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Monitoring data is the important signal for safety situation decision of shield method construction. This paper analyzes the abnormal types appearing in safety monitoring data of shield method construction, and points out its caused by the environmental quantity anomaly, structure form change, misreading mistake, instrument error, and human negligence. Based on the test and analysis of the abnormal monitoring data, it considers the monitoring data as abnormal value if the monitoring data beyond the confidence interval. And then uses the theoretical model to eliminate the observation error and systematic error. Furthermore, this paper analyzes the reasons of abnormal of the shield method construction settlement monitoring data, displacement monitoring data, shaft force monitoring data, deep horizontal displacement monitoring data, the water level monitoring data according to theory above. Monitoring data is an important signal of determine the shield method construction safety situation, its accuracy directly affect the evaluation result [1]. The abnormal of the subsidence, horizontal displacement monitoring, deep horizontal displacement monitoring, axial force monitoring and water monitoring data are all attribute to narrow and complicated of the shield subway construction site. It should analyzed according to the data types and anomaly genesis as well as its surrounding environment change and construction progress, because the abnormal values are not all gross error or human error, so as to ensure the safety of shield construction method. Safety Monitoring Data Exception Type Abnormal environment quantity, morphology changes, misreading mistake, instrument error and human negligence are all reasons to cause abnormal monitoring data [2, 3]. Therefore, it requires a combination of construction environment and other factors on the systematic analysis of outliers. And eliminates the error, identifies human errors and so on, pays close attention to changes caused by the abnormal structure form. Usually, monitoring abnormal value of deep subsidence, horizontal displacement, axial force, horizontal displacement, water level monitoring project are divided into the following several. Abnormal Subsidence Monitoring Data Types (1)Subsidence data mutates while external environment exists no abnormalities; (2)Settlement data presents the phenomenon of when liters down while external environment exists no abnormalities; (3)Settlement deformation mutates while external environment exists abnormalities. Abnormal Displacement Monitoring Data Types (1) Displacement data mutates which show the monitoring stations appear larger displacement while external environment existing no abnormalities; (2) Displacement data presents the phenomenon of when liters down while external environment exists no abnormalities; (3) Shaft deformation amount mutates while external environment exists abnormalities. International Conference on Mechanics and Civil Engineering (ICMCE 2014) © 2014. The authors Published by Atlantis Press 685 Abnormal Axial Force Monitoring Data Types (1) Axis force data mutates which show the monitoring stations appear larger displacement while external environment exists no abnormalities; (2) Axis force data presents the phenomenon of when liters down while external environment exists no abnormalities; (3) Shaft deformation amount mutates while external environment exists abnormalities. Unusually deep horizontal displacement monitoring data types (1) Deep horizontal displacement data mutates which show the monitoring stations appear larger displacement while external environment exists no abnormalities; (2) Deep horizontal displacement data presents the phenomenon of when liters down while external environment exists no abnormalities; (3) Deformation of deep horizontal displacement mutates while external environment exists abnormalities. Abnormal Water Level Monitoring Data Types (1) Deep horizontal displacement data mutates while water monitoring data shows greater change when pit exists no abnormalities; (2) The amount of change in water level upheavals while pit existing no abnormalities. Monitoring Data of Abnormal Cause Analysis If the measurement data beyond the confidence interval, it thought to be outliers, and outliers should contact the surrounding environment and construction conditions further concrete analysis. Observation error and systematic error related theoretical model can be used to eliminate the error, to get accurate value. Subsidence Data Anomaly Genesis Analysis (1) External environment without exception, the monitoring data of mutation. First we should analyze deformation surrounding the construction environment change, Add and subtract inside the support in the foundation pit, precipitation is normal, Can analyze the work basis points or the stability of the monitoring points, if the work of subsidence sink or work basis points rate is faster than monitoring leads to monitoring the overall rise phenomenon, secondly, when Initial monitoring error is bigger may cause abnormal monitoring data next time; May also man-made destruction spot, or the instrument itself, if these conditions do not exist, we should set foot is not straight, human touch dynamic instrument factors such as looking for reason (2) The successive data curve wave fluctuates while external environment existing no abnormalities. First we should analyze the instrument, if the data changes gently, it may be affected by system error, atmospheric refraction, earth curvature, they prominent in summer commonly, observed in a timely manner to the instrument protection measures; Secondly, its monitoring with mulch not keep clear of in time, makes the monitoring data bigger than last time, it appears rise phenomenon, while mulch is cleared in later monitoring, lead monitoring data rising and down at time [4]. Again, its deformation is less than the measurement error, usually at the beginning of the observations and stand out late. In addition, But also from should stand feet is not straight, human touch instruments as factor analysis. (3) The SETTLEMENT exists abnormal values change while external environment exists abnormalities. If the work basis points and the monitoring stations in good: when rains outside and the previous period data is correct, monitoring data than the previous rise within 1~2 mm can think is right. Due to soil and water pressure, make the earth's surface. Artificial support strengthening, causing them to monitor data changes, such as steel support after excavation, the tunnel roof support, the springback amount within 1 mm can think right[5, 6]. Tunnel and foundation pit during unloading, monitoring will send smaller sink, generally within 2 mm. If the above several are not

Anomaly Analysis of Safety Monitoring Data of Shield Method Construction