Abstract: Winds often trigger oscillations of vertical concrete transport machinery, which enlarges the impact space of a cable crane on dam block surface operation and raises the frequency of space conflicts, enhancing the potential of accidents. High conflict frequency in cross operation space under wind loads is a major root of construction accidents during dam concrete pouring. This study explores the wind influence on the operation of a bucket, and constructs an equation for its falling motion under the accident condition. And based on this, we explicitly calculate the impact space of a falling bucket, and analyze the variations in the physical working space of the machines according to the size of dam block surface. Besides, we present a new cyclic network method for simulating cross operation overlapping time and determining the conflict frequency between impact space and working space. A joint probability with the occurrence frequency of different wind speeds is used to characterize the space conflict frequency of three-dimensional cross operation. Comparison with filed data shows that our new model can effectively quantify and predict the space conflict frequency of concrete pouring under various wind loads, thereby being useful for improving dam construction safety management.

Key words: hydro project construction, space conflict frequency, construction safety management, dam construction, wind loads