【作者】 李飞；

【导师】 王述红；

【作者基本信息】 东北大学 ， 岩土工程， 2008， 硕士

【摘要】 为了对地下洞室进行科学合理的开挖设计和施工,就必须对影响工程稳定性的各种因素进行充分的调查。在诸多的影响岩体开挖工程稳定性的因素中,地应力状态是最重要最根本的因素之一。一切与围岩有关的工作,如隧道的布置、隧道支护设计,锚杆支护衬砌设计,是确定工程岩体力学属性,进行围岩稳定性分析,实现岩石工程开挖设计和决策科学化的必要前提条件。对隧道设计来说,只有掌握了具体工程区域的地应力条件,才能合理确定隧道的总体布置,确定其最佳断面形状、断面尺寸、开挖步骤、支护形式、支护结构参数等,从而保证围岩稳定性。所以,研究岩体的初始地应力,测量岩体的初始应力值状态,其目的不单纯在于初始地应力自身理论的发展和测试技术的改进,还在于如何把初始地应力实测值转化为地面和地下工程设计荷载,即初始地应力与地面和地下工程关系的研究。岩体的初始地应力状态的测试及研究的意义是多方面的。地应力测量是用来确定工程岩体力学属性,进行围岩稳定性分析,实现岩土工程开挖设计和决策的必要前提。由于地应力场会受到其他多种因素的影响,因而造成了地应力状态的复杂性和多变性。即使在同一地区,不同点的地应力状态也可能是很不相同的,要了解一个地区的地应力状态,惟一的有效方法就是进行原地应力测量。本论文结合为韩国新北-北山BHL((?))国道改扩建工程,并依据提供科学技术支撑的Geogeny公司来开展研究工作。考虑到本文所依托的工程当时正处于规划与设计施工伊始阶段,相关的前期线路工程地质专项调查论证已经完毕。因此,本文的研究成果是基于野外地质调查和少量室内试验,并结合新北-北山BHL地区刚建的相关工程实例类比而得出的初步认识,其中大量的问题值得深入研究和分析,还需要做大量实际细致的工作。本论文所做的试验研究区域在韩国的Chuncheon-Yanggu地区,属于Kyeonggi断层带的东北部。大部分测试地区属于崎岖不平的多山地段区域。本文对水压致裂地应力测量原理、设备、现场试验方法及数据处理等进行了比较深入的阐述,初步选定十五个钻孔作为水压致裂测量孔,有30个测点,平均每孔两个测点。详细分析了水压致裂曲线压力-时间的特征及破裂压力、重张压力、关闭压力及最大水平主应力的破裂方向的确定方法。此外,在获得已知各个测点的地应力大小和方向后,进一步分析工程区地应力及侧压力系数的分布规律,并采用相关数值分析方法来建立隧道工程区的地应力场分布的模型。在320m以内,测压系数随着深度的不断加深它的值也有下降并趋于稳定的趋势,其中最大主应力方向是北偏东790(N790E)。在收集、分析前人研究的基础之上,通过对初始应力场、深部地质构造、岩石力学特性的现场调查和测试,室内试验分析以及模拟计算,结合地下工程实例,运用工程地质学、岩石力学等多学科理论和方法,了解各种工况条件下其应力、应变状态,综合研究工程岩体的破坏机理,为下一阶段的工程设计、施工和安全运营提供必要的工程资料,并以之为向导,进行工程作业。确定工程区不同隧道部位的平面应力的大小、方向及相应的岩体力学参数,不但可以为了对工程区应力场有一个全面的认识,而且可以为下一步的隧道围岩稳定性分析做充分的理论依据。本文重点研究三个方面。1：通过工程现场地质调查,对隧道工程区的地质环境进行了评价；2：通过水压致裂地应力测量研究工程区地应力相关参数的确定及数据处理；3：在水压力测量地应力及室内试验分析方法相结合下,利用所得到的相关物理力学参数,通过相关数值模拟软件进行数值模拟,研究不同围岩类别下及不同测压系数下的围岩的变形破坏情况,来验证基于地应力测量结果的隧道围岩支护设计的合理性和可能性。主要研究手段：1：进行前人理论和试验的收集、研究。试验收集包括在韩期间野外的现场试验,研究不同应力条件下水压致裂压力-时间曲线特征,总结破裂、关闭及重张压力特征点的方法。2：进行现场测试,分析总结测试结果,获取地应力场的准确资料,关键是对测试曲线的合理解释和破裂、关闭及重张压力特征点的准确识别。得出最大最小水平应力及其随深度变化的情况。3：通过对现场测试所得的相关数据求出最大最小水平主应力、方向及应力随深度变化的情况。其中测压系数随深度变化而变化的分析图对下一步的模拟分析起到关键的作用。4：采用理论分析法和基于数值计算软件,利用所测得不同断面的测压系数随深度而变化的情况,分析模拟部分隧道断面在所测得地应力条件下的应力分布,当测压系数不变在不同种类围岩下及围岩类别不变在不同测压系数下隧道发生失稳破坏的区域,应用到施工的过程中。为隧道的下一步支护提供有力的依据,并验证基于地应力测量结果的隧道围岩支护设计的合理性和可靠性。更多还原

【Abstract】 Knowledge of the in situ state of stress in the Earth’s crust is very important in many problems dealing with rocks in geology, geophysics, as well as civil and mining. In civil and mining engineering, the characteristic of in situ rock stress has potent influence on the failure and deformation behavior around openings and also control the distribution and magnitude of the stresses around underground openings such as mines, shafts and tunnels. As the depth and scale of underground structures tend to increase recently, its importance is getting more attention. The overstressed condition may induce progressive and brittle failures such as spalling, slabbing and rock bursting. In foreign countries, a lot of researches on in situ rock stress have been carried out by in situ tests and data analyses. From them, many empirical and theoretical formulate have been proposed to accurately estimate the initial rock stress such as Korea. In China, on the contrary, a few studies on rock stress have been carried out but their results do not provide with detailed information of the initial rock stress.In this study, the study area was Chuncheon-Yanggu region, the east-north part of Kyeonggi Massif in Korea where most of the study areas are high and rugged mountainous region. The characteristics of initial rock stress there were studied using more than thirty-five field stress measurements in fifteen vertical boreholes were conducted at the depth from 20m to 320m of in situ hydraulic fracturing method test with the help of Geogeny consultants group 1nc.Based on the test data set, it introduces the whole procedure of hydraulic fracturing measurement method, field hydraulic fracturing test system, the technique of geophysical imaging technique and test data analysis to obtain critical pressure parameters from the pressure time records.Based on the measurement data, the main purpose of the study area was that one was to investigate the characteristics of the regional stress state of the target region and the other was to evaluate the potential possibility of stress induced brittle failures at the future excavation work. The study results revealed that the different initial rock stresses had formed with the formation rock type. For the depth less than 320m, the stress ratio (K) had a tendency to decrease and stabilize with the depth. The average orientation of all SH data was approximately 790 from the north (N790E).Based on the collection analyses of predecessors’, on the field investigation about the rock mechanics characteristic, the initial stress field, deep architectonic, indoor test analyses as well as analog calculation and field condition, to know the stress and strained condition under different kinds of behavior situation, analysis rock mass engineering failure mechanism in order to direct the construction on the security transport operation, supplying necessary engineering data and holding the engineering work safely.The keynote of this research has three aspects:the first one is to appraise the geologic environment condition of the tunneling region based on the geologic survey of project site; the second one is to determine the relevant parameters and process the data coming from the hydraulic fracturing method; the last one is between the method of determining the initial stress under the measurement of hydraulic fracturing and the analytical procedure of indoor test, using the numerical simulation software to make the simulating in order to research the rock wall’s variation under different kinds of stress ratio K and rock types to demonstrate the rationality and feasibility of the tunnel supporting.更多还原