中国经历了全球最大规模的城市化过程，城市区域不断向郊区蔓延，郊区已成为中国城市空间结构中的最为重要和敏感的区域，其重要性和复杂性日益凸显。但郊区的快速发展和摊大饼式的扩张模式使得城市功能空间在郊区错位，引发了职住距离过长、公共服务不足、交通环境拥堵等一系列社会经济问题，严重影响了郊区的可持续发展和郊区居民生活质量。因此，诊断中国郊区发展问题，优化郊区城市功能空间布局，探寻有中国特色的郊区良性发展模式，让郊区居民有更多的“获得感、幸福感”，业已成为学界和政府所关注的重要问题。而在人本主义思潮，尤其是在以“物”为内容的传统城镇化向以“人”为核心的新型城镇化转变的影响下，通过郊区居民个体的活动行为，理解和透视郊区化和郊区发展成为了郊区研究的前沿和重要视角。因此，从郊区居民个体的微观视角出发，以日常活动为切入点，揭示郊区城市功能通过日常活动对郊区居民主观幸福感的作用路径，剖析郊区城市功能对郊区居民主观幸福感的影响，不仅能够丰富中国特色郊区理论研究，对于探讨可持续的郊区发展模式、破解中国大城市郊区发展困境、提高郊区居民幸福感也具有重要现实价值。
      基于此，本文以长沙都市区2个典型郊区街道为研究案例，结合多学科理论和研究方法，以“城市功能—日常活动—主观幸福感”为逻辑主线，采用多源数据与微观调研相结合的方式，借助问卷调研、互联网大数据等多源数据，运用数理统计分析、GIS分析技术、聚类稳健标准误回归、结构方程模型等技术方法，识别和分析了长沙都市区郊区城市功能要素及其空间布局，探讨了郊区居民日常活动的时空特征及影响因素，揭示了日常活动对郊区城市功能与居民主观幸福感影响的中介效应，明晰了郊区城市功能对居民主观幸福感的影响和作用路径。本文的主要研究内容包括5个部分：
      第一部分主要介绍本文的研究背景、选题意义，基于文献梳理和总结，构建本文的理论框架和研究设计。基于中国郊区化和郊区发展面临的实际问题，确立了本文的研究目标、内容和技术路线。通过对相关研究的梳理和总结，构建了基于日常活动的郊区城市功能对居民主观幸福感影响研究的理论框架，并对研究方案进行了设计。
      第二部分为长沙都市区郊区城市功能要素的精细识别、分析和评价。首先，结合互联网大数据和遥感影像等多源数据，以城市道路形成的封闭街区地块作为基本单元，通过构建密度指数和利用GIS技术，对长沙都市区郊区城市功能要素进行了精细化识别。其次，采用数理统计以及核密度方法分析了郊区城市功能要素的空间格局特征。结果表明：居住功能和以制造业为主的办公就业功能郊区化扩散和集聚特征显著，在郊区形成了多个居住组团和工业集聚区；行政办公和高等教育功能离心化扩散明显，基础教育功能布局较为均衡，但公共文化体育、医疗卫生以及公共交通等城市功能在郊区的配置仍然不足；专业商业服务功能在近郊区形成了多个商业次中心，高等级商业服务场所在郊区的布局则相对有限。在多样性水平上，由于公共服务和交通功能的郊区化滞后于居住和办公就业功能，城市功能在郊区呈现非协调特征，郊区街道的城市功能多样性水平较低，而单一类型城市功能的空间聚集度较高。再次，基于调查问卷测度了郊区居民对郊区城市功能的主观感知，结果表明：郊区居民对居住区公共文化、体育和医疗等公共服务设施便利性的满意度较低，对商业服务设施的便利性则具有较高满意度。
      第三部分为长沙都市区郊区居民日常活动的时空特征及影响因素分析。首先，基于问卷调查数据，利用统计分析和GIS技术，剖析了案例地郊区居民日常活动行为的时空特征，结果表明：郊区居民的工作活动呈现以近居住地为主、多指向的空间分布特征，通勤距离和通勤时间相对较低；工作日的休闲娱乐活动类型单一，休闲空间向居住区收敛，休息日的休闲娱乐活动类型多样化，休闲空间的扩散态势显著；在居住地附近商业场所购买日常生活用品是郊区居民生活维护活动的主要内容，生活维护活动空间在休息日呈现收敛与分散并存的特征；文化休闲、高等级商品购买以及看病就医活动则仍然依赖于城市中心区。其次，采用聚类稳健标准误回归分析，定量测度了不同时间可达范围内的城市功能客观特征、主观感知对郊区居民日常活动的影响，结果表明：郊区居民的日常活动存在权衡效应，工作学习活动时间会挤压居民休闲娱乐活动的参与，而参与休闲娱乐和生活维护活动的交通出行会降低休闲娱乐和生活维护活动的参与频率。居住区步行可达范围内的郊区城市功能空间是影响居民日常活动的重要因素：在居住区步行可达范围内，城市功能多样性，商业服务、办公就业、公园绿地和公共交通可达性的提高会减少居民交通出行时间，促进休闲娱乐和生活维护活动的参与，而城市功能密度、聚集度和主次干道密度的提高则会增加居民的交通出行时间、减少非工作活动的参与；对居住区公共服务便利性和居住环境舒适性的高满意度会促进居民休闲娱乐活动的参与，对居住区商业服务便利性的高满意度则会促进居民生活维护活动的参与。
      第四部分为郊区城市功能对居民主观幸福感的影响路径分析。首先，采用聚类稳健标准误回归定量测度了郊区城市功能和日常活动对居民主观幸福感的影响，结果表明：过长的通勤时间会降低居民的主观幸福感，休闲娱乐活动的参与能够提高居民的主观幸福感，生活维护活动的参与则能够促进居民心理情绪的积极性，但参与生活维护活动的交通出行时间过长会降低居民生活满意度。相比公共交通45 min可达范围，居住区步行可达范围内城市功能空间与居民主观幸福感的关联更为密切，城市功能的混合多样，商业服务、办公就业以及公园绿地的高可达性会提高居民的主观幸福感，较高的城市功能密度和公共文化体育场馆可达性则会降低居民的主观幸福感，公共交通的高可达性会提高居民生活满意度，但同时也会抑制居民情绪的积极性，对公共服务和商业服务便利性、交通出行便捷性以及居住环境舒适性的高满意度会提升居民的主观幸福感。其次，将日常活动纳入郊区城市功能与居民主观幸福感的研究中，采用结构方程模型揭示了日常活动对郊区城市功能与居民主观幸福感的中介作用，结果表明：居住区步行可达范围内，城市功能的混合多样，充足的公共体育文化设施、商业服务场所、就业机会和公园绿地，以及完善的公共交通，能够通过减少居民通勤和非工作活动的交通出行时间，提高居民对居住区城市功能空间的满意度，促进居民休闲娱乐、生活维护活动的参与，进而提升居民的主观幸福感，而单一类型城市功能的过度集聚以及主次干道密度过高则会增加居民交通出行时间，减少非工作活动的参与而降低居民主观幸福感，过高的城市功能密度会增加交通出行时间、减少生活维护活动的参与而抑制居民情绪感受的积极性，但同时也会提高居民对居住区居住环境舒适性的满意度，进而促进居民休闲娱乐活动的参与和主观幸福感的提升。而公共交通45 min可达范围内，较高的城市功能密度则会减少通勤时间，提高交通出行满意度，促进居民休闲娱乐活动的参与和主观幸福感的提升。
      第五部分为结论与政策启示。基于对主要研究结论的归纳总结，从公共服务功能的优化配置、交通建设和居住环境改善3个方面提出了政策启示，阐述了本文可能的创新点、存在的问题以及未来研究方向。

      China has experienced the world’s largest urbanization, with metropolitan areas continuing to expand to the suburbs, which has become the most crucial and sensitive areas in China’s cities. However, the rapid suburbanization in a ‘pancake’ style has caused the dislocation of urban functional space in the suburbs, resulting in a slew of social and economic issues, such as long working-living distances, insufficient public services, and traffic congestion, which severely impedes the suburbs’ sustainable development and suburban residents’ subjective well-being (SWB). As a results, diagnosing the development problems in China’s suburbs, and optimizing the layout of urban function in suburbs, as well as exploring the suburban sustainable development mode with China's characteristics, consequently improving suburban residents’ SWB have emerged as critical issues for academia and government. In the context of humanism, particularly the transformation from traditional urbanization to the human-oriented urbanization, understanding suburbanization and suburbs based on individual behavior has become a frontier and essential viewpoint. Taking suburban residents’ activities as a starting point, examining and revealing how urban function of suburb affects suburban residents’ SWB is conductive to not only enriching the literature on China’s suburb, but also breaking the development dilemma of the China’s suburbs in big cities, and improving suburban residents’ SWB.
      This study takes Changsha’s typical suburban sub-district as a case study and develops a theoretical analysis framework that can be applied to research the effect of urban function of suburb on suburban residents’ SWB in China’s big city, based on their daily activities, by following the logical line of ‘urban function—daily activity—SWB’. Under the guidance of this framework, this study identifies the spatial characteristics of the urban functional zones in Changsha using multi-source data, and then uses data from a questionnaire in two typical suburban sub-districts to research the spatiotemporal characteristics of suburb residents’ daily activities and the influence of multi-scale urban function space of suburb on residents’ daily activities. In the end, this study adopts the cluster-robust inference regression and Structure Equation Model(SEM) to identify the influencing factors of suburb residents’ SWB and reveal the mediation effect of daily activities between urban function of suburbs and residents’ SWB. The paper can be divided into five sections as follows:
      Section 1 provides an introduction of the study’s background, meaning and develops a theoretical framework based on the review of the literature. Based on the facts and problems of China’s suburbanization, the study aims and research strategy have been designed. Then based on a survey of literature, this study proposes a theoretical framework for the influence of urban function of suburb on suburban residents’ SWB based on daily activities. Finally, the research strategy is developed.
      Section 2 identifies, analyzes and evaluates urban functional zones in Changsha suburbs. To begin with, this study employs weighted density index and GIS methodologies to identify the urban function zones in Changsha suburbs by integrating POI, Internet map, remote sensing data with closed parcel as the basic unit. After that, the spatial characteristics and diversity of urban functional zones in Changsha suburbs are analyzed in comparison to the inner city. The findings show that residential function, as well as office and employment function, exhibits a clear suburbanization tendency, with numerous densely populated residential areas and industrial zones forming in suburbs; although the distribution of administrative and higher education function is decentralizing, and primary education is in a relative spatial balance, the allocation of culture, sports, high-quality medical function and public transport stations remains insufficient in the suburbs; because of the suburbanization of commercial service function, a number of commercial subcenters have emerged in the suburbs, but advanced commercial service function is comparatively inadequate in suburbs. The entropy index and contagion index are used to measure diversity in suburbs at the sub-district scale, and the findings suggest that the degree of diversity of suburbs is low due to the lag of public services and transportation functions compared with residential and industrial function in the progress of suburbanization. On the other hand, the degree of contagion of urban function in suburbs is high when compared to the inner city. Finally, the study investigates suburban residents’ perceptions of the arrangement of urban function zones at the neighborhood and city scale using a questionnaire survey, and the findings indicate that suburban residents are relatively dissatisfied with the convenience of public services, but they are more satisfied with the accessibility of commercial services.
      Section 3 analyzes the spatiotemporal features and influencing factors of suburban residents’ daily activities. Using data from 663 participants’ point-based locations visited and time spent in the previous 7 days in Yueliangdao and Dongjing in 2020, this study researches the spatiotemporal characteristics of suburban residents’ daily activities. The results show that suburban residents’ commuting distance and time are shorter in Changsha suburbs, and the types of leisure activities that suburban residents participate in on weekdays are fewer, with limited leisure space, whereas the types of leisure activities that suburban residents engage in on weekends are more diverse, with an obvious spatial diffuse trend. Purchasing daily necessities at shops around the neighborhood is the primary content of suburban residents’ maintenance activity, and unlike the leisure activity space, the maintenance activity space exhibits agglomeration around the neighborhood as well as diffusion away from neighborhood on weekends. Cultural, advanced shopping, and medical activities are mostly located in the inner city. The influence of objective and subjective characteristics of urban function within different accessibility spaces on resident’s daily activities is evaluated by using cluster-robust inference regression. The findings reveal that there is a trade-off effect in time allocation between activity and travel behavior. Suburban residents who spend more time on subsistence activities attend fewer leisure activities, while those who spend more time on traveling time for leisure and maintenance activities attend fewer leisure and maintenance activities in the suburbs, respectively. The objective characteristics of urban function within 15-min and 30-min walking distance of the neighborhood have the greatest impact on the daily activities of suburban residents. Within walking distance of the neighborhood, increased urban function density, contagion, and main and secondary road density are significantly and positively linked with travel time, and significantly and adversely associated with involvement in leisure and maintenance activities. On the other hand, the diversity and accessibility of commercial services, offices and jobs, and green parks within walking distance of the neighborhood have a large and beneficial impact on participation in leisure and maintenance activities, and reducing travel time. Furthermore, greater perceptions of accessibility to public services and neighborhood environmental livability both considerably boost the frequency of leisure activities, and improved perceptions of access to commercial services encourages engagement in maintenance activities.

      Section 4 researches the impact path of urban function of suburbs on suburban residents’ SWB. The findings of cluster-robust inference regression indicate that the urban function of suburbs, as well as daily activities, have a significant impact on SWB. Lower SWB is significantly related with longer commuting and travel time for maintenance activities. Attending leisure activities significantly and favorably contributes to a high degree of life satisfaction and positive feelings, and maintenance activities are positively associated with emotions. The objective characteristics of urban function within 15-min and 30-min walking distance surrounding neighborhood exhibits a greater association with SWB than the urban function zones within 45-min distance via public transportation. The diversity, accessibility of commercial services, office and employment, green park and road density shows a substantial beneficial relationship with SWB, whereas urban function density and public culture and sport function zone accessibility are found to be detrimental to SWB. The great accessibility of public transportation has a considerable beneficial impact on life satisfaction but a negative influence on pleasant affect. Moreover, higher SWB is associated with greater satisfaction with the arrangement of urban function zones at the neighborhood and city scales. The SEM results demonstrate a mediation effect of daily activities between urban functions of suburbs and SWB. Higher urban function diversity, adequate commercial service, employment, and green space, as well as excellent sports, cultural, and public transportation facilities, within walking distance, has a positive impact on SWB by reducing travel time and increasing satisfaction with the layout of urban function zones, thereby increasing participation in leisure activities and maintenance activities. However, denser major and secondary roads, as well as greater contagion, have a detrimental influence on SWB by increasing travel time and lowering engagement in leisure and maintenance activities. Increased density of urban function reduces SWB by increasing commute time and decreasing engagement in maintenance duties, but also benefits SWB by boosting living environment satisfaction and encouraging engagement in leisure activities. In contrast, the denser urban function within 45 minutes improves SWB by boosting travel convenience satisfaction and engagement in leisure activities.

      Section 5 summarizes the findings and proposes some policy implications. Based on the summary of the main research conclusions, this study puts forward policy implications from three aspects as optimal allocation of public service function, construction of suburban traffic and improvement of living environment, and reviews the contributions as well as the problems in research.