Application of Constant Rate of Strain Tests in Consolidation Analysis of the Band-Shaped Prefabricated Vertical Drains
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ORIGINAL PAPER
Application of Constant Rate of Strain Tests in Consolidation Analysis of the Band-Shaped Prefabricated Vertical Drains for Vietnam Clays: The Validation Analysis Cong-Oanh Nguyen
. Thi-Thanh Tran . Van-Tram Thi Dao
Received: 16 January 2020 / Accepted: 3 October 2020 Springer Nature Switzerland AG 2020
Abstract Band-shaped prefabricated vertical drains in the combination of surcharge preloading have been widely applied in the soft ground improvement cases in Vietnam to eliminate the post-construction settlement of the ground. However, the method of the settlement prediction has remained incorrect on the comparison between the field and calculation. A new procedure for consolidation analysis is proposed to determine the ground settlement more accurately in the routine design of the soft ground improvement. Two case studies are presented to study the ground performance under consolidation with surcharge preloading. The consolidation analysis of the soft ground deposits with the application of the constant rate of strain (CRS) consolidation tests is performed. In addition to that, the input parameters as the
C.-O. Nguyen (&) Southern Institute of Water Resources Research (formerly geotechnical expert at TOA-TOYO Joint venture for Package 1: Cai Mep international container terminal, the construction of Cai-Mep Thi-Vai Port), Ho Chi Minh City, Vietnam e-mail: [email protected] T.-T. Tran Southern Institute of Water Resources Research, Ho Chi Minh City, Vietnam e-mail: [email protected] V.-T. T. Dao Transportation College 3, Ho Chi Minh City, Vietnam e-mail: [email protected]
coefficient of consolidation and compression indices of the soft ground are characterized based on the CRS tests under the strain rate of 0.02%/min. on undisturbed soil samples that are taken at the two sites by stationary piston sampler. On the comparison of calculated and field monitored data of surface settlement, layered settlement, dissipation of the excess pore water pressure, and undrained strength gain, this analysis is also to confirm the appropriate strain rate for CRS tests, which are utilized in the determination of consolidation parameters. Keywords Consolidation CRS FDM IL Piezocone penetration test Undrained shear strength List of Symbols CM Cai Mep site CPTU (CPT) Cone Penetration test with pore water pressure measurement CRS Constant rate of strain consolidation test ch (cm2/d) Coefficient of horizontal consolidation ch(OC) (cm2/d) Coefficient of horizontal consolidation at over-consolidated state ch(NC) (cm2/d) Coefficient of horizontal consolidation at normallyconsolidated state cv (cm2/d) Coefficient of vertical consolidation
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Geotech Geol Eng
cv(OC) (cm2/d) cv(NC) (cm2/d) D (cm) De (cm) dw (cm) E EPC e0 FDM FVT (VST) HP H0 IL n P PHD PVD PW qc (MPa) qT (MPa) qNET (MPa) SP SS suf (kPa) sun (kPa) t (d) U (%) ub (kPa) u2 (kPa) wn (%) wl (or LL) (%) wp (%) r0 c (kPa) r0 p (kPa) rv0 (kPa) r0 v0 (kPa) rv (kPa) r0 v (kPa)
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