Rail services between Sleaford and Lincoln have been suspended after a bank slip caused by recent storms.
Network Rail said it had been monitoring the site at Ruskington after bad weather before Christmas and had detected movement on the bank overnight.
East Midlands Trains is running replacement road services until Monday while the damage is repaired.
Rail services between Sleaford and Peterborough are not affected.
Phil Verster, route managing director for Network Rail, said: "Detailed assessment indicates that we need 2,500 tonnes of stone to sufficiently stabilise the bank to allow trains to run.
"Our engineers will remain in the area for several weeks repairing wider storm damage."