Soil Work Finalized for Belleville Apartments

Preventing differential settlement is critical for new construction projects. See how CNC Foundations helped a client strength the soil for a multi-family building in Richmond, Virginia.

The Problem

CNC Foundations’ Team recently completed ground improvement to support a new six (6) story multi-family, mixed-use building in Richmond, Virginia. As with most urban area projects, this one had numerous challenges such as urban fill, overhead power lines, and an aged neighboring brick building with zero lot line issues. Not only did the new parking structure and building need an increased bearing capacity, the soil conditions noted in the Geotechnical Report would lead to long-term total and differential settlement issues without specialized foundation support.

Our Solution

CNC Foundations was engaged by the General Contractor to evaluate ground improvement options to densify and reinforce the loose sands and silts. Ultimately, Aggregate Piers, also called Vibratory Stone Columns or VSCs, were selected by CNC Foundations’ Engineering team as the most effective option to support this structure and to meet the Structural Engineer’s design criteria.

The Aggregate Piers/VSCs were designed to increase the bearing capacity as well as limit total and differential settlement.

The Results

Our design and installation allowed for an efficient project schedule and sequence because CNC Foundations utilized our direct-push bottom feed method of installation. As a result of using this method, limited spoils generation prevented excess material handling, and it allowed the client to improve their construction schedule as well as minimize extra site grading cost. CNC Foundations provided load tests and computerized pier installation logs to successfully closeout this project within 72 hours of our completion.

Quality Assurance and Control

CNC Foundations creates and implements a comprehensive Quality Assurance/ Quality Control process for every project.

The initial step in each project is validated by an outside, third-party design firm. This process guarantees an independent peer review to ensure that the design will meet the requirements for the project.

An Aggregate Pier design submittal produced for every project includes the calculated pier elastic modulus (pier stiffness) and the top of pier stresses for each footing type on the jobsite. CNC Foundations’ Engineering requires at least one full-scale load test on each and every project. This test is performed on a sacrificial aggregate pier installed at a location determined by the Aggregate Pier Engineer of Record.

CNC Foundations also maintains a computer data acquisition system on its Aggregate Pier equipment. This allows the rig operator to monitor the depth, time, and hydraulic pressure as well as visually verify the placement of the rock in real time as the Aggregate Pier is installed. Because of this, CNC Foundations’ operators provide full-time quality control for the installation of every Aggregate Pier.

Additionally, the data collected from the field (both installation logs and load testing) is submitted daily to CNC Foundations’ office. That data is reviewed by an engineer to assure compliance with the project specifications.

Not sure what geotechnical solution can work for your job? We can help.

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