关中地区城市下垫面雨水入渗性能的研究

发布时间：2019-04-11 13:11

【摘要】：随着城市化进程脚步加快,城市硬化地面增加,降雨径流下渗量减小,城市出现一系列洪涝灾害问题。关中地区位于我国湿陷性黄土广泛分布地区,城市下垫面受到降雨入渗时会遇到湿陷变形的问题。因此,结合关中地区城市下垫面入渗规律解决城市降雨入渗问题迫在眉睫。目前,国外学者提出低影响开发(Low Impact Develpoment,LID)这一理念,旨在解决城市降雨入渗等一系列生态环境问题。LID成功实施的核心在于因地制宜,目前在湿陷性黄土地区开展LID建设无先例可循。本文通过雨水下渗试验和变水头入渗试验研究下凹式绿地技术,分析下凹式绿地对提高降雨入渗量、减小城市洪涝灾害的作用。同时,在增加降雨入渗量条件下,计算降雨对城市绿地周边黄土路基的影响深度。结果表明:(1)不同类型下垫面入渗试验结果表明,入渗率指标规律为:小区绿地(7.02×10-2cm/min)校园绿地(6.48×10-2cm/min)踩踏小路(2.79×10-2cm/min)公园绿地(2.55×10-2cm/min)市政绿地(2.25×10-2cm/min)密实黄土(0.9×10-2cm/min)的规律;90min累计入渗量呈现:小区绿地(5.27cm)市政绿地(2.35cm)校园绿地(1.98cm)公园绿地(1.73cm)密实黄土。入渗速率差异的影响原因包括土壤容重、通气孔隙率、下垫面土壤质地、土体构型,实验发现大孔隙和裂隙的存也显著了提高土壤的入渗能力;(2)表层土的入渗率制约着土壤整体的入渗性能;心土层的入渗速率大于表层土并不能增加整个土体的入渗能力。但是从理论上可以推知:当心土层的入渗能力小于其上层表土时就能够阻碍水的下渗,使整个土体的入渗能力下降;(3)下凹式绿地的下凹深度一般为5~25cm,其蓄渗能力与下凹深度(入渗水头)成正比。同等下渗速率下,下凹式绿地蓄渗效率远高于普通绿地;(4)入渗深度随降雨持续时间的增加而逐渐增加,实验结果表明:12h内同类型绿地、黄土降雨入渗深度呈现:居民区绿地(1.79m)市政绿化带(1.43m)公园绿地(1.39m)黄土(0.35m);(5)降雨对路基影响深度为2m左右,低阶低降雨入渗深度为0.5m,高阶地降雨入渗深度为1.79m,在西安城区范围的湿陷性黄土呈透镜状不连续分布,在LID下渗措施中,可以通过“插管深渗”避过湿陷性黄土层来保证路基的结构稳定性。
[Abstract]:With the accelerating pace of urbanization, the hardening surface of cities increases, the amount of rainfall runoff decreases, and a series of flood disasters occur in cities. Guanzhong area is located in the widely distributed area of collapsible loess in China, and the problem of collapsible deformation will be encountered when the urban underlying surface is infiltrated by rainfall. Therefore, it is urgent to solve the problem of urban rainfall infiltration based on the infiltration law of urban underlying surface in Guanzhong area. At present, foreign scholars put forward the concept of low impact Development (Low Impact Develpoment,LID), which aims to solve a series of ecological environmental problems such as urban rainfall infiltration. The core of lid's successful implementation is to adapt measures to local conditions. At present, there is no precedent to carry out LID construction in collapsible loess area. Based on Rain Water infiltration test and variable head infiltration test, this paper analyzes the effect of lower concave green space on increasing rainfall infiltration and reducing urban flood disaster. At the same time, under the condition of increasing rainfall infiltration, the influence depth of rainfall on loess roadbed around urban green space is calculated. The results are as follows: (1) the infiltration test results of different types of underlying surfaces show that: The law of infiltration rate is as follows: residential green space (7.02 脳 10-2cm/min) campus green space (6.48 脳 10-2cm/min) trampling on path (2.79 脳 10-2cm/min) green space (2.55 脳 10-2cm/min) municipal green space (2.25 脳 10-2cm/min). 2cm/min) compacted loess (0.9 脳 10-2cm/min); The cumulative infiltration of 90min is as follows: 5.27cm municipal green space (2.35cm) campus green space (1.98cm) green space (1.73cm) dense loess. The factors affecting infiltration rate include soil bulk density, ventilation porosity, soil texture and soil configuration. It was found that the existence of macropores and fissures also significantly improved the infiltration ability of soil. (2) the infiltration rate of the topsoil restricts the infiltration performance of the whole soil, and the infiltration rate of the core soil is larger than that of the topsoil, which can not increase the infiltration capacity of the whole soil. However, it can be deduced theoretically that when the infiltration capacity of the soil layer is smaller than that of the upper layer of the soil, it can hinder the infiltration of water and decrease the infiltration capacity of the whole soil. (3) the depth of the concave green space is usually 5? 25 cm, and its infiltration capacity is proportional to the depth of the depression (the head of the infiltration water). Under the same infiltration rate, the storage efficiency of the lower concave green space is much higher than that of the common green space. (4) the depth of infiltration gradually increased with the increase of rainfall duration. The experimental results showed that the same type of green space was found within 12 hours. The depth of rainfall infiltration of loess is as follows: residential green space (1.79m) municipal green zone (1.43m) green land of park (1.39m) loess (0.35m); (5) the influence depth of rainfall on roadbed is about 2m, the depth of low-order and low-rainfall infiltration is 0.5m, and the depth of high-order rainfall infiltration is 1.79m. The collapsible loess in Xi'an urban area is lenticular discontinuously distributed, and in the LID infiltration measures, The structural stability of roadbed can be ensured by "intubation and deep infiltration" to avoid collapsible loess layer.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU992

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