Determination of Shear Strength Parameters by Multistage Triaxial Tests in the Long-Term Analysis of Slopes

Abstract

Accurate determination of soil parameters is of great importance in the analysis of landslides, which is a common type of natural disaster. In the solution of landslide problems, the direct shear box test is generally preferred as a laboratory test type for the determination of the shear strength parameters of soils. However, the need for drained parameters in long-term problems reveals a disadvantageous aspect of this experiment, especially in clayey soils, because pore water pressures cannot be measured in the direct shear box test, which is widely used in the laboratory to determine the shear strength of the soils.

Multistage triaxial compression tests used to obtain shear strength parameters in the laboratory are advantageous compared to conventional triaxial compression tests because of the time and financial concerns, as well as the avoidance of differences between the samples to be tested. In this study, a new method was tried in addition to the methods used to obtain shear strength parameters with consolidated-drained multistage tests in normally consolidated clayey soils and the results were promising. Thus, since it increases the usability of multistage tests, it will be helpful in terms of preventing possible disasters by enabling analysis in many more sites.

Keywords

• Landslides
• multistage triaxial test
• Long-term analysis

References

1. [1] Kondner R.L., Hyperbolic stress-strain response: cohesive soils: Journal of Soil Mechanics and Foundations Division Vol. 89 (1963), p. 115-143.
2. [2] Sridharan, A. M., and S. N. Rao. 1972. New approach to multistage triaxial test. Journal of Soil Mechanics and Foundations Division 98: 1279-1286.
3. [3] Nambiar M.R., G.V. Rao and S.K. Gulhati, Multistage triaxial testing: A rational procedure: Strength Testing of Marine Sediments: Laboratory and In-Situ Measurements Vol. 883 (1985), p. 274-293.
4. [4] TS 1500, İnşaat Mühendisliğinde Zeminlerin Sınıflandırılması, Türk Standartları Enstitüsü, Ankara, 2000.
5. [5] ASTM. 2015. Annual Book of ASTM Standards. Vol. 04.08 & 04.09. West Conshohocken, PA: American Society for Testing and Materials.
6. [6] Ho, D. Y. F., and D. G. Fredlund. 1982. A Multistage Triaxial Test for Unsaturated Soils. Geotechnical Testing Journal (Americal Society for Testing and Materials) 5 (1/2): 18-25.
7. [7] Banerjee, A., Puppala, A. J., & Hoyos, L. R. 2020. Suction-controlled multistage triaxial testing on clayey silty soil. Engineering Geology, 265, 105409.
8. [8] Hormdee D., Kaikeerati N. and Angsuwotai, P. 2012. Evaluation on the Results of Multistage Shear Test Int Jl GEOMATE, 2 (1), 140-143.

9. [9] Sharma, M. S., Baxter, C. D., Moran, K., Vaziri, H., & Narayanasamy, R. (2011). Strength of weakly cemented sands from drained multistage triaxial tests. Journal of geotechnical and geoenvironmental engineering. 137(12), 1202-1210.
10. [10] Skempton, A. W., 1985. Residual Strength of Clays in Landslides, Folded Strata and the Laboratory, Geotechnique, Vol.35, No.1, 3-18.
11. [11] Shahin M., Cargeeg A. 2011. Experimental Investigation into Multistage versus Conventional Triaxial Compression Tests for a c-phi Soil. Applied Mechanics and Materials. Vol. 90-93.
12. [12] Kayatürk D., 2021. Multistage Testing on clayey soils. M.S. thesis, in progress. Sakarya University, Sakarya, Turkey
13. [13] Pagoulatos, A. 2004. Evaluation of multistage triaxial testing on Berea sandstone. M.S. thesis, Univ. of Oklahoma, Norman, OK.