## 3 Analysis of Discussion
### Analysis of Static Loading Test Results
The displacement of the pile body and the resistance of the soil are both zero at the inflection point of the curve, which can be regarded as the rotation center under the static load, and the position of the rotation center is approximately 6 times the pile diameter under the soil surface. With the increase in depth, in the area above the rotation center, the soil resistance around the pile gradually reaches the maximum value, then gradually decreases from the peak value, and decreases to zero near the rotation center. From the perspective of different loading levels, the soil resistance of the soil near the passive zone will increase with the increase in the load, which is consistent with the experimental results of Zhu. Figure 10 shows the soil resistance of the pile body and the displacement of the pile body through quadratic differentiation and difference after fitting the measured bending moment data. Finally, the graph of the change of soil resistance around the pile with the horizontal displacement of the pile body at different depths (1D-4D) of the soil body is obtained, and 1D-4D in the figure represents the depth of the soil layer from the soil surface. It can be seen from the figure that with the increase in the horizontal displacement of the pile body, the soil resistance at different depths under various loads gradually increases, but the development trend of soil resistance does not slow down whether it is the surface layer or the deep soil. When the soils at different depths have the same displacement, the soil resistance of the deep soils increases more. When the soils at different depths reach the same soil resistance, the displacements of the shallow soils are larger than those of the deep soils. Figure 9: The distribution of soil resistance around pile. It can be seen from the above analysis that the whole pile body rotates around the rotation center at 6 times the pile diameter below the mud surface (approximately 0.35 m below the mud surface). According to the arrangement position of the test sensor. Pore water pressure gauges No. 1, 2, 3 and 4 are located in the shallow soil around the pile, pore water pressure gauges No. 5 and 6 are located in the middle soil body, and pore water pressure gauges No. 7 and 8 are located in the deep soil body. For No. 1, 2, 5 and No. 8 pore water pressure gauges, it is located in the passive area where the pile body and the soil body squeeze each other. For No. 3, 4, 6 and 7 pore water pressure gauges, it is located in the active area where the pile body and the soil tend to separate from each other. Figure 11 shows the test results of the pore water pressure at different positions around the pile in the shallow soil in the static load model test. During the test, at the position of the No. 1 and No. 2 piezometers on the front side of the pile body, when the pile body is subjected to an external load, the soil on the front side of the pile body is squeezed, so the pore water pressure at this position rises. When the loading is stopped, the pore water pressure of the soil at the surface dissipates rapidly. For the No. 3 and No. 4 piezometers on the back of the pile body, due to the action of horizontal load, the pile and soil are separated, and the gap between the pile body and the soil is quickly filled with water. When the pile body continues to move forward, the soil behind the pile produces negative pore pressure. With the increase in the displacement of the pile body, the negative pore pressure of the soil at the positions of the No. 3 and No. 4 piezometers behind the pile also increases gradually. The pore pressure of the No. 3 piezometer, which is closer to the pile body, has a greater increase. Because the closer to the pile, the greater the soil displacement and the greater the negative hole pressure. As the loading stops, the pore water redistribution in the soil causes the pore water pressure to gradually fall back to the hydrostatic pressure value at the water level.