The void beneath cement concrete pavement slab (CCPS) is one of the common defects, which can cause the pavement cracking when heavy vehicle load is exerted on the pavement. The void expands when the water trapped inside erodes the inner surfaces of void circularly, bringing more cracks easily. Due to the close relationship with the erosion of the void, the hydrodynamic pressure distribution in saturated void beneath CCPS is investigated in this paper. Firstly, a theoretical expression of the hydrodynamic pressure in saturated void is proposed taking in account the law of mass conservation and the theorem of momentum. Secondly, the deformation patterns of the CCPS and the fluid-structure interaction (FSI) are discussed based on the proposed method. The results show that the hydrodynamic pressure and the water flow velocity in the void are overvalued while the rigid deformation pattern of CCPS is employed and the FSI is ignored. Finally, some influence factors are discussed. It is obtained that, both the maximum hydrodynamic pressure and the average velocity of water increase with the increase of the load amplitude, the vehicle speed and the void dimension. The conclusions are helpful for the prevention and maintenance of void beneath the CCPS.

水泥混凝土路面板（CCPS）下的空隙是常见缺陷之一，当车辆承受重载时会导致路面开裂。当陷在内部的水圆形地腐蚀空隙的内表面时，空隙会膨胀，很容易产生更多的裂缝。由于与孔隙侵蚀密切相关，本文研究了CCPS下饱和孔隙中的水动力压力分布。首先，考虑了质量守恒定律和动量定理，提出了饱和孔隙中水动力压力的理论表达式。其次，基于所提出的方法，讨论了CCPS的变形模式和流固耦合。结果表明，在采用CCPS的刚性变形模式而忽略FSI的情况下，孔隙中的水动力压力和水流速被高估了。最后，讨论了一些影响因素。结果表明，最大流体动压和平均水速都随负载振幅，车速和空隙尺寸的增加而增加。这些结论有助于预防和维护CCPS下方的空隙。