan, membangun rumah di tepi lereng dapat menyebabkan permasalahan pada ketidakstabilan lereng.  

A theoretical solution for pile-supported embankments on soft soils under one-dimensional compression

2008 ◽  
Vol 45 (5) ◽  
pp. 611-623 ◽  
Author(s):  
R. P. Chen ◽  
Y. M. Chen ◽  
J. Han ◽  
Z. Z. Xu
Keyword(s):  
Skin Friction ◽  
Soft Soil ◽  
Closed Form Solution ◽  
Stress Transfer ◽  
Form Solution ◽  
Soil Arching ◽  
Foundation Soil ◽  
Negative Skin Friction ◽  
One Dimensional ◽  
Piled Embankment

Pile-supported embankments are increasingly being used for highways, railways, storage tanks, etc. over soft soil because of their effectiveness in accelerating construction and minimizing deformation. The stress transfer mechanisms among all of the components in a piled embankment, including the embankment fill, the piles and (or) caps, and the foundation soils, are complicated. In this study, a closed-form solution for one-dimensional loading was obtained taking into consideration the soil arching in the embankment fill, the negative skin friction along the pile shaft, and the settlement of the foundation soil. In the derivations, the piles, the embankment fill, and the foundation soil were assumed to deform one-dimensionally. This study investigated the stress concentration on top of the pile, the axial load and skin friction distributions along the pile, and the settlement of the embankment. Comparisons demonstrate that the results from this solution are in good agreement with those obtained using a finite element method. It is worth pointing out that this solution should be applied to the piles close to the centerline of the embankment and not to those near the toe of the embankment because of the two-dimensional loading condition near the toe.

Results from long-term measurement in piles of drag load and downdrag

2006 ◽  
Vol 43 (4) ◽  
pp. 409-430 ◽  
Author(s):  
Bengt H Fellenius
Keyword(s):  
Skin Friction ◽  
Precast Concrete ◽  
Neutral Plane ◽  
Negative Skin Friction ◽  
Shaft Resistance ◽  
Concrete Piles ◽  
Sustained Loads ◽  
Soil Settlement ◽  
The 1960S

Several full-scale, long-term tests on instrumented piles performed since the 1960s and through the 1990s are presented. The results of the tests show that a large drag load will develop in piles installed in soft and loose soils. The test cases are from Norway, Sweden, Japan, Canada, Australia, United States, and Singapore and involve driven steel piles and precast concrete piles. The test results show that the transfer of load from the soil to the pile through negative skin friction, and from the pile back to the soil through positive shaft resistance, is governed by effective stress and that already a very small movement will result in mobilization of ultimate values of shaft shear. The pile toe resistance, on the other hand, is determined by downdrag of the pile and the resulting pile toe penetration. Reconsolidation after the pile installation with associated dissipation of pore pressures will result in significant drag load. An equilibrium of force in the pile will develop, where the sustained loads on the pile head and the drag load are equal to the positive shaft resistance plus the pile toe resistance. The location of the force equilibrium, the neutral plane, is also where the pile and the soil move equally. The drag load is of importance mostly for very long piles (longer than 100 pile diameters) for which the pile structural strength could be exceeded. Downdrag, i.e., settlement of the piled foundation, is a very important issue, however, particularly for low-capacity short piles. Soil settlement at the neutral plane will result in a downdrag of the pile. The magnitude of the downdrag will determine the magnitude of the pile toe penetration into the soil, which will determine the pile toe resistance and affect the location of the neutral plane. Nature's iteration of force and soil settlement will decide the final location of the neutral plane.Key words: piles, negative skin friction, drag load, downdrag, neutral plane, pile settlement.

scholarly journals Downdrag Measurements on a 160-Ft Floating Pipe Test Pile in Marine Clay

1972 ◽  
Vol 9 (2) ◽  
pp. 127-136 ◽  
Author(s):  
M. Bozozuk
Keyword(s):  
Skin Friction ◽  
Compressive Load ◽  
Marine Clay ◽  
Positive Skin ◽  
Negative Skin Friction ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Test Pile ◽  
Excess Pore

Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about [Formula: see text] (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end where the positive excess pore pressures were high and relative movement between the pile and the soil was large, the positive skin friction approached the remoulded strength as measured with the field vane. Skin friction was increasing, however, as positive escess pore pressures dissipated.This paper shows that skin friction loads are related to the combination of (a) in situ horizontal effective stresses, (b) horizontal stresses due to embankment loads, and (c) horizontal stresses due to differential settlement of the fill.

Sign in / Sign up

Export Citation Format

Share Document