The late Pleistocene-Holocene sedimentary facies and geotechnical properties of CLM1 core at Cao Lanh city Mekong river delta

Truong, Hoang Minh; Nguyen, Lap Van; Ta, Oanh Thi Kim; Takemura, Jiro

doi:10.32508/stdj.v16i2.1429

Cited by 1 publication

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References 6 publications

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“…The soil behaviour can be highly influenced by depositional and post‐depositional processes (Truong et al ., 2011; Sarti et al ., 2012). As different facies have distinct geotechnical and geomechanical characteristics (Truong et al ., 2013; Lorenzo et al ., 2014), facies characterization through CPTU could be utilized to make predictions about the 3D spatial distribution of geomechanically ‘weak’ versus ‘strong’ deposits, aside from any specific geographic location. Through the analysis of CPTU profiles, for example, soft, unconsolidated Holocene deposits with low Qc and Fs can be easily distinguished from stiff (high Qc and Fs) and more consolidated Pleistocene sediments, as shown in Fig.…”

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confidence: 99%

Sedimentary facies characterization through CPTU profiles: An effective tool for subsurface investigation of modern alluvial and coastal plains

2023

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Cone penetration tests, a method that is typically used to determine the engineering properties of soils, can be used as an effective tool for refined subsurface stratigraphic investigations of alluvial and coastal plains, aside from the geographic location. High‐resolution calibration of piezocone penetration tests (CPTU) with 20 sediment cores enabled the detailed characterization of alluvial, deltaic and coastal depositional systems of the Po Plain. Twelve cored facies associations, typical of alluvial and coastal plain environments, were characterized based on four distinct CPTU profiles: basic cone resistance (Qc), sleeve friction (Fs), water pore pressure (U) and friction ratio (FR). Sandy facies associations (fluvial/distributary channel, bay‐head delta, transgressive barrier, delta‐front/beach‐ridge) typically have high (>4 MPa) Qc, low‐to‐negative U and low (<2%) FR. Muddy deposits (well‐drained/poorly‐drained floodplain, swamp, lagoon and prodelta) exhibit opposite trends. Heterolithic facies associations (crevasse‐levée, offshore/delta‐front transition) display characteristic seesaw profiles. Plotting of late Quaternary deposits onto the latest version of the cone penetration test typical soil behaviour chart (Robertson, 2010) enables the identification of distinctive facies associations reflecting distinctive grain size. CPTU interpretation leads to sedimentary facies recognition well beyond the simple lithological differentiation and, in particular, allows the refined characterization of clay‐rich and silt‐rich depositional units (swamp clays and peats, central‐inner and outer lagoon, proximal/distal prodelta deposits) that exhibit only subtle differences in lithology. CPTU data can also serve for the accurate detection of key stratigraphic surfaces with potential engineering applications, such as the Pleistocene–Holocene boundary. This latter, a common feature of several alluvial and coastal plain successions, is commonly marked by an abrupt upward decrease of basic cone resistance and sleeve friction from Late Pleistocene, pedogenized, stiff strata to overlying Holocene, organic‐rich, soft deposits. This study offers an updated CPTU‐facies characterization method that could be suitable for subsurface investigations of modern alluvial and coastal plains worldwide.

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