地基承载力问题中的破坏模式与度量标准

针对工程的实际情况,研究重力式结构地基可能的破坏模式,建立合理的地基承载力计算模式。通过对地基承载力研究中的破坏模式、设计荷载的作用面宽度、地基承载力稳定性度量标准等问题的讨论,认为:重力式码头是单向破坏模式,且需同时考虑整体破坏与局部破坏;直立式防波堤应是双向破坏模式,同样需考虑整体破坏与局部破坏。目前的对基床底面实际受压宽度的确定往往会导致地基承载力计算值的偏大。地基承载力问题用整体破坏模式的单一抗力分项系数,只能度量整体破坏,不能反映地基土可能发生的局部破坏;且不能准确反映地基土强度指标的不确定性,应采用强度分项系数与荷载分项系数来共同度量地基的承载能力。

Modes of Failure and Criteria of Measurement in Bearing Capacity of Foundation

In view of practical engineering scenarios,the possible modes of failure of foundations for gravity type of structures are studied to establish rational methods to calculate the bearing capacity of the foundations.Based on the discussions on the modes of failure in the studies of bearing capacity of foundations,the width of the acting plane of design loads and the criteria of measurement of the stability of the bearing capacity of foundations,it is held that the mode of failure of a gravity jetty is unidirectional and it is required to consider simultaneously both the global failure and the local failure;and the mode of failure of a vertical breakwater is bidirectional and it is also required to consider simultaneously both the global failure and the local failure.The current method to determine the actual bearing width of the bottom of a foundation sometimes results in higher value of the calculated bearing capacity of the foundation.If a unitary coefficient of resistance component of the mode of global failure is used to solve the problem of bearing capacity of a foundation,only the global failure can be measured but the possible local failure in the foundation soil may not be reflected and the uncertainty of the strength indexes of the foundation soil can not be correctly reflected.Coefficient of strength component and coefficient of load component should be used jointly to calculate the bearing capacity of afoundation.