某地源热泵场地浅层土壤分层热物性响应实验

浅层土壤导热系数的确定一直是地源热泵系统设计研究中的一个重点。为了获得更精确的土壤热物性,引入分布式光纤测温系统,并在原有柱热源测试模型方法的基础上提出分层热物性测试法并对测试数据进行分析。测试数据包括竖直方向上浅层土壤初始温度分布,稳定功率加热过程中竖直方向地埋管内流体温度随时间变化分布。结果表明:通过分层土壤热物性测试可以更直观地观察地下土壤温度分布,了解土壤中地下水分布情况。并得出竖直方向上不同深度土壤的导热系数、土壤密度与比热容乘积以及回填料热阻分布情况。

分层热物性测试在热泵工程的应用分析

以工程场地测试孔内岩土体垂直分布的热物性参数为研究对象。在传统热物性测试仪器中加入分布式光纤测温系统，进行岩土体初温测试和热物性测试，测定不同深度岩土体初温和加热试验中不同深度循环流体平均温度，并与传统测试结果进行对比分析。结果显示，分层热物性测试结果较为准确，可分析岩土体垂直方向温度分布，进而得出地埋管换热器在垂直方向上导热系数和传热系数。

基于热响应试验地埋管分层热物性研究

以浅层土壤源热泵工程试验孔岩土换热条件下热物性测试为背景,在试验孔内分层布设测温装置,通过孔内原始温度场监测,进行热响应过程温度场及干扰后温度场恢复状态数据记录,研究土壤源热泵系统热响应过程温度场变化规律,供运行期地温场变化分析参考。结合室内岩土热物性试验,通过现场岩土体热响应试验,运用传热学不同计算方法,对浅层土壤源热泵系统分层岩土体热物性参数计算分析,对比得出分层热物性测试参数值较为可靠,为优化设计提供理论依据。

Vertical distributions of VOCs in the Tibetan Plateau background region

Exploring the vertical variation in volatile organic compounds(VOCs)in background regions can provide infor-mation on the spatial distribution of pollutants,providing a scientific basis for atmospheric pollution prevention and control strategies.From 15 August to 5 September 2023,at the Southeast Tibet Mountain Comprehensive Environmental Observation Station(SETS),a tethered balloon was used to sample VOCs every 100 m from the ground to 1000 m.A total of 403 air bag samples were collected,and 39 vertical profiles of VOCs were obtained.Ninety-two VOC species were detected.The VOC concentration at the SETS did not change significantly verti-cally,and the average VOC concentration was 11.1±2.4 ppbv.The main components were alkanes(51.4%),alkenes(18.7%),and halohydrocarbons(18.1%).There was no obvious diurnal change in VOCs and no signif-icant difference between the different layers.When the surface VOC concentration was less than 10 ppbv,the concentrations,components,and sources of VOCs were evenly distributed vertically,and the main sources of VOCs at different heights were vehicle exhaust and background.When the surface VOC concentration exceeded 10 ppbv,the VOC concentration gradually decreased with height.The proportion of alkanes in surface VOCs in-creased,and the source was mainly vehicle exhaust.This study confirmed that VOCs are vertically homogeneous in the background of the Tibetan Plateau,emphasizing the importance of vehicle emissions as a potential source of VOCs.

综合物探技术在第四系地层勘察中的应用

第四系地层作为各类建筑物(构筑物)基础的主要持力层,对工程造价影响较大,第四系地层埋深剧烈变化或侵入风化基岩中极大地增加了施工风险。在分析铁路不同工点类型的勘察要求及难点的基础上,开展物探方法适用性研究,建立第四系地层综合勘察原则;确定了黏土、砂土、碎石土的承载力和压缩模量计算公式;针对任务需求,建立了桥址、浅埋隧道、路基的勘察成果模式。通过大量钻孔的比对表明,以物探为主的第四系地层综合物探勘察可满足勘察精度,以物探参数获取的岩土力学参数对设计具有较强的指导意义。

断块油藏剩余油分布研究──明一西块调整效果

针对油藏构造复杂，砂体发育不稳定的地质特征，注水开发时间长，采出程度较高，剩余油分布零散的开发现状，加强了基础地质研究，重新落实，组合断点，对区块构造再认识，在此基础上，综合参考多种资料，运用油藏工程方法，开展剩余油分布定量化研究，指出了油藏的调整挖潜方向，不仅使区块增传稳产，而且也为同类型油藏开发提供了可贵经验。

Clay mineral expansion of black cotton soil based on interlayer cation hydration

To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.

Numerical analysis of elastic coated solids in line contact

A line contact model of elastic coated solids is presented based on the influence coefficients(ICs) of surface displacement and stresses of coating-substrate system and the traditional contact model. The ICs of displacement and stresses are obtained from their corresponding frequency response functions(FRF) by using a conversion method based on fast Fourier transformation(FFT). The contact pressure and the stress field in the subsurface are obtained by employing conjugate gradient method(CGM) and discrete convolution fast Fourier transformation(DC-FFT). Comparison of the contact pressure and subsurface stresses obtained by the numerical method with the exact analytical solutions for Hertz contact is conducted, and the results show that the numerical solution has a very high accuracy and verify the validity of the contact model. The effect of the stiffness and thickness of coatings is further numerically studied. The result shows that the effects on contact pressure and contact width are opposite for hard and soft coatings and are intensified with the increase of coating thickness; the locations of crack initiation and propagation are different for soft and hard coatings; the risk of cracks and delaminations of coatings can be brought down by improving the lubrication condition or optimizing the non-dimensional parameter h/bh. This research offers a tool to numerically analyze the problem of elastic coated solids in line contact and make the blindness and randomness of trial-type coating design less.

A Hierarchic Method for Studying the Distribution of Phenanthrene in Eisenia fetida

The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals.However, little information is available on the distribution of hydrophobic organic contaminants(HOCs) within earthworms. The aim of this study was to propose a hierarchic method to study the distribution of phenanthrene(PHE), a typical HOC, in Eisenia fetida at several levels: sub-organism(pre-clitellum, clitellum and post-clitellum), tissue(body wall, gut and body fluid) and subcellular(intracellular and extracellular fractions). Earthworms were incubated in the soils amended with low(LC, 10 mg kg-1) and high concentrations(HC, 50 mg kg-1) of PHE and sampled at different time intervals. At the sub-organism level, the distribution of PHE was homogeneous among the sub-organism fractions in the LC treatment but heterogeneous in the HC treatment and gradually reached the following form of post-clitellum ≈ clitellum > pre-clitellum. The uptake and elimination kinetics of PHE in the sub-organism were well described by a one-compartment model. At the tissue level, the concentration of PHE followed the order of gut > body fluid >body wall; while at the subcellular level, the concentration of PHE in the extracellular fraction was 1.23 to 4.68 times higher than that in the intracellular fraction. Therefore, the simple circulatory system of earthworms may account for the PHE distribution at the sub-organism level. Partition pathways(passive diffusion) of PHE between the body wall, body fluid and gut as well as the processes of PHE entrance into the inner cellular compartment via passive diffusion were experimentally supported.