Hitung Balik Nilai Kekakuan Tanah dari Hasil Pile Loading Test dengan Menggunakan Program Plaxis

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

ABSTRAK: Parameter kekakuan tanah (soil stiffness), E, merupakan parameter masukan yang sangat penting dalam metoda elemen hingga. Keakuratan prediksi penurunan pondasi sangat tergantung kepada seberapa akurat nilai kekakuan tanah yang dimasukkan ke dalam program elemen hingga tersebut. Terdapat perbagai cara untuk mendapatkan nilai kekakuan tanah ini, antara lain melalui uji triaxial, uji oedometer, uji pressuremeter atau korelasi dengan data uji sondir dan SPT. Makalah ini menyajikan parameter kekakuan tanah yang diperoleh melalui hitung balik hasil uji beban statis pondasi tiang. Kurva beban vs penurunan tiang yang diperoleh dari uji beban dicocokan dengan hasil analisis program PLAXIS. Masukkan nilai E disesuaikan sedemikian sehingga hasil analisis dan hasil uji beban mencapai kecocokan. Digunakan data uji 15 buah pondasi tiang bor di Jakarta. Selanjutnya nilai E yang diperoleh dari hasil hitung balik dikorelasikan terhadap nilai N SPT, N1(60).

Download Full Paper:  2012-Dec-Gouw-Krisandi-Hitung Balik Kekakuan Tanah




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


Very often many construction jobs involve slope construction, e.g. open cut excavation, retaining wall, construction on sloping ground etc., other than that stability of embankment and natural slopes also need to be evaluated. In such cases slope stability is one of the important factor to be analyzed. Conventional Limit Equilibrium Method (LEM), e.g. Method of Slices  is widely used. With the advance of computer technology, Finite Element Method (FEM) is getting more and more popular, this is also the case in the analysis of slopes. Unlike LEM where the mode of failure is predetermined, FEM locates the potential failure surface by searching the weak points in the ground. Potential failure surface is searched by reducing the soil shear strength. It is known as Strength Reduction or Phi-C Reduction Method. The question often encountered is whether this FEM yield the same safety factor as the conventional LEM method. This paper presents the results of comparative study conducted by both method. It was found that the value of safety factor and the predicted ollapse pattern of both methods have similar results. Largest difference of safety factor was still within tolerable limits (around 5%).

Download Full Paper here: 2012-Dec-GOUW-Dave-Kestabilan Lereng-FEMvsLEM


Deep Excavation Failures, Can They be Prevented?

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

ABSTRACT: The writer has been working in the field of geotechnical engineering since 1984, along the way he has seen a number of deep excavation failures, some with minor casualties, others involving a huge amount of economic loss, some cost no human life, others with a number of fatalities. This paper tries to discuss what could be the causes of those failures, from the possible technical to the non-technical reasons. It also tries to extract what can be learned from those failures, starting from the lack of reliable soil investigation data, inadequate geotechnical design knowledge, poor execution, to poor quality control. The non technical reasons, such as: the lowest bid win policy and its implication are also discussed. Finally, steps to minimize geotechnical failures are suggested.

Download full paper (in English)

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