Project Scope

The project consisted of improving and replacing the existing damaged pavement section, strengthening existing crane rails, replacing utilities and installing new pile supported crane tie downs, bollards and fenders.

Drilling and In Situ and Field Testing

Shallow (10-25 ft) and deep (80 -120 ft) SPT borings with undisturbed samples, Downhole Seismic Testing, Cone Penetration Tests (CPT), field CBR, test pits, concrete coring, pavement coring, PIT tests, PDA tests and plate loading tests.

Geotechnical Analysis and Design

Engineering analysis included pavement and subgrade condition assessments pavement section design, existing pile capacity analysis, new driven pile capacity and length design, soil structure interaction, bulkhead analysis, probabilistic seismic hazard analysis and liquefaction potential analysis

Geotechnical Laboratory Testing

Moisture contents, index testing, sieve analysis, soil classification tests, proctor densities, direct shears, CU triaxial with pore pressure measurement, concrete core compressive strength tests, Marshall tests.

Geophysical Investigations

Ground Penetrating Radar (GPR) was completed to detect existing utilities and the location of cofferdam cells and existing piles, among other substructures

Challenges

The project’s major challenges were stabilizing subgrade for new pavement section that needed to be designed for HS 20 traffic, reach stackers and occasional mobile cranes on a site have loose hydraulic fill deposits with shallow ground water. Also our team had the task of assessing existing damage to storm water and water distribution pipes infrastructure to recommend localized removal and replacement. Another challenge was determining existing piles capacity to value engineer a project concept by other teams neglecting contribution of existing piles and sheet pile cofferdam.

Engineering During Construction

Our firm provided during construction Quality Assurance (QA) testing and Quality Management services. A staff engineer conducted full time monitoring of construction conformance to plans and specifications, delivered daily reports to the owner, managed soil technicians and organized delivery or reports to owners representative. The team’s senior geotechnical engineers provided during construction support on assessments and recommendations to field conditions during construction requiring quick response to prevent affecting project schedule and budget.

Solutions

The use of combinations of methods of field testing, as described above, allowed development of different schemes of zone targeted ground improvements; which led to project cost savings and value engineering. The subgrade was stabilized by selective removal and replacement, subgrade densification and installation of biaxial geogrid on the areas that had substained more damage and where heavier traffic was expected. The use of geogrid involved plate load and CBR testing to confirm its effectiveness. The existing pile capacity was verified by various High Strain Dynamic Tests (PDA) on selected locations in which the crane rail beam had to be demolished and reconstructed.