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Common Approximations to the Water Inflow into Tunnels
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... Goodman's equations are based on very simple assumptions that the tunnel is of infinite length, and that the water table remains constant without changing its position all the time. Further, he considers the only factor affecting the seepage rate is the permeability coefficient of soil [6,7]. In 1993, Zhang, Franklin showed that the seepage rate obtained by the above equation is insignificant, because actual flow rate obtained from field measurements was 90% lower and 30% higher than that given by equations [8]. ...
... The seepage rate at the invert points of both routes is approximately linear with mostly negligible value (10 −5 m 3 /min), and its value is slightly affected by the change in water level. The increase of water level from (1.8) meters to (6.1) meters caused increasing in the maximum water inflow by roughly 15% due to the increase in pore water pressure [7]. The frontal and rear faces exhibit higher values for seepage rate at their crest points as compared to the invert point of the same section and for the selected water level. ...
Water seepage can cause serious problems in geotechnical engineering especially for construction under the water level. Baghdad metro tunnel is one of the leading vital projects to solve the major problem of crowding roadways in a highly population increase city like Baghdad. In this study, the seepage rate that will flow toward different selected points along the tunnel section across Tigris River was calculated during the excavation process, with the consideration of three different water levels of River at maximum, moderate, and minimum water depths. A three-dimensional model of the study has been modeled using the finite element software (PLAXIS 3D V20). The water seepage was observed for six different locations on each route of the tunnel. The study showed that the change of water depth in the river has no significant effect on the seepage – time curve shape. However, increasing the water level in River from minimum to maximum leads to increase the seepage rate about 15%.
... Numerous researchers have proposed various analytical, empirical, semi-empirical, and numerical methods/procedures for estimating steady-state groundwater inflow into rock tunnels (Chen 2010;Farhadian and Katibeh 2017;Hassania et al. 2018;Heuer 1995;Katibeh and Aalianvari 2012;Raymer 2001Raymer , 2005Vanarelli 2007). These methods/procedures can produce varying results. ...
The construction of tunnels in rock terrain has increased in importance around the
world as the need for new transportation routes and water and wastewater convey�ances has grown. Large cities and nearby suburbs have limited space for extensive,
above-ground thoroughfares; therefore, underground systems may be the only via�ble means for developing new infrastructure. Excessive groundwater infow into
rock tunnels under construction can injury personnel and terminate the construc�tion of the tunnel project. Therefore, it is important to accurately estimate ground�water infow into rock tunnels. A semi-empirical procedure for estimating steady�state, groundwater infow in shallow rock tunnels is presented and discussed in this
paper. In addition, this paper presents two case study analyses which include the
Elizabethtown tunnel in New Jersey and the Toledo tunnel in Ohio. Packer test (i.e.,
pressure test) data was analyzed for both case studies utilizing this semi-empirical
procedure. This paper reviews the basic theory behind the procedure and validates
the procedure through case study analyses. It also describes previous proposed
modifcations and clarifes the need for any such modifcations. In general, good
groundwater infow estimates were derived for shallow rock tunnels utilizing this
semi-empirical procedure. This research will beneft large and small municipalities
(e.g., owners of major infrastructure tunnels projects) who need to install under�ground conveyances for water supply lines, sewer lines, railway, and roadways. By
knowing the amount of water that might fow into the rock tunnel during its con�struction, the owners will save money, but more importantly lives if groundwater
infow are estimated accurately
... Numerous researchers have proposed various analytical, empirical, semi-empirical, and numerical methods/procedures for estimating steady-state groundwater in ows into rock tunnels [1,3,6,7,10,[11][12][13]. These methods can produce varying results. ...
The construction of underground excavations and tunnels can only be done safely and economically when the subsurface conditions are adequately understood. Excessive groundwater inflows into rock tunnels under construction can injury personnel and terminate the construction of the tunnel project. Therefore, it is important to accurately estimate groundwater inflows into rock tunnels. A semi-empirical procedure/method for estimating steady-state, groundwater inflows in shallow rock tunnels is presented and discussed in this paper. In addition, this paper presents two case study analyses which include the Elizabethtown tunnel in New Jersey and the Toledo tunnel in Ohio. Packer test (i.e., pressure test) data was analyzed for both case studies utilizing this semi-empirical procedure. This paper reviews the theory behind the procedure, summarizes validates the procedure through case study analyses. It also describes previous proposed modifications and clarifies the need for any such modifications. In general, good groundwater inflow estimates were derived for shallow rock tunnels utilizing this semi-empirical procedure/method.
... Many analytical, empirical, and numerical methods/ procedures have been proposed in older and more recent research papers [1,5,7,[10][11][12][13]. All these methods produce varying results and lack validation through case study analyses. ...
Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. It is the most widely used method/procedure in the tunnel industry. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates. This paper is based on the PhD thesis entitled “Improvements to the Current State of the Practice in Steady-State, Groundwater Inflow Estimates into Rock Tunnels based on the Application of Statistical Analysis Methods of Packer Test Data obtained from Exploratory Borings During Geotechnical Site Investigations.”
... Polubarinova and Kochina (1962) (cited by [11]) derived an approximate expression for estimation the discharge for horizontal tunnel in a fully saturated, homogeneous medium. Goodman (1965) (cited by [12]) considered the tunnel lying beneath a lake or large river. The author considered the lake or river to be an infinite source of water; the equation was derived accordingly for calculating the seepage quantity with steady state inflow along the length of the tunnel. ...
When the sheet pile is used as the reservoir wall or retains the action of saturated fills and cuts for construction works, it will be certain that the seepage occurs from the back side (retained side) to the working place (opposite side). Often, the rate of seepage and its quantity in homogenous strata depends mainly on the permeability of soil. However, the presence of cavity certainly has a direct impact on trend, steady time, and the quantity of seepage. The present study considered a preliminary attempt to measure this impact through physical model. Eighteen model tests are conducted to study the effect of different locations and diameters (size) of single cavity on the seepage problem when it is presented at upstream side (back side) of the sheet pile wall. Period of completion every model test ranged from four to seven days. The start time of seepage when the water began to flow from the downstream side (working place) ranged between 13min and 26min, which depended on the location of cavity and its size. However, the results show that the quantities of seepage generally increase with the smallest size of a cavity and with the farthest horizontal distance from the sheet pile. The maximum quantity has been recorded when the cavity is located at the same level of sheet pile end.
In the practical construction of underground excavations, the groundwater level in the surrounding rock masses can fluctuate due to water accumulation (reservoirs), water abstraction and, in particular, due to the consequences of climate change. This fluctuation causes changes in the geomechanical state of the rock mass and effects on the support structure. This phenomenon and its effects must be predicted in order to get appropriate suggestion for the design and construction measures. The article presents some simulation results that analyse the redistribution of geomechanical processes in the jointed rock mass around a tunnel with and without support as well as the rule of the changes of the internal forces in the support structure when the groundwater level changes by using UDEC.
In this research, considering the experiments of tunnel inflow due to 10 different tunnels in Iran and adopting idea from site geomechanics rating like RMR, a new method has been developed for rating the tunnel site to evaluate the potential of tunnel inflow according to the preliminary investigation data. This method is called Site Groundwater Rating (SGR). Considered parameters in this method are: joint frequency, joint aperture, karstification, crashed zone, schistosity, head of water above tunnel, soil permeability and annual raining. Using these parameters and following SGR method, tunnel site can be categorized into six rates as follow: no risk, low risk, moderate risk, risky, high risk and critical. The method has been checked out with the observed groundwater inflow of Ghomroud tunnel and also, implied to rate the Amirkabir tunnel site in Iran.
The steady gravity flow that is generated by a circular tunnel disturbing the hydrostatic state of a semi-infinite, homogeneous and isotropic aquifer is solved exactly. Many aspects of the flow are found in closed analytical forms such as the water inflow, pressure, leakage and recharging infiltration, which give a complete view of the aquifer in the drained steady state. It is found that the maximum value of the recharging infiltration does not exceed the hydraulic conductivity allowing stating a criteria for recharge intervention to ensure the stability of the aquifer. In addition to the main results, two aspects of the water inflow are treated. These are the necessary modifications that are to be considered in the case of an inclined water table and in the case of a lined tunnel that develops a constant internal pressure. It is also found that under an inclined water table a tunnel may cease to drain on its complete circumferential edge and a limiting condition is stated. Furthermore, the Muskat–Goodman and other water inflow predictions are compared to the exact gravity water inflow.
An analytical solution is derived for two-dimensional, steady ground water flow into a horizontal tunnel in a fully saturated, homogeneous, isotropic, and semi-infinite aquifer. The hydraulic head and streamline distributions in the flow field, as well as the inflow rate, are obtained for a constant hydraulic head boundary condition at the tunnel perimeter. The inflow rate formula derived in this paper is an extension to the Polubarinova-Kochina (1962) formula, which can be considered a special case of the present solution.
Groundwater Englewood
- R A Freeze
- J A Cherry
Freeze, R.A.; Cherry, J.A. (1979) "Groundwater Englewood", New Jersey, Prentice-Hall Inc,
TIC 217571.
Estimating rock-tunnel water inflow
- R E Heuer
Heuer, R.E. 1995. "Estimating rock-tunnel water inflow". Proceeding of the Rapid
Excavation and Tunneling Conference, June 18-21.
Predicting groundwater inflow into hard-rock tunnels : Estimating the high-end of the permeability disterbution
- J H Raymer
Raymer, J.H.,(200 3), "Predicting groundwater inflow into hard-rock tunnels : Estimating the
high-end of the permeability disterbution",RETC. Pp. 201-217