深埋大理岩力学特性研究及其工程应用

发布时间：2018-05-06 14:24

本文选题：PFC~(2D) + 深埋大理岩　；参考：《昆明理工大学》2013年博士论文

【摘要】：21世纪是地下工程向深部发展的世纪,深埋隧洞、核废料储存、深部地热开发都涉及到深埋岩体力学问题。20世纪80年代开始,加拿大、瑞典、日本、瑞士、美国等国都建立了地下实验室,对硬岩高应力破坏的监测技术、理论研究和相关数值分析方面取得了辉煌的成绩,其中以加拿大URL对Lac du Bonnet花岗岩的研究最为卓著。目前对于深埋大理岩力学特性的研究可参照加拿大URL花岗岩的研究思路,主要集中于4个方面：(1)强度特征除了传统的峰值强度和残余强度外,人们还提出了描述裂纹状态的启裂强度和损伤强度。对于小尺度岩块的各种强度阈值可采用试验手段获得；大体积岩体的强度阈值只有通过数值方法获得,近年来基于PFC的SRM(综合岩体模型)对此问题富有成效。(2)开挖损伤区域(EDZ)深埋隧洞开挖后由于应力调整、爆破扰动、温度湿度变化等因素会导致开挖面附近形成开挖损伤区域,了解开挖损伤区域的范围、损伤程度和演化特征对评价围岩稳定、渗透扩散规律和支护措施具有重要意义。(3)革新的试验技术研究目前真三轴试验机越来越普及,但硬岩的试验还要求真三轴加压时能同时监测压缩过程中的声发射、波速变化、渗透率变化,或对不同温度环境的模拟,还应能实现对海量试验数据的高速连续采集。(4)大型原位试验设计和实施室内试验针对小尺度的岩块力学特性开展研究,如果要将相关认识拓展至大尺度岩体还需要设计并开展针对性原位试验。本文主要工作致力于深埋大理岩力学特性的室内试验研究和描述方法研究。前者包括大理岩试样各损伤阈值的测定和峰后力学特性的试验研究,通过与花岗岩试验成果的对比,丰富了目前硬岩的研究成果；后者探讨大理岩力学特性的PFC方法描述,即用PFC描述了隧洞的开挖损伤特征、岩体强度特征和大理岩峰后特征,拓展了PFC方法在硬岩强度特征与开挖损伤区域描述方面的应用。在前述研究成果基础上,利用PFC标定特定岩体质量的开挖损伤深度和形态获得了岩体级别的颗粒细观参数,预测了埋深更大洞段的围岩损伤深度,与常用的连续方法相比,基于PFC的围岩损伤深度预测具有较高的精度,对支护设计具有重要价值。由于锦屏大理岩随围压变化所具有的脆-延-塑性转换特征,决定了它不会出现软岩里常见的大变形破坏,也不全是纯脆性的破坏,因而破损深度不会太深。在围岩破损的预测过程中包含了隧洞掘进方法的影响和围岩应力调整的影响,因此所预测的破损深度基本趋于围岩所处应力环境下的最大破损程度,本文应用PFC2D预测的Ⅲ类围岩破损深度,对支护深度的确定具有较好的指导意义。本文主要工作及创新点： (1)完成10组深埋大理岩试验的单轴压缩室内试验,通过应力-应变曲线确定大理岩的启裂强度、损伤强度和峰值强度； (2)完成12组深埋大理岩的常规三轴压缩试验,确定大理岩的峰值强度、残余强度。并通过试验揭示出大理岩的随围压增高所展示出来的脆-延转换特征,在较高的围压水平下,大理岩展现出理想塑性的力学响应； (3)采用基于Hoek-Brown强度的本构模型对锦屏Ⅱ类围岩进行了损伤深度预测,该模型能够统一描述大理岩在不同围压水平下的脆-延-塑性转换特征： (4)采用PFC方法从细观层面对大理岩的脆-延转换特征进行了描述,研究了基于Bond Particle Model模型的细观参数取值规律； (5)在合理描述大理岩脆-延转换的基础上,发展了基于PFC数值方法的模拟手段对深埋大理岩隧洞的围岩开挖损伤区域进行了直接的描述； (6)根据研究得到的PFC模拟围岩开挖损伤区域的数值方法,对锦屏引水隧洞不同埋深洞段的围岩开挖损伤深度进行预测,并将预测结果与现场实测结果进行了对比； (7)结合目前深埋地下工程在室内实验、现场试验、理论研究、数值分析方法等方面的进展,展望了后续研究工作。 (8)发展了运用PFC方法模拟室内直剪试验来反演模型细观参数的方法。
[Abstract]:Twenty-first Century is the century of deep development of underground engineering. Deep buried tunnels, nuclear waste storage and deep geothermal development all involve the mechanics of deep buried rock mass in the 80s.20. The underground laboratories in Canada, Sweden, Japan, Switzerland and the United States have established the monitoring techniques, theoretical research and related numerical analysis of hard rock high stress damage. Brilliant achievements have been made, among which URL Lac Du Bonnet granite is the most outstanding one in Canada.
At present, the study of the mechanical properties of deep buried marble can be based on the research ideas of URL granite in Canada. It is mainly concentrated in 4 aspects: (1) besides the traditional peak strength and residual strength, the strength and strength of the crack state are also proposed. The strength threshold of mass rock mass is only obtained by means of numerical method. In recent years, the PFC based SRM (Comprehensive rock mass model) has been successful in this problem. (2) the stress adjustment, blasting disturbance and temperature and humidity changes will lead to the formation of excavation damage near the excavation surface after the excavation of the damaged area (EDZ) deep buried tunnel. It is of great significance to understand the area of the damaged area, the extent of the damage and the evolution characteristics of the damaged area, and it is of great significance to evaluate the stability of the surrounding rock, the law of permeation and diffusion and the support measures. (3) the experimental technology of innovation is becoming more and more popular at present, but the test of hard rock also requires that the sound in the compression process can be monitored at the same time when the three axis is pressurized. Shooting, wave velocity change, permeability change, or simulation of different temperature environments should also be able to achieve high speed and continuous collection of mass test data. (4) large scale in situ test design and implementation of laboratory tests to study the mechanical properties of small scale rock blocks. It is necessary to design and carry out a needle to expand the related knowledge to large scale rock mass. In situ test of sex.
The main work of this paper is to study the experimental research and description method of the mechanical properties of deep buried marble. The former includes the measurement of the damage threshold of marble specimens and the experimental study on the mechanical properties after the peak. By comparing with the results of the granite test, the research results of the hard rock are enriched. The latter discusses the mechanical properties of marble. The PFC method is used to describe the characteristics of tunnel excavation damage, rock strength characteristics and the characteristics of Dali rock peak, which extends the application of the PFC method in the characteristics of hard rock strength and the description of the excavation damage area. On the basis of the previous research results, the excavation damage depth and shape of the specific rock mass are obtained by using PFC to obtain the rock mass. The particle size parameters of the grade predict the damage depth of the surrounding rock in the deeper buried depth. Compared with the common continuous method, the prediction of the damage depth of the surrounding rock based on PFC has a high accuracy and is of great value to the support design.
Because of the brittle ductile transformation characteristics of the Jinping marble with the change of confining pressure, it is determined that it will not appear the common large deformation and failure in the soft rock, not all brittle failure, so the damage depth will not be too deep. The predicted damage depth tends to the maximum damage degree under the stress environment in the surrounding rock. In this paper, the damage depth of type III surrounding rock predicted by PFC2D has a good guiding significance for the determination of the support depth.
The main work and innovation of this article are as follows:
(1) the uniaxial compression indoor tests of 10 groups of deep marble tests were completed, and the crack initiation strength, damage strength and peak strength of marble were determined by stress-strain curves.
(2) to complete the conventional three axis compression test of 12 groups of deep marbles, determine the peak strength and residual strength of marble, and reveal that marble is characterized by brittle ductile transition with high confining pressure, and the marble shows an ideal plastic mechanical response under high confining pressure.
(3) the damage depth of Jinping class II surrounding rock is predicted by the constitutive model based on the strength of Hoek-Brown. The model can describe the brittle ductile transition characteristics of marble under different confining pressure.
(4) the PFC method is used to describe the brittle ductile transition characteristics of marble from the meso layer, and the values of the values of the mesoscopic parameters based on the Bond Particle Model model are studied.
(5) on the basis of a reasonable description of the brittle ductile transition of marble, a numerical method based on PFC is developed to describe the damage area of the surrounding rock excavation in deep marbles.
(6) according to the numerical method of simulating the damage area of surrounding rock excavation by PFC, the damage depth of surrounding rock excavation in different burial tunnels of Jinping diversion tunnel is predicted, and the prediction results are compared with the field measured results.
(7) combined with the progress of laboratory tests, field tests, theoretical studies and numerical analysis methods of deep underground projects, the following research work is prospected.
(8) the method of simulating the indoor direct shear test by PFC method is developed to inverse the microscopic parameters of the model.

【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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