Penyelesaian Numerik Advection Equation 1 Dimensi dengan EFG-DGM

Differential equation can be used to model various phenomena in science and engineering. Numerical method is the most common method used in solving DE. Numerical methods that popular today are finite difference method (FDM), finite element method (FEM) dan discontinuous Galerkin method (DGM), which the method includes mesh based. Lately, the developing methods, that are not based on a mesh, which the nodes directly spread in domain, called meshfree or meshless. Element free Galerkin method (EFG), Petrov-Galerkin meshless (MLPG), reproducing kernel particle method (RKPM) and radial basis function (RBF) fall into the category meshless or meshfree. Time integration generally use an explicit Runge Kutta 4th order, Newmark- , HHT- , Wilson-  dll. This research was carried out numerical simulations DE, by combining the EFG method to solve the domain space and time integration with DGM methods. EFG using the complete order polynomial 1, and DGM used polynomial order 1. The equation used advection equation in one dimension. EFG-DGM comparison with analytical results also performed. The simulation results show the method EFG-DGM match the one-dimensional advection equations well

Pengaruh Pelaksanaan Pekerjaan Timbunan terhadap Stabilitas Bendungan Urugan Selama Masa Konstruksi

Abstrak: Pembangunan bendungan harus sesuai dengan tiga pilar Konsepsi Keamanan Bendungan, yaitu keamanan struktur, pemantauan, pemeliharaan, dan operasi, serta kesiapsiagaan tindak darurat. Keamanan bendungan salah satunya dapat ditinjau dari kestabilan lereng pada tubuh bendungan. Penelitian ini dilakukan untuk mengidentifikasi kondisi geologi dan geologi teknik, spesifikasi material timbunan dan analisis faktor keamanan lereng tubuh bendungan. Faktor keamanan yang dianalisis adalah selama pelaksanaan konstruksi bertahap timbunan dan saat konstruksi timbunan telah selesai tanpa beban gempa. Metode analisis stabilitas lereng yang digunakan menggunakan pemodelan dengan perangkat lunak Geostudio. Analisis stabilitas menggunakan bidang gelincir yang stabilitasnya dievaluasi dan dibagi menjadi beberapa irisan dan tegangan normal yang bekerja pada dasar setiap lapisan timbunan. Pada penelitian ini dilakukan pemodelan skenario kenaikan timbunan. Skenario yang dimodelkan sebanyak 10 lapisan dengan tiap lapisan setinggi 7 (tujuh) meter. Initial static stress masing-masing lapisan timbunan didapatkan dari Parent analysis. Hasil analisis pemodelan stabilitas lereng menunjukkan nilai FK cenderung menurun seiring bertambahnya ketinggian lapisan pekerjaan timbunan. Pada pekerjaan timbunan kondisi disipasi tekanan air pori yang dihasilkan saat akhir konstruksi tanpa waktu tunggu disipasi lebih besar dibandingkan dengan adanya waktu tunggu disipasi 7 hari. Perbedaan ketinggian timbunan dan kemiringan tanah dasar dapat mempengaruhi nilai faktor keamanan terutama pada timbunan yang tinggi dan kemiringan tanah dasar yang curam. Kata kunci: pekerjaan timbunan, stabilitas lereng, faktor keamanan, bendungan urugan, Geostudi

Consolidation settlement prediction and monitoring of toll road embankment at STA 23+650 Semarang–Demak Toll Road section

The development of toll road projects in Indonesia is experiencing rapid growth. However, due to the large number of toll roads being constructed over soft soil areas, it is crucial to address the issue of consolidation settlement. This is because settlement can lead to differential or excessive settlement, which potentially damages the structures built on such soil. Unfortunately, consolidation settlement on soft soils is a time-consuming process. Thus, a consolidation acceleration method is needed, one of which is to use a combination of PVD–Preloading. This method can also increase the soil’s bearing capacity, thereby contributing to the preservation and protection of systems that support human activities while maintaining a balance with nature. Therefore, this study aims to investigate consolidation settlement employing PVD–Preloading methods. The analysis focused on a case study conducted at STA 23+650 of the Semarang-Demak Toll Road section. The analysis employed the Asaoka method, integrating field monitoring instruments, along with the Terzaghi method for one-dimensional consolidation. The results showed that the settlement results from the Asaoka and Terzaghi methods correlate with the settlement plate instrumentation in the field

Penyelesaian Numerik Persamaan Advection Dengan Radial Point Interpolation Method dan Integrasi Waktu Dengan Discontinuous Galerkin Method

Persamaan differensial banyak digunakan untuk menggambarkan berbagai fenomena dalam bidang sains dan rekayasa. Berbagai masalah komplek dalam kehidupan sehari-hari dapat dimodelkan dengan persamaan differensial dan diselesaikan dengan metode numerik. Salah satu metode numerik, yaitu metode meshfree atau meshless berkembang akhir-akhir ini, tanpa proses pembuatan elemen pada domain. Penelitian ini menggabungkan metode meshless yaitu radial basis point interpolation method (RPIM) dengan integrasi waktu discontinuous Galerkin method (DGM), metode ini disebut RPIM-DGM. Metode RPIM-DGM diaplikasikan pada advection equation pada satu dimensi. RPIM menggunakan basis function multiquadratic function (MQ) dan integrasi waktu diturunkan untuk linear-DGM maupun quadratic-DGM. Hasil simulasi menunjukkan, metode ini mendekati hasil analitis dengan baik. Hasil simulasi numerik dengan RPIM DGM menunjukkan semakin banyak node dan semakin kecil time increment menunjukkan hasil numerik semakin akurat. Hasil lain menunjukkan, integrasi numerik dengan quadratic-DGM untuk suatu time increment dan jumlah node tertentu semakin meningkatkan akurasi dibandingkan dengan linear-DGM.  [Title: Numerical solution of advection equation with radial basis interpolation method and discontinuous Galerkin method for time integration] Differential equation is widely used to describe a variety of phenomena in science and engineering. A variety of complex issues in everyday life can be modeled with differential equations and solved by numerical method. One of the numerical methods, the method meshfree or meshless developing lately, without making use of the elements in the domain. The research combines methods meshless, i.e. radial basis point interpolation method with discontinuous Galerkin method as time integration method. This method is called RPIM-DGM. The RPIM-DGM applied to one dimension advection equation. The RPIM using basis function multiquadratic function and time integration is derived for linear-DGM and quadratic-DGM. The simulation result shows that this numerical method, close to the results exact well. The results of numerical simulations with RPIM-DGM show, the more nodes and the smaller the time increment, the more accurate the numerical results. Other results showed, integration with quadratic-DGM for a time increment, and a certain number of nodes, further improving accuracy, compared with the linear-DGM

SIMULASI NUMERIK PERILAKU BENDUNGAN KEDUNG OMBO PADA BEBAN SEISMIK

Dynamic simulation with finite element method (FEM) was conducted to predict the response of dams to input a particular earthquake, with more rigorous. This response needed to predict the response of the dam in assessment stage or in the design stage. Dynamic parameter in assessment stage may not available for dynamic simulation with FEM. The proposed of this thesis is to develop signal similarity method to estimate the value of the dynamic parameter. Dynamic simulation with FEM has done for Kedung Ombo dam. Signal input acceleration time history as a result of the recorded Strong Motion Accelerograf (SMA) set on Kedung Ombo dam. Adjustment effort carried on signal acceleration time history to remove nonstandard errors and standard noise. Dynamic simulation performed with a linear elastic model. Dynamic parameter value is obtained by selecting a value in the range of dynamic parameters. The range of dynamic parameters searched with an empirical correlation, where the dynamic parameter is the dynamic shear modulus and damping ratio. Dynamic simulation carried out with 165 variations in the treatment of the range dynamic parameter values. One of 165 treatments has been chosen for the dynamic parameter value on the dynamic FEM simulation. Selection of dynamic parameters based on the similarity of time domain and frequency domain of the signal SMA. The simulation results show that a linear elastic dynamic model and parameters chosen are available to imitate the acceleration time history recorded SMA at the level of certain shear strain. Dynamic parameters soil and foundation resulting from the similarity of time and frequency domain produce value at the appropriate reasonable range. Dynamic simulations also done to study the response of Kedung Ombo dam on Yogya quake in May 2006 based on dynamic parameters that already found. Based on the simulation, amplificaton of peak acceleration on the crest of the dam occurred in the amount of 2,138. The simulation results showed no liquefaction occurred at this dam accordance with the real condition. Dynamic simulation also available to be applied for study the response of dams elsewhere by knowing the recording of the acceleration time history at the dam foundation. The fundamental frequency of Kedung Ombo dam also counted using amplification spectra and FEM. The result of the fundamental frequency with the FEM calculation is 0.773 Hz. Amplification spectra result dominant frequency value that are 0.829 Hz, 1.584 Hz, 1.75 Hz, where the upstream reservoir at EL. 80.26 m. While the results of FEM have mode 1, 2 and 3 in a row on the value of 0.773 Hz, 1.171 Hz and 1.505 Hz

ANALISIS GEOLOGI TEKNIK PADA KEGAGALAN BENDUNG CIPAMINGKIS, BOGOR, PROVINSI JAWA BARAT

Bendung Cipamingkis terletak pada Desa Jatinunggal, Kecamatan Jonggol, Kabupaten Bogor, Provinsi Jawa Barat. Bendung ini dibangun pada tahun 1980 dan merupakan infrastruktur irigasi yang vital karena mengairi sekitar 7805 Ha sawah yang terdapat pada Kabupaten Bogor dan Kabupaten Bekasi. Inisiasi kegagalan bangunan tercatat pada Maret 2016 dimulai pada bagian mercu dan pintu pengambilan hingga kegagalan total terjadi pada April 2017. Penelitian ini difokuskan pada identifikasi parameter geologi teknik untuk memahami penyebab kegagalan Bendung Cipamingkis. Metodologi penelitian ini terdiri dari studi lapangan dan uji laboratorium. Tahap studi lapangan berupa pemetaan geologi dan pemboran geoteknik. Tahap uji laboratorium berupa penentuan parameter keteknikan antara lain slake durabilityindex dan free swell index digunakan untuk mengkonfirmasi ketahanan batuan dan pendugaan nilai pengembangannya (expansivity). Dari hasil penelitian didapatkan bahwa bendung ini berdiri di atas batuan dasar berupa dominan batulempung dan zona sesar mendatar menganan. Hasil laboratorium menunjukan slake durability index 0 - 3.88 % dan free swell index > 50 % dan LL yang berkisar antara 60% - 80%. Dengan adannya orientasi zona sesar mendatar yang tegak lurus dengan as bendung, memungkinkan rekahan-rekahan menjadi jalur termudah untuk air melalui bangun bendung hingga terjadinya erosi dan terbentuk saluran pembuluh. Nilai LL yang tinggi (> 50%) membuat karakteristik mekanik batulempung bergeser pada fase softening – residual strength walaupun dari data SPT menunjukkan nilai yang baik. Faktor lain yaitu bahwa batulempung pada daerah tersebut memiliki tingkat ekspansifitas yang tinggi. Kata Kunci: Bendung, Batulempung, Sesar, Kegagala

Consolidation settlement prediction and monitoring of toll road embankment at STA 23+650 Semarang–Demak Toll Road section

The development of toll road projects in Indonesia is experiencing rapid growth. However, due to the large number of toll roads being constructed over soft soil areas, it is crucial to address the issue of consolidation settlement. This is because settlement can lead to differential or excessive settlement, which potentially damages the structures built on such soil. Unfortunately, consolidation settlement on soft soils is a time-consuming process. Thus, a consolidation acceleration method is needed, one of which is to use a combination of PVD–Preloading. This method can also increase the soil’s bearing capacity, thereby contributing to the preservation and protection of systems that support human activities while maintaining a balance with nature. Therefore, this study aims to investigate consolidation settlement employing PVD–Preloading methods. The analysis focused on a case study conducted at STA 23+650 of the Semarang-Demak Toll Road section. The analysis employed the Asaoka method, integrating field monitoring instruments, along with the Terzaghi method for one-dimensional consolidation. The results showed that the settlement results from the Asaoka and Terzaghi methods correlate with the settlement plate instrumentation in the field