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"In this paper, the problem of natural convective heat transfer of kerosene-cobalt nanofluid inside a quarter circular enclosure in the presence of oriented magnetic field has been studied numerically using two-component non-homogeneous model. The round wall of the enclosure is maintained at constant low temperature; the left vertical wall is adiabatic whereas the bottom wall is considered as heated uniformly and non-uniformly. The effects of Brownian motion and thermophoresis are incorporated into the nanofluid model. The Galerkin weighted residual finite element method has been employed to solve the governing partial differential equations after converting them into a non-dimensional form using a suitable transformation of variables. Comparison with previously published work is performed and excellent agreement is obtained. The effects of various model parameters such as Hartmann number, Rayleigh number and magnetic field inclination angle on the streamlines, isotherms and isoconcentrations have been displayed graphically for both uniformly as well as non-uniformly heated bottom wall. In addition, the heat transfer augmentation for various model parameters as well as various thermal boundary conditions have been done in light of the average Nusselt number from the bottom heated wall. The obtained numerical results show that the average Nusselt number is an increasing function of the Rayleigh number, while it is a decreasing function of the Hartmann number."

"Pada penelitian ini, finit elemen model untuk analisis lengkung 3D telah dikembangkan berdasarkan polynomial berderajat 3 untuk displacement function-nya dan polynomial berderajat 2 untuk geometri lingkungannya (geometri lengkungan boleh sembarang). Sistem koordinat yang dipakai untuk menjabarkan matriks kekakuan elemen lengkung adalah sistem koordinat kurvilinier. Matriks kekakuan yang diperoleh berorde 16x16, dengan nodal degreed of rhythm terdiri dari bagian yang essentials (12 buah) dan bagian yang kurang essentials (4 buah). Karena kompeleksnya fungsi yang diintegralkan untuk memperoleh matriks kekakuan elemen, integrasi numeris dengan metode GAUSS quadrature terpaksa ditempuh. Selanjutnya derajat kebebasan yang non-essential dikondensasikan sehingga menghasilkan matriks kekakuan berorde 12x12, dengan semua derajat kebebasan merupakan EDoR. Dapat disimpulkan pula bahwa sebagai pedoman praktis menggunakan finit elemen model usulan ini untuk analisis cukup diperlukan 4 elemen untuk struktur pelengkung simetris dan 8 elemen untuk unsur pelengkung tak simetris."

"ABSTRAKDengan semakin berkembangnya metode soil improvement, khususnya denganmenggunakan Prefabricated Vertical Drain (PVD), maka diperlukan perhatiankhusus dalam menganalisa PVD. Pada umumnya kecepatan waktu konsolidasidipengaruhi oleh jarak dan panjang PVD. Analisa yang digunakan biasanyamenggunakan model konsolidasi 1 dimensi. Seiring perkembangan teknologikomputansi, perhitungan PVD dapat dilakukan dengan metode elemen hingga 3dimensi. Model 3 dimensi memiliki keakuratan yang baik namun tingkatkompleksitas yang lebih tinggi. Perhitungan PVD pada umumnya menggunakanmodel 2 dimensi / plane strain model. Agar model 2 dimensi memiliki keakuratanyang baik diperlukan ekivalensi permeabilitas tanah asli dan jarak PVD. Penulismenitikberatkan kedua hal tersebut dengan harapan diperoleh model yang tepatdalam perhitungan PVD sesuai dengan kenyataan di lapangan

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ABSTRACTWith the development of the soil improvement method, especially usingprefabricated vertical drain (PVD) it is necessary to analyize accurately. Generallythe rate of consolidation time depends on two factor, spacing and the length ofPVD. One dimension consolidation calculation is often used to analyze PVD.With development in computation technology, PVD calculation can be done byfinite element method three dimension which has good accuration but morecomplex. In fact, two dimension model used to calculate PVD in order to havegood accuration the permeability of soil and the spacing of PVD must beequivalent with three dimension model. Thw writer will focus in these factors inhopes to obtain the right PVD calculation model accordance with the fact in field;"

"ABSTRACTBesar defleksi lateral pada pondasi tiang merupakan salah satu persyaratan desain pondasi tiang yang harus dipenuhi. Defleksi lateral aktual tiang yang terjadi diperoleh dari uji pembebanan lateral pada pondasi tiang dengan sistem pembebanan tertentu sesuai dengan ASTM D 3966-90. Perilaku antara tanah dan pondasi tiang akibat pembebanan lateral dimodelkan secara sederhana dengan model subgrade reaction dimana tanah disimulasikan sebagai kumpulan pegas dengan kekakuan lateral yang berbeda-beda. Untuk mengetahui hubungan antara kekakuan lateral pegas tanah dan nilai N-SPT, maka penulis melakukan perhitungan numerik dengan metode finite-element terhadap 34 data pembebanan lateral tiang dengan pembebanan siklik dan data bor dalam pada masing-masing lokasi uji pembebanan. Perhitungan numerik dilaksanakan untuk tiang tunggal dengan pembebanan lateral pada elevasi cut-off. Hasil yang diperoleh selanjutnya dibandingkan dengan grafik empiris hubungan kh koefisien tahanan lateral tanah dalam kg/cm3 dan nilai N-SPT berdasarkan Yokohama. Simulasi numerik yang dilakukan yaitu dengan menghitung nilai defleksi pada kepala tiang dimana tiang diasumsikan sebagai elemen balok dengan sifat linear elastis. Hasil simulasi numerik menunjukkan bahwa terdapat perbedaan korelasi antara studi kasus dengan 34 data tanah tersebut dengan grafik korelasi dari Yokohama. Selain itu, interpretasi dari hasil yang diperoleh menyatakan bahwa modulus subgrade reaction dipengaruhi oleh nilai N-SPT sepanjang kedalaman tiang dari cut-off level, diameter tiang, defleksi lateral aktual, dan besar beban lateral rencana. Namun, metode instalasi tiang tidak menunjukkan pengaruh yang signifikan terhadap hubungan antara modulus subgrade reaction dan nilai N-SPT.

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ABSTRACTThe magnitude of lateral deflection is one of the requirement in designing pile foundation. The actual lateral deflection is obtained by lateral load test on pile foundation with certain loading system based on ASTM D 3966 90. The behavior between the soil and pile foundation is simply modeled by subgrade reaction model in which the soil is simulated as group of springs with different lateral stiffness. To find out the correlation between the spring lateral stiffness and N SPT value, the author perform numerical calculation based on finite element method of 34 cyclic lateral loading test and deep boring data at each loading test location. The calculation is carried out for single pile with lateral loading at cut off elevation. The results obtained are then compared with the emperical graph of correlation between kh lateral soil resistance cofficient in kg cm3 and N SPT value based on Yokohama. Numerical simulation is carried out by calculating the magnitude of lateral deflection at pile head where the pile is assumed as a beam element with elastic linear model. The results show that there are a difference in the correlation between 34 case studies modeled and Yokohama correlation. In addition, the result interpretation shows that subgrade reaction modulus is affected by N SPT value along the pile length from cut off level to pile toe, actual lateral deflection, and the magnitude of lateral load test. However, pile installation method does not show the significant impact to the correlation between modulus subgrade reaction modulus and N SPT value."

"Pada tahun 2019, terjadi keruntuhan lereng di Lawe Sikap, Kutacane, Nanggroe Aceh Darussalam (Erly Bahsan S.T, 2020). Berdasarkan pengamatan pola keruntuhan, diperkirakan bahwa keruntuhan lereng dikategorikan sebagai keruntuhan guling atau toppling failure (Erly Bahsan S.T, 2020). Berdasarkan kasus tersebut, diperlukan suatu analisis stabilitas lereng untuk menggambarkan perkiraan pola keruntuhan, mencari nilai faktor keamanan lereng, serta faktor apa saja yang menjadi penyebab keruntuhan tersebut. Salah satu metode dalam melakukan analisis stabilitas lereng adalah dengan metode elemen hingga atau finite element method (FEM). Menurut penelitian, ditemukan bahwa FEM lebih unggul dalam melakukan analisis stabilitas lereng dibandingkan dengan limit equilibrium method (LEM) atau metode keseimbangan batas. Pada penelitian ini, penulis menggunakan software MIDAS GTS NX yang merupakan salah satu software untuk melakukan analisis stabilitas lereng yang berbasis FEM. Dalam melakukan analisis stabilitas lereng dengan keruntuhan guling, diperlukan model geometri lereng serta diskontinuitas atau celah antar batuan utuh yang sesuai dengan kondisi eksisting. Selain itu, pemilihan model konstitutif juga berpengaruh terhadap hasil analisis yang dilakukan. Model geometri yang dipilih adalah dengan membuat celah elemen antara batuan utuh (intact rock) dengan sudut kemiringan sebesar 60° searah dengan arah jarum jam. Dalam analisis ini, penulis menggunakan model konstitutif generalized hoek-brown yang dinilai cocok digunakan untuk menganalisis stabilitas lereng batuan. Terdapat beberapa faktor yang berpengaruh terhadap kestabilan lereng batuan, yaitu adanya pemotongan lereng akibat proses konstruksi dan adanya pengaruh dari muka air tanah. Selain itu, MIDAS GTS NX juga terbukti mampu dalam memodelkan keruntuhan guling pada lereng objek studi.

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In 2019, there was a slope collapse in Lawe Sikap, Kutacane, Nanggroe Aceh Darussalam (Erly Bahsan S.T, 2020). Based on the observation of the failure pattern, it is estimated that slope failure is categorized as a toppling failure (Erly Bahsan S.T, 2020). Based on this case, a slope stability analysis is needed to describe the estimated failure pattern, find the value of the slope safety factor, and what factors cause the collapse. One of the methods for analyzing slope stability is the finite element method (FEM). According to the study, it was found that FEM is superior in performing slope stability analysis compared to the limit equilibrium method (LEM) or the boundary equilibrium method. In this study, the author uses the MIDAS GTS NX software which is one of the software to perform slope stability analysis based on FEM. In conducting slope stability analysis with toppling failure, a slope geometry model and discontinuity or gap between intact rock are required according to existing conditions. In addition, the selection of a constitutive model also affects the results of the analysis carried out. The geometric model chosen is to create an element gap between intact rock (intact rock) with a slope angle of 60° in a clockwise direction. In this analysis, the author uses a generalized Hoek-brown constitutive model which is considered suitable for analyzing rock slope stability. There are several factors that affect the stability of rock slopes, namely the existence of slope cutting due to the construction process and the influence of the groundwater level. In addition, MIDAS GTS NX is also proven to be able to model the toppling failure on the slopes of the study object."

"Analisis stabilitas lereng pada umumnya dilakukan dalam bentuk dua dimensi 2D dengan asumsi kondisi plane strain tanpa mempertimbangkan dampak analisis tiga dimensi 3D. Namun, dalam analisis stabiltas lereng khususnya lereng alami yang memiliki kompleksitas geometri lereng perlu dilakukan pemodelan dalam bentuk 3D yang dapat menggambarkan kondisi asli lereng. Dalam penelitian ini dilakukan pemodelan 2D dan 3D dengan metode elemen hingga finite element method untuk mengetahui perbedaan hasil analisis stabilitas lereng 2D dan 3D pada lereng alami yang memiliki geometri kompleks. Penelitian yang dilakukan yaitu dengan membandingkan hasil pemodelan 2D dan 3D lereng studi kasus Pasir Muncang serta melakukan verifikasi perilaku dan sensitivitas model 2D dan 3D terhadap beberapa faktor. Hasil analisis menunjukkan bahwa terdapat faktor-faktor yang mempengaruhi nilai faktor keamanan 2D dan 3D yaitu diantaranya nilai parameter tanah, perbedaan jarak kontur, dan tingkat kehalusan. Faktor-faktor tersebut memiliki pengaruh yang berbeda terhadap hasil model 2D dan 3D sehingga didapatkan rasio nilai faktor keamanan 3D dan 2D lereng alami Pasir Muncang sebesar 1.44. Adanya perbedaan nilai faktor keamanan 2D dan 3D ini mengharuskan adanya pertimbangan dalam pemilihan penggunaan analisis stabilitas lereng dalam bentuk 2D atau 3D.

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The vast majority of slope stability analysis is performed in two dimensional 2D under the assumption of plane strain conditions, without much consideration to the impact of three dimensional 3D analysis. However, in slope stability analysis, especially natural slopes that have complexity of slope geometry, 3D modeling is required which can represent more realistic geometry of slope in third dimension.

This study presents finite element method for calculating the 2D and 3D factor of safety for ldquo Pasir Muncang rdquo natural slope. A comparison of different factor of safety in 2D and 3D analysis, and also verification of sensitivity in 2D and 3D models to several factor are presented.

The result of analysis indicate that there are factors that influence the difference of 2D and 3D factor of safety. These factors are soil parameters, contour spacing, and mesh coarseness which have different effects on the 2D and 3D model results. The ratio of 3D and 2D factor of safety differences on Pasir Muncang natural slope is 1.44. The existence of this difference in 2D and 3D factor of safety requires consideration in the use of two dimensional 2D or three dimensional 3D slope stability analysis."

"ABSTRACT

The finite element method has been applied to the study the behavior of vertically loaded single micro pile, the nine piles in a close group, the three piles in a row group in a homogeneous non linearly behavior medium, that is cohesion less soil.

Bidimensional and axis metric elements have been used in the analysis to determine the stress and the strain state in the soil around the piles and the deformation of the pile due to the grouting pressure of the micropiles.

This paper uses Mohr Coulomb model with a parameter controlling dilatancy.

The effect of grouting pressure in the soil around the member of piles group at three-diameter spacing are presented and analyzed. The efficiency of each piles and piles group at two until five spacing diameter, at 10% up to 50% deformation of pile are shown and studied. Those efficiency graphs are compared with the efficiency of driven pile group and bored pile group.

The effect of dilatancy to the deformation of pile at different grouting pressure is presented.

Using super positioned method that efficiency graph can be used for evaluating the efficiency of bigger micro piles group.

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