The overburden soil layer loads are exerted uniformly on the bedrock through the unconsolidated confined aquifer, making the load keep a constant during the excavation process.

• 有松散承压含水层时，上覆表土层的载荷通过松散承压含水层均匀地作用于下部基岩上，开挖过程中，基岩顶界面上的载荷基本保持恒定；