| dc.description.abstract | Abstract
Construction of earth excavation projects are mostly conducted by on-site engineers or construction-site managers to perform related arrangements according to the contract requirement or resources available on-site and based on personal experience, which typically cannot be assessed by scientific methods to perform systematic analysis, comparison and evaluation. As a result, the ability and experience of the on-site engineer or construction-site manager play a significant role in deciding the success and failure on the work assignment of earth excavation. Consequently, it is an important issue for the current earth excavation process to increase the usage rate of the machinery and lower costs. This research model uses the conventional model adapted by most earth excavation projects in Taiwan involving the use of excavators for excavation in cooperation with dump trucks for carrying and transportation. The earth excavation project as the scope of this research takes into account the factors of (1) multiple construction sites (2) limitations on the number of excavators and vehicles in the truck construction sites (3) construction site earth disposal is transported out once the volume for carrying and transporting is reached (4) machinery transported to the construction site cannot be moved in and out daily due to transportation costs (5) the price of excavated material sold is counted forward to reduce cost. This research establishes a set of mathematically optimized models by using an integer planning as the structure in order to assist the construction site management decision maker to perform a unified planning on the work assignments for the construction teams in light of minimizing the assignment cost incurred so that profit can be increased. In this research model, when the external environment and the criteria of limitation undergo changes, it is able to adjust the parameters according to the latest criteria in order to perform re-assignments on the construction teams including later excavators and trucks. In addition, at the same time, it is able to actively adjust all types of related parameters based on the trend of the sensitivity change of each parameter in order to establish an assignment solution for the excavators and dump trucks according to changes of the actual conditions. This research uses basic data and criteria of limitations to define corresponding limitation parameters, followed by inputting the data into the LINGO 8.0 software a package via the software method of using EXCEL2003 for solutions. An optimized outcome for a total assignment cost generated by the excavation operations of excavators and the carrying and shipping operations of trucks can be obtained. This research model uses a construction excavation process in a construction project performed by a construction company as an exemplary test, in which the two methods of the test result and the manual experience decision are compared. The results indicate that this research model has obvious advantageous effects. Therefore, this research model is suitable to the assignment planning for various types of excavation operations of excavators in cooperation with truck carrying and transportation, such that it can be used as a significant reference basis for decision makers.
Keywords: excavation by excavator, carrying and shipping by truck, sensitivity, optimized, integer planning
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