提高露天矿边坡稳定性的爆破减震缓冲垫

在对岩体高边坡爆破减震分析的基础上提出了一种简便、有效及成本低的降低岩体开挖及边坡爆破震动的缓冲垫装置,不仅可以避免对炮孔半周边岩石产生大量裂缝而且可以避免由于多次爆破震动对边坡岩体产生的累积损伤,使边坡岩体及围岩受到的爆炸冲击荷载低于岩体破坏的门槛值, 大幅度增加岩体边坡稳定性,并提高边坡稳定角度。用爆破实际测震数据说明、工程爆破效果验证,首次用在攀枝花露天铁矿边坡开挖工程中,半孔率可达到95%以上。     

爆炸振动的模拟

本文提出一种模拟爆炸振动时间过程的混合方法.现场记录了单井爆炸产生的地震信号,其中包含从爆炸源发出的辐射地震能量的复杂机制、以及信号传播路径的过滤效应。假定排炮各井的地震效应为线性叠加,则可以模拟爆炸产生的振动。单炮信号与表示点火顺序的脉冲系列混杂在一起.通过模拟过程中点火时间的系统变化,研究了它们对振动的影响,发现振动的峰值可以降低.使用电子点火系统,可以优化爆炸点火时间,以及成功地验证合成地震图.     

钻孔对初始应力场扰动影响的初步研究

地应力测量是获得初始地应力最直接最有效的方法,但在地应力测量打钻的过程中初始地应力会遭到扰动,岩体在打钻后出现卸载现象,初始地应力重新分布,使得测量值与实际初始地应力值有差别.本文应用有限元方法对钻孔地应力测量过程进行模拟,重点研究岩体的性质、边界应力、断裂在钻孔过程中对初始地应力变化的影响,并总结影响初始地应力变化的敏感因素.     

王家店水库混凝土重力坝爆破地震反应分析

通过两种途径分析了王家店水库重力坝在爆破时的地震效应。一是利用实测坝基地振动作为地面运动输入,对坝体进行了地震反应和爆破强度分析,包括具体的振动特性和动力反应。二是通过振动速度分析了坝体混凝土可能产生的最大应力,并与极限强度做了比较,给出了该混凝土重力坝爆破振动控制标准。最后讨论了重复爆破时对大坝可解产生的疲劳影响。上述分析结果表明:最大药量控制在300kg范围内,距大坝1700m处的爆破研究所进行的常年爆炸加工生产,对大坝是安全的,由重复爆炸对大坝引起的低周疲劳影响可忽略。     

地应力对裂隙岩体渗透特性的影响

提出了地应力场中岩体不连续面变形的本构关系，讨论了渗流与应力耦合条件下裂隙岩体渗透张量的计算方法，阐述了地应力对裂隙岩体渗透特性的影响．研究表明，地应力对岩体渗透特性的影响主要是通过改变不连续面的开度和不连续面网络的水力传导路径而产生的；裂隙岩体渗透性随岩体埋深的增加呈负指数减小，随侧压系数的增大呈双曲线减小．渗流场与应力场的耦合理论可望应用于水库诱发地震的研究中     

初始地应力场分析方法的研究

岩体初始地应力场是地震预测和岩体工程设计的重要依据之一,根据实测地应力资料,采取一定的数值分析方法,反演出整个计算区的初始地应力场。本文综述了国内外地应力场的研究现状,介绍并分类归纳了几种典型的地应力场研究方法,并对每个方法的适用范围进行了评价,对以后地应力研究的发展方向提出了建议。     

高铁震源地震信号的稀疏化建模

我国每天有数千趟高铁列车运行在两万多公里的高铁线路上,不但会引起高铁路基的振动,还会激发出地震波.地震检波器所接收到的数据中不仅包含窄带分立谱特性的高铁震源地震信号,还包含宽频带特性的背景信号.如何实现从检波器所接收到的高铁震源地震数据中分离出高铁震源地震信号和宽频带背景信号是准确利用该类信号的关键.考虑到高铁震源地震信号与宽频带信号在频率域明显的形态特征差异,本文首次将形态成分分析这种信号分离手段引入到高铁震源地震信号处理中,实现高铁震源地震信号的稀疏化建模并进而实现从接收数据中分离出高铁震源地震信号以及宽频带背景信号.对北京大学在中国南方某高铁沿线采集到的大量高铁震源地震数据进行处理,结果表明:采用形态成分分析并结合分块坐标松弛算法,能够实现实际采集高铁震源地震数据中的高铁震源地震信号和宽频带信号的分离.     

地应力对裂隙岩体渗透特性的影响

提出了地应力场中岩体不连续面变形的本构关系，讨论了渗流与应力耦合条件下裂隙岩体渗透张量的计算方法，阐述了地应力对裂隙岩体渗透特性的影响．研究表明，地应力对岩体渗透特性的影响主要是通过改变不连续面的开度和不连续面网络的水力传导路径而产生的；裂隙岩体渗透性随岩体埋深的增加呈负指数减小，随侧压系数的增大呈双曲线减小．渗流场与应力场的耦合理论可望应用于水库诱发地震的研究中．      

城市地铁爆破开挖对浅埋地下大直径管道的安全影响研究

在城市浅埋地铁爆破开挖中,经常遇到地下管网、涵洞等构筑物,而爆破地震效应对其影响范围和程度的正确评价就显得尤为重要。本文以长沙地铁爆破开挖为例,以现场实测数据为基础,采用有限单元法,对爆破振动下大直径混凝土污水管道的动力响应、变形和动应力等进行了计算,评价了爆破地震对管道的安全影响。研究表明:管道在控制爆破作用下是偏于安全的;爆心距是影响管道受到爆炸作用力影响大小的最主要因素;对于以实测数据为基础,采用加速度激励的时程分析方法以爆破振动对埋地管道的影响进行评价,是一种可行且较为精确的方法。     

龙滩水电站左岸导流洞爆破振动测试与控制研究

通过对龙滩水电站左岸导流洞爆破开挖振动进行观测、分析和处理,得到了该导流洞爆破开挖振动传播衰减经验公式。根据该水电站导流洞的特点,提出了爆破振动破坏标准,由经验公式和破坏标准,得出了该导流洞新浇混凝土支护区爆破安全控制参量。分析了爆破地震的特点,结合该水电站导流洞的爆破实际,建议了该导流洞相应的爆破降震措施。从工程实施的实际效果看,本文的研究成果与结论获得了较好的应用效果,保证了该工程爆破施工的顺利完成。     

Comparison of seismic effects during deep tunnel excavation with different methods

The rapid release of strain energy is an important phenomenon leading to seismic events or rock failures during the excavation of deep rock.Through theoretical analysis of strain energy adjustment during blasting and mechanical excavation,and the interpretation of measured seismicity in the Jin-Ping Ⅱ Hydropower Station in China,this paper describes the characteristics of energy partition and induced seismicity corresponding to different energy release rates.The theoretical analysis indicates that part of the strain energy will be drastically released accompanied by violent crushing and fragmentation of rock under blast load,and this process will result in seismic events in addition to blasting vibration.The intensity of the seismicity induced by transient strain energy release highly depends on the unloading rate of in-situ stress.For mechanical excavation,the strain energy,which is mainly dissipated in the deformation of surrounding rock,releases smoothly,and almost no seismic events are produced in this gradual process.Field test reveals that the seismic energy transformed from the rock strain energy under high stress condition is roughly equal to that coming from explosive energy,and the two kinds of vibrations superimpose together to form the total blasting excavation-induced seismicity.In addition,the most intense seismicity is induced by the cut blasting delay; this delay contributes 50% of the total seismic energy released in a blast event.For mechanical excavation,the seismic energy of induced vibration(mainly the low intensity acoustic emission events or mechanical loading impacts),which accounts only for 1.5‰ of that caused by in-situ stress transient releasing,can be ignored in assessing the dynamic response of surrounding rock.     

EXPERIMENT STUDY ON ACOUSTIC EMISSION,MICROSEISM AND CHARGE INDUCTION DURING FRACTURE PROCESS OF GRANITE WITH FAULT ZONE UNDER UNIAXIAL COMPRESSION

As the rock samples will produce abnormal signals of acoustic emission, microseismic and charge signals under external loading, the waveform comprehensive monitoring devices are used to synchronously monitor acoustic emission, microseismic and charge signals during the deformation and failure process of granite with fault zone under uniaxial compression. The results show that, the granite with fault zone has obvious synchronous precursory signals of acoustic emission, microseism and charge induction in the elastic deformation stage, and has high amplitude synchronous precursory signals in the instability destruction stage. The influence of fault zone on granite samples strength is remarkable, and the uniaxial compressive strength of samples with the fault zone is greatly reduced. With the angle of the fault zone decreasing, the uniaxial compressive strength of the specimens is reduced, the samples are more liable to instability and the energy of instability destruction is greater. With the fault zone angle of granite samples decreasing, the acoustic emission, microseismic and charge induction signals increase in the deformation and failure process of samples. The samples stress decreases when the acoustic emission, microseismic and charge induction precursory signals appear synchronously. The duration of acoustic emission, microseismic and charge induction precursory signals is increasing in the instability destruction stage. When the angle of the fault zone reaches 30°, the mutability of acoustic emission, microseismic and charge induction signal increases, the time to enter the dangerous stage is much earlier, and the acoustic emission events of large magnitude increase significantly, and the large angle faults of coal mine are more dangerous. The intensive and high amplitude synchronous precursory signals of acoustic emission, microseism and charge induction are produced before the instability destruction, and the signals duration is shorter. The intensive and strongest synchronous precursory signals of acoustic emission, microseism and charge induction are produced in the instability destruction, and the signals duration is longer. Acoustic emission monitoring data can better reflect the micro rupture of rock. And combined with the acoustic emission, microseismic and charge induction precursory signals, the precursory information of rock instability destruction can be obtained more accurately.     

Identification of blasting vibration and coal-rock fracturing microseismic signals

Α new method based on variational mode decomposition (VMD) is proposed to distinguish between coal-rock fracturing and blasting vibration microseismic signals. First, the signals are decomposed to obtain the variational mode components, which are ranked by frequency in descending order. Second, each mode component is extracted to form the eigenvector of the energy of the original signal and calculate the center of gravity coefficient of the energy distribution plane. Finally, the coal-rock fracturing and blasting vibration signals are classified using a decision tree stump. Experimental results suggest that VMD can effectively separate the signal components into coal-rock fracturing and blasting vibration signals based on frequency. The contrast in the energy distribution center coefficient after the dimension reduction of the energy distribution eigenvector accurately identifies the two types of microseismic signals. The method is verified by comparing it to EMD and wavelet packet decomposition.     

Results of Analysis of the Data of Microseismic Survey at Lanzarote Island,Canary, Spain

From the data of a microseismic survey of the Lanzarote Island territory (Canary Archipelago) we obtained a microseisms amplitude distribution in the frequency range 0.3–12.5 Hz. We found a distinguished anomaly such as an amplitude depression, whose size and magnitude depend on the frequency. After studying the statistical and polarization properties of microseism signals we proposed a model explaining this depression, based on the presence of a rigid intrusive body in the center of the island. Results of our survey coincided well with independent detailed gravity survey results whose interpretation also implies the presence of intrusion. We estimated shear-wave velocity for the rocks of intrusion and for surrounding rocks using microseismic data.     

Microseismic monitoring of columnar jointed basalt fracture activity: a trial at the Baihetan Hydropower Station,China

Severe stress release has occurred to the surrounding rocks of the typically columnar jointed basalt after excavation at the Baihetan Hydropower Station, Jinsha River, China, where cracking, collapse, and other types of failure may take place occasionally due to relaxation fracture. In order to understand the relaxation fracture characteristics of the columnar jointed basalt in the entire excavation process at the diversion tunnel of the Baihetan Hydropower Station, real-time microseismic monitoring tests were performed. First, the applicability of a geophone and accelerometer was analyzed in the columnar jointed basalt tunnel, and the results show that the accelerometer was more applicable to the cracking monitoring of the columnar jointed basalt. Next, the waveform characteristics of the microseismic signals were analyzed, and the microseismic signals were identified as follows: rock fracture signal, drilling signal, electrical signal, heavy vehicle passing signal, and blast signal. Then, the attenuation characteristics of the microseismic signals in the columnar jointed basalt tunnel were studied, as well as the types and characteristics of the columnar jointed basalt fracture. Finally, location analysis was conducted on the strong rock fracture events, in which four or more sensors were triggered, to obtain the temporal and spatial evolution characteristics and laws of the columnar jointed basalt relaxation fracture after excavation. The test results are not only of important reference value to the excavation and support of diversion tunnel at the Baihetan Hydropower Station, but also of great referential significance and value to the conduction of similar tests.     

A Tensile Model for the Interpretation of Microseismic Events near Underground Openings

—For small-scale microseismic events, the source sizes provided by shear models are unrealistically large when compared to visual observations of rock fractures near underground openings. A detailed analysis of the energy components in data from a mine-by experiment and from some mines showed that there is a depletion of S-wave energy for events close to the excavations, indicating that tensile cracking is the dominant mechanism in these microseismic events.¶In the present study, a method is proposed to estimate the fracture size from microseismic measurements. The method assumes tensile cracking as the dominant fracture mechanism for brittle rocks under compressive loads and relates the fracture size to the measured microseismic energy. With the proposed method, more meaningful physical fracture sizes can be obtained and this is demonstrated by an example on data from an underground excavation with detailed, high-quality microseismic records.     

基于小波变换的大尺度岩体结构微震监测信号去噪方法研究

为将小波去噪方法应用于大尺度岩体结构微震监测信号的去噪研究,首先在MATLAB环境下进行仿真,验证了使用Symlet6小波进行小波去噪的可行性;利用4种自适应阈值规则对含噪信号进行去噪对比,结果表明4种阈值去噪后的信号在均方差较小的情况下都极大地提高了信号的信噪比,有效地去除了噪声,对不同的含噪信号,无偏似然原则阈值去...     

风暴及台风天气引起的微震现象分析

本文主要利用时频分析法,基于2016年以来山东省泰安台重力仪及宽频带地震仪观测到的资料,对风暴天气和台风天气引起的微震现象进行研究. 结果表明:这两种天气过程产生的微震信号的频率基本分布在2—20 s之间,能量集中在5—7 s,15 s附近存在一个能量平稳加强的频段;风暴天气产生的微震信号具有由高频向低频演化的动态特征;两种天气条件下产生的微震信号均具有连续、高频及持续时间长的性质,反映了微震信号激发源的移动特征。 结合泰安台微震与风暴和台风天气的一一对应情况,认为微震是一种与近海风暴或远海台风活动有关的微震动过程,而不是与地震有关的前兆异常。      

基于稀疏分布特征的井下微地震信号识别与提取方法

井下微震监测获得的地震记录往往包含大量的噪声,记录信噪比很低.有效地震信号的识别与提取是进行后续地震定位等工作之前需要优先解决的问题.经过研究发现,井下水压裂微地震信号具有稀疏分布的特征,而井下环境噪声则具有更多的Gaussian分布特征.为此,本文提出将图像处理领域适宜于稀疏分布信号降噪处理的稀疏码收缩方法应用于井下微震监测数据处理.为解决需要利用与待处理数据中有效信号成分具有相似分布特征的无噪信号序列估算正交基以及计算效率等问题,将原方法与小波变换理论相结合.即通过优选小波基函数作为正交基进行小波变换将信号分解为不同级的小波系数,利用稀疏码收缩方法中对稀疏编码施加的非线性收缩方式作为阈值准则对小波系数进行改造.通过多方面的数值实验证明了该方法在处理地震子波及井下微地震信号方面准确可靠.含噪记录经过处理后有效地震信号的到时、波形、时频谱特征等均能得到良好的识别和恢复.并且该方法具有很强的抗噪能力,当信噪比低至-20~-30db时,仍然能够发挥作用.在处理大量实际井下微震监测数据的过程中,面对多种复杂情况,本方法展现出了计算效率高、计算结果可靠、应用简单等优势,证明了其本身具有实际应用价值,值得进一步的研究和推广.     

煤矿采掘过程中煤岩体电磁辐射特征及应用

运用研制的KBD5矿用本安型电磁辐射监测仪测试了煤矿采掘过程中工作面煤岩体的电磁辐射，分析了电磁信号与采掘工艺及煤岩动力灾害危险性等的关系。研究表明，煤矿采掘过程伴随产生电磁辐射，电磁辐射是煤岩体受到采动影响后应力重新分布或变形破裂趋向新平衡的结果；有煤与瓦斯突出和冲击地压危险时，有明显的电磁异常前兆；采取防治措施后，电磁辐射显著下降。电磁辐射技术在煤矿可以用于预测煤与瓦斯突出、冲击地压等煤岩动力灾害。