Curvature, a mechanical link between the geometrical complexities of a fault: application to bends, kinks and rough faults

SUMMARY Many recent studies have tried to determine the influence of geometry of faults in earthquake mechanics. However, it still remains largely unknown, and it is explored mainly with numerical models. In this paper, we will try to understand how exactly does the geometry come into play in the mechanics of an earthquake from analytical perspective. We suggest a new interpretation of the effect of geometry on the stress on a fault, where the curvatures of the fault that multiply the slip play a major role. Starting from the representation theorem, which links the displacement in a medium to the slip distribution on its boundary, and assuming a 3-D, homogeneous, infinite medium, a regularized boundary-element equation can be obtained. Using this equation, it is possible to separate the influence of geometry, as expressed by the curvatures and torsions of the field lines of slip on the fault surface, which multiply the slip, from the effect of the gradient of slip. This allows us to shed new light on the mechanical effects of geometrical complexities on the fault surface, with the key parameters being the curvatures and torsions of the slip field lines. We have used this new approach to show that, in 2-D static in-plane problems, the shear traction along the fault is mainly controlled by the gradient of slip along the fault, while the normal traction is mainly controlled by the slip that multiplies the curvature along the fault. Finally, we applied this new approach to re-interpret the effect of roughness (why there is a need for a minimum lengthscale in linear elasticity, how to study mechanically the difference of roughness measurements with the direction of slip, scaling of slip distribution versus geometry), bends and kinks (what is the difference between the two, are they sometimes equivalent), as well as to explain further the false paradox between smooth-and-abrupt-bends. This unified framework allows us to improve greatly our understanding of the effect of fault geometry on the mechanics of earthquakes.

Under the Action of Earthquake Mechanics Analysis of the Infill Wall in Plane

Using finite element software SAP2000 solid model element to simulate the infill walls filled wall by the elastic conditions, and to simplify the calculation model, the use of elastic mechanics calculated infill wall subjected to earthquake plane wall crack development trend of the structure designed to prevent cracks in the wall of the measures will certainly help.

Earthquake Mechanics Study with Health Check for a Seismic-Damaged Tunnel Suffered from the Wenchuan Earthquake

The health diagnosis of seismic-damaged tunnel seismically damaged is important in recovering traffic lines for seismic relief and recovery. Taking a tunnel damaged tunnel in the Wenchuan earthquake as an example, the methods of safety check is exposed. The non-destructive test showed that the seismic damage to this tunnel included concrete cracks, hidden cavities, and strength deterioration of lining. Several causes induced in seismic diseases were discussed. The rehabilitation technique, which needs not break off transportation through the tunnel, was also put forward. It is hoped that this earthquake mechanics study can enhance the stability assessment and tunnel reinforcement in a highly seismic region.