Seismic Hazard Assessment For Peninsular Malaysia Using Gumbel Distribution Method

This Paper Presents The Preliminary Study On Seismic Hazard Assessment Which Involved Developing Macrozonation Map For Two Hazard Levels, I.E. 10% And 2% Probabilities Of Exceedance In 50 Years For Bedrock Of Peninsular Malaysia. The Analysis Was Performed Using Statistic Theory Of Extreme Values From Gumbel. The Analysis Covered The Earthquake Data Processing (Such As Choosing A Consistent Magnitude To Be Used In The Analysis And Identifying Main Shock Events), And Selection Of Appropriate Attenuation Relationship. Results Showed That The Peak Ground Acceleration (PGA) Across The Peninsular Malaysia Range Between 10 And 25 Gal For 10% Probability Of Exceedance, And Between 15 And 35 Gal For 2% Probability Of Exceedance In 50 Years Hazard Levels. These Values Were Lower By About 50 To 65% Than Those Obtained From Deterministic Analysis

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

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’s 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

PEMBUATAN PETA MIKROZONASI GEMPA KOTA SEMARANG MELALUI PENGEMBANGAN PROGRAM SEISMIC HAZARD DENGAN MEMPERTIMBANGKAN KONDISI FRAGILITY BANGUNAN

The new Indonesian code for building design, SNI 1726:2012, has been issued recently. It follows the concept of Risk-Adjusted Maximum Considered Earthquake MCE R used by ASCE 7-10 and it provides maps of MCE R for the whole Indonesian Country. Development of seismic risk microzonation of Semarang City is required for disaster preparedness and hazard mitigation. The purpose of this research is then to propose the seismic microzonation of Semarang City based on the seismic hazard analysis, site specific response analysis and risk assessment. The seismic hazard analysis is adapted from ASCE 7-10 to produce MCE R ground motion at bedrock level for the whole area in the city by combining the results of deterministic, probabilistic seismic hazard analysis, and fragility curves of buildings. The analysis was performed by using calculation procedures, seismic source model, attenuation functions, and geological and seismological data previously used to develop national seismic hazard and risk maps by Team for Revision of Seismic Hazard Maps of Indonesia 2010. The site response analysis and risk assessment were conducted by carrying onedimensional ground response analysis. Geotechnical parameters are interpreted from previous and recent measurements and depth of engineering bedrock is estimated based on Single Station Feedback Seismometer measurement. Two engineering bedrock elevation models were performed to obtain the distribution of site response such as peak ground acceleration (PGA), spectral acceleration at ground surface and amplification factor due to ground motions at bedrock. The seismic microzonation is carried out by selecting time histories of ground motion records for input motions in one-dimensional propagation analysis. Five ground motions for all sources and five ground motions for shallow crustal fault sources (with magnitude ranging from 6 to 7 and maximum distance 20 km) are collected from worldwide historical earthquake database records. Site response analysis is then conducted for each ground motion to obtain peak ground acceleration, spectral acceleration and amplification factor. Keywords: Seismic Microzonation, Seismic Hazard Analysis, Site Specific Response Analysis, Single Station Feedback Seismometer Measurement

Pengembangan Peta Elevasi Batuan Dasar Kota Semarang Melalui Penelitian Single Station Feedback Seismometer

Salah satu tahapan penting pada analisa kondisi tanah lokal (Site Specific Analysis/SSA) adalah menenhrkan elevasi atuan dasar (Bedrock). pada SSA gelombang gempa dalam bentuk acceleration time histories dirambatkan dari batuan dasar ke permukaan. Metode invasive dan non invasive adalah dua metode yang sering digunakan untuk meneliti elevasi batuan dasar. Metode invasive memerlukan pengeboran secara langsung ke dalam tanah. Salah satu metode yang sering digunakan ntuk meneliti elevasi batuan dasar dengan pendekatan non nvasive adalah dengan menggunakan gelombang ambien (ambient vibrations). Single station feedback seismometer dapat digunakan untuk menangkap gelombang ambien dengan meletakkan di atas tanah. Gelombang ambien dibangkitkan oleh gerakan benda-benda disekitar seismometer. Metode HVSR (I/orizontal to Vertical Spectral Ratio) selanjutnya digunakan untuk enghitung dan memperkirakan elevasi batuan dasar. Tulisan ini menyajikan hasil penelitian elevasi batuan dasar di Kota Semarang dengan menggunakan single station.feedback seismometer.246 titik pengamatan di wilayah Kota Semarang telah dilakukan untuk menangkap tiga komponen gelombang ambien (NS, EW dan V). Ketiga komponen gelombang tersebut kemudian diolah dengan pendekatan HVSR. Berdasarkan hasil pengembangan peta elevasi batuan dasar kemudian dilakukan pengeboran pada 10 titik. Sampel batuan yang diperoleh dari pekerjaan pengeboran kemudian diuji dengan menggunakan Sonic Yiewer untuk meneliti kecepatan rambat gelombang geser (Vs)

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

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

Evaluation of Lateral and Axial Deformation for Earth Pressure Balance (EPB) Tunnel Construction Using 3 Dimension Finite Element Method

Mass Rapid Transit Jakarta (MRTJ) phase 1 tunnel construction using the earth pressure balance method has been completed and surface settlement and lateral displacement data according to elevation and inclinometer readings has been collected to evaluate the effect of tunnel’s construction on surrounding infrastructure. Soil stratification along the research area, defined according to boring logs and soil parameters for the hardening soil model (HSM) and the soft soil model (SSM), was determined by optimization of stress-strain curve fitting between CU triaxial test, consolidation test and soil test models in the Plaxis 3D software. Evaluation of the result of surface settlement measurements using an automatic digital level combined with geodetic GPS for elevation and position control points showed that the displacement behavior was affected by vehicle load and stiffness of the pavement. Lateral displacement measurements using inclinometers give a more accurate result since they are placed on the soil and external influences are smaller than surface settlement measurement. The result of 3D finite element modeling showed that surface settlement and lateral displacement during TBM construction can be predicted using HSM with 2% contraction. SSM and the closed-form solutions of Loganathan and Poulos are unable to provide a good result compared to the actual displacement from measurements

Estimation of S-wave Velocity Structures by Using Microtremor Array Measurements for Subsurface Modeling in Jakarta

Jakarta  is located on  a  thick sedimentary  layer that  potentially has a very  high  seismic  wave  amplification.  However,  the  available information concerning the  subsurface model and bedrock depth  is insufficient  for a seismic hazard  analysis.  In  this  study,  a  microtremor  array  method  was  applied  to estimate the geometry and S-wave velocity of the sedimentary layer. The spatial autocorrelation  (SPAC)  method  was  applied  to  estimate  the  dispersion  curve, while  the S-wave  velocity  was  estimated  using  a  genetic  algorithm  approach. The  analysis  of  the  1D  and  2D  S-wave  velocity  profiles  shows  that  along  a north-south  line,  the  sedimentary  layer  is  thicker  towards  the  north.  It  has  a positive  correlation  with  a  geological  cross section  derived  from  a borehole down to  a depth of  about 300 m. The SPT data from  the  BMKG site  were used to  verify  the  1D  S-wave  velocity  profile.  They  show  a  good agreement. The microtremor analysis  reached  the engineering bedrock  in a  range from 359  to 608  m  as  depicted by a  cross section  in  the  north-south  direction. The site class was also estimated at each site, based on the average S-wave velocity until 30 m depth. The sites UI to ISTN belong to class  D (medium soil),  while BMKG and ANCL belong to class E (soft soil)