News
Oct. 2007 - Nicholson’s Earth Retention Systems Support Van Andel Institute Expansion
Located in Grand Rapids, Michigan, The Van Andel Institute (VAI) is a premier biomedical research and educational facility. A 240,000-square-foot addition to the existing 162,000-square-foot building is currently under construction and scheduled to open in 2009. Nicholson installed the temporary and permanent earth retention systems that laid the groundwork for this important project.
The existing VAI structure was built on shallow foundations in a river valley. Since these foundations are on sand, there was concern about undermining the existing foundations during the addition’s construction. To minimize the risk of movement, pre-construction surveys were conducted, and after work commenced, a number of automated measurement tools were employed to immediately alert crews if movement was detected.
The CYCLOPS system, developed by Nicholson’s sister company Sol Data, was the key component of the monitoring effort. The system is a fully-automated surveillance system comprised of a motorized total station with computer-controlled video target acquisition. Nicholson temporarily fixed 50 individual prisms at various elevations along the sides of existing buildings and on the new support of excavation walls. The prisms were read automatically by CYCLOPS every 15 minutes - 24 hours a day, 7 days a week. The system detects movements as small as one millimeter and depending on the severity of the movement, the device will notify key personnel by email or cell phone.
Location and movement criteria dictated the earth retention systems chosen for the VAI addition. Temporary systems include simple cantilevered soldier piles and wood lagging, internally-braced soldier piles and wood lagging, post-tensioned anchored soldier pile and wood lagging, and continuous augercast piles with post-tensioned anchors. Jet grout underpinning with soil nails and shotcrete facing was used as a permanent earth retention system.
The three soldier pile-based techniques were used to construct approximately 16,000 square feet of the earth retention at locations where movement was less critical. Soldier piles are typically driven into the ground using pile driving equipment or vibratory hammers. Due to the sensitivity of existing structures, all piling on the VAI project was drilled to minimize vibration. Where cuts were greater than 15 feet, the soldier beam and lagging walls received post-tensioned anchors.
At locations adjacent to the existing historical Emmanuel Lutheran church, the deeper cuts featured an internally braced system where anchors could not be placed underneath the church property.
The addition’s construction sequence required the relocation of the existing VAI truck dock to a temporary location. This temporary location, just above a 3,650-square-foot section of the earth retention wall, imposed additional surcharge loads. In this area it was necessary to use a continuous augercast wall with post-tensioned anchors, a slightly more rigid system. Besides building the wall in this area, the same equipment was also used to construct deep foundations for the temporary dock by placing 50, 120-ton capacity augercast piles.
The site's most sensitive area is located directly under the VAI building’s existing foundations. In this area, a permanent 6,750-square-foot wall was designed using jet grout underpinning with soil nailing. In addition to the face stability issues that come with excavating sand next to the existing footings, there was also concern about sand seams within the till layer directly beneath the upper 15 feet of sand. Jet grouting was selected to provide both ground treatment at the sand seams within the till, and provide face stability and underpinning at the footing locations. The jet grouting process and withdrawal rate is fully automated by pre-programming the parameters into a computer in order to provide uniformly constructed columns.
After the jet grout underpinning columns were constructed and cured, the soil nailing excavation process began. The process involved three stages, repeated in 5-foot lifts. First, the area in front of the wall was excavated, exposing the jet grout columns. Next, soil nails were installed and grouted in place. To complete each lift, a reinforced shotcrete facing was installed.
This project showcased Nicholson’s versatile and innovative earth retention techniques. Nicholson designed and constructed economic excavation support solutions that addressed each location's unique movement criteria and geology.
Date: October 19, 2007
Contact: Brian O'Gara
Phone: 412-221-4500
Fax: 412-221-3127
Email: bogara@nicholsonconstruction.com