scholarly journals Fracture Mechanical Properties of Damaged and Hydrothermally Altered Rocks, Dixie Valley‐Stillwater Fault Zone, Nevada, USA

2019 ◽  
Vol 124 (4) ◽  
pp. 4069-4090 ◽  
Author(s):  
Owen A. Callahan ◽  
Peter Eichhubl ◽  
Jon E. Olson ◽  
Nicholas C. Davatzes
Keyword(s):  
Mechanical Properties ◽  
Fault Zone ◽  
Dixie Valley

Lateral Variations of Interplate Coupling along the Mexican Subduction Interface: Relationships with Long-Term Morphology and Fault Zone Mechanical Properties

2015 ◽  
Vol 173 (10-11) ◽  
pp. 3467-3486 ◽  
Author(s):  
Baptiste Rousset ◽  
Cécile Lasserre ◽  
Nadaya Cubas ◽  
Shannon Graham ◽  
Mathilde Radiguet ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fault Zone ◽  
Interplate Coupling ◽  
Lateral Variations

Optimization of Tunnel Support Type through Fault Zone

2014 ◽  
Vol 580-583 ◽  
pp. 1184-1187
Author(s):  
Ke Li ◽  
Han Guo
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Reinforced Concrete ◽  
Fault Zone ◽  
Critical Issue ◽  
Surrounding Rock ◽  
The Other ◽  
Support Pressure ◽  
Tunnel Support ◽  
Tunnel Safety

The mechanical properties of tunnel surrounding rock in fault zone is usually quite weak, and the support pressure and displacement are larger than other sections, so the support type in fault zone is a critical issue for tunnel safety. Three types of tunnel support through fault zone were analyzed by finite element method (FEM): ①Reinforced concrete support, ②bolting-shotcreting and reinforced concrete support,③grouting and reinforced concrete support. The result shows that support stress and surrounding rock displacement with grouting and reinforced concrete support is quite smaller than the other support types.

scholarly journals Lateral clay injection into normal faults

GeoArabia ◽  
2003 ◽  
Vol 8 (3) ◽  
pp. 501-522
Author(s):  
Wouter van der Zee ◽  
Janos L. Urai ◽  
Pascal D. Richard
Keyword(s):  
Mechanical Properties ◽  
Fault Zone ◽  
Numerical Models ◽  
Clay Content ◽  
Friction Angle ◽  
Fault Gouge ◽  
Analytical Models ◽  
Normal Faults ◽  
Field Observations ◽  
Injection Process

ABSTRACT The clay content of fault gouge is one of the main factors controlling transport and mechanical properties of a fault zone. This paper addresses the process of lateral clay injection into normal faults, which is one of the many processes contributing to the development of clay smear, and can lead to local enrichment of clay in a fault gouge. We combined field observations with geomechanical models to quantify the parameters leading to lateral clay injection into fault zones. Detailed field study shows that a releasing fault bend in a clay layer is required for clay injection to occur. The clay injection process is often associated with the formation of a branch in the fault and the development of a “squeezing block” which injects the clay into the fault zone. A simple analytical model predicts the onset of clay injection when C = σ'v (1 - sin ϕ) / (2 cos ϕ), where C is cohesion (MPa), σ'v is vertical stress (MPa) and ϕ (°) is friction angle. More detailed analysis using 2-D geomechanical finite element models is in good agreement with the analytical models and allows study of the system at higher fault throw. Results of sandbox models containing layers of an elastoplastic clay analogue also compare well with field observations and numerical models, and show the initiation of the releasing step and the evolution of the clay injection process with increasing fault throw. Using our results it is possible to predict the likelihood of lateral clay injection in the subsurface, in settings like the Gharif formation of the Haushi group of Central and South Oman or the Natih formation of North Oman. This requires an estimation of the mechanical properties of the clays at the time of faulting; data which can be obtained from wireline logs and cuttings. This approach to fault seal analysis emphasizes the mechanical aspects of the clay smear process, in addition to the kinematics which were considered in previous analyses. Its application should lead to improved prediction of fault seal processes in the subsurface.

Evidence for postearthquake slip in the Fairview Peak, Dixie Valley, and Rainbow Mountain fault areas of Nevada

1974 ◽  
Vol 64 (3-1) ◽  
pp. 687-698
Author(s):  
J. C. Savage ◽  
J. P. Church
Keyword(s):  
Fault Zone ◽  
Seismic Refraction ◽  
Geodetic Survey ◽  
Mountain Ranges ◽  
First Order ◽  
Elevation Changes ◽  
Dixie Valley ◽  
The Difference ◽  
Earthquake Faults ◽  
Fault Scarps

abstract The U.S. Coast and Geodetic Survey ran first-order level surveys in 1934, 1955, and 1967 across the fault zone associated with the 1954 sequence of earthquakes at Rainbow Mountain (M = 6.6 and 6.8), Dixie Valley (M = 6.8), and Fairview Peak (M = 7.1) in Nevada. The difference between the 1955 and 1967 surveys clearly shows distinct anomalies over distances of several kilometers at all but one of the fault scarps mapped after the 1954 earthquakes. The anomalies resemble deformation produced by normal faulting extending to a depth of at least several kilometers and, consequently, are interpreted as implying continued slip on the earthquake faults in a period beginning at least 6 months after the earthquake. At the Fairview Peak Fault, the inferred postearthquake slip is about 5 per cent of the displacement observed at the time of the earthquake. The difference between the 1955 and 1967 surveys suggests an overall tilt of 2 mm/km down to the west extending over a 90-km distance crossing the fault zone. The difference between the 1934 and 1955 surveys suggests an overall tilt of 0.8 mm/km down to the east extending over a 200-km section. However, these regional tilts might be due to unusually large systematic errors in the level surveys. Gravity and seismic-refraction surveys indicate that the region as a whole is isostatically compensated, although the mountain ranges and intervening basins are not individually compensated. Thus, the regional elevation changes, if they exist, cannot be accounted for by isostasy.

In-situ petrophysical and geomechanical characterization and 3D modelling of a mature normal fault zone (Goddo fault, Bømlo – Norway)

2020 ◽  
Author(s):  
Alberto Ceccato ◽  
Giulio Viola ◽  
Marco Antonellini ◽  
Giulia Tartaglia ◽  
Eric James Ryan
Keyword(s):  
Mechanical Properties ◽  
Structural Analysis ◽  
Fault Zone ◽  
Normal Fault ◽  
Fault Zones ◽  
Fault Rock ◽  
Fracture Patterns ◽  
Fault Zone Architecture

<p>The detailed characterization of internal fault zone architecture and  petrophysical and geomechanical properties of fault rocks is fundamental to understanding the flow and mechanical behaviour of mature fault zones. The Goddo normal fault (Bømlo – Norway) accommodated c. E-W extension related to North Sea Rifting from Permian to Early Cretaceous times [1]. It represents a good example of a mature, iteratively reactivated and thus long-lived (seismogenic?) fault zone, developed in a pervasively fractured granitoid basement at upper crustal conditions in a regional extensional setting.</p><p>Field characterization of the fault zone’s structural facies and analysis of background fracture patterns in the protolith have been integrated with in-situ petrophysical and geomechanical surveys of the recognized fault zone architectural components. In-situ air-permeability and mechanical directional tests (performed with NER TinyPerm III air-minipermeameter and DRC GeoHammer, L-type Schmidt hammer, respectively) have allowed for the quantification of the permeability tensor and mechanical properties (UCS and elastic modulus) within each brittle structural facies. Mechanical properties measured parallel to fault rock fabric of cataclasite- and gouge-bearing structural facies differ by up to one order of magnitude from those measured perpendicularly to it (~10 MPa vs. 100-200 MPa in UCS, respectively). Accordingly, permeability of cataclasite- and gouge-bearing facies is several orders of magnitude larger when measured parallel to fault-rock fabric than that perpendicular to it (10<sup>-0</sup>-10<sup>-1</sup> D vs. 10<sup>-2</sup>-10<sup>-3</sup> D, respectively). Virtual outcrop models (VOMs) of the fault zone were obtained from high-resolution UAV-photogrammetry. Field measurements of fracture orientations were used for calibration of the VOMs to construct a statistically robust fracture dataset. The results of VOMs structural analysis allowed for the quantification of fracture intensity and geometrical characteristics of mesoscopic fracture patterns within the different domains of the fault zone architecture.</p><p>Results from field, VOMs structural analysis, and in-situ petrophysical investigations have been integrated into a realistic 3D fault zone model with the software 3DMove (Petex). This model can be used to investigate the influence of mesoscopic fracture patterns, related to either the fault zone or the background fracturing, on the hydro-mechanical behaviour of a mature fault zone. In addition, the evolution of the hydro-mechanical properties through time can be assessed by integrating the progressive development of brittle structural facies and fracture sets developed during the incremental strain and stress history into the model. This contribution proposes a geologically-constrained method to quantify the geometry of 3D fault zones, as a possible tool for models to be adopted in stress-strain analysis, hydraulic characterization and in the mechanical analysis of fault zones.</p><p>[1] Viola, G., Scheiber, T., Fredin, O., Zwingmann, H., Margreth, A., & Knies, J. (2016). Deconvoluting complex structural histories archived in brittle fault zones. Nature communications, 7, 13448.</p>

Sign in / Sign up

Export Citation Format

Share Document