Fiber optic sensor network for subsurface impact protection system
A subsurface impact protection system for protecting an underground asset is provided. The protection system includes a subsurface polymer layer provided above the asset to prevent impact forces from reaching the asset. A sensor network is embedded in the polymer layer. The sensor network comprises optical fibers each including one or more fiber optic sensors. The optical fibers receive an input signal from a source and transmit it through the fiber. At the output end of the fiber is an optical detector that measures light properties of the output optical signal indicative of environmental conditions near the polymer layer. The sensor network transmits a signal including measured light or environmental parameters to a monitoring computing system. In some embodiments, the polymer layer includes a protective mesh made up of a plurality of high density polyethylene strands in a woven pattern. A method of protecting an underground asset is also provided.
1. A subsurface impact protection system for protecting an underground asset, the protection system comprising:
an elongate planar subsurface polymer layer buried above the underground asset, wherein the polymer layer comprises a protective mesh including a plurality of polymer strands in a woven pattern configured to absorb above-ground impact force from reaching the underground asset, wherein the polymer layer has a width that extends substantially a width of the underground asset and a thickness between a top surface of the planar polymer layer and a bottom surface of the planar polymer layer, and wherein the polymer layer is a separate structure from the underground asset, wherein the underground asset is one or more of a fluid pipeline and a fluid storage vessel; and
a sensor network comprising:
one or more optical sources,
one or more optical detectors,
optical fibers embedded within the thickness of the polymer layer, wherein the optical fibers are one or more of woven into the protective mesh and embedded within respective polymer strands of the protective mesh, each optical fiber among the optical fibers comprising:
an input end coupled to an optical source among the one or more optical sources, wherein the optical source is configured to provide an optical input signal to the input end,
an output end coupled to an optical detector among the one or more optical detectors, wherein the optical detector is configured to detect an output optical signal from the output end and measure a light property of the output optical signal, and
a fiber-optic sensor provided between the input end and the output end, wherein the fiber optic sensor is configured to modulate the light property of the output optical signal relative to the light property of the input optical signal as a function of a condition at the fiber optic sensor, and
wherein the optical detector is configured to generate a sensor signal based on the light property measured for the optical fiber and representing the condition at the fiber optic sensor.
2. The system of claim 1 , further comprising: a monitoring computing system in data communication with the one or more optical detectors, wherein the monitoring computing system is configured to receive the sensor signal from the optical detector, calculate a value of the condition at the fiber optic sensor based on the sensor signal, and output the value to an operator via one or more of: a visual display device, an audio output device and a communications interface.
3. The system of claim 2 , wherein the monitoring computing system is configured to compare the value to a prescribed specification and generate an alert if the value represents a condition that is out of specification.
4. The system of claim 1 , wherein the fiber-optic sensors comprise intrinsic fiber-optic sensors.
5. The system of claim 1 , wherein the fiber optic sensors comprise one or more of: a pressure sensor, a temperature sensor, a humidity sensor, a strain sensor, a rotation sensor, an acceleration sensor, a pH sensor and a corrosion sensor.
6. The system of claim 1 , wherein the sensor network further comprises a plurality of fiber optic data lines configured to transmit data along a length of the polymer layer.
7. The system of claim 1 , wherein the polymer layer comprises a high-density polyethylene (HDPE) mesh.
8. The system of claim 1 , wherein the optical fibers comprise data lines configured to transmit data along a length of the polymer layer.
9. A method of protecting an underground asset using a subsurface impact protection system, the method comprising:
providing a subsurface impact protection system below a surface of the ground and above the underground asset, wherein the subsurface impact protection system comprises:
an elongate planar subsurface polymer layer buried above the underground asset, wherein the polymer layer comprises a protective mesh including a plurality of polymer strands in a woven pattern configured to absorb above-ground impact force from reaching the underground asset, wherein the polymer layer has a width that extends substantially a width of the underground asset and a thickness between a top surface of the planar polymer layer and a bottom surface of the planar polymer layer, and wherein the polymer layer is a separate structure from the underground asset, wherein the underground asset is one or more of a fluid pipeline and a fluid storage vessel; and
a sensor network comprising:
one or more optical sources,
one or more optical detectors,
optical fibers embedded within the thickness of the polymer layer, wherein the optical fibers are one or more of woven into the protective mesh and embedded within respective polymer strands of the protective mesh, each optical fiber among the optical fibers comprising:
an input end coupled to an optical source among the one or more optical sources, wherein the optical source is configured to provide an optical input signal to the input end,
an output end coupled to an optical detector among the one or more optical detectors, wherein the optical detector is configured to detect an output optical signal from the output end and measure a light property of the output optical signal, and
a fiber-optic sensor provided between the input end and the output end, wherein the fiber optic sensor is configured to modulate the light property of the output optical signal relative to the light property of the input optical signal as a function of a condition at the fiber optic sensor, and
wherein the optical detector is configured to generate a sensor signal based on the light property measured for the optical fiber and representing the condition at the fiber optic sensor; and
monitoring the polymer layer using the sensor network, wherein the monitoring step comprises:
generating, using the one or more optical detectors monitoring the optical fibers sensors, a corresponding plurality of sensor signals of conditions respectively at the fiber optic sensors of the optical fibers; and
transmitting the generated sensor signals to one or more external monitoring computing systems.
10. The method of claim 9 , further comprising:
calculating with the one or more external monitoring system, values of the conditions respectively at the fiber optic sensors based on the plurality of sensor signals, and
outputting the values to an operator via one or more of: a visual display device, an audio output device and a communications interface.
11. The method of claim 10 , further comprising: comparing the values to corresponding specifications and generating an alert if any of the values represent a condition that is out of specification.
12. The method of claim 9 , wherein the fiber-optic sensors comprise intrinsic fiber-optic sensors.
13. The method of claim 9 , wherein the fiber optic sensors comprise one or more of: a pressure sensor, a temperature sensor, a humidity sensor, a strain sensor, a rotation sensor, an acceleration sensor, a pH sensor and a corrosion sensor.
14. The method of claim 9 , wherein the polymer layer comprises a plurality of interwoven high-density polyethylene (HDPE) strands.
15. The method of claim 9 , and wherein the step of providing the subsurface impact protection system comprises:
embedding the sensor network within the polymer layer during manufacture of the polymer layer, and
delivering the polymer layer and embedded sensor network underground.
16. The method of claim 9 , wherein the polymer layer comprises a mesh including a plurality of interwoven high-density polyethylene (HDPE) strands, and wherein the step of providing the subsurface impact protection system comprises:
incrementally unrolling the polymer mesh from a roll,
embedding the sensor network into the polymer mesh, and
delivering the unrolled polymer mesh and embedded sensor network underground.
17. The method of claim 16 , wherein the polymer mesh and the embedded sensor network is delivered underground using a trenchless delivery system.
18. The method of claim 16 , wherein embedding the sensor network into the polymer mesh includes weaving the optical fibers into the protective mesh.