Existing consolidation model of ground with vertical drains under instantaneous loading is extended for timedependent loading. According to the consistency of average consolidation degree, the ground with partially penetrated drains is turned into an equivalentdoublelayered ground under single ramp loading, and the analytical solution of onedimensional consolidation is given. Compared with FEM result, the method of equivalentdoublelayered ground can be used to calculate the consolidation degree of ground with partially penetrated vertical drains. The results of the numerical example show that the consolidation degree of ground with partially penetrated vertical drains is reduced under the effect of loading time and the influence on the upper ground is more obvious. In preliminary calculation, multiramp loading can be replaced by a single ramp loading.