A laboratory model experiment system for subgrade drainage is designed and processed (declared a national invention patent); and the study of the subgrade moisture migration and laboratory underground drainage experiment under the influence of groundwater level fluctuation is conducted. By changing the height of the groundwater level

the dynamic response of subgrade humidity is studied in the case of without any waterproof measures

adding ordinary sand cushion

new drain material as underground waterproof and drainage base; and its effect of subgrade is evaluated. The results show that under the influence of the groundwater level fluctuation

the moisture of subgrade near the groundwater changes with the water table accordingly

the upper soil moisture has a relatively substantial increase because of the capillary action; when the water table is low

sand cushion plays a good waterproof and drainage effect; when the water table is high

the rise height of capillary water within the sand cushion is higher than the height of the sand cushion; and the subgrade moisture has a greater changes; new drainage materials can prevent the capillary water entering into the subgrade effectively; and it has good waterproof and drainage effects.