Effect of pore pressure build-up on the seismic response of sandy deposits

2015 ◽  
pp. 1031-1036 ◽  
Author(s):  
F Ardoino ◽  
D Bertalot ◽  
C Piatti ◽  
O Zanoli
Keyword(s):  
Seismic Response ◽  
Pore Pressure ◽  
Pore Pressure Build Up

Pore Pressure Build-up of Silt Soft Clay under Dynamic Loading at Zhoushan Islands

2012 ◽  
Vol 594-597 ◽  
pp. 460-464
Author(s):  
Qian Shi ◽  
Kui Zhou ◽  
Qiang Li
Keyword(s):  
Pore Pressure ◽  
Dynamic Loading ◽  
Dynamic Load ◽  
Soft Clay ◽  
Test System ◽  
Dynamic Responses ◽  
Minor Effect ◽  
Consolidation Pressure ◽  
Anisotropic Consolidation ◽  
Pore Pressure Build Up

The mechanism of dynamic tri-axial test is introduced in this paper and the dynamic responses of silt soft clay at Zhoushan are studied using a dynamic tri-axial test system. The laws of pore pressure build-up of the silt clay are obtained which are affected by the consolidation pressure and dynamic load. The greater the consolidation pressure and the dynamic loading is, the more the build-up of pore pressure is. However, the dynamic load has minor effect on pore pressure build-up under the anisotropic consolidation.

Thermo-poromechanical induced seismic effects during diking

2020 ◽  
Author(s):  
Thomas Nagel ◽  
Francesco Parisio ◽  
Eleonora Rivalta ◽  
Sergio Vinciguerra
Keyword(s):  
Seismic Response ◽  
Pore Pressure ◽  
Temperature Increase ◽  
Numerical Models ◽  
Volcanic Eruptions ◽  
Rate Of Change ◽  
Coupled Processes ◽  
Rock Permeability ◽  
Coulomb Stress Changes ◽  
Stress Changes

<p><span>Dike propagation in the earth crust, often a precursor of major volcanic eruptions, usually generates a seismic response by activating small fractures (micro-seismicity) and larger existing faults (greater magnitude events). The conceptual interpretation is essentially viewed as a fluid-driven fracture advancing in the rock mass and altering the existing state of stress in its surroundings. Because dikes are filled with high-temperature magma, which can exceed 1000 °C, it is likely that they will alter the initial temperature while propagating. The temperature increase can generate pore water pressurization as a function of its rate of change. Pore pressure in turns diffuses through the porous and fractured rock, altering the initial effective stress state. Additionally, hot dikes also generate thermally-induced stresses. The stress changes in the rock are therefore affected by temperature and pore pressure as much as they are by mechanically induced fracturing. In this contribution, we have studied the coupled processes of temperature, pore pressure and deformation induced by diking. We have employed finite element analyses to solve the boundary value problem of a progressing dike. The main goal is to highlight the effects generated by temperature increase in the rock surrounding the dike. Thermal pressurization depends on heat loading rate, hence on diking advancement speed, and on surrounding rock permeability. Rock permeability also controls the diffusion of pore pressure, the size of the area affected by pressurization and the magnitude of pressurization. Results from numerical models show that positive Coulomb stress changes (instabilities) can be triggered by thermal effects at several hundred meters away from the dike, implying that even non-advancing dikes could generate a seismic response. We prove the importance of accounting for thermo-poromechanical effects in studying the seismic response during diking, a widely unexplored field which could have major implications for the assessment of volcanic eruptions’ precursory signals.</span></p>

Solid-phase bulk modulus and microinhomogeneity parameter from quasistatic compression experiments

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. A51-A55 ◽  
Author(s):  
Tobias M. Müller ◽  
Pratap N. Sahay
Keyword(s):  
Bulk Modulus ◽  
Pore Pressure ◽  
Solid Phase ◽  
Additional Parameter ◽  
Direct Measure ◽  
Porous Rocks ◽  
Complete Set ◽  
Pore Pressure Build Up

Quasistatic deformation experiments in the laboratory are key to determining the poroelastic moduli of rocks. For microinhomogeneous porous rocks, it is a challenge to determine a complete set of poroelastic parameters. This is because an additional parameter is required that quantifies the effect of microinhomogeneities because then the unjacketed bulk and pore moduli are no longer the same as the bulk modulus of the solid phase. We found that measurements for the drained and unjacketed bulk moduli together with Skempton’s pore-pressure build-up coefficient were sufficient to determine the solid-phase bulk modulus and the microinhomogeneity parameter. The latter served as a direct measure for the deviation from Biot-Gassmann prediction for the undrained bulk modulus. We applied the results to a set of measured poroelastic moduli in which microinhomogeneities have been made responsible for a non-Gassmann rock behavior. Accordingly, our estimate for the microinhomogeneity parameter quantified the deviation from the Biot-Gassmann prediction.

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