Low coherence optical monitoring system and method for micron settlement of long-span foundation of high speed railway

The invention relates to a low coherence optical monitoring system and method for micron settlement of the long-span foundation of a high speed railway, and belongs to the technical field of photo-electro-mechanical integration measurement. A central liquid storage tank and a reference liquid storage tank are arranged on the foundation of a non-settlement area; a plurality of testing liquid storage tanks are arranged on the foundation of a settlement area; the upper half parts of the liquid storage tanks are filled with gas; the bottom ends of the liquid storage tanks are communicated with one another through a liquid connecting pipeline; the upper ends of the liquid storage tanks are communicated with one another through a gas connecting pipeline; the liquid connecting pipeline for communicating the liquid storage tanks is communicated with the gas connecting pipeline for communicating the liquid storage tanks through a vertical observation pipeline; low coherence optical sensors are mounted inside the testing liquid storage tanks. A signal transmission system converts the measured optical information into an electric signal to be input into a computer, and the settlement is displayed in real time. The low coherence optical monitoring system is stable in performance and is not influenced by severe environments such as a tunnel, and the low coherence optical monitoring method is a novel optical fiber settlement monitoring method suitable for existing structures and new structures.