Abstract：Aiming to study the loess area highway widening project，based on the large-scale foundation settlement simulation test platform，a scale test with the geometry similarity ratio of 1∶1 is carried out；and the roadbed internal soil and the reinforcing material deformation monitoring systems is also established to analyze the response mechanism of internal soil and reinforcement of the roadbed constructed under the conditions of old and new foundation differential settlements. The results show that：under the widened embankment load，the roadbed internal soil experiences a constant process of deformation and coordination with the increasing foundation differential settlement. When the differential settlement S reaches to 9 cm，subgrade and pavement layer appear a slight void. Laying the geotextile material on old and new roadbed splicing segment can lead loose soil to form the compaction complex，which can enhance the overall stability and mechanical properties of roadbed soil and easily form the arch effect. Besides，the geogrid can digest the settlement between new and old roadbed in a certain degree，but the effect is limited. The geogrid inside the soil plays a coordination role in the subgrade soil deformation. The reinforcement force is not uniform and the corresponding alternating of tension and compression strain appears. With the increasing foundation differential settlement，strain show a increasing trend as a whole. When the differential settlement S between old and new foundation reaches to 16 cm，tension and compression strain of geogrid tend to be stable. The ultimate amount of geogrid tensile or compression changes only 2 mm，far less than the destruction limit of geogrid.
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2013, Vol. 32 
