分层土绿色屋顶雨水滞留能力试验和数值模拟研究

Experiment and numerical simulation of rainwater retention capacity of layered-soil green roofs

摘要

【目的】提高绿色屋顶的雨水滞留能力(RRC)已被认为是城市雨水管理的一个重要组成部分,基质层作为绿色屋顶的重要结构,研究分层土基质对绿色屋顶RRC的影响机制,能对绿色屋顶的设计产生积极影响。【方法】建立分层土和两个材料配合比不同的单一土壤的绿色屋顶模型,利用HYDRUS-1D软件反解模块得到分层土的水力参数。通过四个月的干湿循环,研究三种模型的RRC、通过模拟来研究初始含水量、饱和含水量等因素对分层土绿色屋顶RRC的影响并对这些参数进行敏感性分析、通过模拟研究不同暴雨重现期下分层土绿色屋顶的RRC。【结果】结果显示,分层土的RRC分别比单一土壤高了5%和1%;分层土具有更高的峰值排水减少和更长的峰值排水延迟;土的初始含水量、饱和含水量、渗透性、上下两层土的深度比会对分层土绿色屋顶的RRC产生一定影响,饱和含水量的影响最大;土壤表面最大蓄水深度为10 mm时,不同暴雨重现期下绿色屋顶表面径流峰值分别削减了22%、15%、14%和12%。【结论】研究结果表明,分层土的RRC比单一土壤高,有较好的水文性能。为了使分层土绿色屋顶有更好的水文性能,其基质层应采用高渗透性的上层土和低渗透性的下层土,同时两层土的深度比要在一个合理的范围内。暴雨条件下允许土壤表面积水入渗可以有效削减峰值径流,推迟表面径流时间。

Abstract

[Objective] Improving the rainwater retention capacity(RRC) of green roofs has been recognized as an important part of urban stormwater management. As the substrate layer is a key structural element of green roofs, investigating the influence mechanism of layered soil substrates on the RRC of green roofs has a positive impact on green roof design. [Methods] Green roof models were established using layered soil and two single-soil configurations with different material mix ratios. Hydraulic parameters of the layered soil were obtained using the inverse solution module of the HYDRUS-1D software. Through four months of dry-wet cycles, the RRC of the three models was studied. Simulations were performed to examine the effects of initial water content, saturated water content, and other factors on the RRC of layered-soil green roofs, followed by the sensitivity analysis of these parameters. Additionally, simulations were conducted to examine the RRC of layered-soil green roofs under different rainstorm return periods. [Results] The result showed that the RRC of layered soil was 5% and 1% higher, respectively, than that of the single-soil configurations. The layered soil showed greater reduction in peak drainage and longer peak drainage delay. Initial water content, saturated water content, permeability, and depth ratio of upper to lower layers all have certain effects on the RRC of layered-soil green roofs, with saturated water content having the strongest effect. When the maximum surface water storage depth was 10 mm, peak surface runoff of the green roofs was reduced by 22%, 15%, 14%, and 12% under different rainstorm return periods, respectively. [Conclusion] The findings show that layered soil exhibits higher RRC than single-soil configurations, demonstrating better hydrological performance. To achieve better hydrological performance of layered-soil green roofs, the substrate layer should comprise a high-permeability upper soil layer and a low-permeability lower soil layer, with the depth ratio of the two layers maintained within a reasonable range. Allowing surface ponding infiltration during rainstorms can effectively reduce peak runoff and delay the onset of surface runoff.

关键词

绿色屋顶 / 分层土 / 雨水滞留 / HYDRUS-1D软件 / 水文性能 / 径流削减 / 低影响开发 / 暴雨重现期

Key words

green roofs / layered soil / rainwater retention / HYDRUS-1D software / hydrological performance / runoff reduction / low impact development / rainstorm return period

基金资助

广西重点研发计划(桂科AB24010052)

南宁市科学研究与技术开发计划项目“绿色屋顶一体化设计及雨水收集利用关键技术研发与应用”(ZC20223239)

国家自然科学基金“竖向荷载及强降雨耦合作用下粗粒土填料挡墙病害形成机理与防治研究”(52108309)