利用超声波测量土壤团聚体稳定性的关键技术研究

发布时间：2018-11-22 07:52

【摘要】：土壤团聚体是土壤结构的基本组成单位。土壤结构的稳定性,大多数情况下是指团聚体的水稳定性,决定土壤行为、可产值、以及对土壤侵蚀和退化的抑制能力。关于土壤团聚体稳定性的测定,许多学者根据自己研究工作的需要,提出了各自的研究方法和测定方法。现有的利用超声分散研究土壤团聚体稳定性定量评估系统,试验过程中没有针对土水溶液温度快速升高的控制措施,受到土水溶液温度上限的限制,每一次分散试验都不能持续过长时间,而一次试验,不能保证土样被完全分散,因此同一土样完全分散需要多轮次试验。本文针对其存在的不足,进行了如下改进研究:(1)设计了一种新的双层试验容器。针对普通50mL烧杯作为试验容器存在的不足,设计了一种新双层试验容器,并在实验室条件下进行了密封性、流通性、冷却性能的测试,证明新的试验容器设计合理,达到了预期设计要求。为进一步保证试验容器的可靠性,对其进行保温设计,并对保温性能进行理论分析,结果表明试验容器热损失只有系统总输入能量的1‰,试验容器保温性能良好。(2)设计了超声分散测量系统。根据设计的试验容器,针对的研究配套试验设备和器件如超声仪器、超声探头、数据采集系统、循环冷却液体温度测量探头等,进而集成设计了超声分散能量测量系统。在实验室环境下分别进行了超声仪器空载损耗测试和超声仪器振子深入液面不同深度输出功率等性能测试,证明了试验容器控制溶液温度的有效性,为土壤团聚体分散能量测量提供快速高效的硬件平台。(3)通过分析土壤超声分散过程中能量的变化关系,确定了土壤超声分散能量测量的计算方法,在实验室环境下对不同负载下超声仪器输入功率、溶液热功率等分能量进行了测试;在此基础上对红壤进行测试计算,得出其总超声分散能量约183J/g,与原系统多轮试验得到的结果相近,证明此方法可行。(4)进行了超声分散测量系统性能的进一步验证。用超声分散法和湿筛法两种方法对比研究了不同土样的稳定性,并分析了两种方法之间的关联性和差异性,发现强稳定性土样用两种方法分析的结果是一致的,即试样土样稳定性:ZJJXCQ,但是弱稳定土样短时间内被完全分散,从而导致结果出现差异,即弱稳定性的土样不适合用现有设备利用超声分散法分析其稳定性。即现有超声仪器输出功率对于弱稳定性土样来说,功率过大,这也可以作为一个判断土样是否适合使用现有超声分散方法分析其稳定性的方法。通过对土壤粒径动态分布测量的试验设计,并用HN、ZJ、CQ、JX四种土样进行了试验,得出了它们的粒径动态分布规律。HN、ZJ和CQ三种土样都是在200s左右完成了土壤团聚体的主要分散过程,而JX土样在120s左右就完成了主要分散过程。再次验证了该试验系统的可行性。
[Abstract]:Soil aggregate is the basic unit of soil structure. The stability of soil structure, in most cases, refers to the water stability of aggregates, the determination of soil behavior, the value of production, and the ability to inhibit soil erosion and degradation. As to the determination of the stability of soil aggregates, many scholars have put forward their own research methods and methods according to the needs of their own research work. The existing quantitative evaluation system for the stability of soil aggregates by ultrasonic dispersion has no control measures for the rapid increase of soil water temperature during the experiment, which is limited by the upper limit of soil aqueous solution temperature. Each dispersion test can not last for too long, and one test can not guarantee that the soil sample is completely dispersed, so the complete dispersion of the same soil sample requires multiple rounds of tests. In this paper, the following improvements are carried out: (1) A new double-layer test vessel is designed. In view of the deficiency of ordinary 50mL beaker as a test vessel, a new double-layer test vessel was designed, and the sealing, flow and cooling properties of the new vessel were tested under laboratory conditions, which proved that the design of the new test vessel was reasonable. Meet the expected design requirements. In order to further ensure the reliability of the test vessel, the insulation design is carried out, and the thermal insulation performance is theoretically analyzed. The results show that the heat loss of the test vessel is only 1 鈥，

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