The stability of infrastructure along river channel, such as bridges and embankments, is paramount to continuing service and public safety, and therefore, is essential consideration in the design, construction and maintenance. During the design process, infrastructure stability is often assumed to be static, and considered by implementing a safety factor which is produced by an analysis of extreme condition. However, this has failed to consider the variability of natural factors and importantly, the escalating threat of extreme environmental condition, induced by global climate change. This assumption should, therefore, be revisited for developing a more resilient design and maintenance regime. To demonstrate the changing infrastructure stability, an assessment of safety factor of river embankment and bridge foundation as nearby infrastructures along Bengawan Solo River's channel and estuary is presented. This was undertaken to determine the impact of water level fluctuation during two extreme conditions during dry and rainy seasons in several critical locations. The river characteristics (i.e. morphology, water fluctuations, velocity, and sub-soil characteristics), embankment conditions and bridge pile foundation were investigated in-situ to assess the change of safety factor. The laboratory investigation focused on river and embankment characteristics including the analysis of the drying-wetting conditions. In-situ and laboratory investigations found an extreme condition which the infrastructures are subjected into, where the water level and flow velocity were 3 m and 0.04 -0.27 m/s during dry season; and 10 m and 0.46 -0.84 m/s during rainy season. Furthermore, from the analysis, it can be concluded that certain areas in the river do not meet the minimum requirements for bridge foundation and embankment stability.
Slope stability analysis is very important in slope design so it can manage and maintain the infrastructure assets. If the slope is unstable, it can damage the infrastructure around the slope. The method commonly used in slope stability analysis is 2D modeling which assumes the length of the landslide area is not limited or continuous. Landslides that occur in the field are limited and not continuous, so 3D modeling is more suitable than 2D modeling. 3D slope stability analysis has been developed by various researchers. Most of the results of previous studies stated that the 3D and 2D factor of safety ratio were more than one for cohesive soils and less than one for non-cohesive soils. This safety factor affects the amount of reinforcement needed. Differences in 2D and 3D safety factors will cause differences in the amount of reinforcement needed. Therefore, this study was conducted to determine the differences in the 2D and 3D slope stability analysis result. Slope stability analysis was carried out using LEM, where the 2D slope stability used the Fellenius method while the 3D slope stability used the Hovland method. Calculate the required reinforcement amount using geotextiles with Tilt = 250 kN/m. The results obtained from this study are the 2D safety factor is smaller than the 3D safety factor. The 3D and 2D safety factor ratios range from 1.09 -1.397. While the amount of reinforcement required in the 3D analysis is less than in the 2D analysis with the ratio of 3D and 2D reinforcement requirements ranging from 0.5 to 0.955 depending on the width and height of the embankment.
The infrastructure is important for the great life of a region and most of the country. Therefore, infrastructure must be always in proper condition in its functionality. Furthermore, it must follow the main principle which is infrastructure asset management. In this case, geotechnical mapping is also related to the principles of Infrastructure Asset Management in planning, designing, and feasibility studies of an infrastructure project in Badung Regency, hence the infrastructure projects are better prepared. The research methods include collecting soil investigation data, processing soil investigation data, describing the results of soil investigation data with mapping tools, and geotechnical zoning with statistical analysis. The results obtain a geotechnical map of Badung Regency in 2 and 3-dimensional forms. The 2D results in the form of a hard soil depth map can be concluded that South Kuta District has a variable depth of 0.4 -15 meters, North Kuta District has a variable depth of 1.5 -5 meters, Kuta District has a variable depth of 1.5 -10 meters, Mengwi District has a variable depth of 1.5 -10 meters, Abiansemal District has a variable depth of 5-15 meters, Petang District has a variable depth of 5-22 meters. The 3D Zone 1 lithology map can be concluded that the Zone 1 area covered with a hard soil depth of around 5 -10 meters is dominated by sandy silt, silty sand, sand, and a little clayey silt. That area covered with a hard soil depth of about 1.5 -5 meters is dominated by clay, clayey silt, sandy silt, silty sand, and sand with a heterogeneous distribution. The Zone 1 area is dominated by the specific volume saturated value (γsat) range of 1.5 -2.0 t/m3. The values > 2.0 t / m3 are found in Sading area with a hard soil depth of 5-10 meters. The Zone 1 area is dominated by the range of N-SPT values = 0 -30. The N-SPT values > 30 are found in Sading area with hard soil depths of 5-10 meters.
The earthfill dam might be built for all subsoils condition, however the common problems are the seepage flow and dam stability. This study uses numerical simulation model for seepage discharge and slope stability analysis. The characteristic of the dam is obtained from Tugu Dam, Trenggalek, while the subsoil data is varied for five soil types which are clay, silty clay, silt, silty sand, and sand. The first simulation analyze certain subsoil type during various water levels, while the second simulation analyze certain water level elevation during various soil types. Each simulation will be analyzed for seepage discharge and slope stability. The first simulation results show that seepage discharge and water level elevation have a logarithmic correlation with R 2 > 0.75. The largest seepage discharge at 1.90 x 10 -3 m 3 /s is sand soil, while the smallest is clay soil at 1.47 x 10 -9 m 3 /s. The results of the second simulation show that the seepage discharge and saturated volumetric water content also have a logarithmic correlation. Based on these two simulations, the seepage discharge still meets the requirement since plotted below the average annual runoff, which is 1% of the 10-year re-flood discharge. The amount of reflood discharge is calculated using the Nakayasu Synthetic Unit Hydrograph (SUH) which is 5.99 m 3 /s. The safety factor of slope stability is more than 1.2 which is considered as stable dam.
Injection piling method was used as the main pile driving method at the three warehouses in the Eastkal Penajam project, Kalimantan, Indonesia. The subsoil compositions are dominated by clay and sandy soil with very soft to medium consistencies. By using injection pile equipment, it is possible to measure the pile bearing capacity from the loading gauge. Since the soil is dominated by clay, the friction capacity overtime will be improved. For that purpose, the piles were re-injected again after 3, 10, 11, and 25 days. To establish the forecasting expression of pile bearing capacity enhancement for other piles, non-linear regression analysis was performed. To verify the result, pile driving analyzer (PDA) test for selected piles was carried out. The results from PDA test were further analyzed by using both direct fields reading in the PDA data logger and the Case Pile Wave Analysis Program (CAPWAP). A linear regression analysis was carried out to complete the blank data due to the field measurement limitation. In addition to the obtained field data, theoretical analysis of pile bearing capacity with Luciano Decourt method is carried out. From the comparisons of all data, it can be concluded that re-injection pile method provides the highest safety factor followed by PDA test, CAPWAP analysis, and theoretical design calculation with Luciano Decourt method.
Increases in critical land in the Bengawan Solo River Basin contribute to floods and severe damage to infrastructures along the river channel. Additionally, the occurrence of excessive erosion is a source of sediment materials, especially at meandering sections. Riverbank erosion destabilises dykes and sediment deposition decrease capacity, thereby resulting in floods (especially during rainy seasons). Although both phenomena can be evaluated by observing flow velocity and sediment concentration, there is a paucity of field investigations on parameters that affect erosion under dry and rainy seasons. This study investigates the aforementioned parameters and contrasts circumstances during dry and rainy seasons by presenting relevant information on sediment quantity and flow velocity. The results indicate that sediment concentration at the outer banks of the flow path significantly exceeds that at the inner banks, thereby indicating significant occurrence of erosion. Further examination of riverbed material suggests that the interaction between sediment concentration and flow velocity, especially in meandering segments, can provide an estimate of the erosion rate and the change in the morphology of the alluvial river. Sediment concentration is correlated with seasonal conditions such that sediment concentration during the rainy season is approximately five times that in the dry season. This clarifies that more significant river morphology changes occur during peak seasons. Further, the results of the study can be used in river dynamic process prediction, especially in alluvial streams or in soft soil with properties similar to that of alluvial streams.
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