# Study on Load Transfer Mechanism of Pile-Supported Embankment Based on Response Surface Method
## 3 Analysis of the Numerical Simulation Results
### Single-Factor Test and Results Analysis
#### 3.1.1 Cohesion  
As shown in Figure 6a, with the increase in the cohesion of embankment fillers, the pile-soil stress ratio decreased gradually. When the cohesion was greater than 20 kPa, the pile-soil stress ratio tended to be stable. The variation law of the pile-soil differential settlement was basically the same as that of the pile-soil stress ratio. The pile-supported reinforced embankment transferred the embankment load to the pile through the combined action of the soil arching effect and membrane effect. The soil arching effect was essentially due to the stress redistribution caused by the pile-soil differential settlement, but the change in the differential settlement affected the exertion of the membrane effect. In order to clarify the proportion of the load shared by the soil arching effect and the membrane effect in the process of the embankment load transfer, the earth pressure at the top and bottom of the geogrid at the top of the pile cap was extracted. The difference between the earth pressure on the upper part of the geogrid and the filling earth pressure was the load transfer caused by the soil arching effect, and the pressure difference between the lower part and the upper part of the geogrid was the load \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**NO.**} & \multirow{2}{*}{**Cohesion [kPa]**} & \multirow{2}{*}{\begin{tabular}{c} **Angle of Internal** \\ **Friction [°]** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Elastic Modulus of** \\ **Embankment [MPa]** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Geogrid Strength** \\ **[kN/m]** \\ \end{tabular} } & \multirow{2}{*}{**Declaration**} \\ \hline
1 & 6 & 30 & 15 & 30 & Model validation \\
2 & 10 & 30 & 15 & 30 & \\
3 & 15 & 30 & 15 & 30 & \\
4 & 20 & 30 & 15 & 30 & Models 1–6 analyze the \\
5 & 25 & 30 & 15 & 30 & effect of cohesion \\
7 & 6 & 20 & 15 & 30 & \\
8 & 6 & 25 & 15 & 30 & \\
9 & 6 & 35 & 15 & 30 & Model 1 and models \\
10 & 6 & 40 & 15 & 30 & 7–13 analyze the effect \\
11 & 6 & 45 & 15 & 30 & of internal friction angle \\
12 & 6 & 50 & 15 & 30 & \\
13 & 6 & 55 & 15 & 30 & \\
14 & 6 & 30 & 10 & 30 & \\
15 & 6 & 30 & 20 & 30 & Model 1 and models \\
16 & 6 & 30 & 25 & 30 & Model 1 and models \\
17 & 6 & 30 & 30 & 30 & 14–21 analyze the effect \\
18 & 6 & 30 & 35 & 30 & of embankment elastic \\
19 & 6 & 30 & 45 & 30 & modulus \\
20 & 6 & 30 & 55 & 30 & \\
21 & 6 & 30 & 65 & 30 & \\
22 & 6 & 30 & 15 & 6 & \\
23 & 6 & 30 & 15 & 45 & \\
24 & 6 & 30 & 15 & 60 & Model 1 and models \\
25 & 6 & 30 & 15 & 90 & 22–28 analyze the effect \\
26 & 6 & 30 & 15 & 120 & of geogrid strength \\
27 & 6 & 30 & 15 & 150 & \\
28 & 6 & 30 & 15 & 180 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Geometric parameters of factors in single factor test. transfer caused by the membrane effect. After data processing, the development law of the load-sharing ratio of the soil arching effect and the membrane effect could be obtained. As shown in Figure 6b, when the cohesion is 5-20 kPa, the degree of the soil arching effect increased rapidly with the increase in the cohesion, and when the cohesion was greater than 20 kPa, the soil arching effect tended to be stable. The main reason for this was that the soil arching effect is related to the material properties of the embankment filler. Due to the pile-soil differential settlement, a shear surface appeared inside the soil, and the greater the cohesion, the greater the shear stress. Therefore, the greater the proportion of the embankment load above the soil between the piles that is transferred to the pile cap. That is, the degree of soil arching effect increases. In Figure 6a, it can be seen that with the increase in the cohesion, the pile-soil differential settlement decreased gradually. The shear deformation between the top embankment filler on the pile cap and the top embankment filler between the piles was reduced. Therefore, the shear stress decreased and the load sharing ratio of the soil arching effect tended to be stable.