Near-surface stress measurements in the Longmenshan fault belt after the 2008 Wenchuan Ms8.0 earthquake

2015 ◽  
Vol 77 ◽  
pp. 358-377 ◽  
Author(s):  
Chengjun Feng ◽  
Peng Zhang ◽  
Xianghui Qin ◽  
Wen Meng ◽  
Chengxuan Tan ◽  
...  
Keyword(s):  
Surface Stress ◽  
Near Surface ◽  
Stress Measurements ◽  
Longmenshan Fault ◽  
Fault Belt ◽  
Wenchuan Ms8.0 Earthquake

Fracture of Defects Approaching a Free Surface

1975 ◽  
Vol 97 (4) ◽  
pp. 270-277 ◽  
Author(s):  
W. G. Gibbons ◽  
W. R. Andrews ◽  
G. A. Clarke
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Free Surface ◽  
Stress Intensity ◽  
Surface Stress ◽  
Empirical Equation ◽  
Near Surface ◽  
Fracture Characteristics ◽  
Testing Program ◽  
Measured Strain

A testing program has been run using off-centered-cracked (OCC) plate specimens to demonstrate the fracture characteristics of tunnel defects in specimens with various ligament lengths between the near surface crack tip and a free surface. Measured strain values and the fracture results compared favorably with theory up to the limits of the analyses. An empirical equation which calculates the near surface stress intensity provides extended calculational capabilities. In addition, fatigue crack growth and fracture velocities plus fracture toughness were measured for a Cr-Mo-V steel.

Fatigue of Cellulose Acetate and Ductile Metals

2019 ◽  
Vol 1154 ◽  
pp. 112-121
Author(s):  
Wolfgang Gräfe
Keyword(s):  
Experimental Data ◽  
Cellulose Acetate ◽  
Theoretical Consideration ◽  
Surface Stress ◽  
Fatigue Properties ◽  
Ductile Metals ◽  
Near Surface ◽  
Iron Copper ◽  
Plastic Materials ◽  
Fatigue Data

By a theoretical consideration of a viscous body it has been deduced a formula for the description of the fatigue properties of ductile metals and plastic materials. This formula has been compared with experimental fatigue data of Wöhler-curves (S-N curves). For cellulose acetate, iron, copper, nickel, silver, zinc and, to a restricted degree, also for aluminum a sufficient accordance between the experimental data and the theoretical curves has been reached. With this procedure it is possible to determine fatigue limits for these materials. Similar results are obtained for the creep of brass. It is supposed that the cause of the fatigue limit is the near surface stress of the specimen.

scholarly journals Analysis of the Crust Deformations before and after the 2008 Wenchuan Ms8.0 Earthquake Based on GPS Measurements

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Jicang Wu ◽  
Renzhao Liu ◽  
Yongqi Chen ◽  
Conrad Tang ◽  
Guojie Meng ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Active Faults ◽  
Strain Rates ◽  
Strain Accumulation ◽  
Western Sichuan ◽  
Before And After ◽  
Longmenshan Fault ◽  
Inversion Analysis ◽  
Fault Slip Distribution ◽  
Wenchuan Ms8.0 Earthquake

We use the movement velocities of GPS stations in western Sichuan province, China, to determine the distribution of horizontal strain accumulation before the 2008 Wenchuan Ms8.0 earthquake with a piecewise approximation approach and the coseismic displacements to determine the fault slips of the earthquake with an inversion analysis method. The results show that the distribution of the principal strain rates is strongly related to the active faults in the region, but along Longmenshan fault where the earthquake occurred, the strain rates are much lower than the others. The fault slip distribution shows mainly a thrusting with dextral striking, and the fault slips in the upper parts of the fault plane are in general bigger. Using the current strain accumulation rate and the released energy by the earthquake, we predict such a big earthquake in Longmenshan fault zone will happen in 460 to 1380 years.

scholarly journals Generation of Subsurface Anticyclones at Arctic Surface Fronts due to a Surface Stress

2017 ◽  
Vol 47 (11) ◽  
pp. 2653-2671 ◽  
Author(s):  
Liam Brannigan ◽  
Helen Johnson ◽  
Camille Lique ◽  
Jonas Nycander ◽  
Johan Nilsson
Keyword(s):  
Mixed Layer ◽  
Surface Stress ◽  
Ekman Transport ◽  
The Arctic ◽  
Near Surface ◽  
Geostrophic Flow ◽  
Unstable Surface ◽  
Surface Cyclone ◽  
Ekman Flow ◽  
The Right

AbstractIsolated anticyclones are frequently observed below the mixed layer in the Arctic Ocean. Some of these subsurface anticyclones are thought to originate at surface fronts. However, previous idealized simulations with no surface stress show that only cyclone–anticyclone dipoles can propagate away from baroclinically unstable surface fronts. Numerical simulations of fronts subject to a surface stress presented here show that a surface stress in the same direction as the geostrophic flow inhibits dipole propagation away from the front. On the other hand, a surface stress in the opposite direction to the geostrophic flow helps dipoles to propagate away from the front. Regardless of the surface stress at the point of dipole formation, these dipoles can be broken up on a time scale of days when a surface stress is applied in the right direction. The dipole breakup leads to the deeper anticyclonic component becoming an isolated subsurface eddy. The breakup of the dipole occurs because the cyclonic component of the dipole in the mixed layer is subject to an additional advection because of the Ekman flow. When the Ekman transport has a component oriented from the anticyclonic part of the dipole toward the cyclonic part then the cyclone is advected away from the anticyclone and the dipole is broken up. When the Ekman transport is in other directions relative to the dipole axis, it also leads to deviations in the trajectory of the dipole. A scaling is presented for the rate at which the surface cyclone is advected that holds across a range of mixed layer depths and surface stress magnitudes in these simulations. The results may be relevant to other regions of the ocean with similar near-surface stratification profiles.

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