Method for identifying local collapse edge of rock and soil body via distributed spiral parallel line sensor

Abstract

The invention discloses a method for identifying a local collapse edge of the rock and soil body via a distributed spiral parallel line sensor. A TDR measuring instrument samples reflection voltages before and after local collapse of the rock and soil body, sampling curves is obtained, and the sampling curve after deformation is subtracted from the sampling curve before deformation to obtain a difference curve; a first valley point from the starting end point of the distributed spiral parallel line sensor except a blind area is searched from the difference curve and is positioned in an inflection point where the gradient is changed from negative to positive, and the first valley point serves as the left edge of local collapse of the rock and soil body; and a first inflection point where the gradient is changed from positive to negative from the left edge to the tail end point is searched, and serves as the right edge of local collapse of the rock and soil body. The method can be used to find two edges of local collapse of the rock and soil body simply and clearly, the accuracy is high, and local deformation is located.

Description

technical field [0001] The invention belongs to the technical field of detection, and in particular relates to a method for identifying the local collapse edge of a rock and soil body with a distributed spiral parallel line sensor, which can be used for rock and soil body collapse monitoring. Background technique [0002] The monitoring methods of rock and soil collapse and deformation are mainly based on traditional leveling survey and GPS survey. Although the maturity and high precision of these two methods are unquestionable, they are both "point" measurement techniques with low measurement density and poor spatial continuity, making it difficult to solve the problem of "the location of the measurement is not collapsed, and the location of the collapse is not measured". Distributed measurement methods include TDR technology based on coaxial cable and sensing technology based on optical fiber (such as BOTDR, BOTDA, OTDR), but these two measurement methods also have their o...

AI Technical Summary

Problems solved by technology

Although the maturity and high precision of these two methods are unquestionable, they are both "point" measurement techniques with low measurement density and poor spatial continuity, making it difficult to solve the problem of "the location of the measurement is not collapsed, and the location of the collapse is not measured". Distributed measurement methods include TDR technology based on coaxial cable and sensing technology based on optical fiber (such as BOTDR, BOTDA, OTDR), but these two measurement methods also have their own shortcomings

Among them, the coaxial cable distributed measurement technology is currently mainly used in the research of underground displacement distribution measurement of slopes, but it has excellent distributed deformation measurement characteristics and also has shortcomings: First, the coaxial cable is limited by the structure of its central electrical copper wire , its deformation is very limited compared to the deformation in geological hazard measurement; secondly, the deformation of the coaxial cable is limited to the shear deformation of the cable cross-section, and cannot be used for the distribution of deformations such as surface tension, collapse or bulge measurement

Among them, the reliability and stability of optical fiber-based sensing technology plays an important role in the field of construction engineering detection, but it also has an Achilles' heel: the deformation of the optical fiber is very limited, and a larger local deformation similar to ground subsidence will cause the optical fiber A break will disable the entire measurement system

[0003] The invention patent (CN201010566591.0) discloses the spiral parallel cable and its principle for distributed deformation measurement, and the invention patent (CN201110361043.9) discloses the distributed sensing measurement cable for rock and soil deformation with a parallel spiral transmission line structure and its measurement method , but none of them clearly pointed out the collapse edge identification method for local collapse of rock and soil mass

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