Assessment of the impact of proposed cut-off walls on ground-water level regime during extreme hydrological conditions

The groundwater can cause a significant threat to the safety of the tunnels excavated in water-rich areas. To investigate the impact of seepage to tunnels, the most important issues are calculations of the saturated surface and seepage flow. According to the great similarity between temperature field and seepage field in the theoretical foundation, differential equations and boundary conditions, the thermal analysis function of ANSYS could be used to calculate the non-pressure stable seepage based on the iteration method. The saturated surface and seepage flow through the lining are obtained by take a tunnel as an example, under using iteration method programming in ANSYS software. Additionally, on the basis of the correlation analysis, with the reduction of ground water level, the seepage discharge through the lining decreased sharply at the beginning, and then, the reduction trend gets inconspicuous. It has no obvious effect to decrease the water discharge by reducing the ground water level under this condition. Therefore, taking economic benefits into account, it is unadvisable to lower water level blindly. The optimal analysis of the actual conditions should be carried out in engineering practice. It has a certain reference value to the design and construction of tunnels in water-rich areas.

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PROPOSAL OF GROUND WATER LEVEL REGIME USING NUMERICAL MODELLING

17th International Multidisciplinary Scientific GeoConference SGEM2017, Science and Technologies in Geology, Exploration and Mining ◽

10.5593/sgem2017/12/s02.028 ◽

2017 ◽

Author(s):

Dana Barokova

Keyword(s):

Numerical Modelling ◽

Ground Water ◽

Water Level ◽

Ground Water Level ◽

Level Regime

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Liquefaction Analysis Based on Liquefaction Potential Index Method in Prambanan Temple Complex of Jogjakarta

Journal of Advanced Civil and Environmental Engineering ◽

10.30659/jacee.3.2.66-72 ◽

2020 ◽

Vol 3 (2) ◽

pp. 66

Author(s):

Lisa Fitriyana ◽

Bayu Prasetyo Afandi

Keyword(s):

Ground Water ◽

Water Level ◽

Ground Water Level ◽

Ground Acceleration ◽

Index Method ◽

Liquefaction Potential ◽

Liquefaction Potential Index ◽

Potential Index ◽

The Impact ◽

Liquefaction Analysis

Prambanan Temple is a cultural heritage located in Jogjakarta. Tectonically, the Special Region of Jogjakarta and its surroundings are an area with a fairly high level of seismic activity in Indonesia. Geotechnically, the soil in Jogjakarta is sandy with similar gradation. The thickness of the sand ranges from -50 m to -60 m. Whereas, the ground water level is located at a depth of -12 m during dry season and in rainy season, it rises from -6 m to -4 m. The impact of soil types and the high Ground Water Level (GWL) allow it for liquidation to occur during an earthquake. This study was conducted using liquefaction analysis, through Liquefaction Potential Index (LPI) method with ground water level variations. Before analyzing the liquefaction using LPI method, Peak Ground Acceleration (PGA) methods were used, and analysis could then be done through Cyclic Resistance Ratio (CRR) and Cyclic Stress Ratio (CSR) to obtain safety factors and the Liquefaction Potential Index analysis was then conducted. To analyze this liquefaction, earthquake data from 2004 to 2019 and the results of the SPT field test at the Prambanan Temple were needed. From the liquefaction potential analysis through Liquefaction Potential Index (LPI), the results showed that in CSR Seed & Idriss (1971) and CRR Tokimatsu & Yoshimi (1983), GWL 1 m at depths from 4.5 m and above, the potential of liquefaction occurrence was high. The largest PGA value was obtained based on the Matsuchka (1980) method on May 26, 2006 which was 0.102.

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