采空区地表窑洞结构的稳定性研究

发布时间：2018-05-02 09:44

本文选题：采空区 + 地表变形　；参考：《中北大学》2017年硕士论文

【摘要】：随着经济的飞速发展,我国地下采煤现象也愈发频繁,致使一些老能源基地发生大范围的采空区塌陷现象。它的存在会不可避免地对地表及其周围建筑物造成影响,稍有不慎就会引起建筑物失稳、倾斜或开裂等一系列问题,给国家和人民带来严重损失。地下煤矿开采引起的一系列环境岩土问题日益引起人们的重视,研究采空区对地表及其建筑物的影响就变得非常重要。窑洞是世界上现存最多的传统居住建筑形式之一,它具有冬暖夏凉、绿色环保、无污染、低能耗等优点,随着可持续发展和绿色建筑理念的兴起,窑洞建筑又重新得到了社会的认可和重视,因此对窑洞这种特殊拱形结构的研究具有实际意义。本文基于采空区地表及其窑洞结构的破坏机理,主要完成了以下几方面的工作:(1)简单介绍了窑洞的破坏形式,并且对它在仅受自重的情况下进行了受力分析与理论计算,得到无采空区影响时窑洞的变形破坏规律。结果表明:当窑洞仅受自重作用时,拱顶和拱脚处会承受土体之间较大的压力。一旦压力超过土体的极限承载力,拱脚就会发生垂直位移的现象,引起窑洞裂缝或坍塌。另外拱脚以上两侧土体应保持一定厚度的填土,否则也会引起拱脚发生水平位移,致使窑洞发生破坏。(2)利用FLAC3D有限元分析软件分别对开采深度、开采厚度、开采宽度、不同相对位置的各个结构状态进行模拟计算,从窑洞的位移场、应力场和塑性区具体分析其受力变形情况。计算结果表明:(1)窑洞受采空区影响时,竖向最大位移发生在拱顶处,因此在日常使用中应注重拱圈的防护与加固;水平方向最大位移发生在拱圈与窑腿交接处;最大竖向应力发生在窑腿底部,因此可以通过增大窑腿宽度以减小其所承受的压应力;塑性区大部分集中于拱顶和底部进口区域。(2)位于老采空区中央正上方的窑洞沉降量最大,基础各监测点的移动变形具有对称性;老采空区边界上方的窑洞沉降量次之,基础各监测点的移动变形失去对称性,不均匀沉降最明显,对窑洞保护不利,应避免将其建在该区;老采空区外边缘处的窑洞沉降量最小。(3)随着开采宽度和开采厚度的增加,窑洞产生的位移和应力值都随之递增;随着开采深度的增加,窑洞产生的位移和应力值却随之递减。在本模拟条件下其临界深厚比为16,此时存在对地表窑洞沉陷无明显影响的临界深厚比。当超过这一深厚比之后,采空区存在与否,对窑洞已无明显影响,故在实际工程中,应当选择合理的开采尺寸以确保地表及其建筑物处于安全状态。(3)通过选取影响窑洞稳定性较大的四因素三水平,设计正交试验,对其进行极差分析。可知在本模拟试验条件下,窑洞与采空区相对位置影响最为显著,为主要因素;其次是开采宽度和开采深度;而开采厚度的影响较小,为不重要因素。且当开采深度为60m,开采厚度为7m,开采宽度为50m,窑洞位于采空区中央正上方时,拱顶沉降量最大,约为94.22mm,此时窑洞处于最不稳定状态。(4)煤矿开采后及时填充,可利于提高窑洞稳定性,使其沉降量明显减小,即窑洞拱顶沉降量从94.22mm急剧减小至28.47mm,降低了69.78%。且充填材料强度越高,充填效果越明显,窑洞沉降量越小,即采空区充填可有效解决地表建筑物的沉降变形问题。
[Abstract]:With the rapid development of the economy, the underground coal mining phenomenon is becoming more frequent in our country, which causes the collapse of the goaf in some old energy bases. Its existence will inevitably affect the surface and surrounding buildings, and a little carelessness will cause a series of problems, such as the instability, the inclination or the cracking of the buildings, to the state and the people. A series of environmental rock and soil problems caused by underground coal mining have attracted more and more attention. It is very important to study the influence of the goaf on the surface and its buildings. The cave is one of the most existing traditional residential buildings in the world. It has a cold winter, a green environment, no pollution, low energy consumption and so on. With the rise of sustainable development and the rise of the concept of green building, the cave building has been recognized and paid more attention by the society. Therefore, it is of practical significance to study the special arch structure of the cave cave. Based on the destruction mechanism of the ground surface and its cave structure in the goaf, the main work is completed in the following aspects: (1) a brief introduction is made. The failure mode of the cave is carried out and its stress analysis and theoretical calculation are carried out in the case of self weight only. The law of deformation and failure of the cave is obtained without the influence of the goaf. The result shows that the vault and arch foot will bear large pressure between the arch and the arch when the cave is only affected by the weight of the soil. The vertical displacement of the foot will cause the crack or collapse of the cave. In addition, the soil above the two sides of the arch foot should be filled with a certain thickness. Otherwise, the horizontal displacement of the arch foot will be caused, which causes the cave to destroy. (2) the mining depth, mining thickness, mining width, and different relative position of the mining depth, mining thickness, mining width are respectively used by the FLAC3D finite element analysis software. Each structure state is simulated and calculated from the displacement field, stress field and plastic zone of the cave. The calculation results show that: (1) the maximum vertical displacement occurs at the vault when the cave is affected by the goaf, so the protection and reinforcement of the arch ring should be paid attention to in the daily use; the maximum horizontal displacement occurs in the arch ring. The maximum vertical stress occurs at the bottom of the kiln leg, so the width of the kiln leg can be increased to reduce the pressure stress. Most of the plastic zone is concentrated in the vault and the bottom inlet area. (2) the cave settlement in the middle of the center of the old goaf is the largest, and the movement and deformation of the monitoring points of the base are symmetrical; The cave settlement above the goaf boundary is the second, and the movement and deformation of the monitoring points of the foundation are not symmetrical, and the uneven settlement is the most obvious. It is unfavorable to the cave protection and should avoid it in the area. The settlement of the cave at the outer edge of the old goaf is the smallest. (3) the displacement and stress generated by the mining width and thickness of mining, the displacement and stress value of the cave. With the increase of mining depth, the displacement and stress value of cave dwellings decrease with the increase of the mining depth. Under this simulation, the critical depth ratio is 16, and there is a critical deep ratio that has no obvious influence on the cave cave subsidence. In the project, a reasonable mining size should be chosen to ensure the safety of the surface and its buildings. (3) through the selection of the four factors and three levels which affect the stability of the cave, the orthogonal test is designed to carry out the extreme analysis. The second is the mining width and mining depth, and the mining thickness has little influence, which is not important. And when the mining depth is 60m, the mining thickness is 7m, the mining width is 50m, the cave is located at the top of the goaf center, the settlement of the vault is the largest, about 94.22mm, and the cave is in the most unstable state. (4) filling in time after coal mining is available. In order to improve the stability of the cave, the settlement of the cave dome decreases sharply from 94.22mm to 28.47mm, the lower the 69.78%. and the higher the strength of the filling material, the more obvious filling effect, the smaller the cave settlement, that is, the filling in the goaf can effectively solve the settlement and deformation of the surface buildings.

【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD325.3;TU746.1

【参考文献】