Effect of saline intrusion on the properties of cohesive soils in the Red River Delta, Vietnam

• Published in: Marine georesources & geotechnology Vol. 38; no. 1; pp. 23 - 39
• Main Authors: Truc, Nguyen Ngoc, Mihova, Lena, Mukunoki, Toshifumi, Do, Duc Minh
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02.01.2020; Taylor & Francis Ltd
• Subjects: Bearing capacity; Centrifuges; Clay; Clay minerals; Clay soils; Cohesive soils; Deformation; deformation modulus; Environmental degradation; Hygroscopic water; Intrusion; Mathematical models; Minerals; Modulus of deformation; Numerical models; physical property; Red River Delta; Rivers; Safety factors; Saline intrusion; Saline soils; Saline solutions; Saline water; salt-affected soil; Salts; Saltwater intrusion; Saturated soils; Soil; Soil degradation; Soil properties; Soil settlement; Soil water; Zeta potential; Red River Delta
• ISSN: 1064-119X; 1521-0618
• DOI: 10.1080/1064119X.2018.1550827

This study conducted a series of laboratory experiments and established numerical models on selected undisturbed soil samples in the Red River Delta (RRD) to determine the effect of change in soils intruded by saline water. The variation in the technical parameters of soils was verified in soils fully saturated by solution of four salt concentrations, that is, 0.0, 9.9, 19.8, and 33.0 g/L. Results show that the content and composition of clay minerals in cohesive soils before and after saline intrusion are unchanged. The same finding is obtained for clay after removing absorbed water layer by using a centrifuge apparatus. The zeta potential and settlement velocity of soils in the RRD increase when salt is added to the saturated solution. Similarly, the deformation of soils increases proportionally with the salt concentrations of that solution. This result is attributed to the linear decrease in deformation modulus. The decrease in modulus versus salinities is nearly consistent for pressure stages from 100 to 400 kPa. The safety factor of bearing capacity also decreases linearly with salinities. The decrease reaches 12.5-16.3% when soils are in the maximum saline solution. All these changes are considered as the degradation of soils in saline media.