The drain pipe jointing material of cement mortar with addition of water glass can effectively overcome the influence of groundwater and improve the quality of the joints.
在水泥砂浆中掺入水玻璃作为排水管的接口材料，能有效克服地下水影响，提高了接口工程质量。
2
In the meantime the time variation of the water level in the ditch has been taken into account, therefore the groundwater head are time-varying as the groundwater flows toward the drain system.