SETTLEMENT OBSERVATION OF THE 2ND MAINLAND BRIDGE. LAGOS, NIGERIA

The layout is described, and the method and results of observation are detailed in this investigation of the rate of settlement of the foundation of a bridge along a main carriageway in Nigeria. Five periods of observation (1968-1970) are reported and details of the levelling operation are described. Precautionary measures to eliminate errors (at change points and those due to atmospheric refraction) were taken. Difficulties experienced in lagoon levelling were resolved by development of a special method. The permanent bench marks at each end of the lagoon were transfered to alternate piers in the lagoon for each set of levelling operation, so establishing Temporary Bench Mark on individual piers. This ensured the achievement of similar fore-sight and back-sight lengths as well as allowed for 2 or more readings to be taken on most of the points. Other difficulties (caused by the effect of wind vibration, etc.) were also overcome. The computed levels for each of the brass points are tabulated. For a rational comparison, the average of the brass points reading for both east and west carriage wings were obtained and used to get the longitudinal profiles of the settlement pattern along the carriageway. The observations indicate that about 85 percent of the total settlement occurred just after live load and full load were imposed on the foundation. In generalized terms there has been uniform total settlement throught with no appreciable "differential" settlement. The maximum total settlement was approximately 1.5 in., and the maximum differential between east and west carriageway was about 0.5 inch. Recommendations are made on the basis of the observations.

• Corporate Authors:

  Federal Ministry of Works and Housing, Nigeria

  Materials and Research Division, 15 Awolowo Road
  Lagos 12635,   Nigeria 
• Authors:
  • Obembe, J E
• Publication Date: 1972-9

Media Info

• Features: Figures; Tables;
• Pagination: 50 p.

Subject/Index Terms

• TRT Terms: Benchmarks; Bridge foundations; Foundations; Indicators (Instruments); Lagoons; Loads; Recommendations
• Old TRIS Terms: Foundation investigations; Level indicators; Settlement rate
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Research;

Filing Info

• Accession Number: 00081624
• Record Type: Publication
• Report/Paper Numbers: No. 3 Res. Note
• Files: TRIS
• Created Date: Apr 8 1975 12:00AM