To investigate the effect of consolidation soft soil

three groups of model tests were designed. The first group was PVC pile-net composite foundation

the second was pile-cap-net composite foundation

and the third was PVC and sand pile composite foundation. Butter was coated and plastic membrane was covered on inner side wall of model cast to reduce border effect. The gauges were glued with epoxy on the surface of the model with PVC piles and geogrids to measure the stress of PVC piles and geogrids. Soil pressure cells were installed in the middle of piles and the top of the sand piles

and dial indicators were installed in the middle of road and road shoulder to measure deformations. It is that shown: 1) as for the distribution of the road settlement and the differential settlement

the settlements of the third group are the largest and those of the second group are the least; 2) in terms of the stress ratio of PVC pile and soil

the values of the first group and the third group are similar

while the value of the second group is much larger; 3) the change of geogrid strain is disorderly. There are periodic peaks in the strain of geogrid of pile top and periodic troughs in the soil between the piles. The geogrid strain of the second group measured in the corresponding spot is much larger than those of the other two groups. The results of three groups of tests illustrate that if the condition is permitted

it would be the best to adopt the scheme of pile-cap-net composite foundation

which has better reinforcement effect for soft soil.