## 1 Introduction  
With the advent of modern urban subway engineering, the shield tunnel construction technique has also entered a period of rapid development. At the same time, an increasing number of issues in shield tunnel construction have emerged, the most essential of which is the safety problems caused by shield construction to stratum disturbance. Research showedthat shield construction disturbance not only affects the surface road and surrounding buildings (structures) but also affects and even damages various structures below the ground, as well as the internal lining structure of the tunnel deformation and others [1; 2; 3; 4; 5]. Many construction processes with different degrees of surface subsidence, building inclination, underground pipeline damage, and others have occurred, severely compromising the safety of subway construction and inflicting enormous economic losses [6; 7; 8; 9; 10]. In recent years, using theoretical analysis [11; 12; 13], model tests [14; 15; 16; 17; 18], field tests, and other methods [19; 20; 21], scholars have conducted extensive research on ground deformation caused by shield disturbance and have obtained some valuable results [22]. For a single soft soil layer, the prediction of surface subsidence during tunnel excavation was carried out [23]. A prediction was made on the deformation amplitude of stratum disturbance during the excavation of a shallow tunnel after considering various influencing factors, based on this research, a theoretical test on the settlement law caused by the tunnel was performed, and the tunnel settlement gap parameters were calculated based on the settlement caused by tunneling in a specific case [24]. The model test utilizes the downscaling structure and centrifuge facilities, the deformation and stress characteristics of the tunnel under various overburden depths were analyzed by applying the acceleration required by the research institute [25; 26; 27; 28]. Field tests can be achieved on a real-time collection of sensor data to reflect the physical-mechanical behavior of the tunnel's composite strata during shield construction [29; 30; 31; 32; 33]. Through the analysis of the monitoring data, the potential hazards caused by the settlement of the overlying stratum of the tunnel can be evaluated. The monitoring data can also be employed to predict the stratum deformation of the pipe section at various tunnel positions. With the growth of optical fiber sensing technology, weak optical fiber sensing technology has accelerated. Compared to traditional monitoring methods such as single-point or multi-point displacement meters, It has the advantages of relatively small disturbance, temperature compensation function and remote monitoring [34; 35; 36]. The advantages of small size, lightweight, high sensitivity, and high precision have been widely used in practical projects, including mines, bridges, foundation pit and other practical engineering, and can achieve quasi-distributed and distributed measurements [37; 38; 39]. Large-scale engineering problems can be calculated with great efficiency and high accuracy using numerical simulation. In conjunction with a more field-appropriate monitoring method is proposed to improve the accuracy and reliability of analytical results [40; 41; 42; 43; 44; 45; 46; 47; 48]. In this paper, the shield project of \"Keyuan Station-Shenzhen University Station\" section of Shenzhen Metro Line 13 is taken as the engineering background, based on the weak reflectivity fiber grating sensing technology, the field test of layered settlement of composite stratum is carried out. Through the comparison and verification of three-dimensional numerical simulation and weak reflectivity fiber grating field monitoring, the law and distribution characteristics of disturbance settlement of ground surface and overlying strata during shield tunneling are systematically analyzed, and the vertical and horizontal zoning (layer) system of layered settlement of composite stratum with time and space evolution of shield tunneling is constructed.