基于FBG的深海海床超孔压观测设备适用性研究

海床超孔压能够有效地反映海底动力地质过程,其原位观测对于地质灾害的预测与防治起到重要的作用。普通传感技术受限于精度、抗干扰能力、耐腐蚀性、稳定性等深海观测要求,往往无法用于深海原位长期观测,基于光纤布拉格光栅(FBG)压差式传感器研制的海床沉积物超孔压观测设备在海洋领域有极大的发展空间。笔者对FBG传感器的耐压性、耐腐蚀性进行为期3个月的测试,结果表明,20 MPa压力下的海水环境中,FBG传感器有着极高的稳定性,且涂覆光纤比裸露光纤稳定性更高;随后使用涂覆光纤研制了用于室内试验的超孔压观测设备,通过室内模拟试验得出,搭载着FBG压差式传感器的探杆整体性能良好,对超孔压表现出良好的监测能力和灵敏度;且利用压差原理对超孔压直接观测,减小了外界因素的影响。

Applicability of Equipment Based on FBG Sensors for Excess Pore Pressure Monitoring in Deep Seabed

The excess pore pressure of seabed can effectively reflects the dynamic geological process, which in situ observation plays an important role in prediction and prevention of geological disasters. The common sensors are limited to the precision, anti-interference ability, corrosion resistance, stability if used in situ, long-term deep-sea observation sensor. The observation equipment of seabed excess pore pressure has developed based on Fiber Bragg Grating (FBG) differential pressure sensor, which is useful for marine observation. Firstly, the tests of FBG corrosion resistance and pressure resistance last for 3 months. The results show that FBG data is stable under 20 MPa pressure in sea-water, and the coated FBG is more stable than the bared one. Then the probe used for observe excess pore pressure in lab is made by the using of coated FBG. The results show that the probe equipped with the FBG differential pressure sensor performs well in monitoring and sensitivity. It also can reduce the impact of external factors when observe excess pore pressure directly.