# 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
#### 3.1.3 Elastic Modulus of Embankments  
As shown in Figure 8a, the pile-soil stress ratio decreased rapidly with the increase in the elastic modulus of the embankment filler, and reached its minimum value when the elastic modulus was 35 MPa. Then, with the increase in the elastic modulus, the pile-soil stress ratio increased slightly. The main reason for this is that the embankment load transfers to the pile under the combined action of the soil arching effect and the membrane effect. As shown in Figure 8b, when the elastic modulus of the embankment was small, the soil arching effect increased and the pulling film effect decreased. Since the membrane effect had higher efficiency for the load transfer, the pile-soil stress ratio decreased gradually when the elastic modulus of the embankment was less than 35 MPa. As the elastic modulus of the embankment continued to increase, the pile-soil differential settlement tended to be stable, so the membrane effect was gradually stable. A larger elastic modulus could promote the soil arching effect. Therefore, when the elastic modulus of the embankment was greater than 35 MPa, the pile-soil stress ratio increased slightly.  
As shown in Figure 8b, with the increase in the elastic modulus, the load-sharing ratio of the soil arching effect increased rapidly, and when the elastic modulus was 10-35 MPa the growth rate of the load sharing ratio of the soil arching effect was larger. The main reason for this is that when the elastic modulus of the embankment increases, the load transfer of the embankment mainly comes from two parts: the first part is the shear stress caused by the pile-soil differential settlement of the embankment filler at the top of the pile cap and the top of the soil between the piles; the second part is the connection force between soil particles. The greater the elastic modulus of the embankment filler, the greater the deformation resistance of the embankment, and the higher the integrity.  
Figure 8: _Cont._  
From the microscopic point of view, this shows greater connection strength between soil particles. When differential settlement occurs on the subgrade surface, the embankment load on the upper soil between piles transfers to the pile cap through the connection force between soil particles. Therefore, with the increase in the elastic modulus, the load sharing ratio of the soil arching effect increased rapidly under the combined action of shear stress and connection force. In contrast, Figure 8a shows that when the elastic modulus was large, the pile-soil differential settlement gradually tended to be stable. The shear deformation between embankment fillers tended to be stable, that is, the load transferred by the shear stress remained basically unchanged. At this time, the load transfer was mainly caused by the connection force between soil particles. Therefore, as the elastic modulus continued to increase, the growth rate of the load sharing ratio of the soil arching effect gradually decreased.