scholarly journals Investigation on Creep Behavior and Permeability Evolution Characteristics of Sandstone under Different Pore Pressures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hongcai Shi
Keyword(s):  
Pore Pressure ◽  
Creep Behavior ◽  
Mode Analysis ◽  
Permeability Evolution ◽  
Red Sandstone ◽  
Pore Pressures ◽  
Function Relationship ◽  
Fractured Sandstone ◽  
Triaxial Creep Test

To investigate the influence of pore pressure ( σ w ) on the creep behavior and permeability of red sandstone, triaxial creep test with permeability test under different pore pressures was conducted using MTS 815 testing system. The experimental results demonstrate that water has significant weakening effect on the long-term mechanical properties of sandstone, and the long-term strength of sandstone gradually decreases with increase in pore pressures. All permeability-time curves demonstrate a “decreasing-increasing” trend, but two different permeability evolution trends during the steady creep stage are observed, which are related to deviatoric stress. The permeability of both intact ( k 0 ) and fractured sandstone ( k f ) samples increases with the increase in pore pressure, which are in consistent with the failure mode analysis of fractured sandstone samples. However, while the relationship between k 0 and σ w is positive linear, it is a positive exponential function relationship between k f and σ w .

Pore pressures around tunnels in clay

1992 ◽  
Vol 29 (5) ◽  
pp. 819-831 ◽  
Author(s):  
L. Samarasekera ◽  
Z. Eisenstein
Keyword(s):  
Finite Elements ◽  
Pore Pressure ◽  
Earth Pressure ◽  
Dimensionless Time ◽  
Element Analysis ◽  
Initial Stress Field ◽  
Long Term Stability ◽  
Pore Pressures ◽  
Overconsolidated Clays

The pore-pressure generation and dissipation around shallow tunnels excavated in both normally and overconsolidated clays are investigated. The influence of the diameter D, depth of cover to diameter ratio H/D, coefficient of earth pressure at rest K0, and strength and modulus variations with depth on pore-pressure generation are examined. The effects of immediate support on pore pressure are also studied by defining a quantity termed effective stiffness ratio (ESR). A two-dimensional, nonlinear finite element analysis is performed to obtain the pore-pressure generation behav-iour. Strength, modulus, initial stress field, and unloading due to excavation are reflected in this analysis. The pore-pressure dissipation behaviour is investigated by employing an uncoupled consolidation theory using finite elements. A dimensionless time factor is used to present the results of pore-pressure dissipation. These results are presented using nondimensional quantities and in normalized forms. The results are directly applicable to estimation of pore pressures for determining long-term stability of tunnels. Key words : clay, pore pressure, tunnels, uncoupled consolidation, finite elements, stress-strain.

Effect of pore pressure on the permeability evolution in low porous Indian sandstone

2021 ◽  
Author(s):  
Kamal Nanda ◽  
Santanu Misra ◽  
Arghya Das
Keyword(s):  
Pore Pressure ◽  
Gas Permeability ◽  
Knudsen Diffusion ◽  
Fluid Viscosity ◽  
Permeability Evolution ◽  
Permeability Measurement ◽  
Steady State Method ◽  
Pore Pressures ◽  
Structure Of Flow ◽  
Stress Dependent

<p>Permeability evolution of low permeable rocks is of critical importance during the flow of gases in processes like, enhanced reservoir recovery and CO<sub>2</sub> sequestration. Permeability measurement depends on the geometric structure of flow path (hydraulic radius, connectivity, tortuosity), the stress regimes surrounding the rock (isotropic, deviatoric) and the characteristic of the fluid (viscosity, compressibility, pore pressure).  For the case of gas permeability within Knudsen diffusion regime (0.001 < Kn< 0.1), the effect of slippage is prominently observed.</p><p>Laboratory scale permeability experiments on an Indian sandstone having connected porosity ~10%, are performed under hydrostatic condition. Nitrogen gas is selected as pore fluid, to avoid adsorption phenomenon. Transient technique of pore-pressure-pulse decay is used for permeability measurement as it is faster and accurate to measure pressure, than the steady state method. Pore pressures and confining pressures are varied in the study to understand the relative effect of matrix compressibility and fluid compressibility on the permeability. Micro-CT analysis of sample is also performed to quantify the geometric attributes of sample.</p><p>Apparent gas permeability ranging from 0.1 to 1 micro-Darcy is obtained from the experiments. The permeability is found to be decreasing with simple effective stress (σ<sub>ii</sub>-p) for constant pore pressures. But a counter intuitive decrease in permeability with increasing pore-pressure at constant confining pressure is also evident and can be attributed to stress dependent Biot’s coefficient (λ).  Slippage corrected permeability is further analysed theoretically and numerically to formulate nonlinear permeability evolution equation in the functional form, f(σ<sub>ii</sub>-λp)  to support experimental outcomes.</p>

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

scholarly journals Erratum to: Long-term in situ monitoring at Dashgil mud volcano, Azerbaijan: a link between seismicity, pore-pressure transients and methane emission

2010 ◽  
Vol 99 (S1) ◽  
pp. 241-241 ◽  
Author(s):  
Achim Kopf ◽  
Georg Delisle ◽  
Eckhard Faber ◽  
Behrouz Panahi ◽  
Chingiz S. Aliyev ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Methane Emission ◽  
In Situ Monitoring ◽  
Mud Volcano ◽  
Pressure Transients

scholarly journals Study of primary creep behavior of clayey soils in landslide area : suction effect

2018 ◽  
Vol 149 ◽  
pp. 02027
Author(s):  
Dahhaoui Hachimi ◽  
Belayachi Naima ◽  
Zadjaoui Abdeldjalil
Keyword(s):  
Creep Behavior ◽  
Unsaturated Soils ◽  
Primary Creep ◽  
Creep Model ◽  
Clayey Soils ◽  
Landslide Area ◽  
Deviator Stress ◽  
Landslide Process ◽  
The University

Creep behavior of clayey soils plays an extremely important role in the landslide process. The soils that make up these sliding zones are often in unsaturated state. This point indicates the need to take into account the suction effect as hydric parameter on the long-term deformation of clayey soils. In this paper, a primary creep model named Modified Time Hardening (MTH) for unsaturated soils with different matric suction has been built. Based on the literature tests results[1][2], parameters C1 and C2 of the model have relations with suction and deviator stress level respectively. The primary creep strainwill be able to demonstrate unsaturated effect of the soils. comparison between the calculated results and the literature tests results shows a good coherence. The work underway at the university of Orleans will show later the relevance of model used in the present work.

Sign in / Sign up

Export Citation Format

Share Document