原位载荷试验确定复合地基承载力方法研究

Study of method for determining bearing capacity of composite foundation by in-situ loading test

原位载荷试验是确定复合地基竖向承载力最可靠的方法。许多工程实例表明,当载荷试验加载不充分,无法通过极限荷载判断地基承载力特征值时,应根据《建筑地基处理技术规范》方法确定复合地基承载力特征值,但该值有时会偏小,这样的结果会导致设计人员采用的复合地基承载力特征值偏低,设计过分保守,由此造成技术投入加大,工程造价增加的不良结果。通过某工程同场地、同条件的一组素混凝土桩复合地基原位载荷试验数据与一组天然地基原位载荷试验数据对比,研究原位载荷试验测定复合地基承载力特征值方法的不足,讨论产生缺陷的原因。补充完善了《规范》通过载荷试验确定复合地基承载力确定方法,以期更好地促进复合地基技术及原位载荷试验的推广应用。

In-situ loading test is the most reliable method for determining bearing capacity of composite foundation. Many construction projects show that, when loading tests haven't reached a high degree of loading, the characteristic value of subgrade bearing capacity is unable to be determined by ultimate load. In this case, the method suggested by technical code for ground treatment of buildings should be employed to determine the characteristic value of composite foundation being capacity, but sometimes this characteristic value determined by the code is too small, which will lead to the results that the engineer adopted smaller bearing capacity characteristic value of composite foundation than normal in the design, and the design results are too conservative. From this it will bring out the technology investment and the cost of engineering economy increase. disadvantages of the method determined bearing capacity characteristic value of composite foundation by in-situ loading test are analysed by comparing a group of in-situ load test data of the plain concrete pile composite foundation with a group of in-situ loading test data of natural foundation in the same site and the same condition; and the reasons for defects are discussed. This paper complements the method for determining the bearing capacity of composite foundation by the load test proposed by technical code for ground treatment of buildings, and in order to promote the application of composite foundation technique and in situ loading test.