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Overview of considered subsurface features and corresponding model setups. Table 1

Table 1 Overview of considered subsurface features and corresponding model setups. Table 1

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Fig. 1. Study area and location of the cross-section of Fig. 2 (arrow).
Fig. 1. Study area and location of the cross-section of Fig. 2 (arrow).
ig. 2. Top: Geological cross-section of the study area (Figure 3 can serve as legend). The cross-section is the basis for the finite element groundwater models used in this study ottom: Model area, boundary conditions and solution for the hydraulic head field of the most simple model setup (homogeneously distributed hydraulic conductivity, withou unnel and faults). The rectangles mark the detail of the model area which is described in the text and illustrated in Figs. 4-7.
ig. 2. Top: Geological cross-section of the study area (Figure 3 can serve as legend). The cross-section is the basis for the finite element groundwater models used in this study ottom: Model area, boundary conditions and solution for the hydraulic head field of the most simple model setup (homogeneously distributed hydraulic conductivity, withou unnel and faults). The rectangles mark the detail of the model area which is described in the text and illustrated in Figs. 4-7.
Fig. 3. Hydrostratigraphic units of the study area and respective hydraulic properties attributed to the finite element groundwater models. Lithostratigraphic column adapted from Bitterli-Brunner and Fischer (1988).
Fig. 3. Hydrostratigraphic units of the study area and respective hydraulic properties attributed to the finite element groundwater models. Lithostratigraphic column adapted from Bitterli-Brunner and Fischer (1988).
Fig. 5. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the homogeneous model setup with faults. Left: without tunnel; right: with tunnel subsurface feature. At the position of the tunnel, but without the tunnel as structural element (Figure 4 left), the groundwater flow is directed upward, with a pronounced horizontal component. The capture zone of the water passing through the (future) tunnel is a very narrow area originating from the hill in the north of the regarded model detail (in the following and in Figures 4-7, this hill is addressed as the “northern hill”). After the tunnel excavation (Figure 4 right), the capture zone is largely broadened and distributed to the northern hill and to other minor hills. The individual recharge areas on the hills are also broadened. One flow path originates from the valley above the tunnel. This section presents the results of the numerical simulations using the different model setups indicated in Table 1. The distribution of the hydraulic head and flow paths towards the tunnel, visualized by backward tracking of 20 particles from the tunnel perimeter as starting points to the ground surface (or model boundary), are used to
Fig. 5. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the homogeneous model setup with faults. Left: without tunnel; right: with tunnel subsurface feature. At the position of the tunnel, but without the tunnel as structural element (Figure 4 left), the groundwater flow is directed upward, with a pronounced horizontal component. The capture zone of the water passing through the (future) tunnel is a very narrow area originating from the hill in the north of the regarded model detail (in the following and in Figures 4-7, this hill is addressed as the “northern hill”). After the tunnel excavation (Figure 4 right), the capture zone is largely broadened and distributed to the northern hill and to other minor hills. The individual recharge areas on the hills are also broadened. One flow path originates from the valley above the tunnel. This section presents the results of the numerical simulations using the different model setups indicated in Table 1. The distribution of the hydraulic head and flow paths towards the tunnel, visualized by backward tracking of 20 particles from the tunnel perimeter as starting points to the ground surface (or model boundary), are used to
Fig. 4. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the homogeneous model setup without faults. Left: without tunnel; right: with tunnel as subsurface feature.
Fig. 4. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the homogeneous model setup without faults. Left: without tunnel; right: with tunnel as subsurface feature.
Flow rates in liters per day per m tunnel section (I/d per m) into the tunnel perimeter calculated for the different model setups (c.f. Table 1) before and after the tunnel excavation Note: The generally lower flow rates in the aquifer-aquitard and hydrostratigraphic models compared to those of the homogeneous models are due to the lower hydraulic conductivities at the position of the tunnel in these models.
Flow rates in liters per day per m tunnel section (I/d per m) into the tunnel perimeter calculated for the different model setups (c.f. Table 1) before and after the tunnel excavation Note: The generally lower flow rates in the aquifer-aquitard and hydrostratigraphic models compared to those of the homogeneous models are due to the lower hydraulic conductivities at the position of the tunnel in these models.
ig. 6. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the aquifer-aquitard model setup. Left: without tunnel; right: with tunnel as subsurfac ‘ature.
ig. 6. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the aquifer-aquitard model setup. Left: without tunnel; right: with tunnel as subsurfac ‘ature.
‘ig. 7. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the hydrostratigraphic model setup. Left: without tunnel; right: with tunnel as subsurface eature.
‘ig. 7. Hydraulic head field and flow paths towards the tunnel perimeter calculated with the hydrostratigraphic model setup. Left: without tunnel; right: with tunnel as subsurface eature.
Related topics:
Civil EngineeringStratigraphyGroundwater modelingEngineering GeologyPreferential FlowGroundwater flowPore Water PressureSite Analysis
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