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1.
A Column Experiment to Study the Thermo-Hydro-Mechanical Behaviour of Expansive Soils 总被引：1，自引：1，他引：0
Tom Schanz Long Nguyen-Tuan Maria Datcheva 《Rock Mechanics and Rock Engineering》2013,46(6):1287-1301
The study of heat transfer, water flow, and swelling pressure development in engineered clay barriers and the evaluation of the influence of these phenomena on the barrier properties are important issues for predicting the performance of nuclear waste repository facilities. In this work, an experimental setup is presented especially meant to assess the response of the sand–bentonite mixture under conditions close to that of the buffer in a radioactive waste repository. A newly developed column device for laboratory testing of coupled thermo-hydro-mechanical (THM) behaviour of clay-buffer materials is introduced and its calibration, verification and the first experimental data are presented and discussed. The main features of the column device are: hydraulic and thermal gradients are possible to be applied; water content, suction and temperature development can be measured continuously at three locations along the sample height; swelling stress can be measured at top and the bottom of the sample. Measuring transient temperature, water content and suction simultaneously at the same height levels and with special care to minimise the sample disturbance is one of the advantages of the column device proposed here when compared to that previously reported in the literature. The main objectives of this paper are: (1) to describe the experimental device, (2) to introduce the sensors implemented and their calibration, and (3) to present and discuss the first experimental results obtained with the new equipment. The first experimental results show promise in the ability of the newly developed column device to provide reliable data for assessing the THM behaviour of expansive materials that are foreseen as buffer material in high level waste repositories. 相似文献
2.
注浆压力和坐封压力是设计煤矿井下自动封孔装置所需的主要参数,同时也是自动化封孔施工设计的重要依据。以浆液的有效封堵半径为基础,采用理论计算、数值模拟等方法分析了不同注浆压力条件下的封孔效果,结合橡胶的Mooney-Rivlin本构模型的力学特征、挤压密封等原理,研究并确定最佳注浆压力和坐封压力。结果表明,注浆压力为2~4 MPa时浆液的径向封堵范围达2~4 m,可以满足对钻孔的封堵要求;当钻孔直径为96~100 mm时,坐封压力范围为2.2~8.4 MPa,可以使装置达到最佳坐封效果。研究结果可为装置的设计提供理论基础,为装置应用所需技术参数的确定提供理论依据。 相似文献
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本文以高渗透压渗流试验装置模拟已被污染的浅层地下水越流通过弱透水层污染深层地下水的过程,研究了有机污染物(菲)通过饱和粘性土弱透水层时的自然衰减特征,以及非生物因子-配位体对于弱透水层中菲迁移转化的影响作用。研究表明,菲的衰减曲线明显分为三阶段:初期吸附截留显著期,中期微生物降解旺盛期,后期微生物降解稳定期;溶液中共存离子HCO 3-、Ca2+与菲形成络合物,SO42-参与菲的生物降解;溶液中主要配位体不同时,菲与阴、阳离子之间相互作用的方式也不同,以络合作用为主。渗透水中菲含量有99%以上被衰减,仅有极少量菲穿透弱透水层。 相似文献
5.
高铁列车动载会引起环境振动问题。为研究高速列车运行在高架段和路堤段引起的环境振动差异,文章对郑西线高速铁路展开现场测试,对比分析高架段和路堤段地面振动特征及其衰减规律。测试结果表明,路基段的振动响应大于高架段,高架段近场区衰减作用高于路堤段近场区域。振动传播过程中存在多次反弹增大现象,路堤段地面振动反弹增大位置滞后于高架段。高架段和路堤段的二次反弹增大率均明显大于一次反弹增大率。Z振级随距离的衰减符合对数衰减规律,拟合得到黄土地区Z振级衰减公式,最大偏差均出现在反弹增大区。引入无限元-黏弹性耦合边界条件,建立路堤段三维轨道-土体-隔振沟数值模型分析高速铁路隔振沟对减隔振的影响。研究发现空沟对中高频（30～60 Hz）振动波的隔振效果较低频（1～20 Hz）振动波明显,其具有低通滤波作用。空沟比填充沟隔振效果好,但是考虑到沟壁的稳定性,可在空沟中填入软质材料。研究成果可为高速铁路的设计及其环境振动的评价和控制提供参考。 相似文献
6.
大扭矩反扭装置是研制铠装电缆冰下基岩电动机械取心钻具的主要部分之一,该装置的失效将导致钻进无法进行,甚至将造成钻具脱落等严重的孔内事故。设计了铠装电缆钻具反扭装置实验台,并就实验装置的设计思想、设计原则、主要结构参数及初步实验结果进行了详细介绍。该实验台可以测试反扭装置在不同温度冰层和不同孔径任意组合下所能提供的反扭矩大小以及产生的下滑阻力。初步实验验证,该实验台工作性能良好,可以为更好的选择反扭装置类型及最优的使用参数提供重要依据。 相似文献
7.
Keyan Yu Philippe Rosset 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(2):164-178
In Canada, Montreal is the second city with the highest seismic risk. This is due to its relatively high seismic hazard, old infrastructures and high population density. The region is characterised by moderate seismic activity with no recent record of a major earthquake. The lack of historical strong ground motion records for the region contributes to large uncertainties in the estimation of hazards. Among the sources of uncertainty, the attenuation function is the main contributor and its effect on estimates of risks is investigated. Epistemic uncertainty was considered by obtaining damage estimates for three attenuation functions that were developed for Eastern North America. The results indicate that loss estimates are highly sensitive to the choice of the attenuation function and suggest that epistemic uncertainty should be considered both for the definition of the hazard function and in loss estimation methodologies. Seismic loss estimates are performed for a 2% in 50 years seismic threat, which corresponds to the design level earthquake in the national building code of Canada, using HAZUS-MH4 for the Montreal region over 522 census tracts. The study estimated that for the average scenario roughly 5% of the building stock would be damaged with direct economic losses evaluated at 1.4 billion dollars for such a scenario. The maximum number of casualties would result in approximately 500 people being injured or dead at a calculated time of occurrence of 2?pm. 相似文献
8.
In the present study, the seismic hazard in northern Algeria is estimated using both physical strain energy release and Gumbel's extreme values approaches. For six of the most industrial and populated cities in Algeria, seismic hazard is assessed and examined in greater detail. Gumbel's extreme values approach has been used to estimate seismic hazard in terms of magnitude and P.G.A at each point of an equispaced grid all over the north of Algeria. An average attenuation relationship for PGA has been provided using known relations which have been established in regions with similar attenuation characteristics.The results are presented mainly in the form of graphs and contour maps of magnitudes (respectively PGA) with a 60% probability of not being exceeded in the next 100 and 200 years. Globally, they give main features of northern Algeria in terms of zoning (as well as in terms of magnitude and in terms of PGA). They corroborate the ones obtained through other works, especially in the basin areas (Mitidja, Cheliff, Soumam and Constantine Basin). 相似文献
9.
介绍了自行研制的一种新型微型脉冲充磁仪，它由高频开关电源电路、高压充电及大电流快速开关电路等部分组成。阐述了仪器的工作原理和结构设计。通过对“1：25万聂拉木县幅磁性地层研究专题”样品的充磁测试表明，利用新研制的微型脉冲充磁仪进行等温剩磁测定，可以客观、准确地判断岩石样品中的磁性矿物成分。 相似文献
10.
In the present study, the seismic hazard in the city of Patras, central Greece, is estimated. The computations are based on a slightly modified version of the method proposed by Cornell, allowing the introduction of individual attenuation laws for each seismic source.The obtained results emphasize the dependence of hazard on attenuation and the importance of the use of local attenuation laws in seismic hazard assessment.Paper presented at the 21st General Assembly of the European Seismological Commission, held in Sofia, 1988. 相似文献
11.
Seismic attenuation behaviour is controlled by a large number of wave modification mechanisms. The characteristics of some of these mechanisms are specific to a local area, whilst the remainder can be generalised to the entire seismic region. Factors representing these mechanisms are often not resolved. A new attenuation modelling approach is demonstrated in this paper (using Hong Kong as a case study), to evaluate individual regional and local wave modification factors. Shear wave velocity (SWV) information for the four prevalent geological formations found in Hong Kong was first obtained: (a) at shallow depths from instrumented boreholes; (b) at depths of up to 100–200 m from measurements using the Microtremor SPatial Auto-Correlation (SPAC) technique; (c) at depths of up to 1.5 km from the monitoring of quarry blasts; and (d) at depths from 1.5 to 8 km in the hard basement rock layers from results of seismological refraction surveys. The upper-crust amplification factor calculated from the four modelled rock SWV profiles was then combined with predicted attenuation parameters to determine the upper-crust modification factor (filter function) incorporating the local wave modification characteristics associated with Hong Kong geological formations. Such functions may then be combined with the regional attenuation characteristics in that part of the South China region. A seismic attenuation model was developed by combining the upper-crust modification factor with the regional source function of intra-plate earthquakes, based on stochastic simulations. The ground shaking model developed from the presented methodology is supported by the comparison with macro-seismic data of seven historical earthquake events affecting Hong Kong. 相似文献
12.
S. M. N. Shojaee O. Uzol Ö. Kurç 《International Journal of Environmental Science and Technology》2014,11(1):59-68
This paper presents the design, computational analysis and experimental study of passive device configurations which utilized in the Ankara Wind Tunnel to simulate the atmospheric boundary layer within the test section. The study here is part of a joint project between the Aerospace and Civil Engineering Departments at Middle East Technical University, which involves testing of high-rise building models in the Ankara Wind Tunnel. The design consists of spires and rows of cubical surface roughness elements at the inlet. The preliminary computational analysis shows that the current design may provide the desired boundary layer thickness at about 4.0 m downstream of the test section inlet, which leaves enough room for the building models to be placed in the test section. This study also helps obtaining a preliminary understanding of the boundary layer development and reducing the tunnel operation time and cost during the actual experimentation phase. At the end, experimental results show acceptable results of this study. 相似文献
13.
极地冰盖深部“暖冰”层钻进时,由于冰层的温度较高,接近甚至达到冰的压力熔点,回转钻进时产生的切削热量极易使冰屑融化,导致机械钻速慢、取心率低、卡钻事故频发。钻压、转速、切削具结构等参数均对切削热量有一定的影响,有必要设计一套实验装置对切削热量进行测试,从而为设计切削具结构、优化钻进参数组合提供理论依据。以XY-1型岩心钻机钻进系统为平台,利用无线信号传输原理设计了冰层回转钻进切削热量测试实验台。初步测试结果表明,该实验装置能够准确测量钻压、扭矩、切削温度等参数,可用来进行相关的实验研究。 相似文献
14.
Conel M.O’D. Alexander 《Geochimica et cosmochimica acta》2011,75(2):588-607
Here empirical models for calculating self-diffusion coefficients and diffusion matrices are combined with MELTS, a thermodynamic model for silicate minerals and melts, to estimate diffusive dissolution rates, interface melt compositions and melt diffusivities. Simulations of olivine dissolution experiments in basalt show that the overall model is capable of accurately reproducing diffusive dissolution rates, and the resulting diffusion profiles, over a range of pressures and temperatures. However, the overall model is less successful at reproducing olivine dissolution in andesite, diopside dissolution in either basalt or andesite, or anorthite dissolution in picrite. Yet, even for these systems the predicted dissolution rates are generally within about a factor of two of the measured ones. Comparisons between simulations and experiments suggest that errors in the self-diffusion and thermodynamic models are responsible for the differences, and show that dissolution experiments could be a powerful way of testing and calibrating these and similar models. The overall model will also be a useful tool for designing future experiments, and for identifying the parameters that control diffusive dissolution (and crystallization) in silicate melts under a wide range of conditions. 相似文献
15.
土石混合体填筑路堤中的非线性蠕变模型探析 总被引：2，自引：1，他引：1
针对土石混合体填筑路堤工后沉降的非线性蠕变特性,提出了一种能考虑材料非线性黏弹性变形的蠕变模型。基于目前对土石混合体蠕变机理研究,将路堤工后的蠕变沉降部分考虑为非线性的衰减蠕变过程,建立了修正的Kelvin模型、广义修正模型,且得到了模型参数的识别方法;通过对修正模型分析表明,非线性常数取值对蠕变曲线变化有较大影响,修正模型的蠕变长期应变值比Kelvin模型要小;结合相关文献中对土石体填料的蠕变试验研究资料,用修正Kelvin模型对试验结果进行拟合,并对参数进行了反演,反演效果良好。修正模型的建立可为编制非线性黏弹性数值计算软件提供理论基础。 相似文献
16.
监测自然衰减(monitoring natural attenuation,MNA)技术是目前普遍认可的去除地下水中挥发性有机污染物(volatile organic compounds,VOCs)的技术。但受其修复周期长、监测费用昂贵等因素的影响,实地开展MNA技术修复污染场地具有一定的局限性。基于此,本研究运用多相流数值模拟手段识别了某石油污染场地内典型VOCs污染物(苯、甲苯、萘)在地下水中的自然衰减过程并评估了其自然衰减能力。结果表明:采用TMVOC所建立的多相流数值模拟模型能较好地预测和识别VOCs在地下水中的衰减规律;在研究区中,苯、甲苯和萘由于理化性质差异,在地下水中的污染羽分布特征不同,其自然衰减过程受挥发、吸附和生物降解作用的影响程度也不同;挥发和生物降解作用对VOCs自然衰减的影响程度均为苯>甲苯>萘,而吸附作用对VOCs自然衰减的影响程度为萘>甲苯>苯;在污染源被阻断的前提下,苯、甲苯和萘分别在泄漏发生7.0、6.5和6.0年后通过自然衰减达到理想去除效果。本文研究成果可以为水文地质条件类似的VOCs污染场地MNA修复方案的制定和修复效果评估提供理论支撑。 相似文献
17.
土工格室广泛运用于道路或铁路路基的补强和病害整治,针对不同几何尺寸土工格室的整治效果不同,采用焊距为340、400、680 mm和高度为0.10、0.15、0.20 m组合的9种不同规格土工格室进行整治铁路基床下沉病害的现场试验,并与换砂法试验进行了对比,分析不同整治法的轨下动应力衰减规律。结果表明,格室每增高0.01 m,动应力衰减增加约0.6%～1%;焊距每增加100 mm,动应力衰减降低约5%;相比较于换砂法,土工格室法轨下动应力衰减快、分布均,路基强度高,表明换填厚度的大小与整治方法密切相关。在试验的基础上提出了换填厚度设计容许应力法,综合考虑了路基应力水平、格室与砂垫层动应力衰减性能以及路基基床土的容许承载力,为换填厚度设计提供了理论设计方法。 相似文献
18.
Takehiro Koyaguchi 《Contributions to Mineralogy and Petrology》1989,103(2):143-152
The results of high pressure experiments on diffusion and Soret separation in natural silicate melts show that the diffusive behaviour between natural silicic and mafic magmas can be approximately modelled as if the system were a binary mixture of SiO2 and other components such as MgO+FeO+CaO. Steady state compositional profiles across a diffusive interface between silicic and mafic magma layers are calculated on the basis of phenomenological relationships for the fluxes of chemical species and heat in the binary mixtures, using the experimental data of diffusion and Soret coefficients in natural silicate melts. The compositional profiles show a curvature with a minimum SiO2 value within the interface due to the Soret effect and temperature dependence of diffusion coefficient. The compositional gradient at the lower half of the diffusive interface is similar to that resulting from the Soret separation of a mafic melt regardless of the composition of the silicic magmas. These results suggest that picritic magma can be formed in the interfacial region between the mafic and silicic magma layers. The compositional gradient explains chemical variation of mafic to picritic inclusions in a mixed andesite of the Abu Volcano Group, Japan. 相似文献
19.
A method of tremor risk estimation on the basis of seismic emission registered in mining exploitation zones is presented in this paper. A considerable part of the emission registered in these conditions, is generated by mechanical devices used in the mine (miner transporters etc.). Therefore, it is not possible to evaluate the risk of mining rock-bursts properly on the basis of interpretation of emission using known theories and models describing rock mass fracturing. In a new approach presented in this paper, the tremor risk is determined on the basis of time variation of a parameter describing the attenuation of seismic vibrations of the rock medium. The attenuation is assessed from the analysis of seismic emission registered in the frequency range from 30 Hz to 1000 Hz. Information about this parameter is encapsulated in the seismic emission regardless of the means of its generation. The method of estimating the temporal variations of attenuation is based on the analysis of signal envelopes of the microseismic emission. Attenuation trends can be interpreted in a straightforward way. As the stress values keep increasing, the following processes take place in the rock mass: compaction (hardening), dilatancy (softening), and then possibly tremors. At the compaction stage attenuation values are lower, while they increase at the dilatancy stage. This mechanism has been proven in practice. Our results can be used for monitoring tremor risk. 相似文献
20.
井下动力钻具微钻试验装置是为研制新型动力钻具提供试验条件的关键装备,该装备用于原理样机的试验测试,可降低试验成本并缩短研发周期,试验测试结果可为全尺寸物理样机的制造提供参考。本文依据井下动力钻具的工作特点和钻具试验装置测试原理,设计了一套井下动力钻具微钻试验装置,该试验装置区别于常规和传统的微钻实验台,其采用数控闭环控制钻井液动力循环和钻压,实现了水力驱动与钻压给进的精确控制,并验证了井下动力钻具微钻试验装置的可行性,为水力驱动的钻具样机试验研究提供了平台。 相似文献