CN106906824B - Distributed optical fiber prestress intelligent monitoring anchor cable - Google Patents

Abstract

The invention provides a distributed optical fiber prestressed intelligent monitoring anchor cable, which includes an anchor cable, a plurality of pier heads, and a plurality of optical fiber sensors; wherein, the pier heads are sleeved at a certain distance on the whole length of the anchor cable body; An optical fiber sensor is fixed on the pier head. The design of the invention can monitor the stress of the entire length of the anchor cable, thereby deepening the understanding of the anchoring mechanism of the anchor cable. At the same time, the obtained results can be used for the design of anchor cables (that is, special treatment is adopted for the parts that are subjected to large forces).

Description

Distributed optical fiber prestressed intelligent monitoring anchor cable

technical field

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

Background technique

In geotechnical engineering, in order to strengthen unstable strata, more and more people use anchoring reinforcement methods. This effectively increases the safety factor of the formation and ensures the safety of the project during construction and operation.

In 1918, the anchor cable was used for the first time when anchoring the Silixi mine. In the subsequent nearly one hundred years of engineering practice, the anchor cable has been improved many times, and the technology has become more and more mature.

In general, the anchor cable consists of several steel strands. Because of its force mechanism, it is generally necessary to add prestress. Because it can withstand greater stress, it is usually used in large-tonnage anchoring projects. With the continuous expansion of the field of human activities, the ground conditions to be dealt with in geotechnical engineering are more and more complex, and the application of anchor cables is increasing.

Because the anchoring mechanism of the anchor cable is very complex, and there are many factors affecting the anchoring effect, the research on the anchoring mechanism of the anchor cable is still in the exploratory stage. However, the stress mechanism of the anchor cable lacks long-term monitoring, which is far from meeting the needs of engineering construction.

In general, the monitoring of prestressed cables mainly includes internal force monitoring, internal temperature monitoring, corrosion monitoring and wire break monitoring, etc. Among them, cable force monitoring is the most important aspect of monitoring during the operation of prestressed anchor cables, and the cable force can directly reflect The operating state of the prestressed cable.

Cable force measurement methods commonly used in safety monitoring engineering of prestressed anchorage systems include pressure gauge measurement method, resistance strain gauge monitoring method, vibration frequency method, force loop measurement method, magnetic flux method, etc. Among them, the pressure gauge measurement method has a large error; the monitoring results of the resistance strain gauge method are easily affected by the external environment; the measurement results of the vibration frequency method are also inaccurate; the force ring measurement method is cumbersome to install and inconvenient to operate; the magnetic flux method has a slow response. , it is not easy to obtain dynamic parameters. Therefore, there is no solution that can accurately and effectively monitor the full-length stress of the anchor cable.

SUMMARY OF THE INVENTION

In order to solve the above problems, the purpose of the present invention is to provide a new type of anchor cable that can intelligently monitor the stress of the entire length of the anchor cable. There are several optical fiber sensors distributed on the anchor cable. Through these optical fiber sensors, the stress situation of the entire length of the anchor cable can be monitored in real time, and the distribution of the stress on the anchor cable can be judged, so that the high stress part can be individually designed.

In order to achieve the above purpose, the present invention adopts the following design method: a distributed optical fiber prestressed intelligent monitoring anchor cable, several 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 heads can also be sleeved on the anchor cables at different distances.

The upsetting heads are denser around the geotechnical structure surface and at the junction of the free section and the anchoring section.

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

The distributed optical fiber prestressed intelligent monitoring anchor cable further includes a stress monitoring device, the signal output end of the optical fiber sensor is connected to the signal input end of the stress monitoring device, and the stress monitoring device is a fiber grating demodulator.

The beneficial effects of the present invention are:

The invention provides a distributed optical fiber prestressed intelligent monitoring anchor cable. The pier head is sleeved on the anchor cable, and the optical fiber sensor is fixed on the surface of the pier head, so as to solve the problem that the optical fiber sensor cannot be pasted on the surface of the anchor cable; On the whole length of the anchor cable, the pier head transmits the strain of the anchor cable to the sensor, and the stress monitoring device analyzes the stress of the anchor cable, so as to obtain the stress condition of the whole length of the anchor cable.

Description of drawings

FIG. 1 is a schematic structural diagram of the distributed optical fiber prestressed intelligent monitoring anchor cable provided by the present invention.

Detailed ways

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

The distributed optical fiber prestressed intelligent monitoring anchor cable disclosed by the invention is that several pier heads are fixed on the long anchor cable, and optical fiber sensors are fixed on the pier heads, and the anchor cable is monitored by several optical fiber sensors distributed on the anchor cable. The stress of the cable at different positions is analyzed; the stress monitoring device such as a fiber grating demodulator is used to receive the monitoring data of the fiber optic sensors at different positions, and the stress of the anchor cable is analyzed.

FIG. 1 is a schematic structural diagram of a pier head and a sensor installed on an anchor cable provided by the present invention. As shown in the figure, the pier head 2 is fixed on the anchor cable 1 by the through-core hydraulic jack, and the optical fiber sensor 3 is fixed on the anchor cable 2. When the anchor cable 1 is deformed by force, the force deformation is transmitted to the fiber optic sensor 3 through the pier head 2, and the signal output end 31 of the fiber optic sensor 3 is connected with the signal input end of the stress monitoring device, so that the stress at the anchor cable can be connected. The force situation is reflected in real time.

The manufacturing process of the distributed optical fiber prestressed intelligent monitoring anchor cable provided by the present invention is as follows:

1. Install the pier head 2:

First, use the through-center hydraulic jack at a certain distance, which can be the same distance or different distances, and set the pier head 2 on the anchor cable 1. The distribution density of upsetting heads is determined by the actual situation, and the number of upsetting heads should be increased around the geotechnical structural plane and at the junction of the free section and the anchoring section.

2. Fix the fiber optic sensor 3:

Fix on the head 2, for example, use 502 glue to stick the optical fiber sensor 3 on the head 2.

3. Calibration of stress monitoring equipment:

During the installation process of the upsetting head, the upsetting head is squeezed, resulting in plastic deformation. In order to eliminate the plastic deformation and make the results more accurate, through the laboratory test, the measured data of the optical fiber sensor and the actual stress of the anchor cable are compared and analyzed to eliminate the influence of the plastic deformation of the heading on the monitoring results.

4. Buried anchor cable:

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

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

It can be seen from the above embodiments that the distributed optical fiber prestressed intelligent monitoring anchor cable provided by the present invention obtains the strain of the anchor cable by using the heading head and the optical fiber sensor as the strain transmission device of the anchor cable, and then obtains the entire length of the anchor cable. the stress value.

Claims (1)

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;

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

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