A kinematic method for calculating shear displacements of landslides using distributed fiber optic strain measurements

Zhang, Chengcheng; Zhu, Hong‐Hu; Liu, Suping; Shi, Bin; Zhang, Dan

doi:10.1016/j.enggeo.2018.01.002

Cited by 65 publications

(23 citation statements)

References 33 publications

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“…One of the applications of DFOSS is to monitor landslide behavior (Kogure & Okuda, 2018;Schenato et al, 2017;Zhang, Zhu et al, 2018). Recently, based on field observations, it was proposed that the swelling of soils…”

Section: Discussion: Possible Role Of Clay Swelling In Rock Deformationmentioning

confidence: 99%

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Zhang

Xue

2019

Water Resources Research

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Rock deformation induced by pore‐fluid pressure carries useful information about fluid flow owing to hydromechanical coupling. Thus, obtaining spatiotemporal changes in rock deformation could provide improved understanding of the fluid and pressure migration in aquifers or the role of fluid in the evolution of rainfall‐induced landslide. Here we deployed high‐resolution Rayleigh‐scattering‐type distributed fiber optic strain sensing (DFOSS) to measure rock deformation while injecting water into low‐permeability dry sandstone. X‐ray computed tomography imaging was simultaneously used to visualize the water migration. DFOSS measurements showed the rock developed a dilation deformation that grew during water saturating process. The movement of water wetting front can be revealed by the changes in the measured distributed strain. Strain changes were shaped by poroelastic changes due to the fluid pressure buildup and swelling by the water–clay reaction (i.e., adsorption). The latter mechanism caused increase in the strain when water first entered the dry pore spaces and the change in pore pressure was slight. The mechanism continued contributed to the overall deformation to peak magnitude of ~600 μϵ together with poroelastic mechanism. However, after the rock was fully saturated, further deformation during the flow test can be explained by the poroelastic mechanism alone. Our study suggests that the two factors can be employed as signatures for effectively monitoring fluid behavior in natural sediments using DFOSS. Moreover, we obtained the spatial hydromechanical properties, permeability and stiffness, from the distributed strain measurement and pressure responses. Using DFOSS in the field may substantially improve our ability to monitor and model fluid activity related to rock deformations in reservoirs and rainfall‐induced landslides that would help in warning people of risks and preventing disasters.

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Section: Discussion: Possible Role Of Clay Swelling In Rock Deformationmentioning

confidence: 99%

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Zhang

Xue

2019

Water Resources Research

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“…Lately, optical fibers have been used in monitoring the stress of bolts . An optical fiber is embedded in a bolt for monitoring the corrosion of the bolt, the stability of the mine roadway, the deformation of landslide, and the strain of the surrounding rock mass . Monitoring by using an optical fiber can reveal the long‐term stability or deformation of the rock mass and the three‐dimensional deflection profile of the bolt.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and correction of the stress in an anchor bolt based on Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis

Liu

Chai

Chen

et al. 2020

Energy Science & Engineering

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Bolt is an important connection in underground construction and monitoring its stress characteristics is essential to evaluate the effectiveness of bolt. The strain information collected along a rock bolt reveals the long-term movement characteristics of rock mass, which greatly helps toward disaster prevention and risk warning.Grooving on the surface of a bolt and embedding an optical fiber is one of the main methods for monitoring the anchorage performance and stress distribution around the bolt in underground engineering. In this study, Pulse Pre-Pumped Brillouin Optical Time Domain Analysis (PPP-BOTDA) technology is used to evaluate the stress, axial force, and shear stress distribution of the bolt under tensile load for different types (grooved and nongrooved) of bolts embedded in concrete with resin as anchoring agent. The results show that the PPP-BOTDA sensor can be used to monitor the stress state of the bolt embedded in concrete with resin as anchoring agent when the bolt is subjected to a tensile force. However, the apparent stress value measured in this way is not the actual stress value of the bolt, but is an increased value caused due to the groove. The closer to the exposed end of the bolt, the greater is the deviation between the apparent stress value and the actual stress value of the bolt. Based on the monitoring results from this experimental study, a stress reduction calculation method is proposed, which can change the measured value into the actual stress of the bolt. K E Y W O R D Saxial force, bolt, PPP-BOTDA technology, pullout test, shear stress 2012 |

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“…Fiber-optic sensing has advanced significantly in the past few years for strain determination in many areas of earth science and engineering [7][8][9][10][11][12][13][14] . Fiber-optic sensing technologies are normally categorized according to the measurand or the optical scattering mechanism whereby the measurement is made 15,16 .…”

Section: Introductionmentioning

confidence: 99%

Microanchored fiber-optic DSS in boreholes allows strain profiling of the shallow subsurface

Zhang¹,

Shi²,

Zhang³

et al. 2022

Preprint

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Vertical deformation profiles of subterranean geological formations are conventionally measured by borehole extensometry. Distributed strain sensing (DSS) paired with fiber-optic cables installed in the ground opens up possibilities of acquiring high-resolution static and quasistatic strain profiles of deforming strata, but it is currently limited by reduced data quality due to complicated patterns of interaction between the buried cables and their surroundings, especially in upper soil layers under low confining pressures. Extending recent DSS studies, we present an improved approach for strain determination along entire lengths of vertical boreholes by using microanchored fiber-optic cables designed to optimize ground-to-cable coupling at the near surface. We proposed a novel criterion for soilcable coupling evaluation based on the geotechnical bearing capacity theory. We applied this enhanced methodology to monitor groundwater-related vertical motions in both laboratory and field experiments. Corroborating extensometer recordings, acquired simultaneously, validated fiber optically determined displacements, suggesting microanchored DSS as an improved means for detecting and monitoring shallow subsurface strain profiles.

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A kinematic method for calculating shear displacements of landslides using distributed fiber optic strain measurements

Cited by 65 publications

References 33 publications

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Deformation‐Based Monitoring of Water Migration in Rocks Using Distributed Fiber Optic Strain Sensing: A Laboratory Study

Monitoring and correction of the stress in an anchor bolt based on Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis

Microanchored fiber-optic DSS in boreholes allows strain profiling of the shallow subsurface

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