scholarly journals An analytical solution for steady seepage into a defective pipe

2017 ◽  
Vol 18 (3) ◽  
pp. 926-935 ◽  
Author(s):  
Yao Tang ◽  
Dave H. Chan ◽  
David Z. Zhu ◽  
Shuai Guo
Keyword(s):  
Analytical Solution ◽  
Groundwater Flow ◽  
Pressure Distribution ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Infiltration Rate ◽  
Defect Position ◽  
Water Head ◽  
Parametric Studies

Abstract An analytical solution was proposed for the groundwater flow through a defective pipe, which can be used to estimate the water flow rate into the pipe and predict the pore water pressure distribution in surrounding soils. This analytical solution was verified by comparing with experimental results, and the predicted pressure distribution around the defective pipe is proved to be consistent with numerical simulations using the finite element method. From the parametric analysis, the infiltration rate increases as the defect position changes from top to bottom on the pipe, and the effect of defect position is not significant if the water head above the defect is 10 times greater than pipe radius. An approximated solution for estimating the groundwater flow infiltration rate through a circular orifice on the pipe is proposed as well. From the verification and parametric studies, this proposed analytical solution is proved to be an efficient approach for the estimation of groundwater infiltration through a defective pipe.

scholarly journals The Hydromechanical Interplay in the Simplified Three-Dimensional Limit Equilibrium Analyses of Unsaturated Slope Stability

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 73
Author(s):  
Panagiotis Sitarenios ◽  
Francesca Casini
Keyword(s):  
Analytical Solution ◽  
Slope Stability ◽  
Slope Failure ◽  
Failure Modes ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Three Dimensional ◽  
Stability Limit ◽  
Smooth Transition

This paper presents a three-dimensional slope stability limit equilibrium solution for translational planar failure modes. The proposed solution uses Bishop’s average skeleton stress combined with the Mohr–Coulomb failure criterion to describe soil strength evolution under unsaturated conditions while its formulation ensures a natural and smooth transition from the unsaturated to the saturated regime and vice versa. The proposed analytical solution is evaluated by comparing its predictions with the results of the Ruedlingen slope failure experiment. The comparison suggests that, despite its relative simplicity, the analytical solution can capture the experimentally observed behaviour well and highlights the importance of considering lateral resistance together with a realistic interplay between mechanical parameters (cohesion) and hydraulic (pore water pressure) conditions.

Analyses of groundwater flow and plant evapotranspiration in a vegetated soil slope

2013 ◽  
Vol 50 (12) ◽  
pp. 1204-1218 ◽  
Author(s):  
A.K. Leung ◽  
C.W.W. Ng
Keyword(s):  
Groundwater Flow ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Root Water Uptake ◽  
Dry Season ◽  
Climatic Data ◽  
Wet Season ◽  
Soil Slopes ◽  
Transient Seepage

Understanding seasonal hydrogeological responses of vegetated soil slopes is vital to slope stability because pore-water pressure (PWP) varies from positive values upon rainfall in wet seasons to negative values upon plant evapotranspiration (ET) in dry seasons. There are, however, few case histories that report seasonal performance of vegetated soil slopes. In this study, a vegetated slope situated in Hong Kong was instrumented to analyse (i) groundwater flow during rainfall in the wet season and (ii) effects of plant ET on PWP in the dry season. Two- and three-dimensional anisotropic transient seepage analyses are conducted to identify groundwater flow mechanism(s) during a heavy rainstorm. Through water and energy balance calculations, measured plant-induced suction is interpreted with plant characteristic and climatic data. During the rainstorm, substantial recharge of the groundwater table was recorded, likely due to preferential water flow along relict joints and three-dimensional cross-slope groundwater flow. During the dry season, the peak suction induced by plant ET is up to 200 kPa and the depth of influence is shallower than 200% of the root depth. For the range of suctions monitored, root-water uptake is revealed to have been restricted by suction not very significantly and was driven mainly by the climatic variation.

scholarly journals Laboratory study on response of underwater cohesive sediment to columnar vibration source

2018 ◽  
Vol 54 (3) ◽  
pp. 193-202
Author(s):  
Peng Zhao ◽  
Feier Chen ◽  
Guoliang Yu
Keyword(s):  
Pressure Distribution ◽  
Experimental Observation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Near Field ◽  
Mechanical Vibration ◽  
Cohesive Sediment ◽  
Vibration Source ◽  
Soil Pressure

Abstract This paper investigates the responses of cohesive sediment to mechanical vibration by experimental observation, containing: (1) the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration to the vibration source; (2) the soil pressure distribution in the near field centered in an artificial columnar vibration source. Under the mechanical vibration with a frequency of 200 Hz and an amplitude of 1.15 mm, the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment were measured in the sediment of four different depositing conditions. Results of the dynamic soil pressure, dynamic pore water pressure and dynamic acceleration of underwater viscous sediment in the near field responding to artificial vibration source are exhibited and discussed. It is found that, excited by the sinusoidal vibrator, the soil pressure presents a response of statistical sinusoidal fluctuation with the same frequency to the vibration source. In the sediment of lower initial yield stresses, the soil pressure distribution distinctly tends to firstly increase and then decrease with distance. The amplitude of the soil pressure is attenuated exponentially with distance.

Pore Water Pressure Distribution and Dissipation During Thaw Consolidation

2016 ◽  
Vol 116 (2) ◽  
pp. 435-451 ◽  
Author(s):  
Xiaoliang Yao ◽  
Jilin Qi ◽  
Mengxin Liu ◽  
Fan Yu
Keyword(s):  
Pressure Distribution ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Thaw Consolidation

scholarly journals The Risk of Liquefaction Associated with Water Head Fluctuation in the Low-lying Area of Tokyo

2019 ◽  
Vol 8 (2) ◽  
pp. 41-47
Author(s):  
Tomohide Takeyama ◽  
Kazuya Honda ◽  
Atsushi Iizuka
Keyword(s):  
Pressure Distribution ◽  
Pore Water ◽  
Seismic Analysis ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Level ◽  
Flood Damage ◽  
Tokyo Bay ◽  
Ground Settlement ◽  
Groundwater Head

 In the wide area of the eastern part of Tokyo, the ground level is less than mean sea level. This area is more vulnerable to disasters than other areas. If large flood damage such as storm surge should occur in this area, the disaster would be a long-term catastrophe. On the coast of Tokyo Bay, countermeasures have been taken by tide embankments and floodgates. However, considering the damage scale when it occurs, an analysis in this area is very important. In this area, ground settlement occurred and groundwater head dropped because groundwater excessively withdrew by the industrial purpose during the period of economic growth. Currently, the groundwater head recovers and the ground settlement has been subsided. However, due to the groundwater head fluctuation, pore water pressure distribution had been different from hydrostatic pressure distribution. Therefore, in the analysis in this area, it is necessary to consider past groundwater head fluctuation. In this research, the ground settlement and the distribution of pore water pressure are simulated from groundwater level fluctuation over the past 100 years. Then, we conducted the seismic analysis by input the distribution of effective stress calculating from the simulated ground water pressure. The sites analyzed in this research are Tokyo Sea Life Park at the mouth of Arakawa River.

scholarly journals Experimental Study on the Failure Mechanism of Tunnel Surrounding Rock under Different Groundwater Seepage Paths

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yingchao Wang ◽  
Yang Liu ◽  
Yongliang Li ◽  
Wen Jiang ◽  
Yueming Wang
Keyword(s):  
Failure Mechanism ◽  
Water Flow ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Measuring Point ◽  
Groundwater Seepage

The influence of groundwater on tunnel engineering is very complicated. Due to the complexity of water flow water pressure transfer and uncertain defects in the stratum, all of which are key factors with regard to the design of tunnel engineering. Therefore, the variation of surrounding rock during excavation and the deformation and failure of soft surrounding rock under different seepage paths of underground water after excavation systematically. Experimental results showed that the stress change of surrounding rock caused by tunnel excavation can be divided into 3 stages: stress redistribution, stress adjustment, and stress rebalancing. In the process of water pressure loading, water flow rate is closely related to the experimental phenomenon. The between stable loading water pressure pore water pressure of the tunnel surrounding rock and the distance from the measuring point to the edge of the tunnel obey the exponential function of the decreasing growth gradient. With the increase of loading pressure, the pore water pressure and stress at the top of the tunnel increase, and the coupling of stress field and seepage field on both sides of surrounding rock more and more intense. The failure process of the tunnel can be divided into 6 stages according to the damage degree. The final failure pattern of the surrounding rock of the tunnel is mainly determined by the disturbed area of excavation. The arched failure area and the collapse-through failure area are composed of three regions. The surrounding rock is characterized by a dynamic pressure arch in the process of seepage failure, but it is more prone to collapse failure at low water pressure. The results of this study are the progressive failure mechanism of tunnel under different groundwater seepage paths and would be of great significance to the prevention of long-range disasters.

scholarly journals Numerical Analysis of the Effects of Crack Characteristics on the Stress and Deformation of Unsaturated Soil Slopes

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 194 ◽  
Author(s):  
Liuxin Yang ◽  
Enlong Liu
Keyword(s):  
Pore Water ◽  
Unsaturated Soil ◽  
Crack Width ◽  
Evaporation Rate ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Infiltration Rate ◽  
Soil Slope ◽  
Soil Slopes ◽  
Stress And Deformation

Cracks induced by evaporation or rainfall have a great influence on the stability of unsaturated soil slopes, which can lead to landslides during the rainfall process. In order to study the effect of crack characteristics on the evolution of stress and deformation of unsaturated soil slopes, a series of numerical analyses under different conditions were performed using a coupled elastoplastic finite element program that we developed for unsaturated soil. When carrying out the numerical analyses, the effective stress for unsaturated soil proposed by Bishop and an elastoplastic double-hardening constitutive model for the soil skeleton were employed. The varying parameters, including the crack location, the discharge speed, evaporation rate, infiltration rate, and tensile strength, were investigated to study the coupling process of pore water pressure and deformation in the process of evaporation and rainfall infiltration. The numerical results showed that the minimum pore water pressure of the soil slope at the end of evaporation/rainfall decreased gradually and the crack width increased gradually as the crack set closer to the slope; the larger the discharge speed of pore air, the greater the crack width. With the increase in the evaporation rate, the pore water pressure of the soil slope reduced and the crack initiated earlier and became wider. As the infiltration rate increased, the pore water pressure of the soil slope and the crack width increased, but the decreasing duration became shorter. The change of tensile strength had little effect on the pore water pressure, but the development of the crack width changed with evaporation and rainfall infiltration.

scholarly journals Total and Effective Stresses in Backfilled Stopes during the Fill Placement on a Pervious Base for Barricade Design

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 38 ◽  
Author(s):  
Jian Zheng ◽  
Li Li ◽  
Yuchao Li
Keyword(s):  
Analytical Solution ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
The Self ◽  
Underground Mines ◽  
Filling Rate ◽  
Effective Stresses ◽  
Arching Effect ◽  
The Stability ◽  
Backfilled Stopes

Backfill is increasingly used in underground mines worldwide. Its successful application depends on the stability of the barricades built at the base of the stopes to hold the backfill in place, which in turn depends on the knowledge of the pore water pressure (PWP) and stresses during, or shortly after, the placement of the slurried backfill. Until now, self-weight consolidation is usually considered for the estimation of the PWP. There is no solution available to evaluate the total and effective stresses during, and shortly after, the filling operation. As excess PWP can simultaneously be generated (increased) and dissipated (decreased) during the backfilling operation, effective stresses can develop when the filling rate is low and/or hydraulic conductivity of the backfill is high. The arching effect has to be considered to evaluate the effective and total stresses in the backfilled stopes. In this paper, a pseudo-analytical solution is proposed to evaluate the effective and total stresses in backfilled stopes during the backfill deposition on a permeable base, by considering the self-weight consolidation and arching effect. The proposed solution is validated by numerical results obtained by Plaxis2D. A few sample applications of the proposed solution are shown.

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