CN103114561A - Method of embedding fiber optic sensor (FOS) inside clay core wall - Google Patents

Abstract

The invention discloses a method for embedding an optical fiber sensor in a clay core wall. Firstly, according to the physical quantity to be monitored, select the optical fiber sensor, determine the position of the measuring point in the clay core wall and the laying path of the transmission line; then, arrange the optical fiber sensor, lay the bentonite composite waterproof blanket, and stick the sensing end of the optical fiber sensor to the outside of the waterproof blanket, and connect the transmission line placed in the bentonite of the waterproof blanket; finally, with the construction of the clay core wall of the earth-rock dam, fiber optic sensors are arranged in layers according to the position of the measuring points, and the waterproof blanket with the built-in transmission line is vertically laid in the middle of the clay core wall along the laying path until The clay core wall is constructed to the top to lead out the signal transmission lines. The present invention comprehensively applies the bentonite composite waterproof blanket and optical fiber sensor to the clay core wall of the earth-rock dam, which not only exerts the anti-seepage function of the waterproof blanket but also plays the remote measurement function of the optical fiber sensor, and outputs signals through the transmission line to achieve real-time monitoring and information construction function and the effect of long-term monitoring after work.

Description

A method of embedding optical fiber sensor in clay core wall

technical field

The invention relates to a method for embedding a sensor in a dam, in particular to a method for embedding an optical fiber sensor in a clay core wall.

Background technique

Reservoir dams and river embankments mostly use clay core earth-rock dams, that is, earth-rock dams that use cohesive soil with a low permeability coefficient filled in the center of the dam body as anti-seepage equipment. This type of dam is anti-seepaged by a core wall or an inclined core wall, and the upstream and downstream dam shells support the core wall to keep the dam stable.

Reservoir dams and river embankment projects have the characteristics of large investment, long construction period, high quality standards, and great accident hazards. Therefore, the quality of filling soil and construction quality are very high in project construction. As a tool for obtaining quality indicators, monitoring instruments are particularly important in their selection and placement.

Optical fiber sensor is a new high-tech instrument, which has the advantages of strong adaptability, good durability, high precision and stable test, and has been applied in many engineering fields. Optical fiber sensors can not only monitor various data in the process of engineering construction, but also output signals through transmission lines, relying on optical fiber sensors can also realize real-time monitoring, information construction and long-term monitoring after construction.

Based on the above advantages of optical fiber sensors, optical fiber sensors have gradually been applied in reservoir dams and river embankment projects. Such as using different sensors to monitor stress, strain, temperature, displacement, pore water pressure, etc. In the prior art, Ren Liang, Zhang Ying and others proposed the use of FBG sensors in the dam core wall model test in the "Application of FBG Sensors in Clay Core Dam Model Test" (Optoelectronics·Laser, Volume 22, Issue 8, 2011). Fiber Bragg Grating (FBG) strain sensors are buried inside to monitor the change of tensile stress inside the dam under the action of earthquake in real time, so as to realize the method of monitoring the cracking inside the dam in advance. In this method, a thin-diameter tube is used to package the optical fiber sensor, and then the surface of the core wall where the sensor is to be placed is slotted, and the sensor is placed in the slot, and finally filled with clay and compacted.

Although the prior art discloses a method of embedding optical fiber sensors in the clay core wall to monitor various parameters of the dam, there is no follow-up research on the specific embedding process of the sensors and their signal transmission lines, let alone consideration of the seepage during construction. The possible impact of leakage on the placement of sensors and their signal transmission lines, as well as the prevention and control of leakage in later maintenance, have potential safety hazards. The thin-diameter tube encapsulates the optical fiber sensor, puts it in the groove on the surface of the core wall, and then fills it with clay and compacts it. This method of embedding the optical fiber sensor has the following disadvantages: (1) The thin-diameter tube is different from the clay in flexibility. During construction and post-construction deformation, it is difficult to deform synchronously, and gaps are likely to occur during the process, resulting in leakage; (2) Due to the lack of operating standards and control indicators in the clay filling and compaction process, it is difficult to reasonably control during construction, resulting in local pressure failure of the clay. Solid and leaky.

Contents of the invention

The purpose of the present invention is to solve the technical problems in the prior art, to provide a method for embedding optical fiber sensors in the clay core wall, by utilizing the permanent waterproof performance and other outstanding advantages of bentonite composite waterproof blanket (GCL) to improve the performance of optical fiber sensors and The transmission line shall be buried reasonably to prevent leakage and eliminate potential safety hazards.

Specifically, the invention provides a method for embedding an optical fiber sensor in a clay core wall, the method comprising the following steps:

Step 1: According to the physical quantity to be monitored, select the corresponding optical fiber sensor, and determine the position of the measuring point in the clay core wall and the laying path of the signal transmission line;

Step 2: Arrange the optical fiber sensor at the determined measuring point position, and lay the bentonite composite waterproof blanket on the signal transmission line laying path, attach the sensing end of the optical fiber sensor to the outside of the bentonite composite waterproof blanket, and place the signal transmission line of the optical fiber sensor on the In the bentonite of bentonite composite waterproof blanket;

Step 3: Following the construction of the clay core wall of the earth-rock dam, arrange fiber optic sensors in layers according to the determined measuring point positions, and lay the bentonite composite waterproof blanket with built-in signal transmission line upright in the middle of the clay core wall along the laying path until the clay core wall The wall is constructed to the top to lead out the signal transmission line.

Further, the optical fiber sensor is: a pore water pressure optical fiber sensor, an earth pressure optical fiber sensor and a displacement optical fiber sensor.

Further, the bentonite composite waterproof blanket is a sodium bentonite waterproof blanket by needle punching method.

Further, the bentonite composite waterproof blanket is laid in a "zigzag" shape.

Further, after the signal transmission line is drawn out, it is externally connected to the signal receiver.

The inventive method has the following beneficial effects:

(1) The bentonite composite waterproof blanket has good anti-seepage performance, and is vertically laid in the middle of the clay core wall to strengthen the anti-seepage ability of the clay core wall;

(2) The optical fiber sensor signal transmission line is placed in bentonite, which does not affect the anti-seepage effect, meets the transmission requirements, and can also protect the signal transmission line;

(3) The signal transmission line of the optical fiber sensor is used to connect the telemetry equipment externally, which can realize informatization construction, real-time monitoring, and long-term monitoring after construction.

Description of drawings

Figure 1 is a schematic diagram of the structure of an optical fiber sensor embedded in a clay core wall.

Detailed ways

The invention makes full use of the permanent waterproof performance of the bentonite composite waterproof blanket, the construction is simple, not affected by the temperature, the waterproof material and the object are integrated, and the advantages of green environmental protection are combined with the optical fiber sensor which is light, high in sensitivity, and capable of sensing various physical quantities. The transmission line is buried in the clay core wall to prevent leakage, eliminate potential safety hazards, and serve to control and improve the construction quality of earth-rock dams.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Figure 1, where: 1 is an earth-rock dam; 2 is a clay core wall; 3 is a bentonite composite waterproof blanket; 4 is a signal transmission line; 5 is an optical fiber sensor.

Step 1: Select the corresponding optical fiber sensor 5 according to the physical quantity to be monitored, and determine the position of the measurement point inside the clay core wall 2 and the laying path of the signal transmission line 4 .

During the construction of the earth-rock dam 1, it is necessary to monitor the pore water pressure, earth pressure and displacement in the dam, and the corresponding selected optical fiber sensors 5 are: pore water pressure optical fiber sensor, earth pressure optical fiber sensor and displacement optical fiber sensor.

Step 2: Arrange the optical fiber sensor 5 at the determined measuring point position, lay the bentonite composite waterproof blanket 3 on the signal transmission line 4 laying path, and stick the sensing end of the optical fiber sensor 5 to the outside of the bentonite composite waterproof blanket 3; place the optical fiber sensor The signal transmission line 4 of 5 is placed in the bentonite of the bentonite composite waterproof blanket 3 .

Step 3: Follow the construction of the clay core wall 2 of the earth-rock dam 1, arrange the optical fiber sensors 5 in layers according to the determined measuring point positions, and lay the bentonite composite waterproof blanket 3 with the built-in signal transmission line 4 upright on the clay core wall along the laying path 2 in the middle, until the clay core wall 2 is constructed to the top, and the signal transmission line 4 is led out.

The bentonite composite waterproof blanket 3 adopts the acupuncture sodium-based bentonite waterproof blanket, and the signal transmission line 4 of the optical fiber sensor 5 is embedded in the bentonite of the acupuncture sodium-based bentonite waterproof blanket, and several waterproof blankets are arranged horizontally. The core wall 2 is laid vertically upwards. In order to adapt to the settlement and deformation of the earth-rock dam 1 during laying, the bentonite composite waterproof blanket 3 is laid in a "zigzag" shape, and the joint length at both ends is set to 0.5m.

After construction, the signal transmission line 4 is externally connected to the signal receiver. After calibration and inspection, real-time monitoring of the stress and strain change process of water and soil in the dam can be started, providing detailed monitoring information for project management and control.

The present invention comprehensively applies the bentonite composite waterproof blanket and optical fiber sensor to the clay core wall of the earth-rock dam, which not only exerts the anti-seepage function of the bentonite composite waterproof blanket, but also exerts the telemetry function of the optical fiber sensor, and uses the two technologies in a scientific and reasonable manner. In the construction and post-monitoring of earth-rock dams, while ensuring that the placement of optical fiber sensors does not affect the construction of earth-rock dams, the safety hazard of leakage is eliminated, and it has the following beneficial effects:

(1) The bentonite composite waterproof blanket has good anti-seepage performance, and is vertically laid in the middle of the clay core wall to strengthen the anti-seepage ability of the clay core wall;

(2) The optical fiber sensor signal transmission line is placed in bentonite, which does not affect the anti-seepage effect, meets the transmission requirements, and can also protect the signal transmission line;

(3) The signal transmission line of the optical fiber sensor is used to connect the telemetry equipment externally, which can realize informatization construction, real-time monitoring, and long-term monitoring after construction.

Claims (5)

1. the method for an embedded light fiber sensor in earth core, is characterized in that, comprises the following steps:

Step 1 according to physical quantity to be monitored, is selected corresponding Fibre Optical Sensor, and the interior point position of definite earth core and signal transmssion line wiring path;

Step 2, arrange Fibre Optical Sensor on the point position of determining, and lay bentonite composite waterproofing carpet on the signal transmssion line wiring path, the induction end of Fibre Optical Sensor is close to outside bentonite composite waterproofing carpet, the signal transmssion line of Fibre Optical Sensor is placed in the swell soil of bentonite composite waterproofing carpet;

Step 3, follow the construction of earth and rockfill dam earth core, according to the point position of determining, the layered arrangement Fibre Optical Sensor, and with the bentonite composite waterproofing carpet of built-in signal transmission line, in the middle part of uprightly being laid on earth core along wiring path, signal transmssion line is drawn at the top until earth core is constructed.

As claimed in claim 1 a kind of in earth core the method for embedded light fiber sensor, it is characterized in that, described Fibre Optical Sensor is: pore water pressure Fibre Optical Sensor, soil pressure Fibre Optical Sensor and fiber optic displacement sensor.

As claimed in claim 1 a kind of in earth core the method for embedded light fiber sensor, it is characterized in that, described bentonite composite waterproofing carpet is the needle point method sodium-based bentonite waterproof carpet.

As described in claim 1 or 3 a kind of in earth core the method for embedded light fiber sensor, it is characterized in that, described bentonite composite waterproofing carpet adopts "the" shape to lay.

As claimed in claim 1 described a kind of in earth core the method for embedded light fiber sensor, it is characterized in that, be external to signal receiver after signal transmssion line is drawn.