Characterization of thick varved-clayey-silt deposits along the Delaware River by field and laboratory tests
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ORIGINAL ARTICLE
Characterization of thick varved-clayey-silt deposits along the Delaware River by field and laboratory tests Ye Lu • Yong Tan • Guoming Lin
Received: 2 October 2011 / Accepted: 17 September 2012 / Published online: 5 October 2012 Ó Springer-Verlag Berlin Heidelberg 2012
Abstract The existence of thick compressible varved clayey silt deposits along the Delaware River presents one major obstacle for design and construction of structures or industrial facilities in this region. To understand the characteristics of this thick weak soil layer and then develop reliable soil parameters for future earthwork design and construction, a comprehensive soil testing program was carried out. The program consisted of both in situ tests [e.g., standard penetration test borings, piezocone penetration test (CPT) soundings, Marchetti flat dilatometer test soundings, seismic shear wave test soundings, CPT pore pressure dissipation tests, and field vane shear tests] and laboratory tests (e.g., soil index tests, consolidation tests, triaxial tests, and chemical tests). Additionally, a field surcharge test program with and without installation of wick drains was carried out to investigate the compressibility of the thick clayey silt deposit and the efficiency of wick drains to help accelerate consolidation. The field and laboratory test results showed that the varved clayey silt deposit was normally consolidated to slightly overconsolidated and moderately to highly compressible. Its physical
Y. Lu Department of Civil Engineering, Shanghai University, 149 Yanchang Road, Shanghai 200072, People’s Republic of China Y. Tan (&) Department of Geotechnical Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People’s Republic of China e-mail: [email protected] G. Lin Terracon Consultants, Inc., 2201 Rowland Avenue, Savannah, GA 31404, USA
properties were intermediate between those of Savannah muddy clay and Shanghai soft clay, while much closer to that of Shanghai soft clay. Due to its lamination structure in the horizontal direction, the horizontal consolidation coefficient of the varved clayey silts was significantly greater than that in the vertical direction. The measured undrained shear strength of the varved clay silt almost increased linearly with depth. The installation of wick drains in the thick clayey silt deposits accelerated primary consolidation, but showed no effect on the secondary consolidation under constant loading. The findings obtained from this study will be beneficial for future design and construction of earthworks along the Delaware River. Keywords Characterization Varved clayey silt Field exploration test Laboratory test Preloading Wick drains
Introduction The presence of thick (up to 30 m) compressible varved clayey silt deposits at shallow depths on the south bank of the Delaware River presented a major obstacle to the design and construction of the proposed liquefied natural gas (LNG) terminal in Gloucester County, New Jersey. The terminal would include three LNG s
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