目前多数基于GIS的商业区位模型与技术研究,未全面考虑交通网络、道路等级、网点吸引力与竞争因素。针对此局限,借助GIS软件,依托可达性方法与伽萨法则,尝试综合考虑上述因素探讨大卖场可达性与商圈特征。以上海中心城区大卖场为例,采用同心圆法、扇形法与最近邻域法探讨卖场空间特征;利用行进成本分析法计算卖场可达性,并根据伽萨法则叠加了卖场引力因素,得到伽萨法则商圈。结果表明:大卖场集中分布于距市中心4.5~10km范围,各方向扩张不均衡。城区整体可达性较好,浦西优于浦东。外环附近商圈面积大,外环附近与市中心区商圈市场规模大,内环附近商圈面积与市场规模小。伽萨法则商圈市场规模"两极分化"既表明卖场市场竞争激烈地区与网点短缺区并存,也说明网点市场规模与职能存在等级差异。

Recently most relative quantitative modeling studies on retail location, based on GIS technology, did not consider factors simultaneously including traffic network, traffic grade, store attraction and competition. Considering shortages mentioned above, this paper attempts to integrate these factors and make quantitative analysis of large scale shops based on accessibility method, Gasa laws and GIS technique. This study, taking the large scale supermarkets in Shanghai central city as an example, applies the concentric buffer method, sector analysis and nearest neighborhood analysis to explore the supermarket spatial features. Trip cost method is used to investigate quantitatively supermarket accessibility, then delimitating market area is simulated based on trip cost analysis and Gasa rules. The result indicates that the whole accessibility of large scale supermarkets in Shanghai central city is good, and the west is better than the east. Trade areas around the outer ring are greater. There is obvious polarization among Gasa shops' trade areas and size. The characteristics mentioned above show that areas with intense competition among supermarkets coexist with areas lack of supermarkets, and there are grade differences between supermarkets' market size and functions.This study can provide references for urban planners in the aspect of retail network arrangement. Managers can quickly understand the shop trade areas and provide consult for choosing shops location. Some tips for selection of retail locations can also be provided. Although our research suggests that we provide more effective methods toward trade area definition, several problems should be solved in future. Further studies should be done on demand, and purchase ability and residential trip habits from consumers shall be taken into consideration.