共查询到20条相似文献，搜索用时 15 毫秒
1.
根据饱和土Biot理论,在频域内提出了一种适用于弹性波波动问题的有限元-无限元解法,其中有限单元用于近场介质的模拟,而形函数基于一维解析解答的无限单元则被用于人工边界,它可反映波传递到无限远处的特性;应用该法计算算例,以证明其有效性与正确性。在此基础上,对饱和地基中空沟主动隔振效果进行了详细的数值分析,结果表明,空沟深度是影响隔振效果的主要因素,一般沟深越大,隔振效果越好;当沟深一定时,空沟到振源的距离不宜超过1.5倍饱和土剪切波长;空沟的宽度对隔振效果的影响相对较小。 相似文献
2.
Yagoub M. M. Alsereidi Aishah A. Mohamed Elfadil A. Periyasamy Punitha Alameri Reem Aldarmaki Salama Alhashmi Yaqein 《Natural Hazards》2020,100(1):111-132
Prediction and control of blast-induced ground vibration is a matter of concern in mining industry since long. Several approaches ranging from scaled distance regression, different numerical methods to wave superimposition theories have been tried by many researchers for better prediction and control of blast-induced ground vibration. Signature hole analysis is one of the popular simulation methods to predict the ground vibration generated due to production blast. It superimposes the recorded signature hole waveform using a computer program to predict the production blast-induced vibration. The technique inputs the designated time of detonation of each hole and superimposes the waves generated by each hole to predict the nearest value of peak particle velocity and frequency of blast-induced ground vibration. Although a very useful approach, it requires a computer program to simulate the linear superimposition of waveforms. The simulation is not possible for every blast as it takes time and also is difficult for field engineers to simulate every time, whereas it is always easy for blasting engineers to adapt and use an empirical equation/approach for prediction and control of blast-induced ground vibration than simulation. In this paper, an attempt has been made to develop an innovative and simplified analytical approach of signature hole analysis. The simplified sinusoidal wave equation is obtained from recorded signature hole ground vibration waveform properties and is superimposed mathematically according to the multi-hole blast design to predict the production blast-induced ground vibrations. The validation of the developed approach was done in three different sites, and up to 15% more accuracy in prediction of the blast, vibrations are achieved in comparison with signature hole analysis prediction.
相似文献3.
将一种称为Duxseal的工业填料用于自由场主动隔振,发展了一种带孔波阻板（WIB）填充Duxseal的隔振方法,即Duxseal-WIB隔振系统。采用薄层法基本解答作为格林函数的三维半解析边界元法,分析了Duxseal的隔振效果及性能,并对提出的Duxseal-WIB隔振系统进行了现场试验。结果表明,采用Duxseal作为主动隔振屏障可以有效起到振动隔振作用,对距离振源较远处地表位移的隔振效果优于距离振源较近处;土质参数的变化对Duxseal的隔振效果具有显著的影响;在一定范围内增加Duxseal直径、厚度或埋深均可有效提高其隔振效果,其中Duxseal顶面距地表埋深的影响尤为显著;此外,与传统WIB对比,Duxseal-WIB隔振效果较高且相对平稳,在列车运行250 km/h条件下,距离振源中心12 m处测振点X、Y、Z向的地表隔振可分别达到40%、39%和51%。 相似文献
4.
微差爆破模拟天然地震的数值分析与效果评价 总被引：2，自引：0，他引：2
微差爆破可以创造出与天然地震相类似的振动环境。为了更好地对爆破模拟天然地震进行研究和评价,在LS-DYNA软件框架内,建立了适合于爆炸荷载作用下土体动力分析的实用模型,对原位土体场地爆破地震动试验进行了全尺寸数值模拟,并将模拟结果与现场实测数据进行比较分析,验证数值计算的准确性。计算结果表明,模拟得到的场地质点加速度-时程与实测数据比较吻合,因此,可以预先利用数值手段为试验方案设计提供指导;同时,数值模拟还总结了现场试验中未得到的场地压力变化规律和振动规律,分析了爆破地震动与天然地震的异同,丰富了爆破地震动的研究,表明利用爆破手段能够近似地模拟天然地震,为微差爆破模拟天然地震的研究工作提供了经济、简便而实用的方法。 相似文献
5.
Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock 总被引：2，自引：1，他引：1
Most of the railway tunnels in Sweden are shallow-seated (<20 m of rock cover) and are located in hard brittle rock masses.
The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a
blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength
and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish
Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting
to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow
tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the
subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By
varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass
response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of
numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using
a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic.
Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr–Coulomb yield criterion
was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect
the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary
and their mechanisms have also been identified. 相似文献
6.
Vivek K. Himanshu M. P. Roy A. K. Mishra Ranjit Kumar Paswan Deepak Panda P. K. Singh 《Arabian Journal of Geosciences》2018,11(16):460
Excavation of coal, overburden, and mineral deposits by blasting is dominant over the globe to date, although there are certain undesirable effects of blasting which need to be controlled. Blast-induced vibration is one of the major concerns for blast designers as it may lead to structural damage. The empirical method for prediction of blast-induced vibration has been adopted by many researchers in the form of predictor equations. Predictor equations are site specific and indirectly related to physicomechanical and geological properties of rock mass as blast-induced ground vibration is a function of various controllable and uncontrollable parameters. Rock parameters for blasting face and propagation media for blast vibration waves are uncontrollable parameters, whereas blast design parameters like hole diameter, hole depth, column length of explosive charge, total number of blast holes, burden, spacing, explosive charge per delay, total explosive charge in a blasting round, and initiation system are controllable parameters. Optimization of blast design parameters is based on site condition and availability of equipment. Most of the smaller mines have predesigned blasting parameters except explosive charge per delay, total explosive charge, and distance of blast face from surface structures. However, larger opencast mines have variations in blast design parameters for different benches based on strata condition: Multivariate predictor equation is necessary in such case. This paper deals with a case study to establish multivariate predictor equation for Moher and Moher Amlohri Extension opencast mine of India. The multivariate statistical regression approach to establish linear and logarithmic scale relation between variables to predict peak particle velocity (PPV) has been used for this purpose. Blast design has been proposed based on established multivariate regression equation to optimize blast design parameters keeping PPV within legislative limits. 相似文献
7.
8.
Piotr W. Mirowski Daniel M. Tetzlaff Roy C. Davies David S. McCormick Nneka Williams Claude Signer 《Mathematical Geosciences》2009,41(4):447-474
This research introduces a novel method to assess the validity of training images used as an input for Multipoint Geostatistics,
alternatively called Multiple Point Simulation (MPS). MPS are a family of spatial statistical interpolation algorithms that
are used to generate conditional simulations of property fields such as geological facies. They are able to honor absolute
“hard” constraints (e.g., borehole data) as well as “soft” constraints (e.g., probability fields derived from seismic data,
and rotation and scale). These algorithms require 2D or 3D training images or analogs whose textures represent a spatial arrangement
of geological properties that is presumed to be similar to that of a target volume to be modeled. To use the current generation
of MPS algorithms, statistically valid training image are required as input. In this context, “statistical validity” includes
a requirement of stationarity, so that one can derive from the training image an average template pattern. This research focuses
on a practical method to assess stationarity requirements for MPS algorithms, i.e., that statistical density or probability
distribution of the quantity shown on the image does not change spatially, and that the image shows repetitive shapes whose
orientation and scale are spatially constant. This method employs image-processing techniques based on measures of stationarity
of the category distribution, the directional (or orientation) property field and the scale property field of those images.
It was successfully tested on a set of two-dimensional images representing geological features and its predictions were compared
to actual realizations of MPS algorithms. An extension of the algorithms to 3D images is also proposed. As MPS algorithms
are being used increasingly in hydrocarbon reservoir modeling, the methods described should facilitate screening and selection
of the input training images. 相似文献
9.
Indrajit Pal Sankar Kumar Nath Khemraj Shukla Dilip Kumar Pal Abhishek Raj K. K. S. Thingbaijam B. K. Bansal 《Natural Hazards》2008,45(3):333-377
An earthquake hazard zonation map of Sikkim Himalaya is prepared using eight thematic layers namely Geology (GE), Soil Site
Class (SO), Slope (SL), Landslide (LS), Rock Outcrop (RO), Frequency–Wavenumber (F–K) simulated Peak Ground Acceleration (PGA),
Predominant Frequency (PF), and Site Response (SR) at predominant frequencies using Geographic Information System (GIS). This
necessitates a large scale seismicity analysis for seismic source zone classification and estimation of maximum earthquake
magnitude or maximum credible earthquake to be used as a scenario earthquake for a deterministic or quasi-probabilistic seismic
scenario generation. The International Seismological Center (ISC) and Global Centroid Moment Tensor (GCMT) catalogues have
been used in the present analysis. Combining b-value, fractal correlation dimension (Dc) of the epicenters and the underlying tectonic framework, four seismic source zones
are classified in the northeast Indian region. Maximum Earthquake of M
W 8.3 is estimated for the Eastern Himalayan Zone (EHZ) and is used to generate the seismic scenario of the region. The Geohazard
map is obtained through the integration of the geological and geomorphological themes namely GE, SO, SL, LS, and RO following
a pair-wise comparison in an Analytical Hierarchy Process (AHP). Detail analysis of SR at all the recording stations by receiver
function technique is performed using 80 significant events recorded by the Sikkim Strong Motion Array (SSMA). The ground
motion synthesis is performed using F–K integration and the corresponding PGA has been estimated using random vibration theory
(RVT). Testing for earthquakes of magnitude greater than M
W 5, a few cases presented here, establishes the efficacy and robustness of the F–K simulation algorithm. The geohazard coverage
is overlaid and sequentially integrated with PGA, PF, and SR vector layers, in order to evolve the ultimate earthquake hazard
microzonation coverage of the territory. Earthquake Hazard Index (EHI) quantitatively classifies the terrain into six hazard
levels, while five classes could be identified following the Bureau of Indian Standards (BIS) PGA nomenclature for the seismic
zonation of India. EHI is found to vary between 0.15 to 0.83 quantitatively classifying the terrain into six hazard levels
as “Low” corresponding to BIS Zone II, “Moderate” corresponding to BIS Zone III, “Moderately High” belonging to BIS Zone IV,
“High” corresponding to BIS Zone V(A), “Very High” and “Severe” with new BIS zones to Zone V(B) and V(C) respectively. 相似文献
10.
Prediction of ground vibration due to quarry blasting based on gene expression programming: a new model for peak particle velocity prediction 总被引：1，自引：1，他引：0
R Shirani Faradonbeh D Jahed Armaghani M. Z. Abd Majid M. MD Tahir B. Ramesh Murlidhar M. Monjezi H. M. Wong 《International Journal of Environmental Science and Technology》2016,13(6):1453-1464
Blasting is a widely used technique for rock fragmentation in opencast mines and tunneling projects. Ground vibration is one of the most environmental effects produced by blasting operation. Therefore, the proper prediction of blast-induced ground vibrations is essential to identify safety area of blasting. This paper presents a predictive model based on gene expression programming (GEP) for estimating ground vibration produced by blasting operations conducted in a granite quarry, Malaysia. To achieve this aim, a total number of 102 blasting operations were investigated and relevant blasting parameters were measured. Furthermore, the most influential parameters on ground vibration, i.e., burden-to-spacing ratio, hole depth, stemming, powder factor, maximum charge per delay, and the distance from the blast face were considered and utilized to construct the GEP model. In order to show the capability of GEP model in estimating ground vibration, nonlinear multiple regression (NLMR) technique was also performed using the same datasets. The results demonstrated that the proposed model is able to predict blast-induced ground vibration more accurately than other developed technique. Coefficient of determination values of 0.914 and 0.874 for training and testing datasets of GEP model, respectively show superiority of this model in predicting ground vibration, while these values were obtained as 0.829 and 0.790 for NLMR model. 相似文献
11.
In this research, experimental applications have been performed to reduce blast induced vibrations in open pit mines. For
this purpose, artificial discontinuity zones such as barrier holes and trench were opened in a dragline panel of Seyitomer
Lignite Enterprise, Kutahya, Turkey. Peak particle velocities in front of and behind them were measured by seismographs. In
this way, their effect against vibration was observed and compared. Barrier holes were opened 24 m deep through 3 parallel
lines and aligned at 1 m spacing. On the other hand, the trench had 8 m depth and 4 m width. During the research, 209 measurements
were taken belonging to 105 explosions. Twenty-eight explosions were carried out in the barrier holes experiments and 77 explosions
were carried out in the trench experiments. A decrease in vibration of 14.3–18.5% was obtained behind the barrier holes while
a decrease of 24.8–58.1% was provided by the trench. 相似文献
12.
13.
Practical Estimate of Deformations and Stress Relief Factors for Deep Tunnels Supported by Shotcrete 总被引：1，自引：1，他引：1
Summary. Even though ground-support interaction in the vicinity of the tunnel face is a typical 3D problem, tunnel support design is
usually based on simplified plane strain models, which are strongly dependent on the assumed degree of ground stress relief
at the time of lining installation. The paper focuses on tunnels supported by shotcrete close to the face, where the interaction
between the loading process and progressive hardening of the green shotcrete makes the problem time-dependent. A constitutive
law characterized by the time-dependent stiffness and strength of the shotcrete is employed herein. The results of an extensive
parametric study based on 3D axisymmetric models are presented in the form of non-dimensional design charts, which can provide
guidance to a preliminary evaluation of convergences and support loadings.
Moreover a strategy is proposed to enhance the capability of simplified design methods (2D models, Convergence-Confinement
Method). This consists in a “guided estimate” of stress relief factors, which again is based on the results of 3D time-dependent
analyses. Finally, by way of example, the proposed method is applied to two well-documented case-histories. 相似文献
14.
The sediment-hosted disseminated gold deposits in the Oinling region are of sedimentation-slight-metamorphic origin superimposed by hydrothermal reworking at moderate-low temperatures and are well comparable with the typical Carlin gold deposits in the United States.In view of the confusing concept concerning the “sediment-hosted”and “Carlin-type” gold deposits,the authors propose that the term“sediment-hosted gold deposit”should be used in a broad sense which encompasses at least the four subtypes,i.e.,the Carlin type,the metamorphic fine clastic type,the hydrothermal sedimentary type and the vein type.In oter words,the “Carlin-type”should not be used as a synonym for “sediment-hosted”but is recommended as a subtype under the general category of “sediment-hosted gold deposits” 相似文献
15.
Building of models in the Earth Sciences often requires the solution of an inverse problem: some unknown model parameters need to be calibrated with actual measurements. In most cases, the set of measurements cannot completely and uniquely determine the model parameters; hence multiple models can describe the same data set. Bayesian inverse theory provides a framework for solving this problem. Bayesian methods rely on the fact that the conditional probability of the model parameters given the data (the posterior) is proportional to the likelihood of observing the data and a prior belief expressed as a prior distribution of the model parameters. In case the prior distribution is not Gaussian and the relation between data and parameters (forward model) is strongly non-linear, one has to resort to iterative samplers, often Markov chain Monte Carlo methods, for generating samples that fit the data likelihood and reflect the prior model statistics. While theoretically sound, such methods can be slow to converge, and are often impractical when the forward model is CPU demanding. In this paper, we propose a new sampling method that allows to sample from a variety of priors and condition model parameters to a variety of data types. The method does not rely on the traditional Bayesian decomposition of posterior into likelihood and prior, instead it uses so-called pre-posterior distributions, i.e. the probability of the model parameters given some subset of the data. The use of pre-posterior allows to decompose the data into so-called, “easy data” (or linear data) and “difficult data” (or nonlinear data). The method relies on fast non-iterative sequential simulation to generate model realizations. The difficult data is matched by perturbing an initial realization using a perturbation mechanism termed “probability perturbation.” The probability perturbation method moves the initial guess closer to matching the difficult data, while maintaining the prior model statistics and the conditioning to the linear data. Several examples are used to illustrate the properties of this method. 相似文献
16.
饱和土半解析边界元法及在双排桩被动隔振中的应用 总被引：1，自引：1，他引：0
针对均质饱和地基中双排桩远场被动隔振问题,首先,基于饱和多孔介质的边界元法,建立了以薄层法（TLM）基本解作为动力Green函数的饱和土半解析边界元法,该方法可有效地分析饱和半空间的土-结构动力相互作用问题。在此基础上,根据双排桩与周围土体的邻接条件,推导了双排桩对Rayleigh波散射的三维边界元方程;运用上述边界元方程,对双排桩的远场被动隔振问题进行了研究。结果表明：双排桩能够有效地降低屏障后的位移振幅,其隔振效果要优于单排桩;排间净距对隔振效果影响不大,而桩间净距则对双排桩隔振效果起控制作用。 相似文献
17.
Landslide Hazard Zonation using Remote Sensing and GIS: a case study of Dikrong river basin, Arunachal Pradesh, India 总被引：3，自引：0，他引：3
Landslides are among the most costly and damaging natural hazards in mountainous regions, triggered mainly under the influence
of earthquakes and/or rainfall. In the present study, Landslide Hazard Zonation (LHZ) of Dikrong river basin of Arunachal
Pradesh was carried out using Remote Sensing and Geographic Information System (GIS). Various thematic layers namely slope,
photo-lineament buffer, thrust buffer, relative relief map, geology and land use / land cover map were generated using remote
sensing data and GIS. The weighting-rating system based on the relative importance of various causative factors as derived
from remotely sensed data and other thematic maps were used for the LHZ. The different classes of thematic layers were assigned
the corresponding rating value as attribute information in the GIS and an “attribute map” was generated for each data layer.
Each class within a thematic layer was assigned an ordinal rating from 0 to 9. Summation of these attribute maps were then
multiplied by the corresponding weights to yield the Landslide Hazard Index (LHI) for each cell. Using trial and error method
the weight-rating values have been re-adjusted. The LHI threshold values used were: 142, 165, 189 and 216. A LHZ map was prepared
showing the five zones, namely “very low hazard”, “low hazard”, “moderate hazard”, “high hazard” and “very high hazard” by
using the “slicing” operation. 相似文献
18.
空沟是一种常用的连续隔振屏障,可以有效地降低人工振动。以位移为变量的二维格子法在波动问题计算中具有良好的适应性、高效性,兼备有限元与差分法的一些优点,应用该法针对层状地基中作用于路堤上的交通荷载引起振动的空沟竖向隔振问题进行了参数研究,分别考虑了上软下硬地基和上硬下软地基两种情况。研究结果表明：空沟宽度对隔振效果的影响较小;空沟深度与空沟的位置是影响隔振效果的关键因素,它们相互关联,其取值应综合考虑;在上述两类层状地基中,若空沟深度与上层土的厚度接近或相等均对竖向隔振不利;路堤高度越大对竖向隔振效果越不利。 相似文献
19.
浅埋大跨隧道施工爆破监测与减震技术 总被引：4，自引：1，他引：3
以沪-蓉线庙垭分岔隧道工程为背景,研究了其浅埋大跨段掘进爆破的地表震动效应及大断面开挖减震控制技术,并结合爆破监测数据的回归分析,确立了地震波垂向衰减规律的数学模型。综合分析地表及洞内地震波的震动特性发现,地表质点振动主振频率主要集中在低频段;由于表土的滤波作用,主振频率随距离的增加而减小的趋势并不明显;洞内混凝土衬砌减弱了爆破对围岩的冲击,高频地震波衰减极快;开挖区上部的地表振速通常大于未开挖区的振速,浅埋大跨隧道爆破安全控制应以已开挖区顶部的地表振速为准。 相似文献
20.
KKM油田下部砂泥岩互层非均质性强导致井下钻具振动剧烈、PDC切削齿寿命低,且井眼易偏斜。目前在用PDC钻头多采用5刀翼或6刀翼16 mm切削齿以降低井下振动保证PDC钻头寿命,但降低了钻头攻击性导致机械钻速较低。针对KKM油田下部地层特点,优选了4刀翼19 mm复合片PDC钻头。该钻头具有较高的破岩效率和攻击性,可大幅度提高机械钻速;同时通过底部钻具组合动力学分析,优化形成了双稳定器+单稳单弯（0.5°）钻具组合,3个稳定器串联具有较强的稳定降振作用,配合小弯角螺杆钻进可有效提高防斜能力,降低了井下振动,配合大尺寸聚晶金刚石复合片PDC钻头实现了三开井段一趟钻完成的目标,机械钻速提高115.35%。 相似文献