Three-Dimensional Numerical Analysis of Tunnel Seepage Based on the Iteration Method

2012 ◽  
Vol 479-481 ◽  
pp. 2441-2445
Author(s):  
Fu Sheng Liu ◽  
Guo Yuan Xu ◽  
Sheng Bin Hu ◽  
Wen Tong Huang ◽  
Min Hu
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Iteration Method ◽  
Water Discharge ◽  
Seepage Flow ◽  
Economic Benefits ◽  
Ground Water Level ◽  
Engineering Practice ◽  
The Impact ◽  
Saturated Surface

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.

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

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.

Assessment of the effect of atmospheric pressure on the level and ground waters flow

2019 ◽  
Vol 12 (11-12) ◽  
pp. 44-51 ◽  
Author(s):  
S. A. Lavrov ◽  
M. L. Markov
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Atmospheric Pressure ◽  
Unsaturated Zone ◽  
Water Discharge ◽  
Ground Water Level ◽  
Ground Waters ◽  
Barometric Efficiency ◽  
Observation Wells ◽  
Interstitial Air

The problem of understanding the interaction of river and ground water waters is intimately bound to questions of formation and unloading of ground waters in river network. The analysis of the previous researches showed that change of atmospheric pressure affects on the water level in observation wells and water discharge of springs. However, the mechanisms of this influence still weren't completely opened. For the solution of this task the complex laboratory, field and theoretical researches including overseeing by a drain, ground water level, atmospheric pressure and air pressure in an unsaturated (vadose) zone were conducted. On the basis of the conducted researches regularities the connecting size of change of ground water level and a drain of ground water waters with atmospheric pressure were received. As a result of generalization field and laboratory researches it was shown that the crucial role in formation of these regularities is played by the area located over a mirror of ground waters with the isolated interstitial air.With an increase in atmospheric pressure, the volume of interstitial air decreases, and at pressure drop volume increases. It, in turn, leads to change in the level and a flow of ground waters. The settlement formula for numerical assessment of variability of level ground depending on atmospheric pressure (barometric efficiency) and degree of air isolation was received from it in an unsaturated zone. As an indicator of isolation, a characteristic is used such as the volume of interstitial air involved in the inflow (outflow) of water into a measuring well or watercourse and not having direct contact with the atmosphere. Research results showed that, in addition to gravitational force in the movement of ground water and the formation of ground water inflow of rivers and lakes, another force plays a certain role - the pressure difference between atmospheric air and air in the unsaturated zone above the aquifer.

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