Specialist in Design, Supervision/Execution of:

Dewatering,Pumping Test,PDA-PIT-Sonic Logging-Vibration Monitoring,
Pile/Plate Load Test,Soil Instrumentation,Soil Nailing,MicroPile,Grouting
Deep Foundation,Deep Excavation,Slope Stability,Ground Improvements
Geosynthetics & Other Geotechnical Works
Agent of Geotechnical Softwares:
PLAXIS, GEO5, Deltares, DC Software, RocScience, GeoSmart, NovoTech, etc.

Dr. GOUW Tjie-Liong Ir., M.Eng., ChFC.

  • Senior Geotechnical Consultant
  • Chartered Financial Consultant, ChFC
  • Senior Geotechnical Engineering Lecturer/Trainer
  • Provider of Geotechnical Short Course / Training
GTL Brief Profile

My Archives

25
Jul

Dynamic Compaction Design Guideline for Practicing Engineers

Written by Gouw Tjie Liong, Ir., M.Eng, ChFC, PhD. Posted in GTL Paper, Publication

ABSTRACT: During an earthquake, saturated fine sands tends to lose its bearing capacity due to the earthquake induced and accumulated excess pore water pressure. The phenomenon, known as liquefaction, is one of the earthquake hazards that need to be mitigated in an earthquake prone area such as the archipelagos of Indonesia. The occurrence of an earthquake cannot be prevented and, with the present knowledge, is difficult – if not impossible – to predict. However, liquefaction potential can be mitigated by carrying out proper ground improvement methods.   The most common ground improvement schemes that have been widely implemented in mitigating liquefaction potential of saturated fine sands in Indonesia are dynamic compaction and vibro-compaction. However, many practicing engineers are still not familiar with the methods. This paper presents the design, execution, and evaluation methods of dynamic compaction. Two case histories on real projects are also presented as examples.

Full paper download: 04-Gouw-2018-Jun-SEAGS-E-J-32-40-J04-DC-Proposed-Design-Guideline-a

14
Oct

Consolidation parameters – alternative to Casagrande and Taylor methods

Written by Gouw Tjie Liong, Ir., M.Eng, ChFC, PhD. Posted in GTL Paper, Publication

ABSTRACT: For decades, consolidation parameters are derived graphically. Pre-consolidation pressure is derived by Casagrande method where technician has to pick the point of smallest curvature from e-log s’ curve. Coefficient of consolidations is derived by Taylor’s method where technician has to draw a linear line from deformation vs square root of time curve. Both graphical methods can lead to different results depending on the technician’s judgment. Given the same e-log s’ curve, pre-consolidation pressure determined by different interpreters easily varies by three folds. Great variations also obtained in determining coefficient of consolidation through Taylor’s method. As soil compresses, void ratio reduces and so does permeability, hence the higher consolidation pressure the lower coefficient of consolidation should be. However, it is often found that plot of coefficient of consolidation vs consolidation pressures goes up and down irregularly. The author tries to derive pre-consolidation pressure by ‘Parallel Rebound Method’, that is: first line is drawn through unloading part of e-log s’ plot, second line is drawn tangent through initial part of e-log s’ curve parallel to the first line, third line is the normal consolidation line. The intersection of the third line with the second line is the pre-consolidation pressure. With regard to coefficient of consolidation, Asaoka’s method is employed to determine 100% consolidation under constant load, certain degree of consolidation time is then decided to derive coefficient of consolidation. It was found that the resulted coefficient of consolidation curve reduces consistently with higher consolidation pressures. With the help of computer spreadsheet program and mathematical formulation, both methods appear to give consistent results. It was concluded ‘Parallel Rebound Method’ and Asaoka’s method lead to better results in deriving pre-consolidation pressure and coefficient of consolidation, respectively

Full paper download: 170921s-19ICSMGE-GTL-ConsolidationParameters

14
Oct

EFFECTS OF PILE LATERAL MOVEMENT, PILE SPACING AND PILE NUMBERS ON LATERALLY LOADED GROUP PILES

Written by Gouw Tjie Liong, Ir., M.Eng, ChFC, PhD. Posted in GTL Paper, Publication

ABSTRACT: Based on 3D finite element numerical analysis on 3×3 pile group Gouw and Hidayat (2015) suggested that that when base friction of the pile cap and the passive pressure acting against the pile cap are neglected, the effects of the pile cap thickness against group lateral efficiency is marginal and can be safely neglected. They also briefly mentioned that the center to center pile spacing and the lateral movement of the piles also affect the capacity of the laterally loaded group piles. To investigate the effect of the magnitude of pile lateral movement and pile spacing to larger pile groups, the study was continued by carrying further analysis on 5×5 and 9×9 pile groups, taking the same modelling assumption where base friction and passive resistance induced by pile cap were neglected. The study revealed that pile group lateral efficiencies were found to be larger when the center to center pile spacing were wider. It was also found the greater the number of piles in the group the lower the pile lateral efficiency. However, pile head lateral (horizontal) movement only have marginal effect on the lateral efficiency of group piles.

Full paper download: 170926s-PILE2017-GTL-Efffect of Lateral Movement

Geotechnical Course

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