本文關(guān)鍵詞：直流電場抑制潮濕土遺址毛細(xì)水上升應(yīng)用研究　出處：《蘭州大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 潮濕土遺址 直流電場 毛細(xì)水 防潮控制保護(hù) 易溶鹽

【摘要】：土遺址作為一種非常重要的人類文明遺址,在我國境內(nèi)數(shù)量眾多,分布廣泛,所處的自然環(huán)境也千差萬別。現(xiàn)存的土遺址往往具有重大的歷史價值和考古價值,其中杭州良渚古城遺址是眾多歷史文化實(shí)物遺存的典型代表,它對于研究中華文明的起源有著非凡的意義。良渚古城遺址所在地區(qū)氣候溫暖濕潤,屬于典型的潮濕環(huán)境中的土遺址,遺址本體長期遭受地下水毛細(xì)上升作用的侵蝕,穩(wěn)定性較差,如何長久有效地保存遺址本體成為一項極其重要的研究課題。21世紀(jì)以來,隨著國家對文物保護(hù)工作的扶持和重視,文物保護(hù)工作者在露天土遺址的搶險加固保護(hù)中取得了很多優(yōu)秀的成果,并且仍在不斷探索關(guān)于潮濕土遺址保護(hù)方面有效的方法和措施,如使用改性材料加固、表面補(bǔ)砌、回填以及原地展出等。但值得注意的是,如何對潮濕土遺址內(nèi)部的微觀水環(huán)境進(jìn)行有效地控制是處在潮濕環(huán)境中的土遺址長久保存的關(guān)鍵所在,現(xiàn)有的研究成果很少。潮濕環(huán)境下的土遺址產(chǎn)生破壞的主要原因為土體內(nèi)部的毛細(xì)水上升及鹽分的遷移,改變了原有土體的水。鹽平衡結(jié)構(gòu)。對此,本研究提出了利用電化學(xué)的方法來控制土遺址的內(nèi)部環(huán)境,即在土遺址本體中加入直流電場,讓土體內(nèi)部的水分在電場力的驅(qū)動下從陽極向陰極移動,從而抑制毛細(xì)水的上升及鹽分的遷移和富集,使土體內(nèi)部的水-鹽平衡結(jié)構(gòu)維持在最佳狀態(tài),保持土體內(nèi)部賦存環(huán)境穩(wěn)定,從根本上解決潮濕環(huán)境下土遺址的破壞問題。本研究首先以吸水性較好的濾紙為研究對象,進(jìn)行了不計重力的二維平面模擬,研究了直流電場作用下水分的水平運(yùn)移狀態(tài),分析了直流電場驅(qū)動水分運(yùn)移的機(jī)理；其次,以杭州良渚古城遺址為原型,對重塑土樣進(jìn)行直流電場抑制毛細(xì)水上升的三維模擬試驗,研究了直流電場對土樣中毛細(xì)水的抑制作用；然后,進(jìn)行了遺址區(qū)地下水?dāng)y帶鹽分毛細(xì)上升的模擬試驗,研究了在直流電場作用下土樣中水-鹽的運(yùn)移和分布；最后,以同樣處于潮濕環(huán)境中的南京大報恩寺遺址地宮為原型,分析了毛細(xì)水上升造成土遺址破壞的機(jī)理以及直流電場對潮濕土遺址的保護(hù)加固的機(jī)理,應(yīng)用直流電場抑制毛細(xì)水上升的保護(hù)加固技術(shù)構(gòu)想。本文的主要研究內(nèi)容和取得的研究成果包括：1.直流電場抑制水分遷移的平面模擬研究利用纖維結(jié)構(gòu)的潤濕機(jī)理對浸水后的濾紙和有毛細(xì)水補(bǔ)給的濾紙中水分分布狀態(tài)進(jìn)行描述,結(jié)果如下：浸水后的濾紙整體水分分布均勻；有毛細(xì)水補(bǔ)給的濾紙,受粘附作用和毛細(xì)吸附作用影響,濾紙含水率在水平方向隨距透水石距離的增加而逐漸遞減。運(yùn)用Helmholtz-Smoluchowski模型分析濾紙中水分運(yùn)移的機(jī)理,濾紙兩端添加了直流電場后,受電場作用在濾紙中將形成額外的滲透壓,使水分在濾紙的一端積累,試驗表明濾紙含水率在200%以上時直流電場對濾紙中毛細(xì)水的抑制效果較好。2.直流電場抑制毛細(xì)水上升三維模擬研究在無毛細(xì)水補(bǔ)給的條件下,對照組土樣中的水分僅受蒸發(fā)作用影響,試樣整體含水率隨著時間的增加而降低；同一時間下,試樣中的含水率隨高度增加而降低。隨著電滲時間的增加,上行電場組土樣中含水率從初始的隨試樣高度增加而降低變成了隨著試樣高度的增加而增加,電滲促進(jìn)水分向上運(yùn)移效果明顯：下行電場組土樣頂端含水率下降速度大于土樣底端含水率下降速度,且含水率曲線斜率隨時間增加迅速降低,電滲對試樣中水分的抑制效果從下至上逐漸增強(qiáng)。在有毛細(xì)水補(bǔ)給的條件下,上行電場組中干密度為1.50g/cm3的試樣在電場作用144h后頂端含水率較未添加電場時高5%；干密度為1.60g/cm3的試樣的這一差值可達(dá)7.4%,說明電場促進(jìn)毛細(xì)水上升的效果較好。下行電場組中,干密度為1.50/cm3的試樣與對照組中相同干密度的試樣相比,不同高度處含水率隨電滲時間增加而降低,說明電場作用抑制了毛細(xì)水的向上運(yùn)移。3.直流電場控制水-鹽遷移耦合試驗研究天然土試樣和含鹽土試樣在施加下行電場時,毛細(xì)水抑制量均隨高度增加呈線性遞減趨勢；在施加上行電場時,毛細(xì)水促進(jìn)量均隨高度增加呈線性遞增趨勢。在無水分補(bǔ)給的條件下,施加下行電場時,天然土和含鹽土毛細(xì)水抑制量最多可分別達(dá)1.56%和4.68%；施加上行電場時,天然土和含鹽土毛細(xì)水促進(jìn)量最多可分別達(dá)2.09%和1.93%。在蒸餾水補(bǔ)給條件下,施加下行電場時,天然土和含鹽土毛細(xì)水抑制量最多可分別達(dá)5.38%和6.30%；施加上行電場時,天然土和含鹽土毛細(xì)水促進(jìn)量最多可分別達(dá)3.39%和8.81%。在鹽溶液補(bǔ)給的條件下,施加下行電場后,含水率曲線斜率降低,土樣上部含水率減少,下部增加；施加上行電場后,天然土試樣整體含水率升高2%左右,含鹽土試樣整體含水率升高4%左右。試驗首次利用直流電場控制Na+和S042-的運(yùn)移方向,再聯(lián)合物理除鹽方法,將電滲匯集的鹽分脫去,可有效解決鹽類風(fēng)化對古代土建筑的破壞問題。4.直流電場抑制毛細(xì)水上升機(jī)理研究以大報恩寺遺址地宮為原型,根據(jù)毛細(xì)力學(xué)中毛細(xì)作用物理模型和非飽和土力學(xué)中收縮膜(水-氣分界面)的表面張力模型對潮濕土遺址墻體坍塌破壞機(jī)理進(jìn)行了分析。從電滲機(jī)理出發(fā),結(jié)合試驗數(shù)據(jù),對直流電場抑制潮濕土遺址毛細(xì)上升效果進(jìn)行了理論分析。分析認(rèn)為潮濕土遺址在施加直流電場后,土中的水分重新分布,土體整體含水率降低,單位高度上的含水率變化增加。蒸發(fā)作用、毛細(xì)作用、電場作用三者最終達(dá)到動態(tài)平衡,遺址內(nèi)部始終存在較大的基質(zhì)吸力。應(yīng)用直流電場可以從本質(zhì)上解決土遺址中墻體坍塌破壞問題。提出了現(xiàn)場應(yīng)用直流電場對潮濕土遺址進(jìn)行電動控制防潮的技術(shù)構(gòu)想。
[Abstract]:Soil sites as an important site of human civilization, in our country a large number, wide distribution, the natural environment is also different. Existing soil sites often have major historical and archaeological value, of which Hangzhou Liangzhu ancient city site is typical of many historical and cultural relics, it is extraordinary the significance for the study of the origin of Chinese civilization. The Liangzhu ruins of the ancient city area of warm and humid climate, which belongs to the typical soil sites in damp environment, erosion, body site suffered long-term groundwater capillary rise of stability is poor, since how long to effectively preserve the body site has become an extremely important research topic in the.21 Century, with the country of cultural relics the protection of the support and attention, the protection of cultural relics in the open soil site rescue workers strengthened protection and achieved excellent results, and And continues to explore about the methods and measures for the effective protection of wet soil sites, such as the use of modified material surface strengthening, reinforcing masonry, backfill and displays in situ. But it is worth noting that, how micro water environment on internal wet soil sites effectively is the key soil sites in the humid environment the long-term preservation of the existing research results. The main reason is rarely soil sites under moist environment damage to the capillary rise of water and salt migration within the soil, changed the original soil water. The salt balance structure. In this regard, this research proposes the use of electrochemical methods to control soil sites internal environment. Adding a DC electric field on soil sites in the body, let the soil moisture under the driving force of the electric field move from the anode to the cathode, migration and accumulation of salt increased and inhibit capillary water, the soil The water salt balance structure is maintained in the best condition, keep the soil environment stability, solve the problem of soil damage sites in humid environment fundamentally. In this study, using filter paper with good water absorption as the research object, a two-dimensional plane without gravity simulation, the horizontal migration state under the effect of DC field water the analysis of the mechanism of DC electric field driven water transport; secondly, to Hangzhou Liangzhu ancient ruins as the prototype, simulation 3D DC electric field of capillary rise on inhibition of remolded soil samples of DC electric field on the capillary water in the soil samples were then inhibition; site of groundwater carrying salt capillary rise the simulation experiment on the migration and distribution in the DC electric field of soil water and salt; finally, with the same in a humid environment in Nanjing Dabao'en temple ruins of Palace of the Earth As the prototype, analysis of the capillary water rise caused by the mechanism of protection mechanism of soil site failure and DC electric field on the moist soil site reinforcement, application of DC electric field suppression protection of capillary rise reinforcement technology idea. The main research contents and achievements are as follows: 1. the inhibition of moisture migration of plane DC electric field simulated by wetting the mechanism of fiber structure after immersion of filter paper and capillary water filter in water distribution are described. The results are as follows: the whole paper moisture distribution after soaking uniformly; capillary water filter, affected by the adhesion and capillary effect, increase the moisture content of the filter in the horizontal direction with the distance from the permeable distance diminishing. Use Helmholtz-Smoluchowski model to analyze the mechanism of water movement in filter paper, filter paper ends add DC electric field, electric field The role of the formation of additional osmotic pressure in the filter will make water accumulated in the filter paper is paper moisture test shows that the above 200% inhibitory effect of electric field on the capillary water filter in good.2. DC electric field numerical simulation study of inhibition of capillary rise in non capillary water supply conditions, the control group in soil samples only by water evaporation, the whole sample water content decreased with the increase of time; at the same time, water content in the sample rate decreases with height. With the increase of electroosmosis time, water from the initial sample with height increased became increased with the increase of the height of the sample rate of uplink electric field soil like, the moisture migration effect is obvious: promote the electroosmosis of soil samples at the top down field moisture content decreased faster than that of the bottom soil moisture decline rate, water content and slope of the curve with time Increase rapidly decreased, the inhibitory effect of electroosmosis on moisture from the bottom gradually. In the capillary water, the density of 1.50g/cm3 samples in the electric field after 144H at the top of the water content is not added when the high electric field of 5% dry field uplink group; dry density for sample 1.60g/ cm3 the difference up to 7.4%, indicating good electric field promotes the capillary rise of water. The effect of electric field down group, compared with the dry density of 1.50/cm3 samples and the control group in the same dry density samples, water content at different height rate with the working time increased, the electric field induced by the capillary water upward migration of.3. DC electric field control of water salt migration test study on the coupling of natural soil samples and saline soil samples in the field put downward, capillary water suppression were decreased linearly with increasing altitude in exert upward trend; the electric field, promote the quantity of capillary water With the height increased linearly with increasing trend. In the absence of water supply conditions, put downward electric field, natural soil and saline soil capillary water suppression up to 1.56% and 4.68% respectively; the uplink applied electric field, the natural soil and saline soil capillary water promote maximum amount can respectively reach 2.09% and 1.93%. in distilled water. Under the condition of applying downward electric field, natural soil and saline soil capillary water suppression up to 5.38% and 6.30% respectively; the uplink applied electric field, the natural soil and saline soil capillary water promote most can respectively reach 3.39% and 8.81%. in salt solution. Under the condition of applying downward electric field, the moisture content of the slope of the curve decreases the soil water content is reduced, the upper and lower increase; exert upward electric field, 2% increase in natural soil moisture around the whole sample, 4% increase in saline soil sample water content. The first use of DC electric field control test Na The migration direction of + and S042-, and then combined with physical salt removal method, the electroosmotic collection salt off, can effectively solve the problem of soil salt weathering and damage of ancient buildings.4. DC field inhibition of capillary rise mechanism with the Palace of the Earth temple ruins as the prototype, according to the physical model of capillary capillary membrane shrinkage and unsaturated soil mechanics mechanics (water gas interface) the surface tension model is analyzed on wet soil wall sites collapse mechanism. Starting from the electroosmosis mechanism, combined with the test data, inhibition of wet soil sites on capillary DC electric field was analyzed. The effect of rising damp soil sites in the analysis that the applied DC electric field, the soil moisture in the re the distribution of soil water content decreased, the overall height of the unit, the water rate increase. Evaporation, capillary effect, electric field three reach the dynamic balance in the ruins There is always a large matrix suction. The application of direct current electric field can fundamentally solve the problem of wall collapse in earthen sites. A technical conception of on-site application of DC electric field to control damp soil sites by electric control is put forward.

【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU46;TU-87

【引證文獻(xiàn)】

相關(guān)會議論文 前1條

1 周環(huán);張秉堅;李最雄;;用潮汽固化有機(jī)硅材料保護(hù)潮濕環(huán)境土遺址[A];中國文物保護(hù)技術(shù)協(xié)會第二屆學(xué)術(shù)年會論文集[C];2002年

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本文編號：1382634