Tunnel surrounding rock radial stress strain distributed monitoring technology

Abstract

The invention belongs to the technical field of geotechnical engineering monitoring, and relates to a distributed optical fiber sensing technology-based tunnel surrounding rock radial stress strain distributed monitoring technology. A distributed optical fiber sensor is conveyed to a hole bottom of a radial monitoring hole through a supporting rod member; the supporting rod member (1) and a grouting exhaust pipe (13) are plugged in the hole at a hole orifice through a hole orifice fixing system; a grouting hole (4) is connected to a grouting machine through a grouting pipe; a gap between the optical fiber sensor and a surrounding rock is filled by injecting grout which is matched with modulus of deformation of the surrounding rock into the hole, so that the optical fiber sensor and the surrounding rock cooperatively deform; the optical fiber sensor comprises a distributed optical fiber strain optical fiber sensor and a temperature optical fiber sensor; the distributed optical fiber sensor of each monitoring hole is connected in series to an optical fiber strain analyzer Brillouin optical time domain reflectormeter (BOTDR) by fusion welding; measurement and positioning functions ofBrillouin frequency shift on each point of an optical fiber are finished by measuring power of received Brillouin backscattered light; and strain distribution and temperature distribution in the radial direction in the surrounding rock can be obtained to evaluate and forecast the stability of the surrounding rock according to the linear relation between the Brillouin frequency shift and the strain as well as the temperature.

Description

technical field [0001] The invention belongs to the technical field of geotechnical engineering monitoring, and relates to a distributed monitoring technology for radial deformation of tunnel surrounding rock based on distributed optical fiber sensing technology. Background technique [0002] Our country is currently in a period of large-scale construction, and a large number of tunnel projects have appeared in various fields such as transportation, national defense, and water conservancy. During the construction and use of the tunnel, the stress and strain of the surrounding rock will change, and it is an extremely important task to ensure the stability and safety of the surrounding rock. Radial stress and strain monitoring of tunnel surrounding rock is the main means and basis for determining the influence range of tunnel surrounding rock loosening circle, judging the stability of surrounding rock, grasping the development and change law of stress and strain of surrounding...

AI Technical Summary

Problems solved by technology

These monitoring methods can only monitor some information on the surrounding rock interface but cannot understand the stress and strain inside the entire surrounding rock; conventional sensors are mostly point sensors, which are required when the monitoring area is large and the spatial density of monitoring points is high. The deployment of a large number of sensors will inevitably lead to a sharp increase in the complexity and cost of the monitoring work, and the lack of connection between the monitoring data cannot reflect the overall deformation law of the surrounding rock

In addition, due to the interference of corrosion and lightning, the service life and stability of conventional electrical sensing elements are difficult to meet the requirements of long-term monitoring

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