温度与孔隙压力耦合作用下煤岩吸附–渗透率模型研究

为模拟瓦斯抽采过程中温度与孔隙压力对煤岩吸附及渗透特性的影响,利用等温吸附装置、含瓦斯煤热–流–固耦合三轴伺服渗流装置,开展等温吸附试验及不同温度下孔隙压力降低的渗流试验。建立修正的双L吸附模型和考虑温度–孔隙压力耦合作用的煤岩渗透率模型。通过试验结果及试验比对验证其合理性。结果表明:在本文试验条件下,煤岩瓦斯累积解吸量随瓦斯压力降低呈逐渐升高趋势。当温度恒定时,煤岩渗透率在降压过程中呈先降低后升高的趋势。当孔隙压力恒定时,煤岩渗透率在升温过程中呈先降低后升高的趋势。修正后的双L吸附模型比原吸附模型拟合效果更好,能很好反映不同温度下煤岩吸附量与气体压力的变化关系。煤岩瓦斯解吸过程中产生的基质收缩应变随孔隙压力降低而升高。新建渗透率模型与试验数据具有较好的一致性,可以更好的表征不同温度条件下的煤岩渗透率演化规律。     

不同结构形式的后期热液充填裂隙花岗岩常温下物理力学性质研究

在干热岩开采的实际工程中,利用岩体结构面作为热交换通道将减小工程投入,并获得更好的工程效果.而在实际中花岗岩体中的结构面通常被热液充填,形成后期热液充填花岗岩体.研究后期热液填充裂隙花岗岩体 的物理力学性质对实际地热开发中建设人工储留层具有重要指导意义.利用后期热液填充裂隙花岗岩体制备不同结构形式试样,在常温下对4种结...     

The effect of soil mineralogy and pore fluid chemistry on the suction and swelling behavior of soils

Soil suction is one of the most important parameters for describing the moisture condition and engineering behavior of unsaturated soils. Therefore, changes in suction behavior of soils in the presence of saline waters are important for engineered barriers. The aim of this study was to determine the change in suction and swelling behavior of soils, which were exposed to salt solutions (NaCl, CaCl₂, natural seawater) with respect to distilled water. The three soil samples were gathered with different mineralogy and plasticity characteristics and tested for determining matric and total suction values and for obtaining free swelling characteristics in the presence of salt solutions. The bentonitic soil sample had the highest total suction value in the presence of seawater. Kaolinitic and zeolitic soil samples had the highest total suction values in the presence of NaCl solution. The highest modified free swell index value of the samples was obtained in the presence of NaCl solution for all the soil samples. No relationship was found between the total suction, matric suction and the modified free swell index value of the tested soils.     

Trichloroethylene adsorption by activated carbon preloaded with humic substances: effects of solution chemistry

Trichloroethylene (TCE) adsorption by activated carbon previously loaded ("preloaded") with humic substances was found to decrease with increasing concentrations of monovalent ions (NaCl), calcium (until solubility was exceeded), or dissolved oxygen in the preloading solution. For a given percentage of organic carbon removal during humic acid loading, greater reductions in TCE adsorption occurred with increasing monovalent ion concentration and calcium concentration at constant ionic strength. However, this effect was related primarily to the amount of humic material adsorbed--the reduction in TCE adsorption was independent of the ionic composition of the preloading solution when compared at similar humic acid loading. Experiments were performed which showed that calcium ions can associate with humic material after the humic has been adsorbed, which subsequently reduces TCE uptake, but this effect does not dominate when calcium is present during humic loading. At sufficiently high calcium concentrations (approaching solubility), aggregation or co-precipitation of humic acid mitigated the effects of preloading. In contrast to the effects of ionic composition, the presence of dissolved oxygen did fundamentally change the mechanism by which organic macromolecules compete with TCE. TCE uptake was lower when preloading by poly(maleic acid) (PMA) occurred in the presence of dissolved oxygen, even when the amount loaded was the same. One explanation invokes a coupling mechanism promoted by the carbon surface, which results in either additional blockage of TCE sorption sites, additional site competition, or both. In all experiments, the effects of preloading were consistent with those reported previously, which have been interpreted as a loss of high-energy sites available to TCE, causing a significant reduction in the site-energy heterogeneity, and reduced uptake in the low concentration region.     

Uncoupled state space solution to layered poroelastic medium with anisotropic permeability and compressible pore fluid

This paper presents an uncoupled state space solution to three-dimensional consolidation of layered poroelastic medium with anisotropic permeability and compressible pore fluid. Starting from the basic equations of poroelastic medium, and introducing intermediate variables, the state space equation usually comprising eight coupled state vectors is uncoupled into two sets of equations of six and two state vectors in the Laplace-Fourier transform domain. Combined with the continuity conditions between adjacent layers and boundary conditions, the uncoupled state space solution of a layered poroelastic medium is obtained by using the transfer matrix method. Numerical results show that the anisotropy of permeability and the compressibility of pore fluid have remarkable influence on the consolidation behavior of poroelastic medium.     

物质常温自燃火灾危险性评价方法研究

利用DTA、DSC以及C80微量量热仪和TAM air绝热微量热仪,对典型自燃火灾物证样品(浸油脂棉纱和50万单位的棕榈酸酯维A粉)在环境温度条件下放热性能分别进行实验测试与分析,对化学性物质热自燃危险性的评价方法进行初步探索。研究结果表明:采用高灵敏度C80微量量热仪和TAM air绝热微量热仪,对热不稳定性物质低温常温的恒温热解特性进行测试,对热不稳定性物质的稳定性和自燃火灾危险性进行评价,可以更为准确地确定热不稳定性物质发生自燃火灾的条件以及安全储运的温度条件。     

The inhibition effects of several inhibitors on rebar in acidified concrete pore solution

The inhibitive effects of several inhibitors for carbon steel in acidified pore solution (pH 8.0) were studied. Sodium molybdate shows good effect to promote passivation at low concentrations (0.013 wt.%), but for sodium tungstate and sodium nitrite higher concentration (0.045 wt.%) is needed to obtain passivation. Sodium phytate only shows minor inhibitive effects at the concentration level of 0.045 wt.%. At higher concentration level (0.045% ? wt.% ? 2%), the inhibitors sodium molybdate, sodium tungstate and sodium nitrite behave well in the acidified pore solution. For sodium phytate, to obtain obvious inhibition the inhibitor concentration must be above 0.5 wt.%. Molybdate and tungstate are present on the steel surface according to Raman spectrum analysis, which supports the adsorption mechanism of the inhibitors.     

砂桩加固液化砂土振动台试验中的孔隙水压力

以砂桩加固液化砂土的振动台试验为基础,通过测试加固与未加固模型土、同一桩距不同桩长下加固液化砂土的孔隙水压力,试验得出,未加固模型土埋深较浅的土层易液化,液化持续的时间较长,并随着深度的增加,液化程度有减小的趋势.     

Determination of safe mud window considering time-dependent variations of temperature and pore pressure:Analytical and numerical approaches

Wellbore stability is a key to have a successful drilling operation.Induced stresses are the main factors affecting wellbore instability and associated problems in drilling operations.These stresses are significantly impacted by pore pressure variation and thermal stresses in the field.In order to address wellbore instability problems,it is important to investigate the mechanisms of rockefluid interaction with respect to thermal and mechanical aspects.In order to understand the induced stresses,different mathematical models have been developed.In this study,the field equations governing the problem have been derived based on the thermo-poroelastic theory and solved analytically in Laplace domain.The results are transferred to time domain using Fourier inverse method.Finite difference method is also utilized to validate the results.Pore pressure and temperature distributions around the wellbore have been focused and simulated.Next,induced radial and tangential stresses for different cases of cooling and heating of formation are compared.In addition,the differences between thermo-poroelastic and poroelastic models in situation of permeable and impermeable wellbores are described.It is observed that cooling and pore pressure distribution reinforce the induced radial stress.Whereas cooling can be a tool to control and reduce tangential stress induced due to invasion of drilling fluid.In the next step,safe mud window is obtained using Mohr-Coulomb,Mogi-Coulomb,and modified Lade failure criteria for different inclinations.Temperature and pore pressure distributions do not change the minimum allowable wellbore pressure significantly.However,upper limit of mud window is sensitive to induced stresses and it seems vital to consider changes in temperature and pore pressure to avoid any failures.The widest and narrowest mud windows are proposed by modified Lade and Mohr-Coulomb failure criteria,respectively.     

AM常温原位聚合固化盐渍土的力学性能研究

本文探讨了常温下丙烯酰胺单体(AM)、过氧还原体系引发剂(过硫酸铵-过硫酸氢钠)、交联剂(N-N亚甲基双丙烯酰胺)的用量对盐渍土土坯力学性能的影响,得出了丙烯酰胺常温原位聚合的最佳反应条件,从而达到加固改性盐渍土的目的。1在室温下,丙烯酰胺单体用量为盐渍土用量的3%,引发剂用量为丙烯酰胺用量的2%,引发剂体系过硫酸铵-过硫酸氢钠质量比为1∶1,交联剂用量为丙烯酰胺用量的1%,土坯养护28 d后,抗折强度达到5.2 MPa,抗压强度达到16.3 MPa。2和空白土坯试样的力学性能对比,AM常温原位聚合改性后的土坯试样的抗折强度和抗压强度是原来的4~5倍。     

Neurobehavioral approach for evaluation of office workers' productivity: The effects of room temperature

Indoor environment quality has great influence on worker's productivity, and how to assess the effect of indoor environment on productivity remains to be the major challenge. A neurobehavioral approach was proposed for evaluation of office workers' productivity in this paper. The distinguishing characteristic of neurobehavioral approach is its emphasis on the identification and measurement of behavioral changes, for the influence of environment on brain functions manifests behaviorally. Therefore worker's productivity can be comprehensively evaluated by testing the neurobehavioral functions. Four neurobehavioral functions, including perception, learning and memory, thinking, and executive functions were measured with nine representative psychometric tests. The effect of room temperature on performance of neurobehavioral tests was investigated in the laboratory. Four temperatures (19 °C, 24 °C, 27 °C, and 32 °C) were investigated based on the thermal sensation from cold to hot. Signal detection theory was utilized to analyze response bias. It was found that motivated people could maintain high performance for a short time under adverse (hot or cold) environmental conditions. Room temperature affected task performance differentially, depending on the type of tasks. The proposed neurobehavioral approach could be worked to quantitatively and systematically evaluate office workers' productivity.     

火灾对机舱舱壁温度影响研究

采用FDS对舰船动力机舱进行火灾模拟。分不同热释放速率、进风口位置及火源位置设5种情况模拟,分析对机舱舱壁温度分布的影响规律。火源正上方顶部温度升高迅速,应注意结构强度。进风口设置在下部易于为火源提供氧气,不建议采用。进风口设置在顶部时高温烟气不易聚集,有助于降低壁面温度。     

Behaviour of single-sided composite joints at room temperature and in case of fire after an earthquake

In 2003, a European research program entitled “PRECIOUS-Prefabricated composite beam-to-concrete filled tube or partially reinforced-concrete-encased column connections for severe seismic and fire loadings” and funded by the Research Fund for Coal and Steel (RFCS) was initiated for three years (Bursi et al., 2008). The objective of this project was to develop fundamental data, design guidelines and prequalification tools for two types of composite beam-to-column joints able to ensure a suitable behaviour during an earthquake and its eventual subsequent fire. At the University of Liege, as part of this project, analytical and numerical investigations were conducted mainly on single-sided beam-to-column composite joints at room and at elevated temperatures. The present paper summarizes the activities developed within this project and presents the main achievements.     

唐山市泵送混凝土常温下强度增长规律的试验

针对泵送混凝土的强度作为衡量一个建筑物质量指标的重要性,从混凝土绝对龄期方面对标准养护试块强度和同条件养护试块强度做了分析比较,从而得出混凝土强度增长规律及二者之间的折算系数.     

空气压力对人体皮肤温度及热感觉影响的实验研究

以问卷调查的方式,对低压环境下人体皮肤温度随空气压力的变化及其对人体热感觉的影响进行了研究.结果表明,在其他环境参数一定的条件下,人体平均皮肤温度和人体热感觉均随压力降低而降低,且二者变化趋势基本一致.经过统计学分析可知,二者在低压环境下具有较好的相关性,因此在低压环境下皮肤温度可作为表征人体热感觉的一个重要指标.     

环境温度监控系统在泉三高速公路无人机房的应用

在使用计算机进行网络互联的同时,各种家电设备、仪器仪表以及工业生产中的数据采集与控制设备在逐步地走向网络化。利用廉价的51单片机、温度传感器和以太网控制器来实现高速公路无人机房环境温度的监控是有较大意义的。     

Regeneration of ortho-chlorophenol-exhausted activated carbons with liquid water at high pressure and temperature

A study was undertaken of the regeneration of three activated carbons exhausted with ortho-chlorophenol. The regeneration process was carried out using liquid water at 623 K and 150 atm in the absence of oxygen. The efficiency of this procedure was analyzed by determining the rate and amount of ortho-chlorophenol adsorbed in successive adsorption-regeneration cycles. The present procedure showed a much greater efficiency than that reported for chemical and/or thermal regeneration. Effects of this regeneration on the adsorption kinetics, adsorption capacity and textural characteristics of the carbon were investigated. The increase in adsorption capacity of the regenerated carbon compared with that of the original carbon seems mainly due to the opening of porosity during the regeneration treatment.     

静压桩施工超孔隙水压力监测及控制

分析了静压桩施工过程中超孔隙水压力的产生机理,介绍了孔隙水压力测试的监测范围和超孔隙水压力监测方法,并具体阐述了超孔隙水压力的控制措施,以期指导实践,保障静压桩施工安全。     

Single-sided natural ventilation driven by wind pressure and temperature difference

Even though opening a window for ventilation of a room seems very simple, the flow that occurs in this situation is rather complicated. The amount of air going through the window opening will depend on the wind speed near the building, the temperatures inside and outside the room, the wind direction, the turbulence characteristics in the wind and the pressure variations caused by e.g. wind gusts. Finally, it also depends on the size, type and location of the opening. Many of these parameters are unsteady which makes the calculation of air-change rates even more complicated. In this work, full-scale wind tunnel experiments have been made with the aim of making a new expression for calculation of the airflow rate in single-sided natural ventilation. During the wind tunnel experiments it was found that the dominating driving force differs between wind speed and temperature difference depending on the ratio between the forces and the wind direction. This change is also found in the velocity profiles measured in the opening, which might change from wind dominated to temperature dominated under the same wind direction but with increasing temperature difference.