本文選題：植物根系 + 優(yōu)勢流��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：垃圾填埋場封頂覆蓋層處于填埋場表層,是保護填埋場不受到外界侵蝕的一道重要措施。封頂覆蓋層阻滯降雨入滲至垃圾體內(nèi)部,減少垃圾滲濾液產(chǎn)量,避免填埋體內(nèi)部水位過高引起的填埋場失穩(wěn)。在垃圾降解時,產(chǎn)生各種有害物質(zhì),垃圾填埋場封頂覆蓋層可以阻擋有害氣體無組織擴散至大氣中,避免垃圾降解過程中產(chǎn)生的有害物質(zhì)影響附近居民。覆蓋層中上覆耕植土作為植物生長基質(zhì),為填埋場生態(tài)恢復(fù)提供條件。垃圾填埋場封頂覆蓋層從垃圾體頂面至表面依次為:排氣層、防滲粘土層、排水層和植被層。防滲粘土層作為封頂覆蓋層的核心部分,影響著封頂覆蓋層的長期服役性能。很多研究表明,粘土防滲層在干濕循環(huán)、凍融循環(huán)中極易開裂,粘土防滲層一旦開裂,形成裂隙網(wǎng)絡(luò),裂隙作為土體中通道,極易產(chǎn)生優(yōu)勢流,使得土體滲透性明顯增加,雨水更加容易入滲到垃圾體中。粘土防滲層開裂是影響封頂覆蓋層長期服役性能的主要因素。同時在覆蓋層生態(tài)恢復(fù)過程中,植物根系有可能在粘土防滲層中的穿插生長,形成大量根系,水分有可能沿根系優(yōu)先遷移形成優(yōu)勢流,增大粘土防滲層的滲透性。同時植物根系團聚土顆粒,限制土壤開裂。植物根系對粘土防滲層的綜合影響需要進一步研究。本文擬通過含根系的土柱試驗綜合評價植物根系對土體開裂及優(yōu)勢流的作用。采用分層壓實法壓實土柱,在土柱中培養(yǎng)植物,運用二值圖像法和圖像處理技術(shù)計算裂隙率。定量分析在植物生長過程中壓實粘土表面開裂情況,對比同條件下無植物土柱表面裂隙開展情況。結(jié)果顯示當(dāng)壓實粘土中有植物根系時,相對于同條件無植物根系的壓實粘土,表面開裂能得到一定延緩和限制。通過四組土柱試驗,分析覆蓋層在不同狀態(tài)下的滲流特性。首先,進行一組重塑壓實土柱滲流試驗,此組土柱中既無植物根系也無裂隙,模擬剛壓實完成的覆蓋層的滲流特性。其次,進行了一組經(jīng)過一段時間干濕循環(huán)后表面產(chǎn)生開裂的重塑壓實土柱滲流試驗,模擬當(dāng)植物根系尚未生長至粘土防滲層中,已經(jīng)產(chǎn)生開裂的覆蓋層滲流特性。再次,在土柱中培養(yǎng)植物,在植物生長過程中,土體產(chǎn)生開裂,進行當(dāng)土中同時含有植物根系和裂隙時的滲流試驗,模擬植物根系在粘土防滲層中生長,同時產(chǎn)生開裂時覆蓋層的滲透特性。最后為了準(zhǔn)確評價植物根系的作用,進行了土體中含有植物根系但未產(chǎn)生開裂的重塑土柱滲流試驗。四組試驗結(jié)果顯示植物根系和裂隙都會加大雨水入滲到土壤中。植物根系為水分入滲提供優(yōu)先遷移通道,植物根系的優(yōu)勢流作用不可忽略。盡管粘土中裂隙在滲流試驗中會閉合,一定時期內(nèi)雨水入滲產(chǎn)生波動,但整個過程中,水分沿著裂隙入滲形成優(yōu)勢流并未被削弱,土體開裂提高了土壤的滲透性。以亮藍作為染色示蹤劑,在含有植物根系但無開裂的重塑土柱中,進行染色示蹤試驗,定性評價在壓實粘土中染劑沿著植物根系的遷移。結(jié)果顯示隨著深度的加大,染劑在截面的染色范圍逐漸減小,在根系附近土壤中,染劑存在局部優(yōu)先遷移。進一步明確了植物根系在覆蓋層中的作用。
[Abstract]:The top cover layer of the landfill site is in the surface of the landfill. It is an important measure to protect the landfill from the external erosion. The top cover layer block the rainfall to infiltrate into the garbage body, reduce the output of the landfill leachate and avoid the instability of the landfill site caused by the high water level inside the landfill. The top cover layer of the landfill can prevent the harmful gas from spreading unorganized into the atmosphere, avoiding the harmful substances produced in the process of waste degradation and affecting the nearby residents. The cover layer is covered with soil as the base of plant growth and provides conditions for the ecological restoration of the landfill. The cover layer of the landfill is in turn from the top of the garbage body to the surface. It is: the exhaust layer, the impervious clay layer, the drainage layer and the vegetation layer. The impervious clay layer is the core of the top cover, which affects the long-term service performance of the top cover. Many studies show that the clay impervious layer is very easy to crack during the dry and wet cycle and the freeze-thaw cycle. Once the clay seepage layer is cracked, the fracture network is formed and the fissure is used as the mass medium in the soil. It is very easy to produce the dominant flow, which makes the soil permeability increase obviously, and the rainwater is more easily infiltrated into the garbage. The cracking of the clay impervious layer is the main factor affecting the long-term service performance of the top cover layer. It is possible to migrate the dominant flow along the root system and increase the permeability of the clay impervious layer. At the same time, the plant roots reunite the soil particles to limit the soil cracking. The comprehensive effect of the plant roots to the clay impervious layer needs further study. Using the stratified compaction method to compact the soil column, cultivate the plants in the soil column, use the two value image method and the image processing technique to calculate the crack rate. This paper quantitatively analyzes the cracking of the compacted clay surface during the plant growth and compares the surface fissure of the plant without the plant soil column under the same condition. The surface cracking can be delayed and restricted for the compacted clay with the same condition without plant roots. Through four groups of soil column tests, the percolation characteristics of the cover layer in different states are analyzed. First, a group of remolded compacted soil column seepage tests are carried out, and there is no plant root and no fissure in this group of soil columns. Secondly, a group of remolded compacted soil column percolation tests were carried out after a period of dry and wet circulation, and the seepage characteristics of the cracked covering layer have been produced when the plant roots have not yet grown to the clay impervious layer. Again, the plant is cultivated in the soil column and the soil is cracked during the plant growth process. The percolation test of plant roots and fissures in the soil also simulates the growth of plant roots in the clay impervious layer and the permeation characteristics of the covering layer during the cracking. Finally, in order to accurately evaluate the effect of plant roots, the seepage test of the remolded soil column containing plant roots but not cracking in the soil is carried out. The results of the four groups of experiments are carried out. It is shown that the roots and fissures of plants increase rain infiltration into the soil. Plant roots provide a preferential migration channel for water infiltration, and the dominant flow of plant roots can not be ignored. Although the cracks in the soil are closed during the seepage test, the rain infiltration will fluctuate during a certain period, but the water is formed along the fissure throughout the process. The dominant flow was not weakened, the soil cracking increased the permeability of the soil. With bright blue as a dyeing tracer, the staining tracer test was carried out in the remolded soil column containing plant roots but no cracking. The results showed that the dye was migrated along the root system in the compacted clay. The result showed that the dye was dyed in the cross section with the increase of depth. In the soil near the root system, there is a partial preferential migration of the dye, which further clarifies the role of plant roots in the mulching layer.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU993;TU442

【參考文獻】

相關(guān)碩士學(xué)位論文 前1條

1 郭凌波;考慮裂隙網(wǎng)絡(luò)動態(tài)發(fā)展的裂隙土土水特征曲線研究[D];哈爾濱工業(yè)大學(xué);2013年

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本文編號：1983622