STUDY ON EXCAVATION AND MEASUREMENT OF FOUNDATION PIT SUPPORT WITH LOW CLEARANCE OF 5M
Taking the foundation pit of a subway station of the urban rail transit in Suzhou as an example,the construction process was described for the foundation pit enclosure with bored piles+MJS piles with the low clearance of 5m and the zone-based foundation pit excavation with low clearance.Through measurement,the law of enclosure deformation,pier and abutment settlement of adjacent viaducts,changes in surface settlement,changes in supporting axial force and changes in water level were analyzed.Results have shown that when the foundation pit under the cover was excavated from top to bottom,the maximum lateral displacement of bored piles increased,and the site where the maximum lateral displacement occurred at 1.1 times the excavation depth.As the foundation pit was excavated far and far from the bridge pier and abutment,the vertical displacement of the pier and abutment decreased gradually,while the surface settlement on the back side of the foundation pit increased greatly.Obviously,the surface settlement outside the foundation pit was effectively isolated by shelter piles around bridge piles,and the supporting axial force changed instantly with the pit excavation depth increasing.Furthermore,the groundwater level in the northeast corner of the foundation pit was always below the warning level,but without obvious leakage.This study has proven that the construction scheme involving underground diaphragm walls,bored piles and MJS waterproof curtains was reasonable for foundation pits with low clearance of 5 m.
5 m clearancefoundation pit excavationsettlementchange in water level
NETL
NSTL
万方数据
