基于超声波检测砂岩列柱的稳定性分析研究

发布时间：2018-04-12 06:11

本文选题：砂岩列柱 + 超声波　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：云冈石窟在自然环境、气候变化及人为因素的影响下,其稳定状态面临着多方面的威胁:岩体变形、破裂及错位、强度降低等。自开凿以来,对石窟的保护研究工作从未停止,其中地球物理勘探方法的运用最为广泛。在阅读大量文献及参考资料后,发现现阶段研究工作存在一定的局限性:地球物理勘探方法与稳定性分析应怎样进行有效的结合,仍处在探索阶段;针对云冈石窟风化情况尽管采取了不同的地球物理勘探方法,但大部分止步于风化层厚度或风化现状的研究,于后续的稳定性分析没有有效的衔接。因此将以云冈石窟砂岩列柱进行的超声波探测结果,运用于列柱的稳定性分析中,并对列柱的受力特性进行模拟和分析研究,对云冈石窟的保护及修复工作具有十分重要的指导意义。论文包含以下内容:1.阐述了固体弹性力学的基本理论、超声波检测原理及稳定性数值模拟的理论基础,明确了以波速变化确定岩石风化情况的理论依据。2.通过对石窟地区的地质背景的调查,对石质文物目前面临的各种病害进行了说明,如风化病害、盐碱及粉尘污染;并确定了超声波检测的方案,对其数据进行处理后,得到列柱的风化现状。3.对FLAC3D软件进行了简单介绍,并对规则砂岩列柱进行了模拟研究。结果表明:1.石柱底层风化最为严重,表面大部分已是强风化层,由于强风化岩石强度最弱,在面临来自顶底面的挤压时,岩石最易破碎;列柱中部,南侧及东侧风化严重为强风化层,其余方向较好,在面临顶底面的挤压时,其状态较稳定;石柱顶部,强风化分布范围较少,岩石强度较好,在面临顶底面的压力时,表现稳定。2.由列柱的受力变化可得,列柱不仅受压应力,还受拉应力;列柱的主应力主要作用在列柱的北西侧中等风化岩体和微分化岩体上。3.整体来说,列柱目前处在稳定状态,但随着时间的推移,列柱砂岩的抗压强度仍会不断下降,列柱的稳定性会越来越弱。
[Abstract]:Under the influence of natural environment, climate change and human factors, the stability of Yungang Grottoes faces many threats: rock mass deformation, fracture and dislocation, and decrease of strength.Since the excavation, the research on the protection of the grottoes has never stopped, among which geophysical exploration methods are the most widely used.After reading a large number of documents and references, it is found that there are some limitations in the present research work: how to combine geophysical exploration methods with stability analysis is still in the exploration stage;Although different geophysical exploration methods have been adopted for the weathering of Yungang Grottoes, most of them stop at the study of the thickness of weathering layer or the present situation of weathering, and there is no effective connection in the subsequent stability analysis.Therefore, the ultrasonic detection results of the sandstone column in Yungang Grottoes will be applied to the stability analysis of the columns, and the stress characteristics of the columns will be simulated and analyzed.It is of great significance for the protection and restoration of Yungang Grottoes.The thesis contains the following contents: 1.The basic theory of solid elastic mechanics, the principle of ultrasonic testing and the theoretical basis of numerical simulation of stability are expounded, and the theoretical basis for determining the weathering of rock by wave velocity variation is defined.Through the investigation of geological background in the grottoes area, various diseases faced by stone relics are explained, such as weathering diseases, saline-alkali and dust pollution, and the ultrasonic detection scheme is determined, and the data are processed.The weathering status of column. 3.The FLAC3D software is introduced, and the regular sandstone column is simulated.The result shows that 1: 1.The most serious weathering is at the bottom of the column, and most of the surface is already a strongly weathered layer. Because of the weakest strength of the strongly weathered rock, the rock is most easily broken in the face of the compression from the top and bottom, and the weathering in the middle, south and east of the column is a strong weathering layer.The other directions are better, the state of the rock is stable when facing the extrusion of the top and bottom surface, and the distribution range of strong weathering is less at the top of the stone column, and the rock strength is better, and it is stable at the pressure of the top and bottom surface.According to the stress variation of column, the column is not only under compressive stress, but also under tensile stress, and the main stress of column is mainly on the middle weathered rock body and microdifferentiated rock mass on the north and west side of column.As a whole, the column is in a stable state at present, but with the passage of time, the compressive strength of the column sandstone will continue to decline, and the column stability will become weaker and weaker.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631;P512.1

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