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Abstrak :
ABSTRACT
The development and extension of large cities creates a need of multiple shallow tunnels in the soft ground of built areas. Excavating a tunnel generates ground displacements and deformations which can affect existing buildings and services in urban sites and can lead to unacceptable damages. Prediction of the ground settlement caused by the tunnel excavation has been a major engineering challenge.

A numerical simulation using finite element method was implemented in the aim of developing a procedure for forecasting the movement induced by tunneling. This study describes the modelling procedure, comparing one procedure in a complete stages of modelling (called phases modelling) taking into account different phases simulating the different kinds of interaction between the tunnel and the soil (deconfinement, lining installation, pore pressure applied on the lining, and weight of the lining) and one in a simple way called `deconfinement modeling', simulating the excavation using a stress decrease vector exerted on the excavation boundary in the opposite to the initial ground stress described by a scalar parameter A. (the deconfinement rate).

A shallow lined tunnel is analyzed in a two dimensional analyses, and observations are made for the settlement at the surface and at the tunnel crown, the deformations of the tunnel opening, and the stress path around the tunnel. Comparison is conducted using two soil models : the Mohr-Coulomb model and the CJS model.

Observations of the results and comparison with the experimental data demonstrate that the deconfinement modeling is adequate for the analyses of settlement induced by tunneling only if a good modeling of the soil behavior is considered.

Abstrak :
Soil stabilization has been used for an extensive period . Various soil properties can be improved or altered by soil stabilization. There are several techniques available by which soil properties like strength, workability, permeability and volome changes can be improved or altered...

Abstrak :
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.

Abstrak :
ABSTRAK
Skripsi ini membahas nilai parameter kompresi sekunder yang didapatkan dari hasil pengujian tanah lunak di Marunda. Pada tanah lunak, konsolidasi sekunder turut berkontribusi dalam total settlement yang terjadi. Kompresi sekunder terjadi dalam jangka waktu yang lama akibat adanya dilatasi dari struktur tanah. Data yang diperoleh dalam penelitian ini didapat dari hasil uji menggunakan oedometer standar berdiameter kecil dan oedometer modifikasi berdiameter besar. Pengujian dilakukan dengan memberikan variasi beban dan lamanya waktu uji. Dari hasil analisa data didapat nilai Cα yang semakin kecil seiring dengan besarnya tegangan yang diberikan. Semakin lama pembebanan, kurva konsolidasi semakin menunjukkan asimtot.

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ABSTRACT
This paper discuse about the value of secondary compression parameters obtained from the soft soil test results in Marunda. On soft soil, secondary consolidation contribute to the total settlement that occurred. Secondary compression occurs for long periods due to dilatation of soil structure. In this study, data obtained from standart oedometer with small diameter and oedometer modification with large diameter. Testing was done with load variation and duration of the test. From the data analysis, found that Cα values decreased if the load increased. Consolidation curve will be show asymptotes if the loading time more long.

Abstrak :
Indonesia sebagai negara yang berkembang terus melakukan pembangunan fisik terutama di bidang infrastruktur. Namun Indonesia memiliki berbagai macam jenis tanah yang tidak selamanya dapat digunakan untuk bangunan konstruksi diantaranya adalah tanah lempung lunak yang memiliki nilai kuat geser tanah sangat rendah. Untuk itu perlu suatu perbaikan tanah salah satunya dengan perkuatan geotekstil-woven. Dalam perkembangannya pemberian lapisan geotekstil ini telah terbukti keberhasilannya di lapangan. Namun secara laboratorium sedikit sekali penelitian yang telah dilakukan yaitu dengan uji triaksial CU. Penelitian yang dilakukan adalah mempelajari perilaku kuat geser contoh uji terhadap penambahan geotekstil-woven baik satu lapis maupun dua lapis pada rentang kadar air optimum. Contoh uji menggunakan tanah lempung lunak yang berasal dari daerah Ujung Harapan, Jakarta Utara. Teknik pemberian lapisan geotekstil pada contoh uji juga menjadi perhatian khusus pada penelitian ini dimana proses pencetakannya tidak melalui proses pemadatan melainkan proses penekanan langsung pada cetakan contoh uji dengan menjaga γdry yang sama antar contoh uji. Sebagai pembanding terhadap hasil dari triaksial CU dibuat juga pengujian unconfined. Dari hasil penelitian diketahui terjadi peningkatan nilai kohesi dan sudut geser yang mengakibatkan peningkatan nilai kuat geser pada contoh uji akibat pemberian satu lapis geotekstil. Sedangkan dengan dua lapis geotekstil tidak berhasil memberikan kontribusi terhadap nilai kuat geser. Peningkatan nilai kuat geser yang dilakukan di laboratorium diharapkan dapat mendukung keberhasilan penggunaan geotekstil di lapangan.

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Indonesia as a developing country continuously performs physical development particularly in the infrastructure sector. Nevertheless, Indonesia has various kind of soil that not always good for foundation of construction such as soft clay soil which has very low soil shear strength value. Consequently, soil reinforcement is needed; one of the methods is by using geotextile-woven strengthening. During its development, the application of this geotextile layer was successfully proven. However, still few researches done by using triaxial CU testing. The research was performed by studying shear strength behavior of the sample to the addition of geotextile-woven either one layer or two at optimum water content range. The sample was soft clay soil, taken from Ujung Harapan region, North Jakarta. The technique of adding geotextile layer towards the sample was also emphasized in this research, in which the forming was not through compaction process but direct pressing process to the sample by keeping equal &gmma;dry among the samples. As a comparison to the CU triaxial result, unconfined testing was performed as well. From the result of this research can be identified that there is an increase of cohesion value and shear angle, resulting on higher shear strength value of the sample, as a consequence of addition of one layer geotextile. Meanwhile, addition of two layers geotextile gives no contribution towards shear strength value. The increase of shear strength value as a result from this experimental works will support the implementation of using geotextile in the field.

Abstrak :
Pelaksanaan konstruksi terowongan di Indonesia sangat dibutuhkan, khususnya di Daerah Ibukota Jakarta yang memiliki permasalahan lahan untuk transportasi di permukaan tanah. Karakteristik tanah yang lunak, beban bangunan kota Jakarta, serta perubahan pore water pressure menjadi alasan bahwa pembangunan terowongan harus dikaji lebih lanjut. Dalam pelaksanaan konstruksi terowongan di tanah lunak, permasalahan tentang deformasi dan daya dukung tanah terhadap bangunan terowongan merupakan hal yang harus diperhatikan dengan seksama. Untuk itu, penelitian ini difokuskan pada pengaruh pembangunan terowongan terhadap deformasi dan perubahan tegangan di dalam tanah akibat pelaksanaan konstruksi terowongan. Hasil penelitian menunjukkan bahwa tanpa ada perkuatan berupa grouting atau perkuatan lainnya, nilai deformasi pada dinding terowongan dan pada tanah cukup besar. Grouting diperlukan untuk menambah nilai modulus elastisitas (E), kohesi (A) dan sudut geser ( A ) pada tanah lunak yang dianggap terlalu kecil jika digunakan untuk konstruksi terowongan bawah tanah. Penelitian ini menggunakan tanah London Clay yang diasumsikan memiliki sifat dan karakteristik yang hampir sama dengan tanah di Jakarta. Dari pemodelan ini diharapkan menjadi awal dari pemodelan terowongan yang lebih kompleks dan lebih baik di masa mendatang, dikarenakan pada penelitian ini hanya hanya dibatasi pada pengamatan nilai deformasi dan nilai perubahan tegangan menggunakan perhitungan konvensional yang masih sederhana. ...... The construction of the tunnel in Indonesia is needed, especially in Jakarta as a Capital Region who have transport problems on the ground. Characteristics of the soft soil, the city building load, as well as changes in pore water pressure is the reason that the tunnel should be studied further. In tunnel construction, especially in soft ground, the issue of deformation and bearing capacity of the building like tunnel that must be considered carefully. To that end, this study focused on the influence of the tunnel to the deformation and stress changes in the soil due to the construction of the tunnel. The results showed that without any form of reinforcement grouting or other reinforcement, the value of deformation at the tunnel wall and on the ground large enough. Grouting is necessary to increase the value of modulus of elasticity (E), cohesion (C) and friction angle (A) on soft soil that is too small if it is used for the construction of underground tunnels. This study uses London Clay soil is assumed to have the properties and characteristics similar to land in Jakarta. From modeling is expected to be the beginning of the tunnel modeling more complex and better in the future, because this study is only limited to the observation of the deformation values and value changes in voltage using conventional calculation is simple.

Abstrak :
Drawing on years of practical on-site experience, this book presents a new method for controlling "bridge-head bumping" in soft soil ground. Based on deformation compatibility and control theory of structure, it proposes strategies for improving the design method of soft soil ground and the effective "bridge-head bumping" control method. Soft soil ground is chiefly characterized by a large void ratio, high compressibility, high water content, low impermeability, low strength, strong structure and high sensitivity. As a result, it has pronounced rheological properties, and controlling "bridge-head bumping" in soft soil ground is essential to control the amount of soil rheology-induced unstable successive settlement. The book offers extensive information on this and related topics, making it a valuable guide for engineers in Civil Engineering and Geotechnical Engineering alike.