ANALISIS HASIL PENYELIDIKAN TANAH “PLATE BEARING TEST” UNTUK PENENTUAN PARAMETER DISAIN PONDASI (Studi Kasus Lokasi Rencana Pembangunan PLTU Jawa Barat)

Planning the design of building foundations depend on the results of soil investigation. Soil parameters used in the foundation design can be obtained from the results of ground investigation field or laboratory testing. Field investigation of soil that are commonly used to study the behavior and deformation of elastic stiffness and undrained shear strength is the Plate Bearing Test. In this research, soil investigation by Plate Bearing Test and interpretation of the results of investigations done to determine foundation design parameters of power plant building in West Java. Investigations carried out on three-point spread in the location of power plant . the results of plate bearing test are load-settlement curves. Then, analysis of parameters of the investigation done to obtain design parameters of power plant building foundations. The results showed that the subgrade modulus, elastic modulus and undrained shear strength at each point varies with the range of values are 994.77 ton/m3 to 1634.49 ton/m3, 297.57 ton/m3 to 488.94 ton/m2, 0.22 ton/m2 to 0.66 ton/m2. It can be concluded occur inconsistency of subgrade layer at this location. The results of this investigation can then be used as foundation design parameters in the planning of power plant building. For a more conservative design, soil parameters with the smallest value can be used as foundation design parameters

STUDI PROSES GEOMORFOLOGI DENGAN PENDEKATAN ANALISIS UKURAN BUTIR SEDIMEN (Studi Kasus Proses Sedimentasi Muara Sungai Banyuasin Sumatera Selatan)

Sedimentation in estuaries due to deposition of sediment material by geomorphological process that work. It is therefore necessary to study geomorphological process in order to provide an overview of the mechanisms of sedimentation (the process of sediment transport and deposition of material) that occurred. To determine the geomorphology of the most dominant influence on sedimentation in estuaries, the sediment grain size analysis was performed with a statistical approach, then making the relationship between sediment grain size distribution with populations of sediment occurs. In this study used dataestuary sediment grain size of Banyuasin river taken at three points on the mouth of the river estuary. The analysis showed that the dominant geomorphological process influence on sedimentation in the estuary of Banyuasin is fluvial process, where the transport and deposition of sediment carried by the power flow of the river. This is reflected in the values of statistics and sediment populations. The resulting statistical value indicates the condition of energy (power flow) which produces sediment at this location is relatively large, tend to be unstable and fluctuate rapidly. Sedimentary material that was found is dominated by saltation population, and population of suspension amount is less than 20%. This scale indicates that the river flow velocity of Banyuasin is large enough, so the population of saltation carried in large numbers to and deposited at the mouth of the estuary. Meanwhile, the finer particles (suspension population) will be led further into the sea. Population such conditions describes the characteristic of sediment grain size distribution in the fluvial environment of deposition

Upaya Peningkatan Budaya Sadar Bencana Gempa Melalui Analisis Statistik Parameter Geofisika di Kota Bengkulu, Indonesia

Potensi gempa bumi yang sewaktu-waktu dapat terjadi kerap menjadi isu utama bagi pembangunan dan masyarakat. Upaya peningkatan budaya sadar bencana gempa perlu dilakukan guna memberikan edukasi dalam menyikapi bahaya gempa yang dapat terjadi di Kota Bengkulu. Kegiatan ini dilakukan dalam rangka pelaksanaan kegiatan pengabdian berbasis riset, dimana pengukuran geofisik digunakan untuk mendeskripsikan kerentanan seismik Kota Bengkulu, melalui kerja sama kemitraan oleh Badan Penang­gulangan Bencana Daerah (BPBD) Kota Bengkulu. Hasil pengukuran geofisik selanjutnya diolah lebih lanjut untuk mendapatkan parameter amplifikasi (A0) dan frekuensi dominan (f0). Kedua parameter tersebut kemudian dianalisis untuk mendeskripsikan indeks kerentanan seismik (Kg) di Kota Bengkulu. Pema­paran hasil analisis juga dilakukan sebagai transfer pemahaman kerentanan seismik kepada mitra. Hasil kegiatan memperlihatkan bahwa terdapat 211 titik yang diinvestigasi. Secara umum tingkat kerentanan seismik di Kota Bengkulu rata-rata pada level rendah dengan sangat tinggi dengan nilai kerentanan rata-rata berkisar pada 2,69 sampai dengan 36,31. Kecamatan Ratu Samban, Ratu Agung, Gading Cempaka, Kampung Melayu, dan Teluk Segara digolong­kan sebagai wilayah dengan kerentanan sangat tinggi, dengan nilai maksimum rerata sebesar 36,31. Kecamatan Selebar dan Singaran Pati digolongkan sebagai wilayah dengan kerentanan tinggi dengan nilai maksimum rerata sebesar 5,97, Kecamatan Sungai Serut dengan kerentanan sedang dengan nilai maksimum rerata 4,41, dan Kecamatan Muara Bangka­hulu dengan kerentanan rendah dengan nilai maksimum rerata 2,69. Kegiatan ini membantu mitra dalam memetakan kerentanan seismik di Kota Bengkulu

Parametric Study of One-Dimensional Seismic Site Response Analyses Based on Local Soil Condition of Jakarta

Seismic site response analysis is used to estimate the response of soil deposits during seismic loading at any depth of interest and to interpret time histories as well as response spectra. This type of analysis involves many parameters that can affect the character of ground shaking. It is important to know the effect of these parameters in order to perform reliable seismic hazard evaluation at a site. This paper presents the effects of several parameters toward the characteristics of surface response spectra based on the local soil conditions of Jakarta using a one-dimensional (1-D) site response model with total stress approach. A parametric study was performed on two cohesive soil deposit profiles with a different site class, namely medium clay (site SD) and soft clay (site SE). The bedrock layers of both profiles were located at a depth of 300 m. In this study, the analytical methods implemented were the equivalent-linear method and the non-linear method. Several different dynamics soil models were also implemented. In addition, variation of property parameters, such as depth of bedrock, shear wave velocity of bedrock, layer thickness, etc., were studied. The results of this study indicate that all of the studied parameters have a significant effect on the response spectra at the ground surface

ANALISIS KEHILANGAN AIR PADA SALURAN SEKUNDER (STUDI KASUS DAERAH IRIGASI BENDUNG AIR NIPIS BENGKULU SELATAN)

The objectives of this research was to analyze how much the loss of irrigation water that occured in secondary channel at the irrigation area of Air Nipis Dam, South Bengkulu. Water losses were analyzed by using the method of debit in and out. The primary data were flow velocity, water depth, and cross section. In addition to primary data also used secondary data. They were temperature, wind speed, and humidity obtained from the Meteorology, Climatology and Geophysics Departement of Bengkulu. This research analyzed how much effect the percentage of water loss due to seepage and evaporation. From analysis calculations obtained the percentage of water loss value due to seepage and evaporation was not too significant. it can be concluded based on the observation of most water loss occurs due to the other factors, such as leaks in the lines, wild plant vegetation along the channel, etc. The results of this research showed that the percentage of total water loss value occurred on channel BN Kr 4 of 85,40% for the left secondary channel and channel BSB 1 of 74,16% for right secondary channels. While the value of the smallest percentage of total water loss occured in channel BN Kr 7 of 24,14% for the left secondary channel and channel BDA 1 of 22,53% for right secondary channel

PEMETAAN KAPASITAS DUKUNG TANAH KELURAHAN LEMPUING KOTA BENGKULU

Lempuing is one area in the coastal city of Bengkulu with predominantly sandy soil consistency. This study aims to map the soil bearing capacity of sand Village Lempuing based on data sondir. To achieve these objectives, data collection sondir test at some point spread in the city of Bengkulu Lempuing. Once the data is collected sondir required, further soil bearing capacity calculations for the two types of foundation, the foundation palms (shallow foundation) and pile foundation (the foundation). Capacity analysis results show that the depth of the foundation (Df) ? 1 m, license bearing capacity (qa) for the foundation of the palm of the width (B) 0.6m generate value qa ?1,2 kg / cm2. Meanwhile, the bearing capacity of pile foundation at 6m depth ranging between 35-130 tons. Overall analysis results are displayed in the form of maps of soil bearing capacity. Distribution of value in the map shows that the farther from the coastline, the bearing capacity of the ground at the same depth becomes greater its value

ANALISIS POTENSI LIKUIFAKSI DENGAN PENDEKATAN PROBABILISTIK (PERFORMANCE-BASED EVALUATION) DI KOTA PADANG, SUMATERA BARAT

Evaluation of liquefaction potential by the conventional way are based on deterministic methods. The methods use only one condition of earthquake load as parameter in liquefaction analysis. Actually, the strength of earthquake loads are varies. In the other words, there is the uncertainty magnitude of earthquake loading. The uncertainty can be taken into analysis only by using a probabilistic approach. This study describes how to analyze liquefaction by probabilistic method. The method used was performance-based evaluation, developed byKramer and Mayfield (2005, 2007). This method include contributions from all levels of magnitude earthquake (hazard levels) in liquefaction analysis. The research location is in Padang, West Sumatra. Soil Investigation data used are N-SPT and shear wave velocity spread in the city of Padang. Earthquake load parameters used were obtained from PSHA and deagregation analysis. The results of this study show the variation of liquefaction potential across the city of Padang based on liquefaction return period. The location with great potentialfor liquefaction (FS <1) by the probability more than 50% were in the coastal region and northern parts of Padang

PETA PROBABILITAS LIKUIFAKSI KAWASAN LEMPUING KOTA BENGKULU BERDASARKAN DATA UJI SONDIR

As one of the cities on the west coast of Sumatra Island is located in an active seismic lines, causing Bengkulu city into an area that has the potential for an earthquake. This allows also the potential danger of liquefaction when the earthquake occurred. One of the areas in Bengkulu city is the pathway through which the village Lempuing. This study aimed to analyze the potential for liquefaction at the Village Lempuing using probabilistic methods simplified procedure. Probability model used is the probability model developed by Haldar and Tang (1979). The data collected from the results of the geotechnical investigation sondir 6 point spread in the Village Lempuing. Soil resistance parameters in this analysis are based on test data sondir or Cone Penetration Test (CPT). Shear wave velocity data obtained from the correlation of the data CPT Vs. Seismic load parameters used were obtained from the Indonesian Earthquake Zoning Map of 2010 and the seismic history of the city of Bengkulu. The analysis shows the level of probability of liquefaction hazards at the study site is close to 100%. This suggests that the study site has great potential for liquefaction hazards occur when an earthquake occurs

Seismic Response Validation of Simulated Soil Models to Vertical Array Record During A Strong Earthquake

Several soil models, such as linear elastic, equivalent linear, and non-linear models, are employed in seismic ground response analysis. The aim of this study was to validate the seismic responses at ground surface of several soil models with the vertical array record of the Kobe earthquake. One-dimensional seismic response analyses were performed at Port Island using several soil models. The responses at ground surface from the simulated soil models were validated with the vertical array record of the Kobe earthquake. The results showed that the extended hyperbolic model yielded the most appropriate response according to the Kobe earthquake's recorded motion. This means that this model can be considered a suitable soil model to predict the response of strong earthquakes. In general, the results support the recommendation to select the most appropriate soil model for seismic ground response analysis

PEMETAAN POTENSI LIKUIFAKSI WILAYAH PESISIR BERDASARKAN DATA CONE PENETRATION TEST DI KELURAHAN LEMPUING, KOTA BENGKULU

Bengkulu city is one of the cities on the west coast of Sumatra island particularly vulnerable to earthquakes because it is located in an active seismic lines . This vulnerability allows the phenomenon of liquefaction when an earthquake occurs . One of the areas in Bengkulu city which through the lines is Lempuing Village . This study aims to analyze the liquefaction potential based on the data of Cone Penetration Test (CPT) using deterministic methods published by Idriss and Boulanger in 2008 . The data describes soil parameters, collected from the 6 point spread CPT test in Lempuing. Shear wave velocity data obtained from the correlation vs. the CPT data . Seismic load parameters used were obtained from the Indonesian Earthquake Hazard Map of 2010 and the seismic history of the city of Bengkulu. The magnitude of potential liquefaction happens to the value of Safety Factor (SF). The analysis at a depth of 0-2meter showed that most of the area in Lempuing with high potential of liquefaction, indicated by the value of SF is less than 1 . Furthermore , the results of the analysis are  displayed in the form of Liquefaction Potential Map . This map shows that the entire area of Lempuing be in an unsafe condition to the danger of liquefaction during an earthquake with a magnitude > 7.9 earthquake and bedrock acceleration of 0.4 g