Duration of core soil consolidation of earth core rockfill dam

Introduction. Surplus water pore pressure always appears in a clayey soil of the seepage control core of a high earth core rockfill dam. It may reach high values and present threat the dam safety. With time the pore pressure decreases but the soil consolidation may be durable; duration of consolidation process can be determined by the analytical and numerical methods. Our previous studies showed that only numerical modeling of the structure stress-strain state (SSS) and unsteady regime may adequately simulate the process of pore pressure formation and dissipation. Therefore, of interest is the use of numerical modeling also for estimation of soil consolidation process duration in the core of a rockfill dam.

Materials and methods. Study of duration of surplus core pressure dissipation was conducted with the aid of numerical modeling of SSS and seepage regime on the example of an ultra-high rockfill dam with a central core. Analysis was carried out for several options of core clayey soil permeability.

Results. The results of numerical modeling showed that pore pressure in the core considerably affects the SSS of the whole dam, its displacements and stresses. It was established that at permeability exceeding 1 · 10–7 сm/s the soil consolidation completes even during construction period, and at permeability less than 1 · 10–8 сm/s the consolidation continues for dozens of years. As compared to a simple analytical method of the seepage consolidation theory the duration of consolidation process turned to be approximately two times as less. This is related to the fact that numerical modeling takes into account that movement of the seepage flow is realized not only into a drainage facility but also penetrates in the zones with less pore pressure.

Conclusions. By the results of numerical modeling the core soil consolidation is completed two times as fast as compared with the analysis results obtained by a simple analytical method.

1. Akhtarpour A., Salari M. The deformation mechanism of a high rockfill dam during the construction and first impounding. Scientia Iranica. 2020; 27(2):566-587. DOI: 10.24200/sci.2018.20778

2. Sainov M.P. Assessment of crack resistance of ultra-high earth core rockfill dam by pore pressure. Magazine of Civil Engineering. 2022; 6(114). DOI: 10.34910/MCE.114.11. EDN BACLUE.

3. Rasskazov L.N., Yadgorov E.Kh., Nikolaev V.B. Field Observations of Soil Settlements, Displacements, and Pore Pressure in Dams. Power Technology and Engineering. 2018; 51(6):611-620. DOI: 10.1007/s10749-018-0881-9

4. Rasskazov L.N., Yadgorov E.Kh., Burenkov P.M. Pore Pressure Dissipation in the Core of the Nurek Dam. Power Technology and Engineering. 2016; 50(1):54-59. DOI: 10.1007/s10749-016-0658-y

5. Wu Y., Zhang B., Yu Y., Zhang Z. Consolidation analysis of Nuozhadu high earth-rockfill dam based on the coupling of seepage and stress-deformation physical state. International Journal of Geomechanics. 2016; 16(3). DOI: 10.1061/(ASCE)GM.1943-5622.0000555

6. Salari M., Akhtarpour A., Ekramifard A. Hydraulic fracturing: a main cause of initiating internal erosion in a high earth-rock fill dam. International Journal of Geotechnical Engineering. 2018; 15(2):207-219. DOI: 10.1080/19386362.2018.1500122

7. Komasi M., Beiranvand B. Study of Hydraulic Failure Mechanism in the Core of Eyvashan Earth Dam with the Effect of Pore Water Pressure and Arching. Journal of Stress Analysis. 2020; 4(2):55-67. DOI: 10.22084/jrstan.2020.20022.1110

8. Ma H., Chi F. Major Technologies for Safe Construction of High Earth-Rockfill Dams. Engineering. 2016; 2(4):498-509. DOI: 10.1016/J. ENG.2016.04.001

9. Lv X., Chi S. Strain Analysis of the Nuozhadu High Rockfill Dam during Initial Impoundment. Mathematical Problems in Engineering. 2018; 1-12. DOI: 10.1155/2018/7291473

10. Hosseini S.M.M.M., Fard R.A. Pore pressure development in the core of earth dams during simultaneous construction and impounding. Electronic Journal of Geotechnical Engineering. 2003; 8.

11. Razavi B., Parehkar M., Gholami A. Investigation on Pore Water Pressure in Core of Karkheh Dam. International Journal of Civil and Environmental Engineering. 2011; 5(11):539-542. DOI: 10.5281/zenodo.1335522

12. Balanji S.G., Davoudi S., Merufinia E. Investigation the Effects of Pore Water Pressure and Arching on Karkheh Earth Dam Considering the Instrumentation Results. Advances in Environmental Biology. 2014; 8(12):1345-1353.

13. Emadali L., Motagh M., Haghighi M.H. Characterizing post-construction settlement of the Masjed-Soleyman embankment dam, Southwest Iran, using TerraSAR-X SpotLight radar imagery. Engineering Structures. 2017; 143:261-273. DOI: 10.1016/j.engstruct.2017.04.009

14. Feng R., He Y.L., Cao X.X. Different deformation patterns in high core wall rockfill dams: A case study of the Maoergai and Qiaoqi dams. Advances in Civil Engineering. 2019; 2019(1). DOI: 10.1155/2019/7069375

15. Guo Q., Pei L., Zhou Z., Chen J., Yao F. Response surface and genetic method of deformation back analysis for high core rockfill dams. Computers and Geotechnics. 2016; 74:132-140. DOI: 10.1016/j.compgeo.2016.01.001

16. Farajniya R., Poursorkhabi R.V., Zarean A., Dabiri R. Analysis and monitoring of the behavior of a rock fill dam ten years after construction: a case study of the Iran-Madani Dam. Geoenvironmental Disasters. 2024; 11(1). DOI: 10.1186/s40677-024-00295-4

17. Nichiporovich A.A., Tsybulnik T.I. One-dimensional problem of consolidating clay soil in a stressed state corresponding to the plane deformation case. Proceedings of VODGEO, Hydrotechnics. 1972; 34. (rus.).

18. Rashidi M., Heidar M., Azizyan Gh. Numerical Analysis and Monitoring of an Embankment Dam During Construction and First Impounding (Case Study: Siah Sang Dam). Scientia Iranica. 2018; 25(2):505-516. DOI: 10.24200/sci.2017.4181

19. Sari U.C., Wardani S.P.R., Partono W. Influence of pore water pressure to seepage and stability of embankment dam (case study of Sermo Dam Yogyakarta, Indonesia). MATEC Web of Conferences. 2017; 101:05007. DOI: 10.1051/matecconf/201710105007

20. Soroush A., Pourakbar M., Nabizadeh A. 3D numerical analyses of behavior of a high rockfill dam with clay core in narrow canyon. 16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering. 2019.

21. Ramsheh F.A., Rashiddel A., Dias D. FDM analysis of earth dams — end of construction and water seepage (case study: Ivshan Iran dam). Journal of Physics: Conference Series. 2021; 1973(1):012201. DOI: 10.1088/1742-6596/1973/1/012201

22. Sainov M.P., Boldin A.A. Formation of pore pressure in the earth-core rockfill dam due to the dead weight. The Hydrotechnika. 2024; 2(75):10-14. EDN WEKFRK. (rus.).

23. Sainov M.P., Boldin A.A. Assessment of methods for calculating pore water pressure in the earth core of rockfill dam. Proceedings of the VNIIG. 2024; 312:115-126. EDN RKTLGY. (rus.).