Stabilitas Tanah Timbunan Sisi BH-1 Proyek Jalan Akses Pembangunan Jembatan Pulau Balang II

Problem on the road access landfill at Balang Island II Bridge is the landslide at STA 23+025 on left side slope (BH-1) caused by a swamp pond on the roadside. The landfill that cutted into the swampy area made the water get stuck on one side (water could not flow to the original condition). The research method is the form of direct observation in the field which focuses on the results of information and laboratory testing which is then processed and analyzed. The analysis obtained that the soil type on the spot is clay with N-SPT 6 – 29. There are 2 alternatives solutions for the problem. First, if there is a ROW problem, the treatments are watercourse, adding counterweight, wooden pile under the landfill and one layer Geotextile PP 50 (initial ground water level on exsisting condition with 90,4 kPa loads). Second, if there is no ROW problem, the treatments are watercourse, adding counterweight, wooden pile under the landfill and one layer Geotextile PET 100 (initial ground water level on top of landfill with 90,4 kPa loads). Based on technical analysis, the second solution was chosen because it has bigger safety factor, smallest settlement value, and shorter time implementation. However it is still need more detail technical justification to strengthen the desicion.

Experiments on Stability of Tetrapods on Rear Slope of Rubble Mound Structures under Wave Overtopping Condition

In this study, hydraulic model tests were performed to investigate the stability of armor units at harbor side slope for rubble mound structures. The Korean design standard for harbor and fishery port suggested the design figures that showed the ratio of the armor weight for each location of rubble mound structures and it could be known that the same weight ratio was needed to the sea side and harbor side (within 0.5H from the minimum design water level) slope of rubble mound structures. The super structures were commonly applied to the design process of rubble mound structures in Korea and the investigation of the effects of super structures would be needed. The stability number (Nod = 0.5) was applied (van der Meer, 1999) and it showed that the armor (tetrapod) weight ratio for harbor side slope of rubble mound structures needed 0.8 times of that for sea side slope.

Short communication: A new tool to define multiscale bedform characteristics from bed elevation data

Systematic identification and characterization of bedforms from bathymetric data are crucial in many studies focused on fluvial processes. Automated and accurate processing of bed elevation data is challenging where dune fields are complex, irregular and, especially, where multiple scales co-exist. Here, we introduce a new tool to quantify dune properties from bathymetric data representing multiple dune scales. A first step in the procedure is to decompose the bathymetric data based on a LOESS algorithm. Steep dune lee side slopes are accounted for by implementing objective breaks in the algorithm, accounting for discontinuities in the bed level profiles, often occurring at the toe of the lee side slope of dunes. The steep lee slopes are then approximated by fitting a sigmoid function. Following the decomposition of the bathymetric data, bedforms are identified based on zero-crossing, and the relevant properties are calculated. The approach to decompose bedforms adopted in the presented tool is particularly applicable where secondary dunes are large and thus filtering could easily lead to undesired smoothing of the primary morphology. Application of the tool to two bathymetric maps demonstrates that the decomposition and identification are successful, as the lee side slopes are better preserved.

Sensitivity analysis for dam breach parameters using different approaches for earth-fill dam

The prediction of dams breach geometry crucial in studies of dam breaking. The hydrographs characteristics of flood that resulting from breaking of dam is mainly depend on the geometry of breach and the time formation of breach. Five approaches (Froehlich, Macdonald and Langridge-Monopolis, Von thun & Gillete, USBR and Singh % Snorrason) was used in order to predict dam breach parameters (breach width, breach side slope, breach formation time). The Sensitivity analysis was performed in order to assess the effect of each parameter on the resulting hydrograph of the flood. HEC-RAS model was used to calculate the effect of each parameter on the hydrograph of the flood that resulted. The width of breach (Bavg), side slope (z) and formation time of breach (tf) increased by 25%, 50%, 75% and 100% and decreased by 25%, 50% and 75%, respectively. Flood hydrograph was estimated at the dam site for each case. Sensitivity analysis was performed in order to check the effect of each parameter of breach and time of breaching. Sensitivity analysis was performed with Froehlich method with the mode of overtopping failure and maximum operating level at 107.5 meter above sea level. Result of sensitivity analysis show that peak discharge and time to reach it is adequately sensitive to breach side slope, highly sensitive to the breach formation time and less sensitive to breach width.

Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea

The flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore and onshore currents over the east- and west-side slopes in the channel, respectively, is suggested. A bottom intensified flow characteristic was observed at the offshore stations in the Yamato Basin. The asymmetric current system in the channel is also suggested by the asymmetric distribution of water characteristics across the TDSC in Toyama Bay; a cold dense water mass with higher dissolved oxygen (DO) and higher transmittance (Tr) was found over the west-side slope of the channel, whereas a water mass with lower DO and lower Tr was distributed over the east-side slope, suggesting a turbidity current from the head of Toyama Bay. The currents facing the shallower depth on their right-hand-side, along with the density distribution in the TDSC, suggest a density current system under the influence of the earth’s rotation. The dissolved oxygen concentration in the TDSC was significantly lower than that in the offshore region of the same temperature range. This suggests that the water mass over the west-side slope in the TDSC is a modified offshore water mass which experienced significant mixing with the low DO water mass over the east-side slope in the TDSC, probably due to strong shear between the offshore and onshore currents in the narrow channel.

The Failure Mechanism and Stability of the End Slope of Inclined Composite Coal Seam

In view of the inclined occurrence of coal seam in Heishan open-pit coal mine, in the longitudinal exploitation process of the first mining area, the height of the slope at the west end is increasing, and the occurrence of weak interlayer in the slope is in production. The failure mechanism and stability of the end slope of the inclined composite coal seam, which is typical of the West end slope of Heishan open-pit mine, are studied by means of field investigation, theoretical analysis, limit equilibrium analysis, and numerical simulation. The factors affecting the stability of the western side slope and the potential landslide mode are analyzed. The residual thrust method and simplified Bishop method were used to study the stability of two potential landslide modes on the western slope, and the landslide mode, final slope angle, and slope morphology were determined. FLAC3D was used to simulate the western end of the slope, reveal its landslide mechanism, and clarify the evolution law of the slope rock mass displacement. The results show that the landslide mode at the west end of the first mining area is the combined sliding mode of “cutting and bedding.” With the decrease of longitudinal mining depth, the final slope angle functions from 40° to 37°. The stress and strain are concentrated at the weak layer of the coal floor of the western side slope 13-2 and at the foot of the slope. Meanwhile, the failure also occurs inside the slope. The internal cracks connect through the weak layer of the coal floor and slide along the weak layer of the coal floor 13-2. The displacement evolution law of the slope monitoring point shows that the deformation of the slope is mainly horizontal displacement, the maximum displacement deformation is at the foot of the slope, and the degree of displacement deformation of the slope surface is obviously greater than that of the inside of the slope.

Slope Stability Analysis of Highway Embankment with Different Height and Slope by Varying the Properties of Soil

The analysis of slope stability has received wide attention nowdays because of its practical importance. To provide steepest slopes which are stable and safe, various investigation are ongoing. The main objective of the project is to analyze slope of embankment by calculating factor of safety. So that an appropriate side slope can be chosen and use for the construction of highway. For this, limit equilibrium analysis has been done using GEO5 software. Swedish circle method (Graphically) has been used to performed manually analysis. In the present study, data collected from the site which is located near Shivni Village, Ner-Yavatmal road. “The construction of Samruddhi Mahamarg” is being constructed at that site. It is having high embankment heights upto 9meter. The values of unit weight of soil(γ), angle of internal friction(ϕ), cross sectional details of embankment and side slope of embankment were taken from that site. In this study, embankment of different heights (3 to 9m) under different 8 slopes (i.e. 1:2, 1:1.75, 1:1.5, 1:1.25, 1:1, 1:0.83, 1:0.7, 1:0.58), different values of cohesion and friction angle were considered. The analysis has been performed on two different cases: Case I stands for single layer of soil and Case II stands for double layer of soil by varying the value of cohesion and angle of internal friction the changes occur in the value of factor of safety were checked by comparing both results obtained by manual method and by GEO5 software. From this investigation it is found that increasing the value of cohesion and angle of internal friction, the factor of safety against slope stability increases. And for a particular height of embankment factor of safety increases with increase in the flatness of slope. From these results, it is better to use C-ϕ soil rather than ϕ soil as it gives maximum FOS as compared to sandy soil. From the analysis of doubled layered soil, it has been concluded that condition 2(with both soil cohesive) found satisfactory better with respect to condition 1(when one soil cohesive and one soil sandy). By considering condition 2 (both soil cohesive), it has been found that the increment of 25 to 30% in the FOS of condition 1 takes place.