河西地区长城土遗址抗震稳定性研究

发布时间：2018-05-13 02:03

  本文选题：河西地区 + 夯土长城　； 参考：《兰州交通大学》2017年硕士论文

【摘要】：长城是我国古代伟大的军事防御工程,也是中华民族献给世界的伟大历史遗产。甘肃河西地区有汉、明两个时期修筑的长城,在有些地段可以看到汉、明长城并行的场景,这在国内其他地区是很难见到的。但河西地区长城的保存现状并不乐观,且河西地区处于地震多发区,区内断层分布广泛,历史上曾发生过多次大地震。因此,河西地区的长城很容易遭到地震的袭击并产生进一步的破坏甚至垮塌。本文通过查阅文献资料和实地考察,发现多数长城破损严重。保存不好的区段墙体成田埂状,残高0.5m左右,而保存较好的区段墙体残高3m~6m之间。通过室内土工实验可以看出各段长城土体动弹性模量基本都在100MPa以上,烽燧土体的动弹性模量最大,可达129.87MPa。各段长城土体阻尼比在0.063~0.133之间。由于城墙土体内石子较多,因此内摩擦角普遍较大,都在30°以上,最大的为长城乡段达56.71°。而各段长城土体粘聚力变化范围较大在19.17kPa~157.64kPa之间。各段长城土体抗拉强度在0.1MPa~0.3MPa之间。通过数值模拟软件建立了六段长城墙体和烽燧的数值模型,输入山丹6.1级地震波后可以得出:(1)黄羊河农场段长城整体上稳定,不过在墙体底部会有个别区域产生拉裂和掉落,墙体最大拉应力在墙体底部,不过由于副墙的存在对长城墙体有一定的加固作用,因此副墙所在的部位加速度和位移都小于没有副墙存在的部位。(2)金川西段长城在掏蚀处会出现大面积的开裂,墙体有整体倾倒坍塌的可能,墙体的最大拉应力在掏蚀部位,加速度和位移随着墙体的增高而增大,基础掏蚀对长城稳定性影响很大,值得重点关注。(3)王信堡段北侧长城整体上稳定,最大拉应力在长城墙体底侧,加速度和位移随着墙体的增高而不断增大。(4)山丹长城博物馆段长城在地震作用下人为挖的通道周边会产生拉裂和坍塌,从而可进一步造成长城整体的失稳与坍塌,长城最大拉应力在人为所挖的通道周边,而通道上方墙体的加速度和位移也都最大,远大于同等高度处的两侧墙体,因此通道的存在使长城墙体的结构性产生了破坏,在地震作用下极可能坍塌。(5)盐池5号烽燧在地震作用下整体稳定,不过在烽燧底部拐角处会产生拉裂和稍许的脱落,盐池5号烽燧由于形状特殊,烽燧上部加速度和位移都很大,放大效应突出。(6)金塔烽燧整体稳定,在烽燧底部拐角处会出现开裂和脱落,烽燧最大拉应力出现烽燧底部四个拐角处,加速度和位移随着高度的增加而增大,最大处在烽燧四个顶角部位。整体上看在烈度为Ⅷ度的地震作用下,河西地区的长城多少都会产生一定的破坏,尤其对于本身结构就已经发生破坏(如基础掏蚀、人为开挖通道和裂隙)的墙体,在地震作用下极有可能会产生垮塌。由于河西地区发生的地震危险性较大,因此很有必要提前对结构已有破损的长城进行加固。
[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 掳, and the largest is 56.71 掳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，

本文编号：1881144