Dynamic Risk Analysis in Metro Construction Using Statistical Process Control

Table 2

Risk loss classification and the corresponding settlement control range.

Risk loss classification		Control threshold
Grade	Description
Insignificant	Tiny settlement for roadbed,tiny effect for a moving train	−2 mm∼2 mm
Considerable	More slight settlement for roadbed, decrease of comfort for a moving train	−5 mm∼5 mm
Serious	Slight settlement for roadbed, less decrease of safety for a moving train	−8 mm∼8 mm
Severe	Obvious settlement for roadbed, decrease of safety for a moving train	−10 mm∼10 mm
Disastrous	More obvious settlement for roadbed, failure of safety for a moving train	−15 mm∼15 mm