Andy Sugianto
PT. Geotechnical Engineering Consultant

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Replacement of Weathered Clay Shale Using Soil Cement for Bridge Approach Embankment in Purwakarta - Indonesia Albert Johan; Andy Sugianto; Paulus Pramono Rahardjo
Indonesian Geotechnical Journal Vol. 2 No. 3 (2023): Vol. 2, No. 3, December 2023
Publisher : Himpunan Ahli Teknik Tanah Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56144/igj.v2i3.58

Abstract

Clay shale is a sensitive soil material that easily experiences weathering if exposed to open air, sunlight, water. Weathered clay shale is commonly located near the surface and has a soft consistency due to surface water infiltration. Referring to this condition, weathered clay shale is prone to experience soil movement if backfill work is conducted on the top side of weathered clay shale material. Therefore, to minimize the potential of soil movement during backfilling, soil replacement using soil cement is recommended to be conducted to gain higher soil shear strength and to prevent excessive water infiltration to the fresh clay shale. To gain further understanding, a comprehensive study about the replacement of weathered clay shale using soil cement for bridge approach embankment in Purwakarta was carried out. This study comprises site observation, field data collection, laboratory test, explanation about implementation and quality control. The stages in implementation of soil cement is carried out in several stages such as : evaluation of soil condition on the project site, checking the suitability of local soil for the soil cement stabilization, conducting field test trial mockup followed by quality control, conducting crumb test and mechanical properties test for soil cement mixture. Based on assessment results, the soil cement mixture shall be directly compacted after the soil cement mixture is homogeneous to prevent segregation and shall be given a curing time of at least 3-7 days without additional water to gain better soil shear strength. Furthermore, according to the crumb test result, soil cement material was identified as quite impermeable which is verified by evidence that there was no significant change in water content and the soil cement sample could still stand firm after soaked for 7 days.
Sheet Pile Failure Caused by Scouring and Sand Mining at Padang River Bank Hansen Tananda; Andy Sugianto; Paulus Pramono Rahardjo
Indonesian Geotechnical Journal Vol. 2 No. 3 (2023): Vol. 2, No. 3, December 2023
Publisher : Himpunan Ahli Teknik Tanah Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56144/igj.v2i3.59

Abstract

Ground movement occurred on the banks of the river in Padang which has been protected by steel sheetpile which borders the Factory property. Indications of ground movement are detected through visual observations. It was also reported that the day before the incident there had been continuous rain until the next day. Based on the results of the technical drilling, it appears that the soil density becomes lower after 10m depth. There is a layer of sandy silt with a soft to medium consistency at a depth of about 18m to 26m. With soil conditions that are dominated by sandy soil, the risk of scouring due to river flow is one of the things that needs to be considered. Landslides occur gradually because changes in river flow patterns gradually changed due to internal and external factors. Internal factors are caused by the flow and behavior of the river itself, while external factors are the activity of mining of sand material around the riverbanks. Along with the swift river flow, especially during flood water conditions, the layers of soil material move and are washed away by the flow of water so that there is a gap between the sheetpile and the original soil. These conditions cause the passive resistance of the sheet pile to gradually decrease and to experience deformation due to the pushing of the soil material that has experienced a movement. Important findings in the investigation is that the very soft clay layer underneath the sandy layers was not detected prior to the investigation.