# Research on Lateral Bearing Behavior of Spliced Helical Piles with the SPH Method
## 5 Field Test  
The tests were conducted on-site for the soils in the Pearl River Basin in Guangzhou and were separated into two parts to execute the test measurements (Figure 9). The first part was a pile installation test on a helical pile, where the strain gauges were attached 70 mm below the top of the pile, and the strain in a pile was transmitted as a voltage signal, via a bridge box, to a digital acquisition oscilloscope recorder. The second session was the horizontal load-bearing test. The tensile pressure transducer loaded the two piles, the piles were deflected, and the displacement of the spliced piles was measured using the reference rod and reference line as the reference position. The piles should be spaced more than ten  
Figure 8: Spliced pile (**a**) Pile side; (**b**) Soil particle displacement at pile tip. times the pile diameter, to avoid the overlap of soil stresses on the torque and horizontal load-bearing. Three tests were carried out, respectively, and the data were saved. The maximum strain of 95.91 \(\mu\epsilon\) in the spliced pile test corresponded to a torque of 666.23 N\(\cdot\)m and a sunken pile depth of 512.5 mm (Figure 10), with a maximum torque of 621.61 N\(\cdot\)m reached at a sunken pile depth of 568.88 mm during the simulation. The spliced pile simulation was a time-development process of the whole pile into the earth, where the larger value of the corresponding moment of the sunken pile torque was taken, and the whole process was more orderly, with a torque error of 6.7% between the simulation and test (Figure 3). The simulation of the initial period of sinking pile had a rising trend, which was due to the pile tip inserting into the soil and the soil extrusion friction, the soil resistance increased, the torque also increased. When the first blade rotated into the soil, there was shallow soil structure destruction, an upward bulge, the blade began to transfer torque to guide the sinking pile body, the pile body and soil extrusion were dense when the blade rotated into the dense area, it started to shear the soil, the slab of soil gradually relaxed, and then thinned. The interaction between the soil and the pile was weakened. The cycle repeated itself, but the overall trend was increasing. During the test, the initial pile tip had already sunk by 160 mm, due to the self-gravity of the spliced pile. The excess pore water pressure, cohesion, and consolidation structures formed in the test were difficult to set in the simulation, resulting in a significantly higher overall test trend than the simulation data. In the lateral bearing capacity test process, two sinking points at a distance of 1500 mm were selected at the base of the sunken pile and sunk into the spliced pile at a standard depth of 700 mm (Figure 10). Two reference rods were embedded in the pile side of the spliced pile, 200 mm away from the pile axis to ensure that the line between the two reference rods passed through the helical pile axis and were perpendicular to the line between the two piles, as a reference for measuring the displacement of the top of the helical pile. During the test, the distance between the two piles was shortened by turning the tightener with a manual lever to measure the displacement of the pile end and the corresponding force. The displacement and the corresponding oscilloscope strain values were recorded every five revolutions of the force tightener. When the spliced pile was deflected by 7\({}^{\circ}\), we waited for the oscilloscope to stabilize and recorded the value, which corresponded to a horizontal load-bearing capacity of 2903 N. The curve rose overall during the loading, and the slope of the curve changed considerably around 1 kN and 2 kN. The soil stiffness gradually increased within the initial 1 kN, due to soil relaxation and the pile  
Figure 9: (**a**) Field loading test; (**b**) Test measurement system. 1—Data acquisition system; 2—Sinking pile ground; 3—Spliced pile; 4—Strain gauge and winding wire; 5—Bridge box; 6—Tension sensor; 7—Afterburner; 8—Auxiliary pile.