It is difficult to monitor the distributed deformation of overlying stratum during the construction of a shallow tunnel.To address this problem

the distributed optical fiber sensing technology was proposed based on pulse-prepump Brillouin optical time domain analysis（PPPBOTDA）.This technology was applied to a tunnelling project

where a shallow tunnel traverses a highway and a steel workshop located in Yunnan Province.The layout of the monitored pipe equipped with distributed optical fibers was introduced.The monitoring results show that the strain and stress distribution the optical fiber in the overlying stratum are dominated by the properties of rock and soil

the advancement of the tunnel face

the supporting effect of initial lining and the hydrogeological condition.The optical fiber in front of and behind the tunnel face is subjected to tension and compression

respectively.The location of the tunnel face corresponds approximately to the transition zone between the compression and tension zones.Combining with the results obtained by levelling instrument

the feasibility of the distributed optical fiber sensing technology was investigated.The results obtained from these two methods exhibit the same subsidence trend

which demonstrates its feasibility.The distributed optical fiber sensing technology can capture the spatiotemporal evolution of the overburden deformation

and therefore has conspicuous advantages over point-wise monitoring methods.