ANALYSIS OF SLOPE STABILITY AVALANCHE IRRIGATION CHANNELS IN INDRAMAYU USING THE ELEMENT METHOD TO AND HANDLING WITH CORRUGATED CONCRETE SHEET PILE (CCSP)

• Main Author: SUBAGYA, SLAMET
• Format: Theses
• Language: Indonesia
• Subjects: Teknik sipil
• Online Access: https://digilib.itb.ac.id/gdl/view/71066
• Institution: Institut Teknologi Bandung

In the Indramayu irrigation development area, there is a sliding or movement of soil on the slopes of the channel. Slope sliding occurs at the time of excavation and drying work (dewatering). The soil at the site under review is indicated to have medium to high swelling-shrinkage properties. It is indicated by the value of the plasticity index, the PI is greater than 30% and the development value is 20-50%. This research was conducted to determine the mechanism and causes of sliding. After the mechanism and causes of sliding were known, an alternative review of slope reinforcement with Corrugated Concrete Sheet Piles (CCSP) and replacement of selected soil material from the borrow area was carried out. In the analysis to determine the mechanism and causes of sliding, stages are carried out: (i) Field review to identify the location, shape and depth of field of the cladness (slip surface); (ii) Identification of the stages of construction carried out in the field before arriving at the time of the slope sliding; (iii) Inventory of data from field and laboratory soil investigations; (iv) Numerical modeling of the analysis-method of elements up to slope stability. From the results of the field review and identification of the construction stages, it was found that slope sliding occurred shortly after drying. This condition is modeled in numerical analysis-method of elements up to slope stability. The parameters of shear strength and soil stiffness for slope stability analysis were obtained from an inventory of data from field and laboratory soil investigations. Numerical-method analysis of elements up to slope stability is carried out by total voltage analysis and effective voltage analysis. In the software used, total voltage analysis is represented as Undrained C method and effective voltage analysis is represented as Undrained A method. In the analysis of total stress, the parameters of total shear strength and total stiffness are used as inputs. In the analysis of effective stress, the parameters of effective shear strength and effective rigidity are used as input. The Mohr-Coulomb collapse sheath was used as a criterion for collapse. Two stress-strain curves were used in this study: (i) Elastic-plastic stress-strain curve and (ii) Hyperbolic stress-strain curve. The results of the analysis showed that slope sliding occurred due to a sudden decrease in water level (rapid draw down). This condition is indicated by the value of the safety factor, SF is equal to one. Slope stability in existing conditions with M.A.T. -3.2 m obtained an SF value of 1.27, after experiencing a decrease in M.A.T. -6.2 m, SF results dropped to 1.01. This proves that there is an influence from the groundwater level due to the rapid drawdown event that occurs according to conditions in the field. Furthermore, it was found that in the effective stress analysis (Undrained A), the Mohr-Coulomb elastic-plastic model provides a smaller pore water pressure than the pore water pressure calculated using a hyperbolic model (hardening soil). This suggests that the Mohr-Coulomb elasticplastic model is less suitable for shear strength analysis of soft to medium soils at the site under review. An alternative review of slope retrofitting with CCSP yielded an SF value of 1.50 (meeting slope stability criteria). This indicates that slope retrofitting with CCSP provides effective results for handling the slope stability of the channel under review.