Strength Evolution Law and Mechanism Analysis of Red Sandstone Subgrade Soil Under Wetting-drying Cycles

The unconfined compression strength of red sandstone subgrade filling soil after wetting and drying cycles for 6 times was tested by using a self-designed wettingdrying cycle device with compaction of 93% and 95%, and a cement content of 0~7% (0, 3%, 5% and 7%). According to the test results, the strength evolution law of plain soil, cement-modified red sandstone roadbed filling is analyzed: For plain soil, strength is lost under one cycle of wetting and drying; For cement-modified soil, the greater compaction and the higher cement content, the smaller strength loss under wetting-drying cycles. In addition, The strength effect mechanism of dry wet cycles on cement stabilized red sandstone subgrade fill is analyzed. Under wettingdrying cycles, the strength change of cement-soil can be divided into three stages: The strength decay stage, Strength increased slightly stage and strength attenuation stage.1