时差分析作为工程项目管理的核心内容之一，被广泛用于处理延期索赔和工期压缩等实际工程问题。RSM是针对重复性项目而设计的一类新的项目调度工具，在项目计划与调度领域受到广泛关注。在RSM中，目前尚未有普适的时差分析方法，并且已有的时差概念均要求工序必须连续施工。在考虑工序间断的情况下，区分了RSM中子工序使用时差的两种方式，即"调整开始时间"和"延长工期"。通过将CPM网络中的经典时差概念（包括总时差、自由时差和安全时差）与RSM相结合，提出了适用于RSM的新时差概念体系，以及对应的时间参数和时差计算方法。一个管道工程项目验证了算法的有效性。与已有文献相比，本文提出的时差分析方法具有更强的普适性。
Float analysis plays an important role in engineering project management; it aims to determine the amount of time that the duration of a non-critical activity can be extended or the start time of the activity delayed, before it enters the critical path. The critical path method (CPM) has been widely used in the construction industry to determine which activities are on the critical path and which are not. However, there exists another type of construction project, usually referred to as a "repetitive project", for which CPM may not be the best scheduling technique for planners to employ. A repetitive project can be defined as a project which involves a number of units of work to be finished and a set of activities that need be repeated for each unit in the length of the job. Examples of such projects are highways, high-rise buildings and housing projects. Repetitive scheduling model (RSM) is a scheduling technique that may be better suited to repetitive projects than CPM. In RSM, existing float analysis methods are based on the assumption that all activities are performed without interruption. Once the work interruption is in presence, these methods will fail to evaluate the quantification of float. This paper aims to develop a new float analysis method in RSM considering the work interruption. When the work interruption is considered, the amount that the duration of a non-critical activity can be extended may not be equal to the amount that the start time of the activity can be delayed. Therefore, two different ways for a non-critical activity to use float are distinguished, i.e. "changing the start time" or "prolonging the duration". For each way of using float, three types of float are typically calculated, i.e. total float, free float and safety float. A series of numerical algorithms are also proposed to calculate the quantifications of the above floats, which make the float analysis process in RSM can be computerized. Finally, a pipe engineering project is analyzed to validate the proposed method. The results show that the proposed method can provide more effective solutions than existing float analysis methods.
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