Studi Perbandingan Desain Inti Bendung Dengan Pemakaian Material Alternatif Untuk Optimasi Biaya Studi Kasus: Proyek Bendungan Tapin, Banjarmasin, Kalimantan Selatan

Bendungan Tapin merupakan bendungan tipe urugan zonal inti tegak dengan zona inti kedap air menggunakan material lempung. Kendala yang terjadi saat pelaksanaan konstruksi adalah ketersediaan material lempung untuk zona inti yang ada di sekitar proyek. Di sisi lain terdapat material hasil galian spillway yang dibuang begitu saja disekitar area proyek. Adanya permasalahan tersebut, terdapat gagasan untuk memanfaatkan material hasil galian spillway tersebut sebagai material zona inti yang dikombinasi dengan geomembrane untuk meningkatkan impermeabilitasnya. Dalam rangka mendapatkan ukuran zona inti bendung yang optimal, dibuat 5 alternatif desain yang kemudian dianalisa dengan bantuan software SEEP/W dan SLOPE/W. Selanjutnya, hasil perhitungannya dibandingkan dengan perencanaan awal dimana zona inti bendung menggunakan material lempung dari quary. Hasil perhitungan menunjukkan bahwa geomembrane dapat menurunkan nilai rembesan rata rata hingga 89%. Disamping itu, diperoleh efisiensi biaya sebesar 27.53% apabila material galian spillway dipakai sebagai pengganti material lempung untuk bendung inti

Pengaruh Kedalaman Tancap, Spasi, Dan Jumlah Cerucuk Dalam Peningkatan Tahanan Geser Tanah Lunak Berdasarkan Permodelan Di Laboratorium

Belakangan ini pemakaian cerucuk cukup efektif sebagai metode alternatif perkuatan stabilitas lereng maupun perkuatan embankment jalan. Pada embankment jalan, cerucuk digunakan sebagai bahan yang kaku berfungsi untuk menaikkan stabilitas tanah. Sebagai perkuatan lereng, cerucuk sangat efektif berfungsi sebagai pasak/tulangan yang dapat memotong bidang kelongsoran lereng. Sehingga cerucuk dapat memberikan tambahan gaya geser pada lereng yang mampu melawan gaya geser longsoran yang terjadi. Tambahan gaya geser yang dihasilkan oleh cerucuk tersebut dapat meningkatkan angka keamanan (safety factor) stabilitas lereng.Akhir-akhir ini pengembangan teori tentang konstruksi perkuatancerucuk padastabilitas lereng tanah lunak guna menambah kekuatan gesernya(yang mendekati kondisi di lapangan) masih sedikit dan belum memadai.Hanya saja untuk pengembangannya tersebut sangat diperlukan informasi yang rinci dan jelas tentang interaksi antara tanah lunak dengancerucuk. Informasi tersebut dapat diperoleh salah satunya dari penelitian skala laboratorium yang dibuat mendekati kondisi lapangan. Tujuan penelitian ini untuk menjawab bagaimana pengaruh panjang tancapan (rasio tancap) dan pengaruh jarak (spasi) antar cerucuk terhadap penambahan tahanan geser dari stabilitas lereng tanah lunak. Penelitian ini dilaksanakan melalui salah satu cara pendekatan model skala laboratorium, namun perilakunya dibuat mendekati perilaku sebenarnya di lapangan. Bidang kelongsoran lereng yang terjadi di lapangan didekati dengan bidang geser yang sengaja dibuat di laboratorium dengan menggeser contoh tanah (Plab) yang terdapat dalam kotak geser hasil modifikasi yang berukuran relatif besar pada alat geser langsung. Cerucuk yang akan digunakan berupa cerucuk kayu mini dan ditanamkan pada contoh tanah tadi.Variasi rasio tancap (L/D) yang diterapkan sebesar 5, 10, 15, dan 20.Sedangkaan variasi spasi cerucuk yang digunakan sebesar 3D, 5D, dan 8D.Sedangkan untuk variasi jumlah cerucuk yang dipasang yaitu 1 batang, 2 batang, 4 batang, dan 6 batang.Diharapkan dari perilaku skala kecil tersebut dihasilkan tambahan teori mengenai perkuatan lereng dengan cerucuk yang mendekati kondisi sebenarnya di lapangan.Hasil penelitian pendahuluan menunjukkan bahwa semakin besar rasio tancap yang digunakan cerucuk maka semakin meningkatkan tahanan geser tanah lunak.Selain itu tahanan geser tanah lunak juga meningkat apabila spasi antar cerucuk yang digunakan sebesar 3D sampai 5D.Akan tetapi penurunan tahanan geser tanah lunak terjadi apabila spasi antar cerucuk yang digunakan adalah lebih besar dari 5D.Selain itu bahwa tahanan geser tanah menjadi meningkat seiring dengan adanya penambahan jumlah cerucuk. Kelompok cerucuk yang menerima gaya geser horisontal pada arah sejajar terhadap baris kelompoknya (PolaPemasangan 1) menghasilkan tahanan geser tanah yang relatif lebih besar daripada arah tegak lurus terhadap baris kelompoknya (Pola Pemasangan 2). Selain itu bahwa kemampuan kelompok cerucuk dalam menahan geseran horisontal juga dipengaruhi oleh faktor efisiensi. Dimana kemampuan kelompok cerucuk dalam menahan geseran horisontal tidak akan sama dengan kemampuan masing-masing cerucuk dikalikan dengan jumlah cerucuk dalam kelompok yang bersangkutan

Prediction of Flexible Pavement Deflection Based on Falling Weight Deflectometer, FWD, for Highways Traversed by Heavy Overloaded Vehicles (Case Study on Arterial And Collector Roads in Tuban, East Java, Indonesia)

Falling Weight Deflectometer, FWD, is the most popular equipment used to measure the deflection of  flexible pavement in Indonesia. The loading used during application of the FWD equipment generally correlates directly with those of the loads of standard heavy vehicles. Therefore, the resulted pavement deflections obtained from the tests should be also suitable for highways traversed by standard normal vehicles only. This may not be the case for highways in Indonesia, where most trucks are highly overloaded, so much beyond the allowable standard loads. The existing method of FWD test may not be representative anymore to measure the actual pavement deflections under highly overloaded vehicles. In this paper, the authors describe their findings about deflections of flexible pavement when the pavements were subjected by heavily overloaded vehicles. The first step is to modify the FWD equipment with larger falling distances and heavier loads to simulate the highly overloaded vehicles in Indonesia. Based on the results and by using statistical approach, a new mathematical equation can be derived to reflect the functions of actual pavement deflections under much higher loads when compared to those of standard normal load. Therefore, using this new equation one can predict the actual pavement deflection under highly overloaded vehicles, by just performing standard FWD test of standard loads on the pavement, so that the design of overlay thickness can be modified accordingly to be applicable to overloaded traffic in Indonesia

Influence of Residential Spatial Position to Trip Generation in Surabaya

Zonal trip generation is usually assummed to be influenced only by demographic and economic variables. It is seldom to consider spatial position of the zones as an influence variables to its trip generation. In actual condition, people will consider strategic position of residential area when they choose to buy or rent of their home, in accordance with their place of activities such as working, studying for their children and shopping. This research aim is to calculate the influence of spatial position of residential zones from the activities centers to zonal trip generation in Surabaya, Indonesia. Surabaya has several activities centers that can be classified as urban centers and suburban centers. In order to define position of residential zones in relation with activities centers, travel time is defined as a spatial measure which can be measured using Google Maps. Trip generation data is compiled from origin-destination matrix from household interview survey. Regression analysis is used for calculation of the influence of spatial position of residential zones in relation to the activities centres to zonal trip generation. The result shows that travel time to urban center influences reduction of the residential trip generation more than travel time to suburban centers does. However, still many trips were not influenced by travel time from residential to city center since housing ownership in Surabaya is fixed system more than flexible one, and housing at periphery area much cheaper than at city center

Best Practice BRT for Increase TransJakarta Modal Share

TransJakarta since 2004 was expected as the backbone of the public transportation in Jakarta as well as TransMilenio in Bogota. However, the role of TransJakarta only approximately 1, 95% of the overall number of trips has reached 19 million/day. The analysis technique on this paper is descriptive analysis. TransJakarta operational perceived is still not effective, so that the necessary efforts to increase modal share sourced from BRT management best practice in other countries. Efforts could be made to increase modal share, among others, the elimination of thousands of parking and replaced by pedestrian friendly also develop a separate bike lane along 303 km in Bogota (Colombia). TransJakarta operational is still considered less in some aspects that are: total of fTransJakarta fleet, total of feeder route, Transjakarta speed and headway still need improved, overtaking lanes are built along the TransJakarta route, Integration with all public transport is absolutely necessary, integration with pedestrians and bicycle users TransJakarta ticket fares should be integrated with feeder and other public transportation such as KRL, city buses and paratransit and using smartcards. In terms of restrictions on the use of private vehicles can be done in the following ways implement a bike-sharing program, implement program of not using motor vehicles during weekdays for 1 day in a week, providing park and ride, implement fuel restriction program for gasoline purchases, implement car sharing program. If the operational performance of TransJakarta has been improved and restrictions on the use of private motor vehicles are implemented, it is expected that the modal split of road users in Jakarta can be expected to rise to be more ideal. In some other parts of the world some experts say ideal conditions of split capital between public transport and private vehicles can reach 65%: 35%. Hopefully the city of Jakarta can achieve this

Analisis Kebutuhan Perkuatan Geotextile untuk Tinggi Timbunan Badan Jalan yang Bervariasi di atas Tanah Lunak Pada Kondisi dengan dan tanpa Pemasangan PVD (Prefabricated Vertical Drain)

Kebutuhan perkuatan geotextile dipengaruhi oleh kondisi tanah dasar itu sendiri. Perbedaan kondisi tanah dasar ketika dengan pemasangan PVD (Prefabricated Vertical Drain) dan tanpa pemasangan PVD terletak pada daya dukungnya. Daya dukung tanah dasar dengan pemasangan PVD lebih tinggi daripada tanpa pemasangan PVD, hal tersebut dikarenakan kenaikan harga Cu sebagai akibat pemampatan konsolidasi sehingga mempengaruhi jumlah kebutuhan perkuatan geotextile. Pada geotextile dengan Tult yang sama, kebutuhan jumlah perkuatan geotextile dengan pemasangan PVD lebih sedikit daripada tanpa pemasangan PVD, sedangkan pada geotextile dengan Tult yang bervariasi terdapat batasan untuk kondisi tanpa pemasangan PVD. Pada kondisi tanpa pemasangan PVD, semakin tinggi timbunan maka Tult geotextile yang digunakan semakin tinggi, sedangkan untuk kondisi dengan pemasangan PVD, Tult geotextile yang digunakan untuk semua variasi tinggi timbunan dalam penelitian ini minimal 50 kN

Modelling Modal Shift Preference of Freight Transport on Surabaya-Jakarta Corridor : A Preliminary Survey

The market share of freight transport which is dominated by road transport and accompanied by unbalanced of infrastructure’s growth and freight demand has created various negative impacts on existing transportation system. The shift of freight transport from road to rail and sea is expected to reduce those impacts. Research on the behavior of freight mode choice and the extent to which the user is willing to trade off the attribute change needs to be done so that the amount of modal shift will be known. The main objective of the study was to produce a model of mode choice based on preference surveys among forwarders, as well as to provide inputs for policy improvement and or improvement of freight transportation services. One of the surveys to be conducted is the revealed preference (RP) survey. The important stage before the RP survey is to conduct a preliminary survey. This stage aims to determine the important trends related to the choice of modes by the forwarder and test the response rate of respondents. The survey is also useful for assessing the credibility of the data instrument, identifying potential errors in the data instrument, and determining non-conformities in survey management before the actual survey. Data collection was done by sending questionnaires. The structure of the questionnaire consists of questions about characteristics of : shipment, travel, and modes. The results of survey showed relatively low response rate because it was only 8 respondents who were willing to answer the questionnaire. This indicates that the questionnaire needs to be combined with other methods, such as: face to face interviews and or focus groups. The results of the preliminary survey show that the main factors for the choice of existing modes are: shipment costs, loss/damage, and time travel. The implementation of the next stage survey should consider that each company has more than one shipping commodity so it is necessary to group questions and analysis based on each commodity

EFISIENSI DAYA DUKUNG TIANG DALAM GRUP MENGGUNAKAN PENDEKATAN ANALISA FEM 3D

Besar kecil nilai efisiensi pada pondasi tiang dalam grup terjadi karena pengaruh overlapping persebaran tegangan. Beberapa rumus untuk menghitung efisiensi hanya menggunakan tipe pondasi end bearing capacity. Padahal ada tipe pondasi pondasi friction bearing capacity. Yudiawati (2019) mengamati efisiensi full friction didapatkan bahwa kelompok tiang yang lebih dalam memiliki nilai efisiensi lebih rendah. Metode penelitian tersebut dilakukan aktual sehingga biaya dan waktu dihabiskan besar dan variasi diuji sedikit. Sehingga perlu  metode lebih efektif yakni Finite Element Method  3D (FEM 3D). Dengan FEM 3D jumlah variasi yang diujikan bisa lebih banyak dan waktu yang digunakan juga relatif singkat. FEM 3D dipilih karena memiliki karakteristik yang paling mendekati dengan yang aktual. Hasilnya efisiensi pada FEM 3D menunjukkan bahwa tipe pondasi pondasi mempengaruhi besar kecil nilai efisiensi. Tipe pondasi full friction memiliki 40% nilai efisiensi lebih kecil dibandingkan tipe end bearing capacity. Selain itu Semakin panjang kedalaman tiang maka semakin kecil nilai efisiensi. Pada tipe pondasi end bearing capacity pengaruh kedalaman tidak terlalu signifikan hanya sebesar 1-5%. Sedangkan pada tipe full friction pengaruh kedalaman terhadap nilai efisiensi bisa mencapai 5-10%. Pada penelitian ini Nilai efisiensi pada tipe End bearing adalah berkisar antara 0,45-0,9. Sedangakan untuk tipe full friction berkisar antara 0,23-0,65

Analysis of Settlement of the Road with Full Scale Geotextile Reinforcement on the Very Soft Soil (Case Study in Tapin Regency, South Kalimantan)

Abstract, in case of the construction of road in soft soil, it is necessary toconsider the use of materials around the road construction site, and not touse selected material which is imported from outside the road constructionsite. Thus, aim to overcome the difficulties of using selected materials, namely the difficulty to obtain the materials, the price of expensivematerials , the freight of material that could takes a long time period, highcost, and the use of materials that tend to be environmentally unfriendly. Itis very necessary to learn about the use of nonstandard additive materials, taken to the road construction site, but with the use of geotextilereinforcement. The research method used is a full scale method in the formof trial embankment, so that the performance of the road can be observedfor a long period of time due to the traffic and soil settlement. The resultsobtained is settlement that occur on the road from the combination ofordinary embankment material and local material, most frequently occuredin a larger percentage of ordinary embankment than the local material. While the visual value is relevant to the settlement in which a largerpercentage of ordinary embankment results in a better visual value, due tothe quality of the ordinary embankment material is better than the localmaterial