本文關(guān)鍵詞： 模擬月壤 土拱效應(yīng) 三維離散元 PFC3D　出處：《中國地質(zhì)大學（北京）》2010年碩士論文　論文類型：學位論文

【摘要】： 當前,人類面臨煤炭、石油和天然氣等現(xiàn)有傳統(tǒng)能源日益枯竭的局面。于是,人們將目光投向了擁有豐富資源的月球。為了開發(fā)和利用月球資源,美國、俄羅斯等國家興起新一輪世界性的“重返月球”熱潮。中國也制定了探月工程“三步走”的計劃,其中第三步以及未來月球基地的建設(shè)過程中,必將涉及到月壤原位勘察測試取樣。為了確保在月球上順利而完整的實現(xiàn)原位取樣,先期必須在地球上進行相關(guān)的模擬試驗。根據(jù)地球上原位取樣的經(jīng)驗,經(jīng)常會遇到取土器鉆進后,土樣采取率達不到要求,甚至是根本取不到土樣的情況。通過對有關(guān)土力學機理的分析,很可能是在鉆進的過程中受到了土拱效應(yīng)的影響。 本文首先選用與月壤樣品具有相似礦物化學組成的火山噴發(fā)物質(zhì)-靖宇火山灰作為制備模擬月壤原物質(zhì),制得火山灰試樣。并對火山灰試樣進行基本物理力學性質(zhì)試驗。結(jié)果表明:用雷蒙磨粉碎、并過0.5mm篩的火山灰試樣及其與金剛砂的配合物,顆粒形狀與月壤相似,土粒比重略小于典型月壤的土粒比重,平均粒徑與內(nèi)摩擦角跟月壤接近,可以用來模擬月壤。 然后通過模擬月壤土拱效應(yīng)驗證試驗表明:在模擬月壤中很容易出現(xiàn)土拱現(xiàn)象,并且形成土拱的難易程度與取樣圓管孔徑、模擬月壤的相對密度有關(guān)�？傮w來說:相同孔徑時,相對密度越大,越容易成拱;相同密實度時,孔徑越小,越容易成拱,且密實度較大時成拱高度約為孔的半徑。 通過土拱效應(yīng)對原位取樣影響的試驗研究從機理上解釋了可能造成原位取樣失敗的原因:受土拱作用的影響,土拱以下的土樣被擋在管外,較難進入試驗管中。同時,已進入管中的土樣在試驗管下壓過程中因為土拱的影響會變得較松散,致使土樣與管壁的摩擦力不足以在提取試驗管時將土樣取出,從而造成了鉆取原狀土樣時的失敗。 最后運用三維離散元軟件PFC3D模擬壓管試驗表明,圓柱墻在下壓的過程中,土體中出現(xiàn)了明顯的土拱現(xiàn)象。 本文研究表明,在進行原位取樣的過程中非常容易產(chǎn)生土拱效應(yīng)。特別是月壤取樣時,為了確保原位取樣的順利完成,更應(yīng)該加強對土拱效應(yīng)的研究。
[Abstract]:At present, mankind is faced with the situation that coal, oil and natural gas and other existing traditional energy are increasingly exhausted. Therefore, people have turned their eyes to the moon, which is rich in resources. In order to develop and utilize the lunar resources, the United States. Russia and other countries have a new round of worldwide "return to the moon" upsurge. China has also formulated a "three-step" plan for lunar exploration, the third of which is in the process of building a future lunar base. In order to ensure the successful and complete in situ sampling on the moon, the related simulation tests must be carried out on the earth in advance. According to the experience of in situ sampling on the earth. It is often encountered that the rate of soil sample can not reach the requirement, even the soil sample can not be obtained, after drilling with a soil collector, the mechanism of soil mechanics is analyzed. It is very likely that the soil arch effect affected the drilling process. In this paper, the volcanic eruption material, Jingyu volcanic ash, which has similar mineral chemical composition to the lunar soil sample, is first selected as the raw material of the simulated lunar soil. The basic physical and mechanical properties of the pozzolanic sample were tested. The results showed that the ash sample and its complex with Emery were comminuted by Ramon mill and passed 0.5mm sieve. The particle shape is similar to that of the lunar soil, the specific gravity of the soil is slightly smaller than that of the typical lunar soil, and the average particle size and the angle of internal friction are close to the lunar soil, which can be used to simulate the lunar soil. Then through the simulation of the lunar soil arch effect verification test shows that the soil arch phenomenon is easy to occur in the simulated lunar soil and it is easy to form the soil arch and the pore diameter of the sampling pipe. The relative density of the simulated lunar soil is related to the relative density of the lunar soil. On the whole, the higher the relative density of the lunar soil is, the easier it is to form arch with the same pore diameter. At the same compactness, the smaller the aperture, the easier it is to form arch, and the higher the density, the higher the arch height is about the radius of the hole. Through the experimental study on the effect of soil arch effect on in-situ sampling, the possible reasons for failure of in-situ sampling are explained from the mechanism: under the influence of soil arch, the soil samples below the soil arch are blocked out of the pipe. It is more difficult to enter the test tube. At the same time, the soil sample already in the pipe will become looser because of the influence of the soil arch during the compression process of the test tube, so the friction between the soil sample and the pipe wall is not enough to remove the soil sample from the test tube when it is extracted. As a result, the failure of drilling for the original soil sample is caused. In the end, the results of three dimensional discrete element software PFC3D show that the soil arch appears in the soil during the compression process of the cylindrical wall. In this paper, it is shown that the soil arch effect is very easy to occur in the process of in-situ sampling, especially in the case of lunar soil sampling, in order to ensure the successful completion of in-situ sampling, the study of soil arch effect should be strengthened.
【學位授予單位】：中國地質(zhì)大學（北京）
【學位級別】：碩士
【學位授予年份】：2010
【分類號】：P184

【引證文獻】

相關(guān)會議論文 前1條

1 譚松成;段隆臣;高輝;;重力環(huán)境對月壤三軸模擬試驗結(jié)果的影響分析[A];顆粒材料計算力學研究進展[C];2012年

相關(guān)博士學位論文 前1條

1 胡勵;機械產(chǎn)品設(shè)計中的顆粒離散元仿真技術(shù)及實現(xiàn)[D];武漢大學;2013年

相關(guān)碩士學位論文 前1條

1 劉天喜;淺層月壤采樣過程的機土耦合作用研究[D];哈爾濱工業(yè)大學;2011年

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本文編號：1484599