基于单元格的城市内施工场地动态安全布局优化模型研究

Facility site layout planning is a crucial task in the field of construction site management to resolve space conflict in allocating different facilities at different locations during different time stages of a construction project to support site activities. Improper site layout plan decreases working efficiency and causes productivity loss. It is found that facilities and site area representation in previous studies are over simplified using “point” notation with regular shape representation only. Overall design flexibilities and accuracy are thus limited and conventional solution methods can be enhanced. ..Following the recent works done by the investigators relating to the facility layout optimization, this proposal presents a new discretized facility layout optimization model in which the whole study site area is discretized into small cells for representation such that irregular site areas and facilities can be modeled and available site areas can be better utilized. This approach can also be applied to deal with dynamic problems considering safety. Design criteria are to (1) fulfill the area size and shape requirements of different facilities, (2) minimize the material flow costs depending on the horizontal and vertical (tower crane) travel distances between different facilities, facility set up, demolition, and relocation costs, and (3) satisfy the safety separation and environmental requirements for different facilities. Actual site data will be collected as model inputs to enhance the overall model reliability and practical applicability. The optimization problem is formulated as a binary-mixed-integer-linear- programming problem, with the cell usages as key decision variables, that is solvable by a standard branch-and-bound technique and global solution can be obtained...Modeling results will be assessed by comparing the observed site facility layout and optimized facility layout patterns. The proposed work enables site managers to equip a practical decision making tool for identifying optimal locations for all fixed or temporary facilities in a site to minimize the generalized material transportation cost fulfilling construction safety and environmental requirements. Improvements in site layout planning applying the proposed discretized facility layout optimization model will provide benefits in improved safety, decreased spatial conflicts for facility location, reduced material transportation cost, improved overall efficiency and a reduction in the unnecessary movement of materials and equipment, increased productivity, and reduced project delays.

施工场地布局的合理程度与施工效率和安全息息相关。而部分场地布置优化模型以“点”或“矩形”表示临时设施，忽略其形状及面积对场地布局的影响，不适用于城市内面积狭小且不规则的施工场地。申请者前期研究以“点”的表示方式，分别实现了塔吊、临时设施和材料堆放点在场地和高层建筑内的动态安全优化布置。本课题拟用连续单元格表示场地设施，满足设施布置形状多样性的要求；基于设施与道路间的关系，同时优化两者的布置，以期达到充分合理利用场地面积的目的。根据设施之间及设施与道路的安全和材料运输关系，基于混合整形规划理论，引入相应的决策变量和限制条件；以满足场地安全要求和降低材料运输成本为目标，建立优化模型；利用分支定界法结合并行计算求解。研究将根据优化结果与工程数据的对比，结合工程师建议对优化模型修改和完善。课题从场地布局模型的通用性入手，提高了场地布局优化模型的空间分析精度和实用性，具有较高的理论意义和使用价值。

本课题引入单元格作为表示施工场地和临时设施的基本单元，在以充分利用有限施工场地空间为目标的情况下，对各临时设施在连续平面空间布置的相互影响机理进行深入探讨。研究首先引入单元格将连续空间进行分割，并建立基于单元格的施工场地平面空间属性数据库，随后将施工场地的连续平面空间转化为离散的单元格数据，旨在缩小模型分析数据量的同时，最大程度地提高施工场地平面空间分析的精细度。基于混合整形线性规划理论，依照单元格属性参数和单元格之间的拓扑位置关系设置限制条件，在确保临时设施布置连续性的情况下，通过相邻单元格的灵活组合形成各种形状的临时设施空间；随后基于临时设施之间的平面运输关系，在考虑安全的条件下，合理穿插临时道路；最终，以运输成本作为目标函数，形成临时设施和道路的优化布置模型。研究利用Python程序语言作为开发平台，采用Gurobi优化软件中的分支定界法求解，实现计算迭代过程，最终得到临时设施和道路布局的最优布置方案。随后研究继续对临时塔吊的运输路径进行了精细化分析。在单元格模型的基础上，将材料存储与需求点在模型中标记，引入相应的变量和限制条件，优化了塔吊运输路径，从而提高了运输效率。另外，由于城市内的施工场地较小，在施工过程中，部分材料将运输至建成的楼层存储。因此，在场地优化模型的基础上，将已建好楼层作为另一部分的场地可用部分加入到场地中，材料运输施工现场将同时考虑场地内和施工现场的可用空间。同时，由于城市内基本为高层建筑，施工电梯在楼层中的爬升将影响到物料和人员运输的效率。研究建立了优化模型，同时考虑了材料存储位置和施工电梯的爬升时间表，提高了施工物料运输的效率。