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SUMMARYAn analytical method is presented for analysis of slope stability involving cohesive and non-cohesive soils. Earthquake e!ects are considered in an approximate manner in terms of seismic coe$cient-dependent forces. Two kinds of failure surfaces are considered in this study: a planar failure surface, and a circular failure surface. The proposed method can be viewed as an extension of the method of slices, but it provides a more accurate treatment of the forces because they are represented in an integral form. The factor of safety is obtained by using the minimization technique rather than by a trial and error approach used commonly.The factors of safety obtained by the analytical method are found to be in good agreement with those determined by the local minimum factor-of-safety, Bishop's, and the method of slices. The proposed method is straightforward, easy to use, and less time-consuming in locating the most critical slip surface and calculating the minimum factor of safety for a given slope.

Based on the evanescent wave resonance, a photonic crystal sensing structure with air slot-porous silicon-air slot Fabry–Perot cavity (F–P cavity) is proposed. Taking the F–P cavity as the sensing unit, when the gas to be detected is filled into the sensing unit, the refractive index of the air slot will be changed and the refractive index of the porous silicon layer will also be varied, both of which will shift the resonant peak and greatly increase the sensitivity of the sensor. By adjusting the structural parameters, the quality factor (Q value) can be optimized. A model for the relationship between the resonant wavelength and the refractive index of the detected organic gas was established, and the refractive index sensing performance was analyzed. The results show that the Q value of the structure can attain to 12312.2 and the sensitivity is about 8661.708 nm/RIU, which can provide effective theoretical reference and technical guidance for organic gas detection with low concentration.

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