本文選題：河西地區(qū) + 夯土長(zhǎng)城��； 參考：《蘭州交通大學(xué)》2017年碩士論文

【摘要】：長(zhǎng)城是我國(guó)古代偉大的軍事防御工程,也是中華民族獻(xiàn)給世界的偉大歷史遺產(chǎn)。甘肅河西地區(qū)有漢、明兩個(gè)時(shí)期修筑的長(zhǎng)城,在有些地段可以看到漢、明長(zhǎng)城并行的場(chǎng)景,這在國(guó)內(nèi)其他地區(qū)是很難見(jiàn)到的。但河西地區(qū)長(zhǎng)城的保存現(xiàn)狀并不樂(lè)觀(guān),且河西地區(qū)處于地震多發(fā)區(qū),區(qū)內(nèi)斷層分布廣泛,歷史上曾發(fā)生過(guò)多次大地震。因此,河西地區(qū)的長(zhǎng)城很容易遭到地震的襲擊并產(chǎn)生進(jìn)一步的破壞甚至垮塌。本文通過(guò)查閱文獻(xiàn)資料和實(shí)地考察,發(fā)現(xiàn)多數(shù)長(zhǎng)城破損嚴(yán)重。保存不好的區(qū)段墻體成田埂狀,殘高0.5m左右,而保存較好的區(qū)段墻體殘高3m~6m之間。通過(guò)室內(nèi)土工實(shí)驗(yàn)可以看出各段長(zhǎng)城土體動(dòng)彈性模量基本都在100MPa以上,烽燧土體的動(dòng)彈性模量最大,可達(dá)129.87MPa。各段長(zhǎng)城土體阻尼比在0.063~0.133之間。由于城墻土體內(nèi)石子較多,因此內(nèi)摩擦角普遍較大,都在30°以上,最大的為長(zhǎng)城鄉(xiāng)段達(dá)56.71°。而各段長(zhǎng)城土體粘聚力變化范圍較大在19.17kPa~157.64kPa之間。各段長(zhǎng)城土體抗拉強(qiáng)度在0.1MPa~0.3MPa之間。通過(guò)數(shù)值模擬軟件建立了六段長(zhǎng)城墻體和烽燧的數(shù)值模型,輸入山丹6.1級(jí)地震波后可以得出:(1)黃羊河農(nóng)場(chǎng)段長(zhǎng)城整體上穩(wěn)定,不過(guò)在墻體底部會(huì)有個(gè)別區(qū)域產(chǎn)生拉裂和掉落,墻體最大拉應(yīng)力在墻體底部,不過(guò)由于副墻的存在對(duì)長(zhǎng)城墻體有一定的加固作用,因此副墻所在的部位加速度和位移都小于沒(méi)有副墻存在的部位。(2)金川西段長(zhǎng)城在掏蝕處會(huì)出現(xiàn)大面積的開(kāi)裂,墻體有整體傾倒坍塌的可能,墻體的最大拉應(yīng)力在掏蝕部位,加速度和位移隨著墻體的增高而增大,基礎(chǔ)掏蝕對(duì)長(zhǎng)城穩(wěn)定性影響很大,值得重點(diǎn)關(guān)注。(3)王信堡段北側(cè)長(zhǎng)城整體上穩(wěn)定,最大拉應(yīng)力在長(zhǎng)城墻體底側(cè),加速度和位移隨著墻體的增高而不斷增大。(4)山丹長(zhǎng)城博物館段長(zhǎng)城在地震作用下人為挖的通道周邊會(huì)產(chǎn)生拉裂和坍塌,從而可進(jìn)一步造成長(zhǎng)城整體的失穩(wěn)與坍塌,長(zhǎng)城最大拉應(yīng)力在人為所挖的通道周邊,而通道上方墻體的加速度和位移也都最大,遠(yuǎn)大于同等高度處的兩側(cè)墻體,因此通道的存在使長(zhǎng)城墻體的結(jié)構(gòu)性產(chǎn)生了破壞,在地震作用下極可能坍塌。(5)鹽池5號(hào)烽燧在地震作用下整體穩(wěn)定,不過(guò)在烽燧底部拐角處會(huì)產(chǎn)生拉裂和稍許的脫落,鹽池5號(hào)烽燧由于形狀特殊,烽燧上部加速度和位移都很大,放大效應(yīng)突出。(6)金塔烽燧整體穩(wěn)定,在烽燧底部拐角處會(huì)出現(xiàn)開(kāi)裂和脫落,烽燧最大拉應(yīng)力出現(xiàn)烽燧底部四個(gè)拐角處,加速度和位移隨著高度的增加而增大,最大處在烽燧四個(gè)頂角部位。整體上看在烈度為Ⅷ度的地震作用下,河西地區(qū)的長(zhǎng)城多少都會(huì)產(chǎn)生一定的破壞,尤其對(duì)于本身結(jié)構(gòu)就已經(jīng)發(fā)生破壞(如基礎(chǔ)掏蝕、人為開(kāi)挖通道和裂隙)的墻體,在地震作用下極有可能會(huì)產(chǎn)生垮塌。由于河西地區(qū)發(fā)生的地震危險(xiǎn)性較大,因此很有必要提前對(duì)結(jié)構(gòu)已有破損的長(zhǎng)城進(jìn)行加固。
[Abstract]:The Great Wall is a great military defense project in ancient China and a great historical heritage dedicated to the world by the Chinese nation. In Hexi region of Gansu Province, there are Han Dynasty, the Great Wall built in Ming Dynasty, and the scene of Han and Ming the Great Wall can be seen in some areas, which is very difficult to see in other parts of China. However, the status quo of the Great Wall preservation in Hexi area is not optimistic, and Hexi region is in an earthquake prone area, where faults are widely distributed, and there have been many large earthquakes in the history. As a result, the Great Wall in Hexi is vulnerable to earthquake damage and even collapse. Through literature review and field investigation, it is found that most the Great Wall are seriously damaged. The poorly preserved section wall is in the shape of field ridge, and the residual height is about 0.5 m, while that of the better preserved section wall is between the residual height of 3m~6m. It can be seen that the dynamic elastic modulus of each segment of the Great Wall soil is above 100MPa, and the dynamic elastic modulus of Feng Sui soil is the largest, which can reach 129.87 MPA. The damping ratio of the Great Wall soil is between 0.063 and 0.133. Because there are more stones in the soil body of the city wall, the angle of internal friction is more than 30 擄, and the largest is 56.71 擄in the Changcheng section. However, the cohesive force of each the Great Wall soil varies greatly between 19.17kPa~157.64kPa. The tensile strength of each the Great Wall soil is between 0.1MPa~0.3MPa. Through numerical simulation software, the numerical model of six the Great Wall walls and beacons is established. After input of Shandan magnitude 6.1 seismic wave, it can be concluded that the Great Wall of the Huangyang River farm section is stable on the whole, but at the bottom of the wall, there will be a few areas where the cracks and falls will occur. The maximum tensile stress of the wall is at the bottom of the wall, but because of the existence of the secondary wall, the Great Wall wall can be strengthened to a certain extent. Therefore, the acceleration and displacement of the secondary wall are smaller than that of the non-accessory wall.) the Great Wall in the western section of Jinchuan will have a large area of cracking at the excavation site, and the wall may collapse, and the maximum tensile stress of the wall is in the erosive site. The acceleration and displacement increase with the increase of the wall, and the foundation excavation has a great influence on the stability of the Great Wall. It is worth paying more attention to the Great Wall in the north side of Wangxinbao section. The maximum tensile stress is on the bottom side of the Great Wall wall. Acceleration and displacement increase with the increase of wall. 4) the Great Wall of the Great Wall Museum section of Shandan will crack and collapse around the artificially excavated passage under the earthquake, which will further cause the instability and collapse of the Great Wall as a whole. The maximum tensile stress of the Great Wall lies around the artificially excavated tunnel, and the acceleration and displacement of the wall above the tunnel are also the largest, which is much larger than that of both sides of the wall at the same height, so the existence of the passage causes the damage to the structure of the Great Wall wall. Under earthquake action, it is very likely that Yanchi 5 will collapse.) Yanchi 5 is stable under the earthquake. However, at the corner of the bottom of the beacon, there will be a crack and a little shedding. Because of its special shape, Yanchi No. 5 has a special shape. The acceleration and displacement in the upper part of the Feng Sui are both very large. The amplification effect is prominent. The Feng Sui of Jinta is stable as a whole. At the corner of the funnel bottom there will be cracking and shedding, and the maximum tensile stress of the Feng Sui will appear at the four corners of the bottom of the beacon. The acceleration and displacement increase with the increase of height. On the whole, under the earthquake of intensity 鈪，

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