Reinforcement of side ditches: when the longitudinal slope at the bottom of the ditch is more than 3% in the soil section, reinforcement measures shall be taken; When paving the side ditch with dry rubble, rubble with flat surface shall be selected, and each masonry joint shall be embedded tightly with small stones. When paving with mortar rubble, the mortar for masonry joints shall be full and the trench body shall not leak water.