THE DESIGN OF THE CONSTRUCTION OF RETAINING WALLS ON THE RIVER SLOPES OF KUIN

North Kuin Street, North Kuin, North Banjarmasin Subdistrict, South Kalimantan Sub-district is right on the outskirts of Kuin River. Precisely the road that is in front of the Sultan Suriansyah Mosque, where the road has experienced cracks that can potentially occur landslides. In the event of an avalanche, it will result in obstructed traffic activities on the road which also affect the economy of the surrounding community. So from that the soil retaining wall is needed to maintain the stability of the land on the outskirts of the Kuin River so that landslides do not occur. This design begins with identifying problems that occur. Next is data collection of investigations in the field and laboratory. Then the data obtained are analyzed and interpreted and then visualized in the form of stratigraphy by plotting the type of soil by the results of sondir and boring that have been interpreted. After that, check the initial condition of the slope so that the shape of the avalanche can be identified. Then proceed with calculating the forces acting on the retaining wall due to traffic loads and other loads above it to obtain carrying capacity from the ground. Then proceed with modeling and analysis using Geo Studio 2012 software to see the value of SF (safety factor). At the end of the calculation the volume and price of the work unit are calculated to obtain the amount of the budget plan (RAB). From the results of the analysis of the design of anchor plaster, it was obtained a box profile of FSP VIL steel plaster with a total length of 28 m plaster. At stake uses a steel pipe with a diameter of 91.44 cm which is set at a depth of 28 m. For slope stability with pile reinforcement obtained SF = 1.835> 1.5, it can be said to be safe. Based on the calculation of the volume and price of the work unit, this design requires a cost of Rp. 7,340,166,486, Keyword : Landslide, Retaining Wall, Design Of Plaster CERUCUK Volume 4 No. 1 2020 (83-106) 84


Background
Banjarmasin is one of the cities in Indonesia that has many rivers in several areas. Therefore, in the city of Banjarmasin, there are many roads on the banks of the river. One of them is North Kuin Road; this road is on the edge of the Kuin River. Precisely in front of the Sultan Suriansyah Mosque, where roads in the surrounding area have cracks that have the potential for landslides. This event can be influenced by several factors. The main factors that influence are erosion / scour due to the flow of the Kuin River which causes a lot of soil mass to be washed away, so that the mass resistance of the soil will decrease which results in damage to the road. Another factor that affects road damage is that the load passing over it is too heavy.
The design and manufacture of retaining walls in the area of road damage is the right solution. This design aims to be able to support the soil on the road and function to hold the soil and prevent the danger of landslides due to water loads, soil weight and the load that works. The retaining wall can be said to be safe if the retaining wall has been considered for its safety factor, both against the danger of shifting, the danger of overthrowing, the decrease in carrying capacity of the soil and faults. On retaining walls, stability is one aspect that should not be ignored, because the stability of the retaining wall greatly affects the age of the retaining wall design itself.
If a landslide occurs, the disruption of activities on the road will also affect the economy of the surrounding community. So from that the soil retaining wall is needed to maintain the stability of the land on the outskirts of the Kuin River so that landslides do not occur. The construction of a retaining wall must be thoroughly mature and based on the calculation of stability and also meet the requirements of safety factors.

Problem Formulation
In this Final Project the problem raised is regarding the design of the construction of a retaining wall that is suitable for the surrounding area, safe, Volume 4 No. 1 2020 (83-106) 85 and able to cope with the landslide and fulfill the technical requirements used.

Designing Purpose
The purpose of this design is : 1. Design the construction of a retaining wall that is suitable for the surrounding area, safe, and meets the technical requirements used, 2. Get the design results in the form of a drawing plan / DED (Detail Engineering Design).
3. Obtain estimates of the Budget Plan (RAB).

Problems Limination
The limitation of the problem in this Final Project is : 1. Land data that is used as the basis of reference in design is sondir data, borlog data, and SPT data, 2. There is no review of road planning issues, 3. Design slope stability planning using alternative slope reinforcement. 4. In planning to calculate the budget plan (RAB).

Benefits of Design The
The benefit of this design is to provide an alternative design for retaining wall on the river slope for the city government so that it can be handled safely.

Case Study Locations The
The location of the construction case study is in the Kuin Utara Street Section, North Kuin Village, North Banjarmasin District, South Kalimantan Province.

Avalanches and Slopes
According to Arsyad (1989: 31) landslides occur as a result of the sliding of a volume of soil above a somewhat impermeable layer of water that is saturated with water. Layers consisting of clay or containing clay content will act as launchers. Based on the movement of its demise, landslides are grouped into several parts, namely : a. Natural slopes, namely slopes formed by natural activities, such as erosion, tectonic movements, and so on.
b. Man-made slopes, due to excavation or cutting on native soil. c. Landfill slopes, such as landfills for roads.

Slope Stability
According to Craig (1989), gravitational forces and seepage tend to be the cause of slope instability. As for ways to make slopes safer, according to Wesley (1997), namely using : 1. Reducing the driving force or driving moment, that is by changing the shape of the slope.
2. Enlarges the resisting force, that is by giving the land to the foot of the slope (counterweight) or by making a retaining wall.
Gravitational forces and seepage cause instability on natural slopes, slopes formed by heaps and excavations. Slope failure types are divided into rotational collapse, translation collapse, and combined collapse.
In this design, a reinforced river slope will be used again as a local road that can be used by the community around the design site so that the traffic load used is evenly distributed.
Based on the results of the SPT testing, to be able to determine the soil profile, the data is correlated with the existing provisions, so that the data from the N-SPT test can be used in this design and to obtain the undrained shear strength value, the formula is used : CERUCUK Volume 4 No. 1 2020 (83-106) 87

Lateral Soil Pressure
Lateral soil pressure is a major design parameter in the problem of retaining walls. There are two classical theories that discuss lateral soil pressure : 1. Theory of Coulomb lateral soil pressure (1776) 2.
Rankine lateral soil pressure theory (1857) Both of these theories provide an analysis of the magnitude and direction of the two types of lateral soil pressure called active pressure and passive pressure.

Soil Retaining Walls
Soil retaining wall is a construction that is built to hold land that has a slope/slope where the soil is not stable so that it can occur collapse / landslide on the land. The retaining wall is used to withstand lateral soil pressure caused by native soil or unstable soil.
There are various types of soil retaining walls as follows (Braja M Das,

Plaster
Plaster is a construction that can withstand the pressure of the surrounding soil, preventing the occurrence of landslides and usually consists of plaster walls and supports. Construction of plaster walls consists of several plaster sheets which are fixed into the ground, and form a vertical continuous wall formation which is useful for holding back soil or sloping land. Plaster consists of parts that are made in advance (prefabricated) or printed in advance (pre-cast).
The function of plaster is ; a. Land retaining structures, for example on cliffs of highways or cliffs river.
b. Soil retaining structure at the excavation. The purpose of making RAB is to find out the price of parts/work items as a guideline for issuing costs during the implementation period. Besides that, the buildings to be erected can be carried out effectively and efficiently.

Design Stages
To provide an overview of the stages and simplify the achievement of goals, it can be made the flowchart of activities as follows :

The Topographic Data
On the Kuin Utara Street section, it experiences cracks on the part of the road.
Distance from the landslide area from the river bank to 4.8 m.
From topographic mapping, topographic maps are obtained that describe the contours at the location of the investigation, and the cross-section of the river. In the cross-section of the river, a cross-section of the stratigraphy can be made. The following is a picture of the topographic map and transverse river cross-section.
Based on the analysis in the field it can be seen that avalanches are caused by erosion / scour caused by the flow of the Kuin River which causes a lot of land mass to be washed away so that the resistance of soil mass decreases which results in cracks on roads that have the potential for landslides.

Land Data
In the design required data that supports the design such as testing data in the field. Retrieval of data in the field in the form of sonder test data (CPT) of 1 test point. Not to forget also testing boring (SPT) which is around the sonder test point.

Data Interpretation
Based on the results of the SPT testing, to be able to determine the soil profile, the data is correlated with the Terzaghi and Peck 1967 tables, empirical formulas according to Stroud (1974), and empirical formulas according to Hara et.
Al. (1971). Based on these correlations, the following land parameters can be taken : To determine the content weight γ of the soil also use using the table N-SPT Relations Against the Consistency of Clay Soils. Therefore the soil profile can be divided according to the consistency of clay.
The soil at this location is considered saturated clay so that the inner shear angle ( ) = 0, is considered saturated because it conditions the soil in the most critical condition to be able to make a safer design.
Based on the results of the sonder test, to be able to determine the soil profile, a table of interpretation of the results of land investigation is used using a sondir on the civil engineering book page 132. Based on these correlations, the planning parameters are as follows : Tabel 4.2 Profile Of Soil Layer Based on CPT Test

Stratigraphy
Based on the results of soil classification, the soil stratigraphy is divided into several layers based on the testing points of boring and sondir as a reference of the depth of the slope, so that the most conservative values are taken :

C Residual Determination
From observations in the field, the road cracking point was seen 4.8 meters from the edge of the river slope. Because the slopes experience symptoms of the landslide, so the value of shear strength at a depth of the soil approaching the landslide needs to be corrected to Cu Residual.
Residual Cu is determined by estimating the safety value of SF ± 1 by assuming that the landslide is approaching in the field so that the slip plane is set at that depth, in this design the collapse field reaches ± 8 meters depth. Volume 4 No. 1 2020 (83-106) 93 So that the soil profile data reaches a depth of ± 8 meters using Cu residual with a value of 0.35 tons / m2. The soil at ± 8 meter depth is considered to be soft soil with a friction angle of 0 because it is considered to be saturated clay.

Parameter Desain
Soil design parameters can be seen in the following table:

Calculation Of Soil Pressure Coefficient
In calculating the soil pressure coefficient using the theory of Rankine, as follows :

Geostudio Program
In this analysis traffic loads, loads outside the road, and road pavement are included in the GeoStudio program. The load on road and road construction is 21.3 kN / m2 while the off-road load is 10 kN / m2. In this analysis, percutaneous will be added using steel plaster. The results of the previous analysis, namely the initial conditions obtained SFcritical = 0.959 according to conditions in the field.
After being given percutaneous with steel plaster and calcined, it was obtained SFcritical = 1,835. The safety factor that was obtained was not SF ≥ 1.5 based on Pd. T 09-2005-B is taking into account high-risk factors. From the results of this analysis, it can be concluded that the slope is safe after being given steel plaster reinforcement with SF = 1,835 ≥ 1,5.
Picture 4.9 Slope Landscaping Results After Being Given Strengthening

Cost Budget Calculation
Tabel 4.5 Budget Plan Tabel 4.6 Recapitulation Of The Budget plan 5. Closing

Conclusion
Based on the results of the plasterboard construction design as an alternative to handling landslides in the North Kuin Street section, North Volume 4 No. 1 2020 (83-106)