Risk Assessment of Deep Foundation Pit Construction Based on Analytic Hierarchy Process and Fuzzy Mathematics

Table 6

Risk list.

Risk type	Branch engineering	Risk unit	No.	Risk event
Construction risk	Main envelope structure	Diaphragm wall	1	Ground-to-wall invasion
			2	Equipment overturn
			3	Insufficient verticality
			4	Bulge
		Drilling piles	5	Equipment overturn
			6	Enclosing line
			7	Broken pile
	Foundation strengthening works	High-pressure rotary jet pile	8	Ground deformation caused by reinforcement
			9	The curtain is not closed
			10	Encounter obstacles
		Triaxial mixing pile	11	Ground deformation caused by reinforcement
			12	Encounter obstacles
	Precipitation engineering	Foundation pit precipitation	13	Water grade does not meet 1 m below the excavation surface
			14	Causes excessive deformation of the surrounding surface
			15	A water source channel is formed inside and outside the pit, unable to precipitate
	Earth excavation	Support frame removal	16	The support end face does not fit the continuous wall
			17	Support active head is too long
			18	Steel rafters are not tightly installed
			19	Prestress is not applied in a timely manner
			20	Too much or too little prestress is applied
			21	Prestress loss is not added in time
			22	Insufficient steel support reserves
		Excavation	23	Excessive displacement of envelope structure
			24	Pit bottom uplift
			25	Unsupported exposure time is too long
			26	Excavator crash support or support fall
			27	Excavation in layers and blocks without time-space effect, insufficient sloping
			28	Timely construction of cushion and floor
			29	Longitudinal soil instability
	Structural engineering	Construction	30	Waterproof layer failure
			31	Irregular scaffolding
			32	Scaffolding centralized loading
			33	Insufficient formwork reinforcement
			34	Concrete pouring discontinuity
			35	Concrete curing is not timely