Effect of Pile Cap Thickness and Magnitude of Lateral Movement on Group Capacity of Laterally Loaded Piles

ABSTRACT: The capacity of laterally loaded group piles are conventionally analyzed by simply reducing the lateral subgrade reaction of the soil, kh. The lateral subgrade reaction is reduced to 0.35 kh, when the piles center to center distance is at 3 pile diameter and linearly increases up to 1.0 kh when the piles center to center distance is equal or higher than 8 pile diameter. It seems there is no consideration to the thickness of the pile cap and magnitude of lateral movement of the piles on this conventional approach. By using 3D finite element geotechnical software, the effect of these two factors can now be investigated. This paper presents the study on the impact of those two factors on lateral capacity of group piles. The study reveals that when base friction of the pile cap and the passive pressure acting against the pile cap is neglected, the effects of the pile cap thickness against group lateral efficiency is marginal and can be safely neglected. The center to center pile spacing and the lateral movement of the piles do play important roles in the capacity of the laterally loaded piles. The greater the pile spacing the greater the lateral group efficiency, so does the lateral movement.

link to download full paper: http://www.ejge.com/2015/Ppr2015.1320ma.pdf

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Seberapa Besar Pengaruh Efek Gangguan dan Hambatan Alir pada Prefabricated Vertikal Drain ?

Sejauh ini teknik perbaikan tanah yang terbanyak diaplikasikan di Indonesia adalah aplikasi vertikal drain untuk meningkatkan kuat geser undrained dan untuk mempercepat penurunan konsolidasi pada tanah lempung lunak. Terdapat banyak makalah-makalah akademis yang mengatakan bahwa efektifitas vertikal drain perlu diperhitungkan terhadap efek gangguan saat pemasangan (smear effect) dan efek hambatan alir (drain resistance). Makalah ini menganalisa dan membahas seberapa besar efek dua faktor tersebut dalam kasus nyata di dua proyek perbaikan tanah di Balikpapan dan Bontang, Kalimantan, Indonesia. Dari analisa data-data penurunan dan monitoring piezometer terlihat bahwa efek gangguan dan efek tahanan alir tersebut dapat dikatakan tidak berarti. Dengan kata lain dalam proyek dengan vertikal  drain yang dipasang sedalam 12 dan 27m ini kedua efek tersebut dapat diabaikan.

Download full paper: GOUW-2015-1125-EfekGangguan-HambatanAlir-PVD

 

IMPORTANCE OF ELONGATION FACTOR in Determining GEOSYNTHETICS STIFFNESS for Finite Element Calculation

Abstract: The application of geosynthetics for reinforced earth, also known as mechanically stabilized earth, is gaining popularity in Indonesia. At the same time, many engineers have started using geotechnical finite element software in designing the geosynthetics reinforced earth. Unfortunately, many of them still do not know the importance of elongation factor in determination of the geosynthetics stiffness to be input into the finite element calculation. Some engineers even said that elongation of the geosynthetics need not be considered in selecting the right geosynthetics material, only the breaking strength and the type of geosynthetics need to be considered. Such misconception can lead to bad performance or even failure of the geosynthetics reinforced earth. This paper elaborates the importance of the elongation factor and the correct procedure in determining the stiffness of geosynthetics materials for finite element software input.

Keywords: Elongation, stiffness, geosynthetics, finite element analysis

Download full paper: Gouw-2015-0927-ElongationFactorinGeosynthetics-Proc-SLOPE 2015

DISC – Penggolongan Kepribadian

Prilaku manusia bisa dikategorikan dalam 4 huruf DISC. Yang artinya lebih kurang:

D = Dominance,
Kategori orang yg menekankan hasil nyata dan mempunyai tingkat keyakinan tinggi. Tipe No nonsense. Biasanya selalu melihat gambaran besar (sasaran akhir), berani menerima tantangan2, bicara lurus dan tidak bertele-tele.
Biasanya pemimpin besar politik masuk kategori ini. Contoh: Churchill, Lee Kuan Yew, Lincoln dll.

I = Influence,
Kategori orang yg menekankan mempengaruhi/merayu orang, keterbukaan dan hubungan satu sama lain. Prilaku umum: antusiastik, optimistik, suka kerja sama, dan sangat tidak suka kalau diacuhkan.
Biasanya artis2 tergolong ini.

S = Steadiness,
Orang yg menekankan kerja sama, ketulusan dan ketergantungan satu sama lain. Prilaku utama: tidak suka diburu-buru, pendekatan masalah tenang termasuk alon alon asal ke lakon, supportive dan sederhana.
Biasanya orang2 jenis ini tidak suka perubahan. Tipe ingin hidup tenang, intrinsik agak tidak suka tantangan baru. Memerlukan dorangan seorang pemimpin.

C = Conscientious,
Orang yg menekankan kualitas, akurasi, presisi, keahlian, dan kompetensi.
Prilaku utama: menikmati ketidak-tergantungan pada orang lain (independen), selalu mencari alasan objektif, menggali hingga detail, was was kalau kalau berbuat salah.
Engineer harus mempunyai sifat ini.

Kalau digambarkan dalam figuratif binantang adalah sbb:

D = Hiu
I = Teddy bear
S = Domba
C = Burung hantu

Termasuk golongan manakah anda?

Live like a Pencil

A Pencil Story
I believe I was born for a purpose!
I hesitated what I am for?
I seek and realized I am born to write!
To write meaningfully…
And I start writing…
Inherently, at times I make mistake…
But I know mistake is only a word…
And I can learn from the mistake…
Mistake is a clue to redo,
Redo in a different way,
I have the in built power
to get up and make correction!
One of the days I do worn up,
I was dull and blank….
However, I believe what is important is inside,
So, I go and sharpen myself,
To dig the inner side of me,
And I find I can write even better.
Although my life is getting shorter,
and will eventually die off..
But I know, what I will leave behind is a legacy for the world to read and learn!!
(GTL-SG-MRT-150818 freely rewritten from BillyK)

A Geotechnical Short Course on Ground Improvement

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Jakarta, 1-3 September 2015

Covering theoretical design calculation,execution, monitoring and interpretation. Practice design and data interpretation session shall be given.

  1. PRECOMPRESSION With VERTICAL DRAINS: Basic Principles, Type of Vertical Drains, Application, Design Method and Calculation, Installation, Instrumentation, Monitoring, Interpretation, Asaoka Method, and Case Histories.
  2. VACUUM PRELOADING: Surcharging vs Vacuum Method; Execution; Monitoring System; Improved Ground; Application Examples and Case Histories (with projects in Indonesia and Vietnam)
  3. Liquefaction potential analysis:What is Liquefaction; Liquefaction Phenomenon; Liquefaction induced Damages; Identifying Liquefaction Potential; Cyclic Stress Ratio – CSR; Assessing Liquefaction through SPT data; Assessing Liquefaction Potential through CPT data; Liquefaction of Deeper Layer; Calculation Examples. Analysis of Liquefaction potential by using Novo Liquefaction software shall be given.
  4. DYNAMIC COMPACTION: Equipment, Mechanism, Execution procedure, Design Guidlines and Case Histories.
  5. VIBROCOMPACTION – VIBROFLOATATION – STONE COLUMNS: Vibro Compaction Mechanism, Dry Process, Wet Process, Vibroflotation, Vibrocat, Stone Columns, Design Guidelines, Case Histories.
  6. JET GROUTING: Various Grouting Techniques, Equipment, Execution, Formation, Cementand Composition, Application of Jet Grouting.

click here for detail, 2015-09-010203 – Course Ground Improvement

Kinerja Jangka Panjang Angkur Tanah dan Pengaruhnya Terhadap Stabilitas Dinding Diaphrgama – Sebuah Studi Kasus

Abstrak: Krisis ekonomi berkepanjangan semenjak akhir 1997 mengakibatkan banyak proyek yang terbengkalai cukup lama, diantaranya adalah galian basement yang ditinggalkan begitu saja. Makalah ini membahas salah satu proyek dengan galian basement yang sudah diselesaikan hingga kedalaman final antara 14-16.5m dari muka tanah asli. Sistem dinding penahan tanah yang digunakan adalah dinding diaphragma dengan tiga dan empat lapis angkur tanah. Saat krisis ekonomi melanda, kegiatan proyek dihentikan total, dewatering air tanah tidak lagi dilakukan, hanya pemompaan air permukaan saja yang dilakukan, itupun dengan intensitas yang sangat kurang. Galian dibiarkan terbuka selama lebih dari 6 tahun. Pertengahan Juni tahun 2003, dilakukan pengukuran-pengukuran, diantaranya: defleksi dinidng penahan tanah, gaya-gaya yang bekerja pada angkur tanah. Pengukuran ini diikuti dengan evaluasi terhadap kinerja angkur tanah dan keamanan dinding diaphragma. Diketahui bahwa angkur tanah mengalami kehilangan gaya-gaya yang cukup signifikan, yang bila dibiarkan akan dapat mempengaruhi keamanan dinding diaphragma. Disimpulkan bahwa diperlukan konstruksi berm untuk menambah kesatabilan dinding diaphragma sebagai tindakan preventif.

Download full paper: GTL-J03-2004-HATTI-Kinerja Jangka Panjang Angkur Tanah

A Geotechnical short course on Slope Stability, Lateral Earth Pressure and Deep Excavation with application of Geo5 softwares

Jakarta, 24-26 June 2015

Background: In our practice as geotechnical and civil engineers we are often faced with excessive slope movement and even slope failures; excessive ground movement and failure of deep excavations, be an open cut or supported excavation, is also one of the construction problems we often encountered. Those failures are often caused by lack of adequate geotechnical design knowledge and construction processes. This short course is designed for consulting engineers, contractor, and academican to enhance their knowlege and skill in appreciating important factors affecting the stability of slopes and deep excavations so as to design and execute deep excavation projects safely. Case studies of slope and deep excavation failures shall be presented and discussed. The participants shall have chances to learn how to model a proper slope stability and deeep excavtion analysis by using GEO5 softwares.

Course Topics: The course shall be conducted by refreshing the basic relevant geotechnical theory, followed by the in depth discussion of geotechnical engineering knowledge and how to implement those knowledge into practice. The course shall cover the following subjects:

  1. SLOPE STABILITY ANALYSIS: Examples of slope failures; Factors affecting slope stability; Slope types; Infinite slope; Planar Failure; Slip Circle Analysis; Fellenius, Bishop Method and Others; Geosynthetics Reinforced Slopes; Earthquake effects. Case studies by using GEO5 Software.
  2. LATERAL EARTH PRESSURES: Various earth retaining structures; Lateral earth pressures and their coefficients; Earth pressure at rest; Rankine, Coulob, Caquot Kerisel lateral earth pressure theories; Load induced lateral earth pressures. Calculation of lateral earth pressures by GEO5 Software
  3. DEEP EXCAVATION: Execution of deep excavation and Its supporting structures covering Soldier Piles, Secant Pile and Diaphragm walls; Ground Anchors, Quality control; Examples of deep excavation failures; Causes of the failures, followed by discussion on the designing and monitoring aspects. Case studies in desingning deep excavation project by GEO5 Softwares.

for further info: 2015-06-24-25-26-Course on Slope-EarthPressure-DeepExcavation

How to model repetitive loading in Plaxis 2D?

A graduate student from Texas A&M University asked:
I’m currently working on a project related to Rail Embankments. How a repetitive/ cycling loading can be simulated in a typical FEM model (I’m using PLAXIS 2D) considering the effect of fatigue.

My answer:
Use HS small soil model, cyclic loading can then be simulated by choosing dynamic analysis and the loading vs time can be created by making a text file first in Notepad (left column is time, right column is magnitude of loading).