Cyclic Secant Shear Modulus and Pore Water Pressure Change in Sands at Small Cyclic Strains

Abstract. There are many factors causing land subsidence, and groundwater extraction is one of the most important causes of subsidence. A set of coupled partial differential equations are derived in this study by using the poro-elasticity theory and linear stress-strain constitutive relation to describe the one-dimensional consolidation in a saturated porous medium subjected to pore water pressure change due to groundwater table depression. Simultaneously, the closed-form analytical solutions for excess pore water pressure and total settlement are obtained. To illustrate the consolidation behavior of the poroelastic medium, the saturated layer of clay sandwiched between two sand layers is simulated, and the dimensionless pore water pressure changes with depths and the dimensionless total settlement as function of time in the clay layer are examined. The results show that the greater the water level change in the upper and lower sand layers, the greater the pore water pressure change and the total settlement of the clay layer, and the more time it takes to reach the steady state. If the amount of groundwater replenishment is increased, the soil layer will rebound.

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Assessment of the self-desiccation process in cemented mine backfills

Canadian Geotechnical Journal ◽

10.1139/t07-051 ◽

2007 ◽

Vol 44 (10) ◽

pp. 1148-1156 ◽

Cited By ~ 60

Author(s):

Matthew Helinski ◽

Andy Fourie ◽

Martin Fahey ◽

Mostafa Ismail

Keyword(s):

Pore Water ◽

Volume Change ◽

Pore Water Pressure ◽

Water Pressure ◽

Pressure Change ◽

Soil Matrix ◽

Mine Backfill ◽

Fine Grained ◽

Key Characteristics ◽

Conventional Manner

During the placement of fine-grained cemented mine backfill, the high placement rates and low permeability often result in undrained self-weight loading conditions, when assessed in the conventional manner. However, hydration of the cement in the backfill results in a net volume reduction—the volume of the hydrated cement is less than the combined volume of the cement and water prior to hydration. Though the volume change is small, it occurs in conjunction with the increasing stiffness of the cementing soil matrix, and the result in certain circumstances can be a significant reduction in pore-water pressure as hydration proceeds. In this paper, the implications of this phenomenon in the area of cemented mine backfill are explored. An analytical model is developed to quantify this behaviour under undrained boundary conditions. This model illustrates that the pore-water pressure change is dependent on the amount of volume change associated with the cement hydration, the incremental stiffness change of the soil, and the porosity of the material. Experimental techniques for estimating key characteristics associated with this mechanism are presented. Testing undertaken on two different cement–minefill combinations indicated that the rate of hydration and volumes of water consumed during hydration were unique for each cement–tailings combination, regardless of mix proportions.

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LABORATORY TESTS ON SHEAR MODULUS AND VOLUMETRIC STRAIN OF SANDY SOIL INFLUENCED BY PROPAGATION OF EXCESS PORE WATER PRESSURE

Journal of Japan Society of Civil Engineers Ser C (Geosphere Engineering) ◽

10.2208/jscejge.69.239 ◽

2013 ◽

Vol 69 (2) ◽

pp. 239-258

Author(s):

Hiroshi NAKAZAWA ◽

Takahiro SUGANO

Keyword(s):

Shear Modulus ◽

Pore Water ◽

Sandy Soil ◽

Laboratory Tests ◽

Pore Water Pressure ◽

Water Pressure ◽

Volumetric Strain ◽

Excess Pore Water Pressure ◽

Excess Pore

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A Simulation Study on the Spatial-Temporal Characteristics of Pore Water Pressure and Roof Water Inrush in an Aquiclude

Shock and Vibration ◽

10.1155/2021/6643894 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Tao Yang ◽

Ji Li ◽

Longwen Wan ◽

Sheng Wang

Keyword(s):

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Water Inrush ◽

Pressure Change ◽

Coupling Model ◽

Early Warning Systems ◽

Temporal Characteristics ◽

Working Face

As the working face advances, the overlying aquiclude is subjected to periodic dynamic loads, causing pore water pressure distortion, which provides important forewarning for a water inrush disaster in shallow coal seams. In order to analyze the pore water pressure in an aquiclude and determine the spatial-temporal characteristics of the water inrush, the aquiclude is simplified into a saturated, porous, liquid-solid medium and a viscoelastic dynamic model is created to obtain the analytical solution of the pressure distribution. FLAC3D is used to develop a fluid-solid coupling model and to analyze the characteristics of the pressure change and overburden under different mining intensities. This study on pore water pressure in an aquiclude and the determination of the spatial-temporal characteristics of the water inrush provides a foundation for developing early-warning systems for roof water inrush.

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