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工程科学与技术:2019,51(6):115-123
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高地应力水平对爆破开挖损伤区声波检测及损伤程度评价的影响
(1.武汉大学 水资源与水电工程科学国家重点实验室, 湖北 武汉 430072;2.武汉大学 水工岩石力学教育部重点实验室, 湖北 武汉 430072;3.雅砻江流域水电开发有限公司, 四川 成都 610056;4.中国电建集团 华东勘测设计研究院有限公司, 浙江 杭州 310014)
Effects of the High In-situ Stress Level on the Acoustic Detection and the Damage Degree Evaluation of the Excavation Damage Zone
(1.State Key Lab. of Water Resources and Hydropower Eng. Sci., Wuhan Univ., Wuhan 430072, China;2.Key Lab. of Rock Mechanics in Hydraulic Structural Eng. of Ministry of Education, Wuhan Univ., Wuhan 430072, China;3.Yalong River Hydropower Development Co., Chengdu 610056, China;4.Huadong Eng. Corp. Ltd., Power Construction Corp. of China, Hangzhou 310014, China)
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投稿时间:2018-12-07    修订日期:2019-06-17
中文摘要: 随着地下工程埋深的不断增加,深部岩体工程中围岩开挖损伤区深度及程度的准确评价逐渐受到深部高地应力场的影响,其影响程度的合理评估成为研究重点。依托某水电站深埋引水隧洞开挖工程,采用应力逐步解除方案,通过在取样区域外围钻设形成环形封闭边界的常规取样孔,逐步解除取样区域内岩体应力,并在取样区域内进行钻孔与低应力取芯,继而利用声波检测装置对外围应力解除孔和内部取芯孔周边岩体的损伤程度进行检测,以此获得相同位置岩体在不同地应力条件下的损伤区深度及程度的声波检测结果。同时,结合内、外取芯孔获取的不同应力水平下的岩芯,开展室内试验,基于Hoek-Brown强度经验公式,利用声波波速计算得到相同位置岩体在不同地应力条件下的岩体单轴抗压强度,从而判断不同地应力条件对爆破开挖损伤区声波检测结果及损伤程度评价的影响。研究表明:高应力条件下,常规取样与声波检测法会在一定程度上低估围岩的损伤区深度和损伤程度,同时严重高估岩体单轴抗压强度。当初始应力水平为45 MPa时,围岩损伤区深度和损伤程度大约会被低估约10%~30%;当地应力水平由45 MPa降至30 MPa时,岩体的单轴抗压强度会被严重高估约30%~100%。因此,高地应力水平对爆破开挖围岩损伤区声波检测与评价结果存在明显影响,工程中运用波速指标评价岩体质量必须考虑地应力水平对声波检测的影响,并进行适当修正。
中文关键词: 地应力  围岩损伤  声波检测  岩体质量
Abstract:With the increasing depth of underground engineering, the accurate evaluation of the depth and the degree of excavation damage zone (EDZ) in deep rock engineering is gradually influenced by the high geostress field and it is important to assess the impact reasonably. Relying on the excavation of a deep diversion tunnel, the drilling plan of distressing the in-situ stress step by step was adopted. At the outer zone of sampling area, conventional sampling holes were drilled in the form of a circular closed boundary. And boreholes and low stress coring were also carried out at the centre of the sampling area. The acoustic detection results of the depth and the degree of the damage area under different in-situ stress levels were obtained at the same location by acoustic detection device, and laboratory tests were carried out based on the core samples from the holes above. The uniaxial compressive strength of rock mass under different in-situ stress levels were given from acoustic wave velocity results by Hoek-Brown strength empirical formula to represent rock mechanics properties. These above contributed to judge the influence of the different in-situ stress levels on acoustic detection and damage degree evaluation in blasting EDZ. Researches showed that the conventional acoustic detection of excavation damage zone in high stress area would underestimate the depth of surrounding rock and the damage degree, which would be underestimated about 10% to 30% when the initial stress was 45 MPa. When the local stress level was reduced from 45 MPa to 30 MPa, the uniaxial compressive strength of rock mass would be seriously overestimated about 30% to 100%. Therefore, the high in-situ stress level had a significant impact on the results of acoustic detection and damage zone evaluation of surrounding rock. The effect of in-situ stress level on acoustic detection must be taken into account and corrected properly by reducing and increasing in evaluating rock mass quality by using wave velocity index in engineering.
文章编号:201801364     中图分类号:TU452    文献标志码:
基金项目:国家重点研发计划项目(2016YFC0401802);国家自然科学基金项目(51779192);国家自然科学基金雅砻江联合基金项目(U1765109)
作者简介:刘晓(1993-),男,博士生.研究方向:岩石动力学.E-mail:xliuwhu@whu.edu.cn
引用文本:
刘晓,严鹏,卢文波,陈明,王高辉,宁金华,倪绍虎,刘军.高地应力水平对爆破开挖损伤区声波检测及损伤程度评价的影响[J].工程科学与技术,2019,51(6):115-123.
LIU Xiao,YAN Peng,LU Wenbo,CHEN Ming,WANG Gaohui,NING Jinhua,NI Shaohu,LIU Jun.Effects of the High In-situ Stress Level on the Acoustic Detection and the Damage Degree Evaluation of the Excavation Damage Zone[J].Advanced Engineering Sciences,2019,51(6):115-123.