Subsurface contour unevenness in seismic microzoning of a point facility

Abstract

Introduction. Unconformable bedding of layers in the upper part of a geological section is widely applied in seismic microzoning (SMZ) practice. This challenges the use of some popular software for interpreting the effect of soil massif on the seismic wave field. The use of complex processing software, such as the finite element method, often appears unprofitable in the practice of SMZ for point facilities.

Aim. To develop simple techniques for obtaining solutions acceptable in terms of accuracy and labor costs for SMZ tasks including the unevenness of the subsurface contour.

Materials and methods. The paper considers the results of SMZ at the construction site of an extra critical point facility in Khabarovsk, Russian Federation. The main methodological approach of this study represents soil conditions by a series of models formed based on well data. We use computer simulation of wave fields to determine the response spectra and dynamic coefficients of each model. Seismic intensity increments are calculated using the direct SMZ method.

Results. Response spectra and dynamic coefficients obtained for each model were used to calculate increments and values of total seismic intensity. These values take into account the subsurface contour unevenness to define the boundaries of exact seismic intensity values.

Conclusions. The described methodology is supplemented with the results of SMZ during surveys for the construction of a point facility, taking into account the subsurface contour unevenness.