Application Of Fiber Bragg Grating Sensor In The Monitoring Of Soil Foundation

In recent years, the transportation enterprise of our country has obtained a huge development. With the large-scale construction of highway, the problem of soft soil foundation’s treatment is becoming more and more important. Although the method of making soft soil foundation solid becomes increasingly perfect, it can make the soft soil foundation settled to be strong enough. But its late stability is also an important problem. If the soft soil foundation could not be improper handled or its long-term stability is not enough, it will cause the harm of roadbed, such as slump, subsidence and cracking, thus affect the normal function of the road. It is necessary to find a method to monitor the stability and the working state of the soft soil foundation, then we can take corresponding measures to reinforce the soft soil foundation before it affect the normal use of the road.The fiber Bragg grating sensing technology has gained continuous development and has been applied to practical engineering these years. This provide a new method for the real-time dynamic monitoring of the soft soil foundation. The fiber Bragg grating sensor combined with practical engineering, not only can monitor the working state of the roadbed, provide the alarm information, also can provide valuable experimental data for mechanical analysis.Using geogrid which is commonly used in the treatment of the soil foundation as the packaging materials of the fiber Bragg grating. The sensor which using the improved the encapsulation methods are made for the requirements of monitoring on the soft soil foundation. Demarcate the sensor through the indoor calibration test. The test shows that the sensitivity coefficient of the sensor is very close to the sensitivity coefficient of the bare fiber. This indicates that the sensor can meet the needs of the road monitoring. Buried these sensors in the experiment road in Angola, then test the strains of the road under moving load at the end of the pavement construction, collect the data of strains, then dispose the data and analyze it.Simulating the process of the load application by using the finite element software ABAQUS. Build corresponding pavement mechanics analysis model based on the actual pavement structure. Then comparing the results of simulation analysis with the road test data to verify the reliability of the collected data using the sensor. The results of the test and software simulation show that this encapsulation method not only can protect the fiber Bragg grating efficiently, can also ensure the reliability of the measured data. It can meet the needs of soil monitoring, and provide a new method for monitoring the soil foundation.