Soil bearing capacity is the ability of the soil to withstand the load of the structure without experiencing excessive collapse or deformation. In general, the bearing capacity of the soil is expressed in units of pressure and is influenced by several factors such as soil type, density, moisture content, and depth of the foundation. In the context of geotechnical engineering, determining the carrying capacity value is essential for designing a safe and stable building foundation. Classical approaches such as Terzaghi's theory and other empirical methods are still widely used, but continue to be refined to accommodate the complexity of soil characteristics in different regions (Namdar, 2020); (Tahmid et al., 2021); (Adunoye et al., 2024).

Soil settlement is the vertical movement of the soil surface downwards due to the load working on it, both the load from the structure, the load of the backpile, and changes in soil conditions. This phenomenon occurs due to compression of soil grains or the release of water from soil pores.

According to Das (2011), settlement is defined as the vertical deformation of the soil that occurs due to a reduction in the volume of soil pores under the influence of stress. The magnitude of the decline depends on the type of soil, load characteristics, depth of the soil layer, and drainage conditions.

Elastic deformation is the vertical deformation of the soil that occurs immediately after the load is applied, without requiring time for the release of

pore water. This phenomenon is generally dominant in sandy, gravel, or high- permeability soils, as the pore water can move quickly so the response is almost immediate. This theory is based on soil mechanics and the theory of elasticity (Boussinesq, 1885), which states that the stress in the soil due to surface load can be calculated, and the deformation that occurs is proportional to that stress.

The Vesic method was used to calculate the elastic decrease based on the parameters of the CPT, and the pole load data from the PDA results and using the soil elasticity modulus parameter from the correlation.

Using the formulation of Vesic (1977):

𝑠 = 𝑞.𝐵.(1−𝑣2) × H

𝐸

Where :

s = Drop of the elastic of the pole (m or mm)

q = load pressure (kN/m²), assumed to be 100 kN/m² (133–143 tons) B = foundation width = 0.3 m (for 30x30 square pile)

Es = modulus of soil elasticity (kN/m²) (from UDS data) v = Poisson ratio of soil, average 0.30 – 0.35

H = soil layer thickness (m)

One of the methods of testing the carrying capacity of foundations that is currently used uses the Pile Driving Analyzer (PDA) test dynamic test method. The dynamic test method is considered more economical and efficient than static load testing with reliable results. In addition to the relatively fast test time, where in a day multiple pile tests can be carried out and can be carried out on a limited work area, the PDA test can also evaluate the axial bearing capacity, integrity or integrity of the pile, as well as evaluate the maximum decrease and permanent decrease of the pile foundation or drill.

Rausche, F. (2015) explained that PDA data analysis was carried out using the Case Method procedure which included measuring velocity and force data during the test (re-strike) and calculating dynamic variables in real-time to get an idea of the bearing capacity of a single mast foundation. The follow-up analysis carried out is the CAPWAP analysis, which is the signal matching analysis (SMA) method using PDA test results data to provide more detailed analysis results, such as: the amount of end resistance and friction resistance of the single pole foundation, the efficiency of the punching device, the descent, and the simulation of static loading test.

ASTM (2017) in its standard D4945-17 provides an explanation of the testing procedures and steps using the PDA test. The foundation of the pillar tested was already in a state of implantation then the pillar was hit several times. The punch is stopped after obtaining good enough recording quality and high punch energy. The number of hits required is determined by the fluctuations in the amount of energy actually received by the pole. The quality of the recording

also depends on the accuracy of the instrument installation as well as the performance of the computer and electronic system. If the instrument is not properly installed or the computer system is not working as expected, it will be immediately known from some of the initial impact recordings. The ideal hammer weight for PDA testing is recommended to be 1-2% of the mast foundation capacity required to be achieved. Meanwhile, the number of pile foundations to be tested ranges from 1-2% of the total number of piles or at least 1 (one) test for each pilecap. The stages of implementing the PDA test are explained as follows:

Placement of 2 pairs of sensors opposite, one pair of sensors consists of a strain transducer and an accelerometer, which are mounted under the mast head with a minimum distance from the mast head to the sensor of 1.5D - 2D, where D is the diameter of the mast).

As a result of the hammer impact on the mast head, the sensor will pick up the vibrations that propagate on the mast and convert them into electrical signals, which are then recorded and processed with a Pile Driving Analyzer (PDA). The results of the PDA recordings were further analyzed with the CAPWAP software.

CAPWAP (Case Pile Wave Analysis Program) is a numerical analysis application program that uses data input in the form of force and velocity measured by PDA. The CAPWAP analysis aims to estimate the total bearing capacity of the pole, the distribution of the ground resistance force along the pole and at the end of the pole, as well as separate it into dynamic and static resistance parts.

Analysis using CAPWAP will produce: Bearing capacity (Ru); End Style (Rb); Swipe force (Rs); Displacement (DMX) as seen in Figure 1.

The results of the UDS test in the laboratory from the results of soil investigation as presented in Table 1 show that the soil layer at the BH 1 drill point generally consists of 3 (three) stratigraphy, namely very soft clay (CL) up to a depth of 18 m and clay with high plasticity (CH) at a depth of >18 m.

Table 1. BH Laboratory Results 1

The results of the UDS test in the laboratory from the results of soil investigation as presented in Table 2 show that the soil layer at the BH 2 drill point generally consists of 3 (three) stratigraphy, namely very soft, saturated (CH) to a depth of 22 m and rigid (CH) at a depth of >22 m

Table 2. BH Laboratory Results 2

Based on the data of the laboratory test report, the dry content weight of the soil was 0.74–1.26 g/cm³. With an empirical approach: E = 500 × γ_d The estimated modulus E = 370–630 kN/m², so that the decrease that occurred ranged from ±12–13 mm.

PDA testing was carried out at 2 points in 2 different building periods, namely Point A3 TP 9 in the parking building and point B2. TP.7 in the Rawat Building. Test results of A3 TP.9 pile (Square Pile 30x30 cm, L = 36.3 m, Penetration Length 35.3 m).

Table 3 shows the test mast capacity of 143.0 tons with a friction resistance of 113.0 tons and an end resistance of 30.0 tons. The total decrease was 19.4 mm

with a steady decrease of 2.0 mm. Meanwhile, the B2 TP.7 (Square Pile 30x30 cm, L = 36.5 m, Penetration Length 35.5 m) shows a test pole capacity of 133.0 tons with a friction resistance of 99.0 tons and an end resistance of 34.0 tons. Total decrease of 18.0 mm with fixed decrease of 1.4 mm.

Figure 3. PDA Test Location and Data Table 3. CAPWAP Analysis Results

Table 3. CAPWAP Analysis Results

Figure 4. Results of the A3 Pole PDA Test Graph. TP.9 and B2. TP.7

CPT testing was carried out at four points (Figure 5) with a maximum depth of 38 meters. With a qc value of 250 kg/cm² at a depth of >35 m, which indicates solid soil conditions in the lower layer.

Figure 5. CPT Chart Results Table 4. Decrease Calculation Results

Table 4. Decrease Calculation Results