An analytical method for predicting the groundwater inflow to tunnels in a fractured aquifer

Su, Yue; Huang, Yong; Shen, Huan; Jiang, Yin; Zhou, Zhifang

doi:10.1007/s10040-022-02485-6

Cited by 8 publications

(1 citation statement)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Maleki, 2018 introduced a new method for estimating groundwater inflow using main geological and hydraulic parameters, as well as the radius of the tunnel. Furthermore, Su et al, 2022, proposed a method for calculating hydraulic-head distribution and flow behaviors in fractured aquifers based on a fracture network model and the cubic law. The method treats the rock matrix as impermeable, with groundwater flowing only through the network of fractures and faults.…”

Section: ()mentioning

confidence: 99%

Enhancing analytical methods for estimating water inflow to tunnels in the presence of discontinuity areas

Farhadian,

Bahmani Shahraki

2024

Environ Earth Sci

View full text Add to dashboard Cite

There are various methods for calculating the inflow of water into excavated tunnels in rock formations, including empirical, analytical, and numerical methods. Analytical equations are widely used due to their simplicity and reliance on assumptions. However, past studies have shown that the measured water inflow into rock tunnels is often lower than the values estimated using analytical equations. Moreover, results obtained using analytical equations are highly dependent on the tunnel geometry and environmental conditions. Hence, this study employed finite element numerical modeling to simulate the effects of various factors, including fault distance from the tunnel, permeability coefficient, fault width, tunnel radius, rock mass permeability, and groundwater level, on the water inflow into the tunnel. The analytical method 2 was then used to estimate the water inflow, and the results were compared with the numerical modeling outputs. Subsequently, modified equations were developed to estimate the water inflow under different conditions, including cases where the fault intersects or does not intersect the tunnel. The correlation between the results obtained from the equations and the numerical modeling outputs was evaluated using R and R 2 statistics. The obtained values were within an acceptable range, indicating the validity of the proposed models. Furthermore, the histograms of the residuals for both models showed a good fit. To validate the proposed models, the analytical method and the proposed equations were used to estimate the water inflow into the Amirkabir tunnel, respectively. The results showed that the values obtained using the new equations were closer to the actual values than those obtained using the analytical method. This study highlights the importance of considering various factors in estimating the water inflow into rock tunnels and provides new equations that can improve the accuracy of such estimates.

show abstract

Section: ()mentioning

confidence: 99%

Enhancing analytical methods for estimating water inflow to tunnels in the presence of discontinuity areas

Farhadian,

Bahmani Shahraki

2024

Environ Earth Sci

View full text Add to dashboard Cite

show abstract

Effects of flow dimension in faulted or fractured rock on natural reductions of inflow during excavation: a case study of the Horonobe Underground Research Laboratory site, Japan

Ishii

2023

Hydrogeol J

View full text Add to dashboard Cite

Major inflows of groundwater can occur during excavation in faulted or fractured rock masses, even if pre-excavation grouting is applied; postexcavation grouting may then be required to reduce these inflows. However, the diffusion equation for fluid pressure suggests that inflows may reduce naturally by 50–90% or more within days or weeks when the dimension of the flow in faults or fractures that feed the inflow (flow dimension) is close to 1, but inflow reduction is minimal when the flow dimension is close to 3. Therefore, if the flow dimension is close to 1, the natural reduction in inflow may obviate countermeasures. Nevertheless, this natural reduction being dependent on flow dimension is seldom considered explicitly when planning excavations or countermeasures. To verify the applicability of the relationship between natural changes of inflow and the flow dimension, this study measured changes in inflow at six locations at the Horonobe site, Japan, where major inflows occurred during excavations of tunnels or shafts in faulted or fractured siliceous rocks. The flow dimension at each location was assessed using pre-excavation packer tests in surface-based boreholes. The results confirm that changes in the inflows during the days and weeks immediately after their commencement depended consistently on the assessed flow dimension. Natural reductions in inflow during excavation are predictable based on the flow dimension, which can be estimated using pre-excavation borehole investigations or from the initial changes in inflow during the first several days. This approach may be helpful for improving the efficiency of excavations.

show abstract

The effect of fracture aperture and matrix permeability on suitability of the equivalent porous medium model for steady-state flow in fractured porous media

Han,

Ma,

Qian

et al. 2024

Hydrogeol J

View full text Add to dashboard Cite

An analytical method for predicting the groundwater inflow to tunnels in a fractured aquifer

Cited by 8 publications

References 40 publications

Enhancing analytical methods for estimating water inflow to tunnels in the presence of discontinuity areas

Enhancing analytical methods for estimating water inflow to tunnels in the presence of discontinuity areas

Effects of flow dimension in faulted or fractured rock on natural reductions of inflow during excavation: a case study of the Horonobe Underground Research Laboratory site, Japan

The effect of fracture aperture and matrix permeability on suitability of the equivalent porous medium model for steady-state flow in fractured porous media

Contact Info

Product

Resources

About