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"This thesis presented a numerical study of the improvement of soft soil using columnar inclusions. Review of analytical studies has been concentrated to British Standard BS8006, modified Terzaghi theory, and arching theory. Numerical model in this study is using FLAC3D code to generate 3D model. The materials properties uses in this model refer to typical values. Some of important design variables have been considered in our parametric study. The most efficient platform thickness is lm for loading 30kPa or more, in point of view to minimize the proportion stress on soft soil or to maximize ratio of load transferred to columns. Optimal area ratio A, is in range from 5% to 10% its depends on the considered parameters, but 10% is acceptable for most parameters. Study of stress distribution on column indicates that the negative friction will act on top part of column in any level of loading. Due to the mechanism of stress distribution, inclusion system could settle as a group. The maximum of stress reduction ratio Sr and stress concentration ratio Er is obtained for the same value as Terzaghi analysis."

"This thesis continues the same research last year with a different condition. It presented a numerical study of the improvement of solt soil using columnar inclusions with Fixed Base End Condition In this new condition the inclusions are assumed reach rock like layer condition. Review of analytical studies has been concentrated to British Standard BS8006, modified Terzaghi theorem, and arching theorem Numerical model in this study is using FLAC3D code to generate 3D model. The materials properties uses in this model refer to typical values. Some of important design variables have been considered in our parametric study. The most efficient platform thickness is 1m for loading 3OkPa or more, in point of view to minimize the proportion stress on soft soil or to maximize ratio of load transferred to columns. Optimal area ratio A, is in range from 5% to 10% its depends on the considered parameters, but 10% is acceptable for most parameters. Study of stress distribution on column indicate that the negative friction will act on top part of column in any level of loading. Due to the mechanism of stress distribution, inclusion system could settle as a group. The maximum of stress reduction ratio S, and stress concentration ratio E, is obtained for the same value as Terzaghi analysis."

"Pupuk berperan dalam penyediaan unsur hara bagi keperluan tanaman yang dibedakan menjadi dua jenis pupuk yaitu, pupuk organik dan anorganik. Pemberian pupuk (organik dan anorganik) secara berlebih membuat kondisi lahan menjadi kekurangan unsur hara yang berpengaruh dalam kesuburan tanah, perubahan struktur tanah dan pencemaran lingkungan. Penelitian ini memanfaatkan metode resistivitas untuk mengamati perubahan nilai resistivitas akibat pemberian pupuk organik dan anorganik pada lahan pertanian di Kecamatan Caringin, Kabupaten Bogor. Pemilihan metode resistivitas geolistrik karena dapat memetakan karakteristik tanah dengan cepat dan murah. Data yang digunakan dalam penelitian ini terdiri dari data resistivitas lapangan dan sampel tanah. Pengukuran resistivitas lapangan dilakukan sebanyak 5 kali pengukuran (1 kali sebelum diberi pupuk dan 4 kali setelah diberi pupuk) pada setiap lintasan (lintasan Organik dan lintasan Anorganik). Konfigurasi yang digunakan merupakan konfigurasi dipole-dipole dengan panjang lintasan 6 meter dan elektroda sebanyak 16 batang. Sedangkan pengukuran sampel tanah dilakukan di laboratorium sedimentologi, FMIPA UI untuk mendapatkan klasifikasi tekstur tanah dan grafik resistivitas fungsi kadar air. Hasil yang didapat menunjukan bahwa perubahan nilai resistivitas dalam rentang 27 jam setelah diberi pupuk (organik dan anorganik) cenderung mengalami penurunan yang disebabkan oleh kadar air dan reaksi larutan kimia pupuk dan penurunan resistivitas pemberian pupuk organik lebih tinggi dibandingkan larutan anorganik.

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Fertilizers play a role in providing nutrients for plant needs and are categorized into two types of fertilizers, namely, organic and inorganic fertilizers. Excessive application of fertilizers (organic and inorganic) causes a lack of nutrients that affect soil fertility, changes in soil structure, and environmental pollution. This study uses the resistivity method to observe changes in resistivity values due to applying organic and inorganic fertilizers on agricultural land in Caringin District, Bogor Regency. The geoelectric resistivity method was chosen because it can map soil characteristics quickly and cheaply. The data used in this study consisted of field resistivity data and soil samples. Field resistivity measurements were carried out five times (1 time before being fertilized and four times after being fertilized) on each line (Organic line and Inorganic line). The configuration used is a dipole-dipole configuration with a line length of 6 meters and a total of 16 electrodes. Meanwhile, soil sample measurements were carried out at the sedimentology laboratory, FMIPA UI to obtain a soil texture classification and a resistivity graph of the water content function. The results showed that the change in resistivity values within 27 hours after being given fertilizer (organic and inorganic) tended to decrease due to the fertilizer solution's water content and chemical reaction. The decrease in resistivity of organic fertilizer application was higher than inorganic solutions."

"Several studies have already been published in order to better understand the behaviour of interfaces. Different experimental methods, including direct shear tests, simple shear test, and tortional ring test, and also various constitutive models were presented to modelize the behaviour of the interface. These studies revealed that the main factors that affect the behaviour of the interface include the roughness of the interface, the soil mineralogy, the soil density, and the normal stress applied. This work was therefore directed primarily to better understand the overall behaviour of the interface and the influence of these factors in a monotonic and cyclical solicitation. Through the simulation of a direct shear test at constant normal stress (CNL) in FLAC 5.0, several typical behaviours, including degradation of shearing resistance and contractancydilatancy, have been observed and modelled. At first, the law of Mohr-Coulomb and its correspondent failure criterion have been implemented. Then several models have been proposed to model more precisely the behaviour. Finally, two cyclicals laws, the law of Ramberg-Osgood law and Byrne, originally developed for the soil, have been implemented in this model. This study has verified the consistency of the results and has determined whether the injection of such laws is sufficient to modelize the behaviour of the interface under cyclic loading. "

"This book highlights the use of Solidification/Stabilization (S/S) to treat lead-contaminated soils, which are widely present in China. It reveals the evolutionary mechanism of the structural characteristics of Pb contaminated soil during the S/S process. In addition, the book systematically analyzes laws influencing the S/S process and its internal mechanisms, and develops new models for the strength prediction and Pb leaching prediction of S/S monolith. The results can provide essential theoretical guidance and parameter-related support for the design of Pb-contamiated soil S/S remediation and recycling solutions."

"Penelitian ini meninjau seberapa besar pengaruh campuran kapur dan pasir terhadap perilaku kompresibilitas terutama indeks pengembangan apabila mengalami kondisi loading-unloadingreloading. Tanah yang digunakan adalah tanah lempung ekspansif daerah Perumahan Eucalyptuss Lippo Cikarang dengan bahan stabilisasi 15% kapur hidup (CaO) dan 10% pasir dari daerah Cimangkok. Pengujian dilakukan dengan masa pemeraman selama 0 hari, 4 hari, dan 7 hari.. Hasil pengujian konsolidasi menunjukan bahwa proses stabilisasi mampu menurunkan Compression Indexs sebesar 21,03%, menurunkan Recompression Indexs sebesar 21,83%, menurunkan Swelling Indexs sebesar 40,38%. Hasil pengujian Swelling Pressure menunjukan bahwa proses stabilisasi mampu menurunkan nilai swelling potential sebesar 21,98% dan menurunkan swelling pressure sebesar 10,59%.

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The study reviewed the influence of lime and sand mixture on the compressibility behavior especially for the expansion index when the soil have loading-unloadingreloading conditions. We use an expansive clay soil at Eucalyptuss Lippo Cikarang housing with using 15% calcium oxide (CaO) and 10% sand from the area of Cimangkok as stabilizing materials. Test conducted by the curing for 0 days, 4 days, and 7 days. Test results showed that the stabilization process of consolidation can make compression index lower by 21.03%, recompression index lower by 21.83% and swelling index lower by 40.38%. Test results showed that the stabilization process can reduce the swelling potential of 21.98% and reduce swelling pressure by 10.59%."

"Pemeliharaan aset adalah kegiatan yang bertujuan untuk memastikan kelangsungan fungsional dari suatu sistem produksi sehingga sistem tersebut dapat diharapkan untuk menghasilkan output sesuai dengan yang diharapkan. Sistem pemeliharaan dapat diartikan sebagai bayangan dari sistem produksi, pemeliharaan mungkin akan lebih intensif dilakukan ketika sistem produksi beroperasi pada kapasitas yang sangat tinggi. Kerugian produksi seperti penghentian produksi yang tidak terencana, kebocoran pipa, kerusakan peralatan dan tertundanya kegiatan pengeboran karena ketidaksiapan peralatan sangat tidak diinginkan. Sejumlah strategi pemeliharaan untuk sumur-sumur yang ada diharapkan dapat meminimalisir kehilangan produksi dalam upaya memenuhi target produksi minyak dan gas. Menentukan strategi pemeliharaan aset yang paling tepat merupakan proses manajemen pemeliharaan yang kompleks dan penting. Memverifikasi dan mengukur efektivitas strategi pemeliharaan aset merupakan tantangan yang signifikan dalam pemeliharaan aset. Selain itu, manajemen pemeliharaan aset mencapai biaya siklus hidup aset yang minimum dengan langkah-langkah optimasi proses yang tepat. Oleh karena itu, sangat penting untuk membuat program pemeliharaan yang detail, jelas dan terstruktur yang dapat mengarah pada stabilitas sistem atau pemeliharaan aset untuk kelancaran dan keamanan operasi fasilitas produksi. Dengan membuat standar pelaksanaan berdasarkan Work Breakdown Structure (WBS), diharapkan semua elemen pemeliharaan yang ada akan tercakup, sehingga mengurangi risiko kerusakan aset.

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Asset maintenance is an activity aimed at ensuring the functional continuity of a production system so that the system can be expected to produce output as expected. The maintenance system can be interpreted as a shadow of the production system, maintenance might be more intensive when the production system is operating at very high capacity. Production losses such as unplanned shutdowns, pipe leaks, equipment damage and delayed drilling activities due to equipment unpreparedness are highly undesirable. The purpose of asset maintenance is to ensure the functionality of a production system, thereby enabling the system to produce the expected output. Production losses, such as unplanned production stoppages, pipeline leaks, equipment damage and delayed drilling activities due to equipment unpreparedness, are highly undesirable. The most appropriate asset maintenance strategy must be determined through a complex and important maintenance management process. Verifying and measuring the effectiveness of asset maintenance strategies represents a significant challenge in asset maintenance. Furthermore, asset maintenance management is designed to achieve minimum asset lifecycle costs through the implementation of appropriate process optimisation measures. It is therefore of 2 paramount importance to create a detailed, clear and structured maintenance programme that can lead to system stability or asset maintenance for the smooth and safe operation of production facilities. By creating an implementation standard based on the Work Breakdown Structure (WBS), it is expected that all existing maintenance elements will be covered, thereby reducing the risk of asset damage."