不同排水材料对轻型种植屋面土壤热湿环境的影响

构建了由碎石、陶粒、玻璃轻石、HDPE和PVC排水板5种排水材料组成的佛甲草轻型种植屋面模拟试验平台（室内自然状态），测定了各材料处理土壤以及土壤底部空气的温、湿度。结果表明：土壤湿度在少雨季节受到不同排水材料的显著影响，而在雨量充沛的季节差异不显著。在干旱月份，与碎石处理相比，具有蓄水性能的4种排水材料（陶粒、玻璃轻石、HDPE和PVC排水板）有明显的抗旱优势，平均土壤湿度提高了约35%；然而，这4种材料的蓄水量大小对处理之间的土壤湿度没有显著影响；另外，材料的排水性能对土壤湿度有显著影响，通水量大的HDPE排水板在雨后初期土壤湿度显著小于其他材料。土壤（空气）温度没有受到材料蓄水性能的影响。轻型种植屋面土壤热湿环境的变化不完全由材料蓄水性能所决定；同时，其具有明显的保温（冬季夜间）隔热（全年白天）作用，且热工性能存在季节性和日内差异。

Effects of different drainage materials on soil hygro-thermal environment of extensive green roof

Five kinds of drainage materials were chosen such as gravel, ceramsite, glass pumice, HDPE and PVC drainage boards, to establish a simulation test bed of extensive green roof with Sedum lineare Thunb (indoor natural state). The temperature and moisture of the soil, as well as the temperature and relative humidity of the air at the bottom of soil layer by different material treatments were measured. The results showed that:The soil moisture was affected significantly by different drainage materials during the less rain season, but the difference was not significant during the rainy season. In drought month, four kinds of drainage materials with water retention performance such as ceramsite, glass pumice, HDPE and PVC drainage boards, had obvious drought resistance advantage compared to gravel treatment, and the average soil moisture was increased by about 35%. However, the size of the water retention of these four materials had no significant effect on the soil moisture among the treatments. Other than that the drainage performance of the materials had a significant effect on the soil moisture. Early after the rain, the soil moisture of the HDPE drainage board with larger water flux was significantly smaller than other material treatments. Soil temperature and soil air temperature were not affected by water retention performance of the materials. It is indicated that the changes of soil hygro-thermal environment on the extensive green roof are not completely determined by the water retention performance of the materials. Meanwhile, the extensive green roof has both heat-insulating(all year daytime) and heat-preservation(winter nighttime) effects, and its thermal performance has seasonal and intraday differences.