土工格栅加筋垫层的效果检验

VERIFICATION OF REINFORCED EFFECT ON GEOGRIDCUSHIONFOR FOUNDATION STRENGTHENING

泉州市两个古建筑城门楼工程(朝天门和临漳门)对沉降敏感,原设计采用桩基础加钢筋混凝土板的地基加固方案,因其造价昂贵,施工困难,而改为土工格栅加筋垫层的方案。由于当地首次采用加筋垫层,为了检验其效果,进行了多达21组载荷试验,并进行了沉降观测。结果表明,土工格栅加筋垫层可使地基承载力成倍提高,同时能有效地均衡差异沉降和减少总沉降量。建筑物的实际沉降非常小,朝天门城门楼的最大沉降量不超过1cm,临漳门则几乎测不出沉降量,完全能满足工程要求,由此节省了300多万元资金,并使施工大为简化。

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.