Ground motion of a semi-cylindrical hill with a subsurface linear crack under SH wave

An analytical method is provided for ground motion of a semi-cylindrical hill with a subsurface linear crack under SH -wave. A suitable Green’s function for the problem discussed in this paper is constructed by complex function and multi-polar coordinate systems. It is the fundamental solution of the displacement field for an elastic half space with a semi-cylindrical hill under an out-plane harmonic line source which is loading at an arbitrary point in the basal body. According to the displacement field solution of scattering of SH wave by a semi-cylindrical hill, the Green’s function of this paper is used to construct a subsurface linear crack. With the boundary condition, a series of infinite algebraic for the problem can be set up. And the displacement field of a semi-cylindrical hill with a subsurface linear crack impacted by SH wave is expressed. The numerical example shows the influence of wave numbers, the length of crack, the incident angle and the ratio of hill on the hill’s displacement

Dynamic Analysis of a Shallow Buried Tunnel Influenced by a Neighboring Semi-cylindrical Hill and Semi-cylindrical Canyon

This paper provides a dynamic analysis of the response of a subsurface cylindrical tunnel to SH waves influenced by a neighboring semi-cylindrical hill and semi-cylindrical canyon in half-space using complex functions. For convenience in finding a solution, the half-space is divided into two parts and the scattered wave functions are constructed in both parts. Then the mixed boundary conditions are satisfied by moving coordinates. Finally, the problem is reduced to solving a set of infinite linear algebraic equations, for which the unknown coefficients are obtained by truncation of the infinite set of equations. The effects of the incident angles and frequencies of SH waves, as well as of the radius of the tunnel, hill, and canyon on the dynamic stress concentration of the tunnel are studied. The results show that the hill and canyon have a significant effect on the dynamic stress concentration of the tunnel

An Investigation of Calibration Phantoms for CT Scanners with Tube Voltage Modulation

The effects of calibration phantoms on the correction results of the empirical artifacts correction method (ECCU) for the case of tube modulation were investigated. To improve the validity of the ECCU method, the effect of the geometry parameter of a typical single-material calibration phantom (water calibration phantom) on the ECCU algorithm was investigated. Dual-material calibration phantoms (such as water-bone calibration phantom), geometry arrangement, and the area-ratio of dual-material calibration phantoms were also studied. Preliminary results implied that, to assure the effectiveness of the ECCU algorithm, the polychromatic projections of calibration phantoms must cover the polychromatic projection data of the scanning object. However, the projection range of a water calibration phantom is limited by the scan field of view (SFOV), thus leading to methodological limitations. A dual-material phantom of a proper size and material can overcome the limitations of a single-material phantom and achieve good correction effects

A Normalized Hysteretic Energy Spectrum for Energy-Based Seismic Design

To disclose the impacts of hysteretic energy (HE) demand on energy-based seismic design, this paper introduces the dimensionless parameter βEH to express the cumulative HE indirectly and establishes the βEH spectrum for energy-based seismic design. After analyzing numerous seismic responses of a single degree-of-freedom (SDOF) system, the author set up a simplified βEH spectral formula based on the genetic algorithm. Then, 750 ground motion records were selected according to Chinese site classification, and used to examine the effects of soil type and damping ratio on the βEH spectra. The results show that the soil type, site group and damping ratio have significant effects on the βEH spectra; the ductility ratio has an impact on the spectral value but not the spectral shape