Application of physics-data-driven method to identify the weak interlayers in underground geotechnical engineering

Abstract

The accurate description of the internal structure of weak interlayers is a prerequisite for the safe construction of deep geotechnical engineering with complicated geological conditions. Geophysical tomography techniques are usually used to detect the mechanical properties and spatial distribution and of deep weak interlayers. However, the mechanical properties of weak interlayers cannot be measured directly and the spatial distribution is conventionally difficult to explain by geophysical tomography techniques with ambiguous and inaccurate. In this work, a novel Physics-Data-Driven Method (PDDM) is proposed to identify the internal structure of weak interlayers based on inverse analysis. The constrained covariance matrix is constructed based on the results of geophysical tomography, and a structure similar to “fault core-damage zone-host rock” is achieved, which accurately describes the spatial distribution of weak interlayers. The field application results of Xiluodu underground chamber show: 1) Compared with conventional inverse analysis, PDDM enhances the convergence of simulation results to the field observations, with the relative error basically within 20%, meeting the engineering precision requirements; 2) PDDM can continuously optimize the spatial distribution of the weak interlayer based on the results of geophysical tomography, and finely identify the internal structure and distribution range. The results of PDDM have positive significance for engineering disaster prevention near weak interlayers.