A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
A dynamic modeling approach to simulate groundwater discharges into a tunnel from typical heterogenous geological media during continuing excavation
Abstract Most of the analytical and numerical models of tunnel groundwater inflow ignore the excavation process, leading to inaccurate prediction of discharge rate. A dynamic modeling approach was introduced by redevelopment of MODFLOW to simulate the change of groundwater flow step by step in accord with tunnel excavation. The drilling tunnel was conceptualized as a changing boundary condition, which was modeled by dividing the drilling process into a series of successive steps. The impact of permeability heterogeneity on groundwater flow was studied through a comparison between a homogeneous hydraulic conductivity case and a synthetic heterogeneous one. It was found that the discharge rate at drilling front kept stable in the homogeneous case, resulting in a linear increase in the total discharge rate, similar to the analytical solution by Perrochet (2005). In contrast, the front and total discharge rate were influenced significantly by the variability of permeability in the heterogeneous case. The time-dependent discharge rate at a given place was subject to an exponential decay for both cases with the maximum inflow occuring at the beginning of excavation. The relationship between discharge rate and hydraulic properties was further investigated in a high-K zone. It revealed that maximum discharge rate was proportional to hydraulic conductivity (K) and specific storage (Ss). The decaying rate of discharge was time-dependent and also proportional to the value of K and Ss. The water budget analysis demonstrated that water released from storage of the high-K zone was the major source of tunnel discharge at early times.
A dynamic modeling approach to simulate groundwater discharges into a tunnel from typical heterogenous geological media during continuing excavation
Abstract Most of the analytical and numerical models of tunnel groundwater inflow ignore the excavation process, leading to inaccurate prediction of discharge rate. A dynamic modeling approach was introduced by redevelopment of MODFLOW to simulate the change of groundwater flow step by step in accord with tunnel excavation. The drilling tunnel was conceptualized as a changing boundary condition, which was modeled by dividing the drilling process into a series of successive steps. The impact of permeability heterogeneity on groundwater flow was studied through a comparison between a homogeneous hydraulic conductivity case and a synthetic heterogeneous one. It was found that the discharge rate at drilling front kept stable in the homogeneous case, resulting in a linear increase in the total discharge rate, similar to the analytical solution by Perrochet (2005). In contrast, the front and total discharge rate were influenced significantly by the variability of permeability in the heterogeneous case. The time-dependent discharge rate at a given place was subject to an exponential decay for both cases with the maximum inflow occuring at the beginning of excavation. The relationship between discharge rate and hydraulic properties was further investigated in a high-K zone. It revealed that maximum discharge rate was proportional to hydraulic conductivity (K) and specific storage (Ss). The decaying rate of discharge was time-dependent and also proportional to the value of K and Ss. The water budget analysis demonstrated that water released from storage of the high-K zone was the major source of tunnel discharge at early times.
A dynamic modeling approach to simulate groundwater discharges into a tunnel from typical heterogenous geological media during continuing excavation
Xia, Qiang (author) / Xu, Mo (author) / Zhang, Han (author) / Zhang, Qiang (author) / Xiao, Xian-xuan (author)
KSCE Journal of Civil Engineering ; 22 ; 341-350
2017-03-27
10 pages
Article (Journal)
Electronic Resource
English
Control of contaminated groundwater during tunnel excavation
| British Library Conference Proceedings | 2006
A Dynamic Modeling Approach to Predict Water Inflow during Karst Tunnel Excavation
| DOAJ | 2022
| British Library Conference Proceedings | 2001