The type of foundation that is often used in Banjarmasin is for wooden poles and concrete poles in building construction as processing on swamp land (wet = peat) in the form of soft soil. There is a phenomenon that the application of this type of foundation in the field preceded the research, so that the development of field applications preceded the scientific literature. Further research is needed on the application of foundation materials in soft soils with shallow foundation types.
In this research, field observation studies will be conducted at various locations of low-rise simple buildings and other uses such as fences and retaining walls in Banjarmasin and the surrounding area. It is investigated in detail by identifying its application techniques in the field. Then a comparison of types, types, materials (materials) and techniques (methods) will be carried out in other areas (outside Banjarmasin) and even from outside the region. From the identification, the advantages and disadvantages of each type with various functions and uses of the foundation will be obtained.
The purpose of this study is to provide an applicative description of the foundation in Banjarmasin with comparison of other materials from other areas. There will be a comparison of foundation materials that can be applied to soft soils and how the application techniques are implemented in the field. It is necessary to reveal how to build or carry out the foundation by considering the condition of the type of soft soil and even water, namely swamp, either slightly dry or high water conditions.
1.1. Foundation In Soft Soil
Wooden poles are widely used for the construction of house elements in Banjarmasin. The wood used is ironwood. The wooden pile foundation uses foundation construction, including log construction, kalam kalang galam construction and kaca puri construction [1]. This castle glass foundation, according to Iskandar [2], is considered to behave like a continuous foundation with a long foundation is the length of the galam pole used.
Ironwood is used as a house pole in the form of a beam as the main material for poles and sticks that rest on the ground as a support for the house building [1], while galam wood (Melalueca leucadendron) is used as a pillar pile. Cerucuk aims to increase soil shear resistance in another sense is soil improvement [3],[4], [5], [6], [7], [8], With this niche, the carrying capacity of the soil has increased. This galam wood cerucuk foundation is very suitable for conditions in swampy areas that are always watery (submerged) because it has a unique property that if it is always submerged, its strength will always be maintained as evidenced by the old building with the galam wood foundation being dismantled. more than 20 (twenty) years [2], [9]. The commonly used galam cones are 3 (three) and 4 (four) meters long for 1 (one) floor buildings and a minimum length of 7 (seven) meters for 2 (two) floors. The diameter of galam wood on the market is about 12 (twelve) centimeters. For the carrying capacity of a single galam tree trunk, the maximum load that can be carried is 170–300 kN [10].
The development of the wooden pole construction of the Kacapuri type is a theoretical variation. The bottom of the pole/stick is called Kaca Puri while the top is called kalang sunduk. The end of the pole is buried in the ground. Theoretically, this alternative castle glass foundation variation has a calculation of being able to withstand a load of 1.25 tons which is expected to be able to support the load of the residential floor structure of 150 kg/m2–250 kg/m2 [1].
Foundations in Banjarmasin are adapted to the soil conditions which have a layer of soft soil with a thickness of up to 25 (twenty five) meters and hard soil on average at a depth of about 35 (thirty five) to 45 (forty five) meters [9], [10]. The carrying capacity of this swamp is very low at 0.2 kg/cm2 [12].
Soil conditions in Banjarmasin which are mostly swamp land (wetlands) have different conditions between one land plot and another [13], the general conditions are dry soil (overgrown with plants/grass), slightly wet or slightly dry marked by the presence of water during foundation excavation, and soil with high water (fully submerged in water) as shown in Fig. 1.
The house construction system in Banjarmasin is a wooden pole construction [12], consisting of a row of ironwood poles with short distances to carry the load of the building evenly. Meanwhile, the development of a replacement for ironwood poles is reinforced concrete poles [14].
House buildings in Banjarmasin are generally constructed on stilts where the floor of the house is above the ground with wet land conditions [13]. To support this condition, poles are used to support the building of the house. The house is in the form of wooden poles using ironwood material (Fig. 2). At the top, after the wooden pillars, a frame construction is used which is usually also made of ironwood material. For infilling/covering walls, bricks are used which are installed standing up, in order to keep the building load lighter. This standing masonry is also suitable for filling walls which are generally constructed of wood frames as well. The wooden frame of this wall is a row of poles that are installed along the wall at a distance of 1 (one) meter.
Variations and modifications of wooden poles are found using concrete poles and foundations, while the top of the building from the floor upwards continues to use wooden frame construction. The size of the slab foundation looks about 90 x 90 cm. The concept of replacing the construction of a row of wooden poles and changing the loading system into a local bearing load. As a result, there must be the use of larger horizontal wooden beams as a load divider between the concrete piles. The large wooden beams used must of course be larger than the wooden beams composed of wooden poles [13].
1.2. Foundations Other Than Wooden Piles
For the construction of modern (permanent) buildings, variations and modifications are carried out in the form of replacing wooden pole materials with concrete pole materials [13]. While the foundation is used concrete slabs.
For the concrete slab foundation, galam piles are used to improve the bearing capacity of the soil (Fig. 3). Group composition is used. For one concrete slab, several combinations of the number of stakes and the width of the concrete slab are used. From the field findings, the smallest concrete slab size is 90 x 90 cm using a minimum of 9 (nine) galam stakes measuring 3 to 5 meters. Concrete slab measuring 120x120 cm uses 16 to 25 pieces of galam stakes measuring 5 to 7 meters. The use of galam piles in this group arrangement is commonly used to accept local loads such as the concrete slab foundation mentioned above.