论文部分内容阅读
目的:土质覆盖层下的城市固体废弃物由于生化降解反应具有更高温度,该温度梯度增强了土质覆盖层内的水蒸气扩散,在覆盖层的蒸发模拟中不容忽视。与水蒸气扩散相关的参数一般通过瞬态剖面法测量,但在一定蒸发边界下的土体干燥过程会持续很长时间,因此这种传统测量方法十分耗时。本文旨在提出一个底部加热的新方法加速黄土土柱脱湿,更为高效地获取水蒸气运移相关参数。创新点:1.提出一个全新的底部加热方法用于加速土体脱湿,同时利用提出的数值模型反分析得到水蒸气运移的相关参数挠曲度τ;2.发现底部加热加速脱湿的根本原因在于极大增强的水蒸气扩散。方法:1.研制一套室内黄土土柱试验装置(图3);2.在土柱底部施加恒温70°C,监测黄土的水热响应(图4);3.提出一个数值模型模拟这一水热耦合运移过程,利用该模型反分析影响水蒸气运移的关键参数,包括试验黄土的挠曲度τ和经验蒸发公式的参数a。结论:1.在相同蒸发边界下,相比不加热的情况,底部加热使土柱脱湿加速了最高22天;2.在第15天前,加热增强的水蒸气流量主导黄土蒸发过程,一直占总水分损失量的50%以上;3.试验及数值模拟结果均表明,相比传统方法,本文提出的底部加热法可更为高效地获取水蒸气运移参数。
Objective: Urban solid waste under soil cover has a higher temperature due to biodegradation reaction. The temperature gradient enhances water vapor diffusion in soil cover. It can not be neglected in the evaporation simulation of cover. The parameters associated with water vapor diffusion are generally measured by the transient profile method, but the drying process of the soil under a certain evaporating boundary will last a long time, so the traditional measuring method is very time-consuming. The purpose of this paper is to propose a new method of bottom heating to accelerate the dehumidification of loess soils and to obtain the relevant parameters of water vapor transport more efficiently. Innovative points: 1. Proposed a new bottom heating method for accelerating soil dehumidification, while using the proposed numerical model back analysis of the relevant parameters of water vapor transport flexure τ; 2. Found that the bottom of the heating accelerated dehumidification The fundamental reason is the greatly enhanced water vapor diffusion. Method: 1. To develop a set of indoor loess soil column test device (Figure 3); 2. Apply a constant temperature of 70 ° C at the bottom of soil column to monitor hydrothermal response of loess (Figure 4); 3. Propose a numerical model to simulate this The model is used to inversely analyze the key parameters affecting water vapor transport, including the flexural strength τ of the test loess and the parameter a of the empirical evaporation formula. At the same evaporation boundary, bottom heating accelerated soil column dehumidification up to 22 days at the same evaporation boundary; 2. On day 15, heating enhanced water vapor flux dominated the loess evaporation process Accounting for more than 50% of the total amount of water loss.3. The experimental results and numerical simulations show that the bottom heating method proposed in this paper can obtain the water vapor transport parameters more efficiently than the traditional method.