1. The number of piles used in design can be determined based on settlement control conditions, i.e., the allowable settlement;
2. The overall safety factor of the foundation must not be reduced, and verification should be carried out according to the actual state of the combined action of piles, soil, and pile cap. The joint action of piles and soil is a complex process. As settlement develops, the load sharing between piles and soil continuously changes. As a control for the most unfavorable state, the load at the pile top may approach or equal the ultimate bearing capacity of a single pile. To ensure the safety of the pile foundation, it is stipulated that the sum of the pile group bearing capacity and the soil bearing capacity, calculated based on the characteristic value of bearing capacity, shall be greater than or equal to the sum of the vertical force acting on the top of the pile cap under the standard combination of actions and the self-weight of the cap and the soil above it;
3. To ensure the joint action of piles, soil, and pile cap, friction piles should be used so that the pile foundation produces allowable settlement, the bottom of the pile cap does not become separated from the soil, and the resistance of the bearing stratum at the pile tip is fully mobilized during the settlement process of the pile foundation. At the same time, the pile tip should be placed in a relatively good soil layer to prevent excessive settlement and achieve the expected settlement control. To ensure that the bottom of the pile cap does not become separated from the soil, when the soil at the bottom of the pile cap is underconsolidated soil or soft soil with little value for bearing capacity utilization, it should also be treated.