VERIFICATION OF REINFORCED EFFECT ON GEOGRIDCUSHIONFOR FOUNDATION STRENGTHENING

In Quanzhou city,there are two ancient city-gate buildings which need to be reconstructed,i. e.,the Chaotianmen and Linzhangmen city gate buildings. The foundations of the two structures are very sensitive to settlement and have to be strengthened. The original design scheme was pile foundation plus concrete slab with steel bar reinforcement. Since it is expansive and hard to construct,an alternative method is taken into account. The geogrid reinforcement cushion is used underneath the footing. However,due to lack of experience of local soil,21 field loading tests were carried out to verify the effect of geogrid cushion. The results show that the bearing capacity of the foundation reinforced with geogrid cushion is increased almost twice as the natural foundation. Meanwhile,the deformation behavior of the reinforced foundation is also improved. The differential settlement is harmonious and the total settlement can also be reduced. The in-situ monitoring shows that the maximum settlement for Chaotianmen city gate building is less than 1.0 cm,while for Linzhangmen city gate building almost no settlement is observed. It means that the new design can completely meet the requirement of those structures. Moreover,the cost of reconstruction work was reduced more than 3 million RMB and the construction was also simplified.