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11.
The objective of this project was to characterize the freeze-thaw properties of recycled concrete (RCA) and asphalt (RAP) as unbound base and to assess how they behaved in the field for nearly 8 years. This paper includes an examination of existing information, laboratory studies of freeze-thaw behavior, and evaluation of data from MnROAD field-test sections in a seasonally cold region, i.e., in Minnesota, USA. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. One test section included 100% RAP, another 100% RCA, a third one a 50/50 blend of RCA/natural aggregate, and a fourth one only natural aggregate (Class 5) as a control. The stiffness (i.e., elastic modulus) was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation, along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance. The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a, as well as by field-scale tests incorporating a falling-weight deflectometer. Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory, and the change in their resilient modulus was measured. In the field-test sections constructed with the same materials as the base course, temperature, moisture, and field modulus (from falling-weight deflectometer tests) were monitored seasonally for nearly 8 years. From the temperatures in the base course layer, the number of freeze-thaw cycles experienced in the field was determined for each test section. Inferences were made relative to modulus change versus freeze-thaw cycles. Conclusions were drawn for long-term field performances of the recycled base (RAB) in comparison to natural aggregate. 相似文献
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在羌塘盆地已经发现了190余处油气显示。近年笔者在盆地北部晚侏罗世地层中发现了迄今最大规模的沥青脉。研究结果表明，该沥青脉产出于上侏罗统索瓦组地层之中，地层下部系与沥青脉的形成有一定关系的中株罗统夏里组局部含油气显示的盐丘。沥青族组分(％)为：饱和烃5．72、芳烃18．46、沥青质52.37、非烃23．45，说明核沥青脉经过了运移、氮化的过程。同时，沥青脉产出于复背斜范围内，利于油气聚集成藏。这一发现对于羌塘盆地的油气地质的作用具有现实意义。 相似文献
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塔中地区志留系沥青砂岩成岩作用及其对储层性质的影响 总被引：5，自引：0，他引：5
运用沉积学原理对塔中地区志留系经历复杂成岩演化的沥青砂岩进行研究分析,了解到该岩石主要经过压实作用、胶结作用和溶蚀作用等成岩作用。其胶结物的主要类型有绿泥石、伊利石、高岭石、伊-蒙混层等粘土矿物以及碳酸盐矿物、石英、长石、黄铁矿等。孔隙类型以粒间孔隙、粒内孔、铸模孔、特大孔、裂缝孔隙等为主,其中以粒间孔隙最为发育,低地温梯度有利于在深层形成次生孔隙。志留系沥青砂岩储层物性受沉积和成岩双重因素的影响,成岩演化阶段处于晚成岩A期。根据影响储层物性的储层成岩作用,可将成岩相类型划分为不稳定碎屑溶蚀成岩相、压实-弱溶蚀成岩相、压实充填成岩相、压实压溶成岩相、碳酸盐胶结成岩相等几种主要类型,成岩相类型决定了储层性质,不稳定碎屑溶蚀成岩相和压实-弱溶蚀成岩相是本区较好的油气储层。 相似文献
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ZHAO Wenzhi WANG Zhaoyun HE Haiqing ZHANG Mingjie WANG Hongjun WANG Yunpeng & QIN Yong . Research Institute of Petroleum Exploration & Development PetroChina Beijing China . PetroChina Exploration & Production Beijing China . Department of Geology Lanzhou University Lanzhou China . Guangzhou Geochemical Institute Chinese Academy of Sciences Guangzhou China . China University of Mining Technology Xuzhou China 《中国科学D辑(英文版)》2005,48(4):441-453
It has been proven in exploration practice that thecarbonates in China not only can generate hydrocar-bons, but also form commercial reservoirs. The car-bonates are different from clastic rocks in view of theirdeposition environment as well as their sedimentaryand diagenetic processes. Therefore, the evaluationcriteria and hydrocarbon generation mechanism forcarbonates can not be the same as that for clasticrocks, and it is important to establish a special hydro-carbon generation mechanism and… 相似文献
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This article presents the development of a J2 small strain plasticity model based on bounding surface concept, along with numerical examples to demonstrate model behaviors and identification of model parameter using laboratory test data. The model is motivated by the need for simulating permanent deformation accumulation of asphalt concrete mixtures, which leads to rutting in flexible pavements under repeated traffic loading. The proposed model accounts for the observation that rutting is mostly caused by shearing and takes advantage of the fact that bounding surface concept allows for the progressive accumulation of plastic deformation under constant amplitude loading condition. Analytical solutions are given for typical laboratory testing conditions. The model can be calibrated using repeated simple shear test data that are typically available for asphalt concrete mixtures. It is shown that the model is easy to use and provides a promising alternative for modeling permanent deformation accumulation in materials subjected to repetitive (cyclic) loading. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Eyal Levenberg 《国际地质力学数值与分析法杂志》2013,37(9):1016-1033
The paper deals with inferring the mechanical layer properties of pavement systems by way of inverse analysis. The proposed scheme is based on the availability of sensory gear embedded within the system ‐ collecting different types of response traces resulting from moving wheel loads. The inverse analysis task simultaneously exploits the readings from all available sensors and therefore formulated as a multicriterion optimization problem. Data from an experimental asphalt pavement are employed to demonstrate the scheme. A versatile and computationally efficient layered viscoelastic pavement model is offered and implemented as a forward solver. Recoverable layer properties, elastic and viscoelastic, are derived and also compared with laboratory values. Results and possible future uses of the work are discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The deleterious effect of moisture in the microstructure of asphalt mixtures, usually referred to as moisture damage, has been recognized as a main cause of early deterioration of asphalt pavements. The initiation and evolution of moisture‐related deterioration is strongly influenced by the internal air void structure of asphalt mixtures. Despite its importance, the majority of works conducted on the micromechanical modeling of asphalt mixtures overlook the role of the air void structure, mainly because of its high complexity and variability. This paper explores the influence of air void variability on the performance of asphalt mixtures subjected to moisture diffusion processes. A stochastic modeling technique based on random field theory was used to generate internal distributions of physical and mechanical properties of the asphalt matrix of the mixture that depend on probable air voids distributions. The analysis was conducted by means of a coupled numerical micromechanical model of moisture damage. The results showed that the variability and distribution of air voids are decisive in determining the moisture‐dependent performance of asphalt mixtures. Furthermore, it was also shown that a stochastic characterization of the diverse air void configurations is a feasible and useful approach to better represent and understand mechanically related deterioration processes in asphalt mixtures. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献