CN106906824B

CN106906824B - Distributed optical fiber prestress intelligent monitoring anchor cable

Info

Publication number: CN106906824B
Application number: CN201610203841.1A
Authority: CN
Inventors: 汪小刚; 王玉杰; 贾志欣; 林兴超; 赵宇飞; 曹俊杰; 孙平; 段庆伟; 刘立鹏; 曹瑞琅; 殷殷
Original assignee: China Institute of Water Resources and Hydropower Research
Current assignee: China Institute of Water Resources and Hydropower Research
Priority date: 2015-12-22
Filing date: 2016-04-01
Publication date: 2020-10-09
Anticipated expiration: 2036-04-01
Also published as: CN106906824A

Abstract

The invention provides a distributed optical fiber prestress intelligent monitoring anchor cable which comprises an anchor cable, a plurality of pier heads and a plurality of optical fiber sensors, wherein the anchor cable is fixedly connected with the pier heads; wherein, the pier head is sleeved on the whole length of the anchor cable body at certain intervals; an optical fiber sensor is fixed on each pier head. The design of the invention can monitor the stress of the whole length of the anchor cable, thereby deepening the understanding of the anchoring mechanism of the anchor cable. Meanwhile, the obtained result can be used for designing the anchor cable according to the design (namely, special treatment is adopted on the part with large stress).

Description

Distributed optical fiber prestress intelligent monitoring anchor cable

Technical Field

The invention belongs to the field of geotechnical engineering, mainly relates to an anchor cable pre-buried in the geotechnical engineering, and particularly relates to a distributed optical fiber prestress intelligent monitoring anchor cable for monitoring the prestress condition of the anchor cable in real time through an optical fiber sensor.

Background

In geotechnical engineering, people increasingly adopt an anchoring reinforcement mode for reinforcing unstable strata. Therefore, the safety factor of the stratum is effectively increased, and the safety of the engineering during construction and operation is ensured.

In 1918, when people anchor the west mine, the anchor cable is used for the first time. In the next over a hundred years of engineering practice, the anchor cable has been improved many times and the technology has become more mature.

Typically, an anchor cable is made up of a number of steel strands. Prestressing is generally required because of its force mechanism. Because it can bear large stress, it is usually applied in large tonnage anchoring engineering. With the continuous expansion of the field of human activities, the formation conditions to be treated in geotechnical engineering are more and more complex, and anchor cables are more and more applied.

Because the anchoring mechanism of the anchor cable is very complex and the factors influencing the anchoring effect are numerous, the research on the anchoring mechanism of the anchor cable is still in the exploration stage. The stress mechanism of the anchor cable is lack of long-term monitoring, and the requirement of engineering construction cannot be met far away.

Generally, the monitoring of the prestressed cable laying mainly comprises internal force monitoring, internal temperature monitoring, corrosion monitoring, wire breakage monitoring and the like, wherein the cable force monitoring is the most important aspect of monitoring during the operation of the prestressed anchor cable, and the cable force can directly reflect the operation state of the prestressed cable laying.

Common cable force measuring methods for safety monitoring engineering of the prestressed anchoring system comprise a pressure gauge measuring method, a resistance strain gauge monitoring method, a vibration frequency method, a force measuring ring measuring method, a magnetic flux method and the like. Wherein, the error of the measurement method of the pressure gauge is larger; the monitoring result of the resistance strain gage method is easily influenced by the external environment; the measurement results of the vibration frequency method are also not accurate enough; the force measuring ring measuring method is complicated to install and inconvenient to operate; the flux method has slow response and is not easy to obtain dynamic parameters. Therefore, a solution for accurately and effectively monitoring the overall length stress of the anchor cable does not exist.

Disclosure of Invention

In order to solve the above problems, the present invention provides a novel anchor cable capable of intelligently monitoring the stress condition of the entire length of the anchor cable. The anchor cable is provided with the plurality of optical fiber sensors, the stress condition of the whole length of the anchor cable can be monitored in real time through the optical fiber sensors, and the distribution height of the stress on the anchor cable is judged, so that the high-stress part can be independently designed.

In order to achieve the above object, the present invention adopts the following design method: a distributed optical fiber prestress intelligent monitoring anchor cable is characterized in that a plurality of pier heads are fixed on the anchor cable, and an optical fiber sensor is fixed on each pier head.

The pier heads are sleeved on the anchor cables at the same distance; the pier head can also be sleeved on the anchor cable at different distances.

The heading heads are dense around the rock-soil structural surface and at the joint of the free section and the anchoring section respectively.

The pier head is fixed on the anchor cable through a through hydraulic jack.

The distributed optical fiber prestress intelligent monitoring anchor cable further comprises a stress monitoring device, the signal output end of the optical fiber sensor is connected with the signal input end of the stress monitoring device, and the stress monitoring device is an optical fiber grating demodulator.

The invention has the beneficial effects that:

the invention provides a distributed optical fiber prestress intelligent monitoring anchor cable, which solves the problem that an optical fiber sensor cannot be adhered to the surface of an anchor cable by sleeving a pier head on the anchor cable and fixing the optical fiber sensor on the surface of the pier head; the pier heads are reasonably distributed on the whole length of the anchor cable, the pier heads transmit strain of the anchor cable to the sensor, and the stress monitoring device analyzes stress of the anchor cable, so that the stress condition of the whole length of the anchor cable is obtained.

Drawings

Fig. 1 is a schematic view of a distributed optical fiber prestress intelligent monitoring anchor cable structure provided by the invention.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

The invention discloses a distributed optical fiber prestress intelligent monitoring anchor cable, which is characterized in that a plurality of pier heads are fixed on a long anchor cable, optical fiber sensors are fixed on the pier heads, and the stress on different positions of the anchor cable is monitored through the plurality of optical fiber sensors distributed on the anchor cable; and receiving data monitored by the optical fiber sensors at different positions through a stress monitoring device such as an optical fiber grating demodulator, and analyzing the stress condition of the anchor cable.

Fig. 1 is a schematic structural diagram of a pier head and a sensor mounted on an anchor cable according to the present invention. As shown in the figure, the pier head 2 is fixed on the anchor cable 1 through a feed-through hydraulic jack, and the optical fiber sensor 3 is fixed on the anchor cable 2. When the anchor cable 1 is stressed and deformed, the stress deformation is transmitted to the optical fiber sensor 3 through the pier head 2, and the signal output end 31 of the optical fiber sensor 3 is connected with the signal input end of the stress monitoring device, so that the stress condition of the anchor cable can be reflected in real time.

The manufacturing process of the distributed optical fiber prestress intelligent monitoring anchor cable provided by the invention comprises the following steps:

1. the pier mounting head 2:

firstly, the pier heads 2 are sleeved on the anchor cables 1 by using the feed-through hydraulic jacks at certain intervals, which can be the same interval or different intervals. The distribution density of the upset heads is determined by actual conditions, and the number of the upset heads is increased around the geotechnical structural plane and at the joint of the free section and the anchoring section.

2. Fixing the optical fiber sensor 3:

the optical fiber sensor 3 is fixed to the abutment 2, and is attached to the abutment 2 by, for example, 502 glue.

3. Calibrating stress monitoring equipment:

during installation of the upset, the upset is extruded and plastically deformed. In order to eliminate plastic deformation and enable the result to be more accurate, the measured data of the optical fiber sensor and the actual stress condition of the anchor cable are compared and analyzed through an indoor test, and the influence of the plastic deformation of the upset head on the monitoring result is eliminated.

4. Burying anchor cables:

the anchor cable 1 is buried in the rock soil, and the signal output terminal 31 of the optical fiber sensor fixed to the anchor cable 1 is also exposed out of the rock soil.

After the anchor cable is buried, the signal output end 31 of the optical fiber sensor 3 is connected to a stress monitor for monitoring.

According to the embodiment, the strain of the anchor cable is obtained by using the upset head and the optical fiber sensor as the strain transmission device of the anchor cable, so that the stress value of the anchor cable in the whole length is obtained.

Claims

1. A distributed optical fiber prestress intelligent monitoring anchor cable is characterized in that a plurality of pier heads are fixedly sleeved on the anchor cable, and an optical fiber sensor is fixedly arranged on each pier head;

the pier head is fixed on the anchor cable through a feed-through hydraulic jack;

the stress monitoring device is connected with the signal input end of the stress monitoring device through the signal output end of the optical fiber sensor, and the stress monitoring device is an optical fiber grating demodulator;

the pier heads are sleeved on the anchor cables at the same or different distances;