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All Journal Jurnal Teknik Sipil dan Perencanaan KURVATEK Journal of the Civil Engineering Forum
Ismanti, Sito
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Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Electrical & Electronics Engineering Engineering Social Sciences

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The Correlation of Liquefaction Potential and Probability on Excess Pore Water Pressure in Kretek 2 Bridge Area Zakariya, Ali; Rifa'i, Ahmad; Ismanti, Sito
Journal of the Civil Engineering Forum Vol. 10 No. 1 (January 2024)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jcef.7002

Abstract

Liquefaction is soil condition associated with the drastic increase in pore water pressure of uniform sandy soil due to an enormous earthquake. Therefore, this study aimed to investigate the correlation of liquefaction potential with excess pore water pressure ratio in nine boreholes located at Kretek 2 Bridge area using empirical and numerical methods. Liquefaction potential was estimated based on a semi-empirical method simplified by Idriss and Boulanger (2008), and safety factor (SF) value of <1.0 was used to represent the existence of its potential. The result showed that liquefaction potential was dominant at depths of 1.5 to 6.0 m, with the exception of BH-9 with 16.5 m and BH-4. Furthermore, the excess pore water pressure ratio was estimated using empirical method developed by Yegian and Vitelli (1981) as well as Serafini and Perlea (2010). Numerical analysis was also conducted for comparison purposes and the process focused on using Deepsoil v7.0 to generate excess pore water pressure by considering soil conditions and dominant seismic sources in Kretek 2 Bridge area. The result showed that the ratio of excess pore water pressure was greater or equaled 0.8. Both empirical and numerical methods produced similar values for BH-1, BH-2, BH-8, and BH-9 at a depth of 1.5–3.0 m, 3–4.5 m, 3.0 m, and 16.5 m, respectively. This showed a correlation between excess pore water pressure ratio and liquefaction potential values at the same depth. However, numerical method tended to overestimate the ru value, necessitating the use of empirical method to obtain a more reliable result.
EFFECT OF USING LIME AND FLY ASH AS A CEMENT SUBSTITUTE FOR SOIL STABILITY Dias Dwi Hatmoko; Rifa’i, Ahmad; Ismanti, Sito
KURVATEK Vol 9 No 1 (2024): Energy Management and Sustainable Environment
Publisher : Institut Teknologi Nasional Yogyakarta

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Abstract

Subgrade is the lowest layer that receives the load on it if it does not have carrying capacity that is allowed then need for soil stabilization. Chemical soil stabilization is often done with the addition of cement but the use of cement material will cost quite high, it is necessary to alternate other materials for the substitution of cement to reduce the implementation costs incurred. Cement will be replaced as a stabilizing material in this research with additional materials like lime and fly ash. In this research, soil material was taken from the Sentul – Karawang Toll Road Project STA 24+300, with fly ash from PT PUSRI as the stabilization material, and lime material obtained from the market in Yogyakarta. The stabilization material will be used with a fixed lime percentage of 4.2% of the dry weight of the soil, and fly ash at 1.4%, 2.1%, 2.8%, 3.5%, and 4.2% of the dry weight of the soil. The soil samples were tested for physical and mechanical properties, including Standard Proctor and California Bearing Ratio (CBR). All test results were compared to select one variation, which was then designated as the Optimum Mix Design (OMD) sample. The test results of the soil sample + 4.2% lime + 2.1% fly ash yielded a CBR value of 15.52%, indicating an increase of 1078.02% from the initial 1.44%, and were formally designated as an OMD sample. The CBR value satisfies the subgrade requirements, namely >6%.
Behaviour of Axial Bearing Pile under Liquefaction Condition Based on Empirical and 3D Numerical Simulation Zakariya, Ali; Rifa’i, Ahmad; Ismanti, Sito
Jurnal Teknik Sipil dan Perencanaan Vol 25, No 1 (2023)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jtsp.v25i1.42954

Abstract

The liquefaction phenomenon affects to bearing capacity losses of building foundations. When liquefaction occurs in loose sandy soils, the pore water pressure increases, and the effective soil stress decreases significantly. This study deals with the bored pile foundation of Kretek 2 bridge, which is located in an area with high vulnerability to liquefaction. The study aimed to estimate the axial load-bearing capacity of the foundation of Kretek 2 bridge under liquefaction conditions. This study compares the results of calculations using empirical approaches with 3D numerical simulation modeling using MIDAS GTS NX. The results of the empirical calculations show a reduction in the axial bearing capacity of the foundation under liquefaction conditions of 2.88-8.16% and 2.63-7.23% for the approach of Reese and Wright 1977 and O’Neill and Reese 1989, respectively. While using 3D numerical modeling, although there was a decrease in skin resistance, there was no significant decrease in the total bearing capacity, and it was still above the design load (3632.563456.02 kN). Based on these results, the bearing capacity of the installed Kretek 2 Bridge foundation is still capable of receiving loads during static and liquefaction states.
Co-Authors Dias Dwi Hatmoko Rifa’I, Ahmad Veithzal Rivai Zainal Zakariya, Ali