26
May

PROTECTION OF SLOPE SURFACE WITH GEOFOAM VERSUS COMPACTED-FILL

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

BY: ANTHONY GUNAWAN PHD & DR. GOUW TJIE-LIONG

ABSTRACT: Slope failures are very common in hilly areas with high precipitation, Indonesia is one of the countries which experiences frequent slope failures. According to Indonesian National Board for Disaster Management, more than 600 slope failures occurred in 2018, resulting in more than 100 deaths. Slope protection is an important aspect of geotechnical engineering in Indonesia. One common method for slope protection is construction of retaining structures such as gabion. In most cases gabion with rock-fill is an effective solution in mitigating slope failures. However, in some cases, the extra load from the rock-fill aggravate the stability of slope instead. One particular example is taken from a case study in Puncak. A 28 m high slope, with a villa beside the peak of the slope, had experienced multiple slope failures ever since the construction of villa 30 years ago. Currently, the slope has a gradient (horizontal versus vertical) of 0.35:1 for the bottom 5 meters; 0.7:1 for the next 8 m; 1.3:1 for the following 10 m; and near vertical for the last 5 m. A retaining system using gabion and rock-fill behind the gabion was modelled with GEO5 and PLAXIS. PLAXIS analysis show that failure will occur in the midst of construction. Alternative fill using a light-fill material, geofoam, was then carried out and the construction can be carried out successfully. The retaining structure also acts as an erosion control and reduces water infiltration from rainfall.

Download Full Paper: http://indogeotek.com/wp-content/uploads/2019/11/AG-GTL-190927s-GeoFoamProtectedSlope-Slope2019-Bali.pdf

26
May

Numerical Modelling of Energy Pile by Different Constitutive Models

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

BY: ANTHONY GUNAWAN PHD & DR. GOUW TJIE-LIONG

ABSTRACT: Energy pile is an innovative technology which combined foundation pile with heat pumps. Through this integration, foundation pile can then serve as cooling and heating system, in summer and winter, respectively. During energy pile operation, the pile is subjected to heating and cooling cycles. The thermal cycles induce thermal-induced settlement, and predicting this settlement is a major challenge. As the thermal loading of energy pile is cyclic in nature, constitutive model capable of modelling cyclic hysteresis is necessary. In this paper, a model energy pile embedded in saturated sand and subjected to 5 thermal cycles are back-analyzed using hardening soil with small strain stiffness model. To highlight the importance of modelling cyclic hysteresis, two constitutive models which cannot model the cyclic hysteresis, i.e. hardening soil model and Mohr Coulomb model are used to back analyse the same test. Results show that hardening soil with small strain stiffness model can model the test reasonably well, while hardening soil and Mohr coulomb model severely underestimate the thermal-induced settlement.
Download full paper: http://indogeotek.com/wp-content/uploads/2019/11/AG-191014-16ARC-Taipei-Numerical-Model-of-Energy-Pile.pdf

26
May

Vibrocompaction Proposed Design Guideline for Practicing Engineers

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

ABSTRACT

Vibrocompaction is one of the suitable methods to improve liquefiable sand layer. Due to the relatively young age of this technology in Asia, not many engineers are familiar with vibrocompaction design techniques. This paper aims to provide design guidelines for practicing engineers on vibrocompaction. The paper covers the vibrocompaction working principles, its different types, its applicability to soil types, as well as its design and execution methods. Two case studies are presented. The first case study was the application of vibroflotation to compact reclaimed sand up to 17 m thick in Batam, an island nearby Singapore. The reclamation process caused the upper 3 m of sand above the seawater level reached dense condition inducing difficulty for the vibroflot to penetrate and densifying the loose sand below it. The solution to overcome this difficulty is discussed in this paper. The second case study was the densification of 12m thick loose silty fine sand in East Borneo to prevent differential settlement of a 44 m diameter oil tank to be constructed on the site. On this site, a problem was encountered during backfilling, the backfill material could not flow out of the probe. The solution to this problem, and other problems encountered during execution of the project are presented. Conclusions and recommendations drawn from the case studies are presented.
Full Paper Download: GOUW-2019-16ARC_Vibrocompaction Proposed Design Guideline for Practicing Engineers

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