CAUSEWAY BUILDING DAMAGE ANALYSIS (Case Study of Torobulu Ferry Port Crossing)

Torobulu Port has been protected from waves by a 238-meter causeway. This study evaluates the performance of the Causeway building and the function of the Torobulu Port building. The CERC technique (1984) was utilized to calculate wave period height, whereas the circular letter of the minister of public works No. 01/SE/M/2011 on operational rules and maintenance of coastal safety buildings was utilized to calculate building condition index. This analysis determined that the causeway is still non-overtopping, so it continues to safeguard the port region from wave threats. The study of the building condition index reveals favorable results, with a value of 1.20 and an index of 0.0 1.15, allowing for physical condition and function-based action recommendations.


INTRODUCTION
Indonesia has more than 17,000 islands and a coastline of more than 80,000 kilometres, which is twice the circumference of the Earth at the equator. The highest and lowest tides have an impact on the coastline. Coastal areas also alter. Depending on their causes, coastal alterations may be gradual or rapid. Changing coastlines are the result of both natural and human processes. Hydrooceanographic processes such as wave surges, current shifts, tidal variations, and climate change have an effect on natural factors [1].
Waves shape harbors, shipping channels, and coastal structures. It is necessary to know the wind direction, wave direction, and wave height when designing coastal structures. Wind, tides, volcanism, earthquakes, ships, and other factors can generate ocean waves [2]. The velocity of the wind causes erosion, abrasion, and sedimentation. In addition to creating the shoreline, causing currents and sediment transfer perpendicular and parallel to the coast, and acting on coastal structures, waves can also create the shoreline. Erosion can erode the coastline and cause damage to residential and public structures, roads, places of worship, offices, and schools, among other things [3].
Therefore, coastal protection structure constructions are technically required to protect damaged areas. Torobulu Crossing Port is located in Torobulu Village, Laeya District, South Konawe District, at a southern latitude. Islands, littoral lowlands, and mountains range between 0 and 2,400 meters above sea level. For a port with a 238-meter causeway, the port area has low waves, but massive structures reflect large waves.
Performance of beach safety structures in Munte Village, North Luwu District. Hard and soft shore protection techniques are comparable [4]. The average wave height at the beach is 0.86 meters, but the groin and disconnected breakwater reduce it to 0.26 meters. 30% of beach safety structures are effective. The high and low tides are measured. GPS, complete station, jalon prism, and meter measurements. The survey form requires STABILITA || Jurnal Ilmiah Teknik Sipil Civil Engineering Volume 11, Nomor 1, Februari 2023 45 performance assessments of buildings, protected objects, sediment capture, engineering data, building conditions, and diagrams and photographs of buildings. The elevation of the sand in front of the seawall building against abrasion at Mampie Tourism Beach, Polewali Mandar Regency, by 8-15 cm demonstrates that this seawall building is effective at enhancing sedimentation and overcoming abrasion [5].
Breakwater Performance Against Waves at Manado Port, Wave Forecasting was evaluated utilizing the wave hindcasting method with wind data from 10 years of Bitung Maritime BMKG, including wave height, duration, and sea level elevation. In January 2014, westward waves at Manado port waters attained H = 1,483 meters and T = 5,118 seconds. The run-up height is between 1.398 and 1.93 meters. For milestones 10, 20, 30, 50, and 100, run-up heights ranged from 1,995 to 2,456 meters. demonstrates kman barrier against the current surge, which safeguards the tranquillity of the harbor pond [6].
Performance of the Tinobu Beach Safety Building, Lasolo District, North Konawe Regency. Based on Ministry of Public Works circular letter No. 01/SE/M/2011, the function and physical condition of Revetment 01 Tinobu Beach were evaluated. The building's physical condition index was 2.5, indicating that repairs are necessary and that action recommendations should be reviewed. The Tinobu Beach Safety Building has a building condition index of 2.25, indicating that it is in fair condition but requires surveillance. The Revetment 02 Tinobu Beach safety building has a building condition index of 1.4, which indicates that it is inacceptable condition but requires monitoring [7]. The complex bathymetry of the domain generates complex wave patterns in the domain's center. Breaking is essential (the spots parallel to the beach and perpendicular to these figures portray a circular pile if there is complete reflection). [8] Waves have harmed the Causeway structure. In this study, the author analysed the condition and performance evaluation of Causeway, but in the circular letter of the Ministry of Public Works No. 01/SE/M/2011 In terms of the weight of physical components according to the type of building, the Causeway can be categorized as "jetty." Therefore, there is a need for technical analysis of the sea area that directly interacts with the causeway so that the causeway does not cause significant damage that can threaten the coastal area or there is no error in the planning process of a coastal building, so it is important to conduct research on the assessment of the condition and performance evaluation of the causeway building of the Torobulu Ferry Crossing Port".

RESEARCH LOCATION
South Konawe Regency is a regency in the province of Southeast Sulawesi, Indonesia. Its capital is Andolo. This regency comes from the results of the expansion of Kendari Regency which was passed by Law Number 4 of 2003 geographically the SouthKonawe subdistrict K area is bordered each by: The north is bordered by Konawe Regency and Kendari City. To the west it borders Bombana Regency. To the south it borders Muna Regency. To the east it is bordered by the Banda Sea and the Maluku Sea.
This research was conducted in Laeya District, a sub-district in South Konawe Regency, a division of Lainea sub-district whose government center is located in Punggaluku sub-district.
This causeway is in Torobulu Village, there was damage to the causeway with the length of the causeway (Jt-1) is 50 meters, (Jt-2) is 19 meters, (Jt-3) is 19 meters, (Jt-4) is 95 meters, and (Jt-5) is 55 meters. but considering the magnitude of the waves that occur cause the amount of energy that occurs due to wave blows, where massive buildings cause considerable reflections, even during the season high waves of water overflow over the causeway building of the port verry Torobulu. This is what causes damage and changes in the shape of the building. The wave height, Hb, and coastal slope, give a scale of length and time scale for the shear wave, which is proportional to Hb/β and √Hb/β respectively, but does not STABILITA || Jurnal Ilmiah Teknik Sipil Civil Engineering Volume 11, Nomor 1, Februari 2023 46 affect the threshold of instability, that shear instability requires a very small value of N (N to about 0.001) so that shear waves can hardly be generated on the coast [9]

STAGES OF RESEARCH
At this stage the author identifies problems in the field which are then raised as topics or research titles. Based on the views of the community at the time of review at the research site, the community stated that the cause of damage to the coastal protection building was caused by the natural process where sea waves hit the beach protection building. A repeating solution procedure for solving the slope wave equation develops (combined refraction-diffraction). Existing models to investigate wave diffraction in coastal areas have one of two main problems; [10]  The width of the peak is a masonry coated by asphalt. The condition of the peak width is still in good condition.

External bodies
The outer body is a masonry wall, the condition on the first scour jetty or (Jt-1) suffered damage or scouring that was quite severe along 50 m. This damage or scour caused by waves has not been solved optimally when there is a tide. So, it needs to repair stucco on the jetty or causeway. Body condition, in good condition because there is additional armor, the condition of the outer body has been damaged or avalanche on the jetty wall along 50 m Figure 2.

Inner body
The outer foundation on the jetty (Jt-1) underwent slight scouring.
The process of this research stage is carried out with rare workmanship in outline described as in the following flowchart image.

RESULTS AND DISCUSSION
In determining the direction and height of waves requires analyzing wind data, effective fetch, forecasting waves in the deep sea, when the maximum significant wave repeat. The calculation analysis is as follows: From the results of wind data analysis with Wind Rose above, it can be concluded that prevailing wind occurs in the East direction with a percentage of 23.22%, while the most dominant wind speed occurs at speeds of 2-4 m / sec in the Southeast which is 10.77%. The results of the fetch calculation are listed in table 2.  Based on the results of the recapitulation of the fetch calculation above, the dominant fetch is the South fetch.
The illustration depicts natural forces, such as tides, waves, and ocean currents, that can cause devastation across the ocean when combined with strong winds. Second, by users, such as neglecting to maintain jetties, which results in a backlog of overuse of marine STABILITA || Jurnal Ilmiah Teknik Sipil Civil Engineering Volume 11, Nomor 1, Februari 2023 48 resources such as fish, resulting in ecosystem imbalances in the waterways. There is scouring of the causeway body The part of the building that experiences the heaviest pressure is the side facing the sea and is in the range against tides and wave seen in figure 4. where damage is more common (Crushed or perforated structures, natural stone or concrete blocks detached from place, eroded natural stone, broken/split concrete blocks). In this section it is necessary to have material in prime condition (shape, size, strength), therefore a replacement for new material (amor) or repair with the same strength is preferred, Revetment is located on the beach. wave properties necessary for port engineering calculations. To improve the practical applicability of such models, methods were developed to accommodate the structural effects of debris mounds often found along the sides of Port inlets [11], Surface water waves in coastal waters are generally modelled using the light slope equation. One of the parameters in the coastal boundary conditions for the equation is the direction in which the wave approaches the shore. [12] At certain times part of the building was not submerged. In this section, it is still feasible to do maintenance by rearranging the arrangement of existing materials to improve building performance. Good The condition of the building structure is assessed based on several indicators that become requirements if there is damage. This indicator will be different for each type of building, observations made on the causeway are as follows: The top of the building and its elevation, Loss of protective layer. Changes in the angle of inclination of the body, the condition of the constituent materials, and the body of the building that is scoured so that it loses volume. The effect of changes in ocean state, as measured by significant wave height Hs, at the joint distribution of height and periods of individual waves is considered. Wave data, obtained from Wave rider buoys. [13] CONCLUSION Based on the results of the analysis and discussion can be concluded as follows: where STA 0+000 has a good building condition index, 0+050 is good enough, 0+069 is good enough, 0+088 is good, 0+183 is good and 0+238 is good. So, in this case the function of the building is categorized as GOOD.