26
May

STATRAPID – ALTERNATIF UJI BEBAN STATIK

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

ABSTRAK: StatRapid merupakan suatu teknik uji beban pondasi tiang yang relatif baru, yang dikembangkan sebagai alternatif uji beban statik dan uji PDA. Dalam uji StatRapid ini, beban plat baja modular yang dikombinasikan dengan sistem pegas dijatuhkan dari ketinggian tertentu, menumbuk dan menekan kepala tiang ke dalam tanah. Durasi tumbukan dibuat cukup lama sehingga tiang berperilaku kuasi-statik. Masa beban tumbukan yang diperlukan hanya 5% dari masa yang diperlukan untuk uji beban statik. Saat tumbukan terjadi, gaya, pergerakan, dan percepatan kepala tiang diukur. Dari pengukuran tersebut perilaku beban vs penurunan dan beban statik yang ditimbulkan dapat diturunkan. Makalah ini membahas metode dan interpretasi serta perbandingan uji StatRapid ini dengan uji beban statis. Disimpulkan bahwa StatRapid merupakan sebuah alternatif yang cukup baik bila diperlukan uji beban yang cepat dan handal.
Full Paper Download: Gouw-KOGEI_2019-STATRAPID-Paper-rev01

07
Nov

Estimating Pile Axial Bearing Capacity by c-phi Derived from Pressuremeter Test

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

ABSTRACT: Due to its rather brittle nature, retrieving undisturbed samples of Jakarta cemented greyish stiff clay, often found at a depth of 30 to 120m, is very difficult. Good and reliable effective shear strength parameters, i.e., c’ and f’ values, obtained from triaxial test are hardly available.  By modifying cavity expansion theory, Gouw (2017) was able to derive these effective shear strength parameters through Pressuremeter in situ test stress strain curve. It was found Jakarta cemented clay exhibiting a drained behaviour when loaded. Its effective cohesion, c’, values are linearly increasing with depths, averaging from around 95 kPa at 20 m to around 475 kPa at 100m depth, while its effective friction angle f’ values are within 20o – 30o, averaging to around 24o. The values found to be similar to the values derived from CIU triaxial compression test from relatively good undisturbed samples. This paper presents the methodology in deriving the shear strength parameters and then applying the derived Pressuremeter c’ and f’ values to estimate the pile axial bearing capacity through finite element simulation and comparing it with the commonly known SPT method applied in Jakarta.
Download Full Paper: http://indogeotek.com/wp-content/uploads/2019/11/GTL-181108s-HATTI-SEAGC-PileCapacityFromPMTdata.pdf

06
Nov

PROTECTION OF SLOPE SURFACE WITH GEOFOAM VERSUS COMPACTED-FILL

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

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