A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Micropiles in Karst: Interstate 70, Frederick County, MD
The cutter and pinnacle features of karst present foundation challenges as encountered by the interchange and frontage road improvement project along Interstate 70 (I-70), Frederick County, Maryland. The project area traverses a karst area with an aggressive sinkhole occurrence rate of approximately eight new sinkholes per year, with 147 known sinkholes documented by 2003. Two pump stations lift and remove storm water from geosynthetic lined storm water ponds. The deep foundation system for these pump stations required penetrating 34 m (110 ft) or more of soil and epikarst to bear in competent material. Micropiles are well suited for the anticipated subsurface conditions since installation techniques enable a production pile to also serve as a verification hole of the bond length. Proper application of pile termination criteria ensure an acceptable foundation element and will aid in minimizing grout loss. A total of 61 micropiles were installed for the two pump stations. The 180 mm (7 in) O.D. micropiles were bonded into limestone rock to provide an axial resistance ranging from 355 to 445 kN (80 to 100 kips). Pile depths varied from 8 to 49 m (25 to 161.5 ft), indicating the highly variable subsurface rock contours. Three load tests were performed, with one micropile exhibiting a plunging-type failure when it was bonded in and subsequently sheared a pinnacle.
Micropiles in Karst: Interstate 70, Frederick County, MD
The cutter and pinnacle features of karst present foundation challenges as encountered by the interchange and frontage road improvement project along Interstate 70 (I-70), Frederick County, Maryland. The project area traverses a karst area with an aggressive sinkhole occurrence rate of approximately eight new sinkholes per year, with 147 known sinkholes documented by 2003. Two pump stations lift and remove storm water from geosynthetic lined storm water ponds. The deep foundation system for these pump stations required penetrating 34 m (110 ft) or more of soil and epikarst to bear in competent material. Micropiles are well suited for the anticipated subsurface conditions since installation techniques enable a production pile to also serve as a verification hole of the bond length. Proper application of pile termination criteria ensure an acceptable foundation element and will aid in minimizing grout loss. A total of 61 micropiles were installed for the two pump stations. The 180 mm (7 in) O.D. micropiles were bonded into limestone rock to provide an axial resistance ranging from 355 to 445 kN (80 to 100 kips). Pile depths varied from 8 to 49 m (25 to 161.5 ft), indicating the highly variable subsurface rock contours. Three load tests were performed, with one micropile exhibiting a plunging-type failure when it was bonded in and subsequently sheared a pinnacle.
Micropiles in Karst: Interstate 70, Frederick County, MD
Kutschke, Walter G. (author)
Geo-Denver 2007 ; 2007 ; Denver, Colorado, United States
2007-10-14
Conference paper
Electronic Resource
English
Piles , Drilled shafts , Karst , Micro piles , Deep foundations , Maryland
Micropiles in Karst: Interstate 70, Frederick County, MD
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