Retaining Wall
Nicholson Construction Company 12 McClane Street Cuddy, PA 15031 Telephone: 412-221-4500 Facsimile: 412-221-3127
Diaphragm Walls by Thomas D. Richards, Jr. P.E. Nicholson Construction Company, Cuddy, Pennsylvania
Presented at: Central PA Geotechnical Conference Hershey, Pennsylvania March 23-25, 2006
05-01-145
Diaphragm Walls
Thomas D Richards, Jr P.E. Nicholson Construction Company Central PA Geotechnical Conference - March 23-25, 2005
INTRODUCTION The purpose of this paper is to describe the application, construction process, and design methods for diaphragm walls, since this topic has not been addressed much if at all at previous Hershey conferences. Diaphragm walls are a method of creating a cast in-situ reinforced concrete retaining wall using the slurry supported trench method. As such, they are often known as slurry walls. However, the term “diaphragm walls” Concrete diaphragm slurry walls were first introduced in the United States in the 1960s, and have found a niche in urban environments such as Boston, New York City, and Washington, DC. APPLICATIONS Diaphragm walls are most commonly used : • • • • • in areas with dense and historic urban infrastructure, where a very rigid earth retention system is required, where noise and vibration must be limited, where the geology and groundwater preclude the use of conventional earth retention systems and/or where dewatering is not practical
Compared to other wall types, diaphragm walls are considered to be very stiff with respect to ground movement control (Clough and O’Rourke, 1990). Diaphragm walls are often attractive in granular soils with a high groundwater level, especially when a low permeability layer underlies the granular soils. The diaphragm walls are typically terminated in the underlying low-permeability layer which can consist of soil or rock. Keying into this low permeability layer reduces groundwater seepage below the wall. (Pearlman, 2004) Projects that have used these walls include: • • • •
Diaphragm Walls by Thomas D. Richards, Jr. P.E. Nicholson Construction Company, Cuddy, Pennsylvania
Presented at: Central PA Geotechnical Conference Hershey, Pennsylvania March 23-25, 2006
05-01-145
Diaphragm Walls
Thomas D Richards, Jr P.E. Nicholson Construction Company Central PA Geotechnical Conference - March 23-25, 2005
INTRODUCTION The purpose of this paper is to describe the application, construction process, and design methods for diaphragm walls, since this topic has not been addressed much if at all at previous Hershey conferences. Diaphragm walls are a method of creating a cast in-situ reinforced concrete retaining wall using the slurry supported trench method. As such, they are often known as slurry walls. However, the term “diaphragm walls” Concrete diaphragm slurry walls were first introduced in the United States in the 1960s, and have found a niche in urban environments such as Boston, New York City, and Washington, DC. APPLICATIONS Diaphragm walls are most commonly used : • • • • • in areas with dense and historic urban infrastructure, where a very rigid earth retention system is required, where noise and vibration must be limited, where the geology and groundwater preclude the use of conventional earth retention systems and/or where dewatering is not practical
Compared to other wall types, diaphragm walls are considered to be very stiff with respect to ground movement control (Clough and O’Rourke, 1990). Diaphragm walls are often attractive in granular soils with a high groundwater level, especially when a low permeability layer underlies the granular soils. The diaphragm walls are typically terminated in the underlying low-permeability layer which can consist of soil or rock. Keying into this low permeability layer reduces groundwater seepage below the wall. (Pearlman, 2004) Projects that have used these walls include: • • • •
References: Bonita, G. (2005) "United States Capital Visitor Center ", Proceedings of 21st Central PA Geotechnical Conference - March 23-25, 2005 Clough, W.G. and O 'Rourke, T.D., 1990. "Construction induced movements of in-situ walls." Design and Performance of Earth Retaining Structures, ASCE GSP No.25, 439 - 470. PLAXIS, 1998. Finite Element Code for Soil and Rock Analyses. Brokgreve and Vermeer, et al., (ed.), Balkema. Rotterdam, Brookfield, Version 7, A.A. Pearlman, S.L., Boscardin, M.D., Walker, M.P. 2004. “Deep Underground Basements for Major Urban Building Construction,” Presented at Geo-Support 2004, Jan. 28-31, 2004, Orlando, FL. Terzaghi, K., Peck, R. B., and Mesri, G., 1996. Soil Mechanics in Engineering Practice, Third Edition, John Wiley & Sons, New York, NY, 349-360. WALLAP, 1997. Anchored and cantilevered retaining wall analysis program, D.L. Borin, MA, Ph.D., CEng., MICE. Geosolve, Users Manual, Version 4. Diaphragm Walls 21st Central PA Geotechnical Conference - March 23-25, 2005 Page 17 of 17