Effect of soil structure disturbance on the shear strength of black volcanic ash soil

Okri Asfino Putra, Noriyuki Yasufuku, Ryohei Ishikura, Ahmad Rifa'i, Adel Alowaisy, Yuko Kawaguchi

Research output: Contribution to journalConference articlepeer-review


The effect of soil disturbance on the shear strength of black volcanic ash soil was investigated using a constant volume direct shear apparatus. Disturbance of soil structure was considered as the pore size distribution which obtained from the soil-water characteristic curve (SWCC). The disturbed sample was used as a representation of soil structure disturbance due to earthquake shakes. A series of cyclic tests were conducted under unsaturated and saturated samples. It was found that the undisturbed samples exhibit a unimodal pore structure, and the disturbed samples indicate to a bimodal pore structure. Since the pore structure of the disturbed sample is unstable, the degradation index value is higher than that of the undisturbed sample and increases with the increasing number of cycles. In other words, the cyclic normalized vertical stress of disturbed samples degrades faster. Furthermore, the degradation index value in the normallyconsolidated samples was found to be larger than the overconsolidated. It might be attributed to increasing of the pore water pressure during shearing. Where in the over-consolidated samples is lower than normally-consolidated. On the other hand, the normalized shear stress of unsaturated samples, it is slightly larger due to the suction forces in the total strength of soils.

Original languageEnglish
Article number02004
JournalE3S Web of Conferences
Publication statusPublished - Mar 13 2020
Event4th International Conference on Earthquake Engineering and Disaster Mitigation, ICEEDM 2019 - Padang, Indonesia
Duration: Sept 25 2019Sept 27 2019

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Energy(all)
  • Earth and Planetary Sciences(all)


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