关键词: 道路工程；黄土半填半挖路基；模型试验；毛细阻滞层；盲沟

Abstract: Aim at the problem of water-induced damaged subgrade in Longdong loess area, the treatment technology of capillary barrier layer combined with vertical and horizontal blind ditches was proposed, taking the half-filled and half-excavated subgrade as the research object. Through the subgrade model tests under three working conditions, the variation law of the internal humidity of the subgrade under the action of simulated top ponding infiltration and groundwater capillarity was analyzed. Research results show that setting blind ditch on the upper part of the subgrade can promote the early water drainage of the subgrade; setting capillary retarding layer at the base of fill road can effectively block the rise of underground capillary water and ensure that the volume moisture content of filled subgrade and slope is in a relatively stable state (25.5%). The volume moisture content of each soil layer of the subgrade increases significantly under the comparison condition without any setting, moreover, the difference of the volume moisture content of the soil layer at subgrade filling and excavation junction reaches 20%. Thus, it can be seen that the significant difference of moisture content at subgrade filling and excavation junction may be the main reason for settlement, deformation and even slipping of subgrade in subsequent operation.

Key words: highway engineering; the half-filled and half-excavated loess subgrade; model test; capillary barrier layer; blind ditch