Pengujian Skala Penuh Dan Analisis Perkuatan Cerucuk Matras Bambu Untuk Timbunan Badan Jalan Di Atas Tanah Lunak Di Lokasi Tambak Oso, Surabaya

Bamboo pile-mattress was proposed as an alternative ground reinforcement to support road embankment on soft soils for the Surabaya Eastern Ring Road Project. A full scale test program was performed to investigate reliability of the reinforcement system since standard calculation for this type of construction was not available. The full scale program was consisted of ground settlement monitoring by settlement plates and pore water pressure monitoring by piezometers. Readings were taken for each stage of embankment construction. Analytical and numerical analyses were also performed to verify the full scale test results. Analytical calculation for immediate settlement was performed based on the elasticity theory, for consolidation settlement was performed by the 1-D Terzaghi\u27s consolidation theory. Numerical calculation was performed using the finite element method utilizing a commercial software package called PLAXIS. In the finite element analyses, subsurface soil and embankment were modeled as elastic-plastic solid materials using the Mohr-Coulomb failure criteria. Bamboo piles and mattress were modeled as elastic-plastic springs and elastic-plastics beams, respectively. Monitoring records and analysis results show that bamboo pile-mattress reinforcement has effectively increased stability. Consolidation settlement was found to be relatively uniform. Results also show that monitoring records and analysis results are relatively similar

Finite Element Simulation of Vacuum Preloading at Palembang – Indralaya Toll Project

Methods for the prediction of soil behavior during the application of vacuum preloading are available but have not been used precisely and have not been proven yet in Indonesia. There are two common approaches to vacuum preloading simulation, based on the application of a uniform external load to the vacuum area, and based on suddenly lowering the groundwater level to create vacuum conditions, respectively. This affects the settlement, lateral deformation, and pore pressure predictions. The objective of this research was to improve the prediction of soil behavior based on high-quality field data by using state of the art vacuum preloading simulations. The results were compared with those of a series of instrumentation equipment, i.e. a settlement plate, an extensometer, and a piezometer. This research used data from the Palembang-Indralaya Toll Road, a section of the Trans Sumatera Toll Road that is approximately 22 km long and has an embankment height of about 4 m to 9 m. It was built over a swampy soft soil area, using vacuum preloading to improve the soil. Axisymmetric analysis of vacuum preloading was conducted for a single-drain system, plane-strain analysis was conducted for single- and multiple-drain systems, and 3D analysis was conducted for single-drain, multiple-drain, and cluster-drain systems. The results show that the proposed method produced a good correlation between the predicted data and the recorded monitoring data

Finite Element Simulation of Vacuum Preloading at Palembang – Indralaya Toll Project

Methods for the prediction of soil behavior during the application of vacuum preloading are available but have not been used precisely and have not been proven yet in Indonesia. There are two common approaches to vacuum preloading simulation, based on the application of a uniform external load to the vacuum area, and based on suddenly lowering the groundwater level to create vacuum conditions, respectively. This affects the settlement, lateral deformation, and pore pressure predictions. The objective of this research was to improve the prediction of soil behavior based on high-quality field data by using state of the art vacuum preloading simulations. The results were compared with those of a series of instrumentation equipment, i.e. a settlement plate, an extensometer, and a piezometer. This research used data from the Palembang-Indralaya Toll Road, a section of the Trans Sumatera Toll Road that is approximately 22 km long and has an embankment height of about 4 m to 9 m. It was built over a swampy soft soil area, using vacuum preloading to improve the soil. Axisymmetric analysis of vacuum preloading was conducted for a single-drain system, plane-strain analysis was conducted for single- and multiple-drain systems, and 3D analysis was conducted for single-drain, multiple-drain, and cluster-drain systems. The results show that the proposed method produced a good correlation between the predicted data and the recorded monitoring data

IZGLAĐENI MREŽNI SEIZMIČKI UČINAK PRIMIJENJEN ZA UPORABU ZEMLJIŠTA, STUDIJA SLUČAJA NA OTOKU KALIMANTAN, INDONEZIJA

Smoothed gridded seismicity is an analysis model in seismicity that allows for the obtaining of a rate based on the b-value and the same magnitude range. The data study has been collected and analyzed from a background source gathered by PusGen, referred to as the PusGen catalogue, with approximately 70 thousand data points. Two software programs (i.e. USGS PSHA and OpenQuake) were utilized in this study, and both programs have been proven as reliable in the creation of the 2017 Indonesia Earthquake Hazard Map. The final steps are to compare the acceleration map results with the Kalimantan Island land-use map and to analyze suitability development planning against potential hazards and earthquake risks. The results stated that: (1) acceleration due to the shallow background earthquake for the Kalimantan region, range from 0.00-0.25g (using USGS PSHA) and 0.0-0.4g (using OpenQuake); (2) meanwhile, based on the deep background earthquake source, the maximum accelerations that occur are 0.15g and 0.25g when using USGS PSHA and OpenQuake, respectively; (3) the utilized of land-use for the current and future years is in line with the results of the acceleration simulation. The study recommends to take into account the seismic aspects in new planning of the capital city, mining and residential areas in order to reduce the existing risks.Izglađeni (filtriran) mrežni seizmički učinak temelji se na analizi seizmičnosti, tj. izračunu vrijednosti b i odgovarajuće magnitude. U studiji su prikupljeni i analizirani podatci pozadinskoga izvora, prikupljeni u PusGen katalogu koji obuhvaća približno 70 000 podataka. Korištena su dva programska paketa koja su ranije pouzdano upotrijebljena kod izradbe karte potresnih rizika Indonezije 2017. godine, odnosno njihovi dijelovi nazvani USGS PSHA i OpenQuake. Završni dio računa bila je usporedba karte ubrzanja s kartom uporabe zemljišta na otoku Kalimantan te analiza daljnjega održivog razvoja s obzirom na opasnosti i rizik potresa. Dobiveni su sljedeći rezultati: (1) sila ubrzanja s obzirom plitke potrese u prostoru Kalimantana mijenja se 0 – 0,25 g (prema USGS PSHA), odnosno 0 – 0,4 g (OpenQuake); (2) temeljem dubokih seizmičkih izvora najveće ubrzanje izračunano je u intervalu 0,15 – 0,25 g (USGS PSHA, OpenQuake); (3) uporaba zemljišta, kako danas, tako i u budućnosti, treba pratiti rezultate simulacija (ubrzanja), za koje je preporučeno da postanu dio urbanoga planiranja glavnoga grada regije, ali i okolnih prostora u kojima se rudari

Pengaruh Strength Reduction Tanah Clay-Shale Akibat Pelaksanaan Pemboran Terhadap Nilai Daya Dukung Pondasi Tiang Di Jembatan Suramadu Berdasarkan Analisis Hasil Tes OC

. Suramadu Bridge, which will connect Surabaya and Madura, is designed to have 5,438 m total span. Considering bridge construction that is above sea and huge design load on its pile foundations, conventional static loading test can not be performed at the main bridge. Alternative pile load test that can be performed is OC Test, which followed Osterberg Cell Test procedure. Equipped with load cell, telltale, and strain gauge, this test can provide load-displacement curve of end bearing and skin friction at any depth. Soil investigation result shows existence of clay-shale layer, which contains montmorillonite, at bore pile's location. This soil is sensitive to lateral pressure reduction caused by boring and weathering process so that strength reduction can occur. Strength reduction of soil makes end bearing and skin friction difficult to be predicted. Strength reduction effect toward end bearing and skin friction are determined by means of comparing OC Test result to prediction result based on common empirical correlation. For end bearing, OC Test result shows value that close to prediction result's. Therefore, strength reduction of end bearing caused by boring is relative small. On the other hand, skin friction measurement result shows that its value is much smaller than prediction result's. For increasing bearing capacity, grouting through the pile base was conducted. Test result shows increasing of value either end bearing and skin friction after grouting through the pile base. Compared to end bearing's value, skin friction's value rise more and close to prediction value

Determination of The Site Amplification on Deep Soil Layer Using 1-D Site Response Analysis (Case study: Jakarta City, Indonesia)

The dynamic response of deep soil layers is used in the development of microzonation maps. The empirical correlation between standard penetratation blow count numbers and S-wave velocity was derived for practical purposes in site characterization based on local data in a case study in Jakarta, Indonesia. For estimating the intensity of potential earthquake shaking at the ground surface as a function of depth to the bedrock surface layer, 1-D site response analysis was carried out in 5745 simulations. The site amplification values were then evaluated by dividing the spectral acceleration (SA) at ground surface by the SA at rock outcrop. Plots of the SA amplification values at interested depth intervals of the bedrock surface layer were assigned. The results showed that the site amplification values estimated by considering the local depth of the bedrock surface layer were generally smaller than the SA amplification values from the Indonesian seismic building code SNI-1726-2012. Also, there appears to exist a tendency of lower levels of mean regression of amplification, in particular for the soft soil site class

The effect of weathering process to determination of residual shear strength of clay shale with triaxial multi-stage system

The slope failure on clay shale with many joints under a layer of tuff breccia shortly after stress release due to cutting activity have triggered the need to investigate clay shale residual shear strength. A series of triaxial testing on undisturbed samples of clay shale have been performed to determine the residual stress for multi-stage system operation. In the first stage, residual shear strength without stress release were obtained. Then, testing continued by releasing whole-cell pressure. The triaxial test was proceed to the second multi-stage system to obtain residual shear strength parameters. Tests were conducted to investigate the effect of drying process to reduce residual shear strength up to 80 days. During the period, the maximum percentage of residual internal angle friction without stress release (Øurp) and residual internal angle friction with stress release (Øurf) were reduced by 11% and 5%, respectively. Both paremeters are compared to the peak shear strength condition

Zonasi Hazard Gempa Bumi Untuk Wilayah Jakarta

Several damaging earthquakes occured in the last decades in Indonesia have alerted the government to mitigate future damages due to earthquake. One of method to minimize the damages is by performing seismic hazard assessment and risk evaluation as the hazard zonation with respect to ground motion characteristics taking into account sources, local geological and soil conditions. This paper performs a microzonation study for Jakarta. Local site effects are assessed by carrying out ground response analysis performed with the NERA routines. The zonation maps are produced with respect to ground shaking intensity in accordance with the manual proposed by World Institute for Disaster Risk Management

Shear strength degradation of Semarang Bawen clay shale due to weathering process

The effect of weathering processes in decreasing the shear strength of clay shale had been done in this study. The drying process of clay shale with sunlight in the laboratory up to 80 days had been conducted to create the conditions of weathered sample. The peak and residual shear strength parameters of unsaturated and saturated clay shale were obtained from triaxial laboratory test, and all samples were tested on each 8 days of weathering process. Decrease of shear strength in peak and residual condition was obtained during 80 days of the drying process. The residual shear strength parameters were distinguished between residual shear strength without stress release and with stress release of confining pressure. The results up to 80 days of unsaturated clay shale showed that the cohesion at peak stress conditions reduced to 30% based on initial shear strength before the occurrence weathering, while the internal angle friction reduced to 64%. Residual cohesion without and with stress release reduced to 4% and 1%, respectively while residual internal angle friction without and with stress release reduced to 15% and 5%. Similar situation also occurs for the saturated clay shale samples