Strength and Deformation Characteristics of Bandung Lacustrine Clay Under Consolidated-Undrained True Triaxial Testing

Dedi Apriadi, Rahmat Kurniawan, Syahidus Syuhada — Tue, 21 Jul 2026 00:00:00 +0700

The effect of intermediate and principal stress rotation is commonly ignored in the determination of soil stress deformation behavior under two-dimensionally or plane strain conditions. In actual field conditions, soil receives the load three-dimensionally and undergoes stress rotation to reach a stable condition. Therefore, a stress deformation test considering the effect of the intermediate and principal stress rotation to obtain real soil behavior was conducted. Bandung lacustrine soft clay is formed by the deposition of clay soils in the giant ancient lake which is estimated to have about 200 m depth from the ground surface. Undisturbed soil samples from this soft clay were taken and investigated in the laboratory by using Consolidated-Undrained True Triaxial Test. The experiment shows that effective shear strength (ϕ') increases with increasing stress variation (b) up to 10% in the increment of intermediate principal stress 0.5 times to the major principal stress. Giving load with principal stress rotation changed from 0 (zero) degrees to 90 (ninety) degrees produces a decrease in undrained shear strength (S_u/σ_c) up to 15%. The stiffness modulus and the Skempton A_f parameter also increase with increase in stress variation. The results obtained from this study is considered important to evaluate the suitable soil constitutive model for finite element load-deformation analysis.

Study on Permeability and Triaxial Experiments of Clay under Dry-Wet Cycles and Compaction

Gang Zeng, Zijian Qian, Xinyang Chen — Tue, 21 Jul 2026 00:00:00 +0700

The permeability and mechanical properties of clay are significantly influenced by the seasonal wet-dry cycles and compaction. In this study, laboratory experiments were conducted to investigate the effects of the number of wet-dry cycles and compaction degree on clay behavior. The results indicated that the initial compaction degree had a significant influence on the permeability characteristics of soil specimens subjected to wet-dry cycles. Specifically, the permeability coefficients significantly decreased with increasing compaction degree. The measured permeability coefficients for low, medium, and high-compacted samples were 5.48×10^-8 m/s, 8.33×10^-9 m/s, and 7.29×10^-10 m/s, respectively. After three wet-dry cycles, the permeability coefficients of the low and medium-compacted samples decreased to 1.16×10^-8 m/s and 9.08×10^-9 m/s, whereas that of the high-compacted sample increased to 6.76×10^-9 m/s. A relatively strong linear relationship was observed between the permeability coefficient and the compaction degree on a semi-logarithmic plot. Both cohesion and internal friction angle increased with increasing compaction degree. With a growing number of wet-dry cycles, the failure mode of the specimens gradually transitioned from strain-hardening to strain-softening behavior. The modified Duncan-Chang model showed a relatively good fit for the stress-strain relationship of the sample. This research offers theoretical references and technical support for practical applications in clay-related engineering fields.

Geotechnical Engineering Journal of the SEAGS & AGSSEA

Strength and Deformation Characteristics of Bandung Lacustrine Clay Under Consolidated-Undrained True Triaxial Testing

Study on Permeability and Triaxial Experiments of Clay under Dry-Wet Cycles and Compaction