Monitoring Shear Strain in Shallow Subsurface Using Mini Pipe Strain Meter for Detecting Potential Threat of Slope Failure

Abstract

The following study examines a new soil measurement method to achieve simple and reliable slope monitoring to ensure labor safety. The method measures the increase in shear strain in the shallow subsurface of the slope. The target that is measured in the soil using this method is different from that of the conventional methods, which use extensometers and inclinometers. Although the increase in shear strain in the shallow subsurface is considered negligible, this study discusses the potential application of the measurement for detecting the potential threat of slope failure. A mini pipe strain (MPS) meter was developed to measure shear strain in the shallow subsurface of slopes. A full-scale test model of slope failure was constructed via excavation to examine the detectability of the threat of slope failure using an MPS meter. Corresponding to the development of slip surfaces in deep positions, less than 0.5 % of shear strain in the shallow subsurface is clearly observable. Although the inverse of the shear strain rate (1/ν) showed a drastic decrease prior to failure, the slope did not fail immediately; in addition, creep phenomena was observed. An unstable slope may be considered a stable one because of the lag time prior to failure. Identifying the second or third creep could provide a few minutes for workers to escape. Accordingly, the threat of workers being injured by collapsing soil can be reduced by using the proposed method and sensor.

Development of the surface displacement velocity in a full-scale loamy model slope under multistep excavation

“…They reported an accelerated increase in the displacement prior to failure and tried to predict the failure time by the inverse-velocity method to improve the method. Tamate and Hori (2018) reported the results of monitoring the deformation of a shallow surface layer in a model slope under excavation by a pipe strain meter and observed an accelerated increase in the deformation of the layer prior to slope failure. Zhou et al (2020) and Zhou and Ye (2021) reported the accelerating increase of the displacements on the slopes excavated for coal and copper mining.…”

Finite Element Analysis Method of Slope Stability based on Fuzzy Statistics

“…Because the parameters used in geotechnical analysis have a certain type of fuzzy uncertainty, the uncertainty or quantity is scattered. This is due to many reasons, such as test methods, etc., people can not accurately obtain the calculation mechanical parameters needed for calculation and analysis, and the value of mechanical parameters at a certain point in the calculation model can only be given a general range, for example, the measured value of friction angle or cohesive force in the rock and soil slope can never be a fixed value (Tamate & Hori, 2018). Each experiment will lead to some data that is different from the previous values, thus showing a certain distribution in a certain range.…”