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1.
为了解决寒区沥青路面低温开裂现象,设计适用于寒冷地区应用的新型沥青混合料.基于小梁弯曲试验获取基质沥青、沥青胶浆、沥青细料组合体低温应力-应变曲线,以弯曲应变能密度临界值评价上述3类结合材料的低温抗裂性能.掺配不同粒径的胶粉颗粒使之与AC-13混合料中的细矿料级配一致,并替换50%,的常规细矿料从而制备寒区高性能沥青混合料.通过车辙试验、小梁弯曲试验、冻融劈裂试验对其路用性能进行评价.结果表明常规沥青细料组合体极差的低温抗裂能力是寒区沥青混合料低温开裂的重要原因.以同级配的胶粉颗粒体替代50%,的常规细矿料后,沥青混合料的路用性能得到明显改善,其低温抗裂性能、水稳定性能有较大提高,但其高温稳定性能略有降低.该项研究为后续寒区沥青路面的设计及施工奠定理论基础.  相似文献   

2.
采用常规低温性能试验和Superpave低温性能试验,研究了不同类型多聚磷酸(PPA)改性沥青胶结料的低温性能,对比分析了沥青胶结料低温性能评价指标之间的相应关系,并采用小梁弯曲试验和冻断试验验证了沥青混合料的低温抗裂性能,研究了沥青胶结料与混合料低温性能之间的相关性.最后对不同低温性能评价指标的合理性和不足之处进行了较为深入的分析.结果表明,PPA掺入减小了沥青的延度和劲度模量,老化对PPA改性沥青低温性能的影响显著;应变能密度指标表明PPA可以改善沥青混合料低温抗裂性;PPA复配SBR的改性沥青低温效果要优于SBR改性沥青;冻断温度与冻断强度能较准确地评价多聚磷酸改性沥青混合料的低温抗裂性能.  相似文献   

3.
矿料级配对沥青混合料低温性能的影响   总被引:17,自引:3,他引:17  
为了研究级配对沥青混合料低温性能的影响,探讨沥青混合料低温性能评价方法,借鉴SHRP和贝雷法级配初拟几种级配,对其低温性能进行了试验研究和比较,并推荐了低温性能好的级配。在分析沥青路面低温开裂机理和分析试验结果的基础上,提出了沥青混合料低温性能的合理评价方法,认为沥青混合料低温收缩性和低温柔性是反映沥青路面低温抗裂性能的2个方面,小的收缩性和高的低温柔性使沥青混合料具有较高的抗低温开裂的潜能;应综合收缩系数和低温破坏应变2个指标评价沥青混合料低温性能。  相似文献   

4.
沥青混合料低温抗裂性评价方法研究   总被引:16,自引:0,他引:16  
一般评价沥青混合料低温抗开裂性能可从两方面进行,一方面看其在低温下的变形能力;另一方面看其在低温断裂时所能承受的断裂拉力的大小,但以往多以其变形能力这一单一指标来衡量沥青混合料的抗开裂能力是不全面的,为此从如何综合反应沥青混合料断裂时的应力,应变大小的角度出发,提出了评价沥青混合料低温抗开裂性能的压缩应变能指标及计算方法,并对两种改性沥青混合料进行了冻断试验和压缩应变性能试验,比较了它们的试验结果。  相似文献   

5.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

6.
通过间接拉伸开裂(IDEAL-CT)试验方法,研究了不同级配及油石比条件下超薄磨耗层混合料的抗裂性能。结果显示,级配变密会导致混合料整体强度上升,抗变形能力下降,同时会加快裂缝扩展速度,混合料抗裂性能下降。油石比的增加会使混合料抗变形能力提升,延缓裂缝扩展速度,使得混合料抗裂性能增强。皮尔逊相关性分析结果表明,随着超薄磨耗层混合料的孔隙率和沥青膜厚度的增加,混合料整体强度降低,抗变形能力提升,裂缝开裂速度下降,混合料整体抗裂性能增强,因而超薄磨耗层混合料设计过程中可通过提升孔隙率和沥青膜厚度来增强混合料的抗裂性能。对于IDEAL-CT试验指标,断裂能不适用于评价超薄磨耗层混合料抗裂性能。  相似文献   

7.
为了研究厂拌热再生SBS改性沥青混合料的抗裂性能,采用半圆弯拉试验,通过断裂能分析中低温条件下旧料掺量、再生剂掺量对再生沥青混合料抗裂性能的影响;同时借助数字散斑技术,对半圆弯拉试验加载全过程中试件表面图像进行散斑处理,对其裂缝尖端水平应变场信息以及裂缝扩展特征进行评价,对比分析水平应变-时间曲线的变化规律;并研究长期老化和冻融循环作用对再生沥青混合料抗裂性能的衰减特性。研究结果表明:中低温条件下,再生沥青混合料的抗裂性能随旧料掺量的增加呈二次多项式递减,使用再生剂无法改变这种递减关系,但有助于减缓其劣化趋势,当旧料掺量(质量分数,下同)小于30%时,再生沥青混合料抗裂性能接近新拌改性沥青混合料,但抗老化性能较差;再生沥青混合料砂浆易形成受力薄弱界面,再生剂可延长其开裂时间,并提高裂尖水平应变峰值,尤其对于大比例废旧SBS改性沥青混合料(RAP-SBS)再生改善效果更明显;影响再生沥青混合料低温抗裂性能的各因素依次为温度、旧料掺量、长期老化,其中温度的影响最显著;再生沥青混合料低温抗裂性能对冻融循环次数的敏感度随旧料掺量的增加而增大,指数模型可以较好表征再生沥青混合料低温抗裂性能随冻融循环次数的衰减状况,其损伤程度随冻融次数的增加大致分为快速损伤期和稳定损伤期2个阶段。  相似文献   

8.
为了确保沥青路面在低温下的抗裂稳定性,就必须用实验方法来评定它在低温条件下的性能,然而到目前为止仍未有统一方法,因此尽快找到一种科学而又实际的评价指标,对于沥青路面低温缩裂问题的解决有着深远的意义.以沥青混合料低温抗裂性评价指标作为研究对象,在分析目前一些评价方法的基础上,通过对不同品种沥青混合料试验结果进行分析总结,发现沥青混合料的低温压缩应变能指标,更能反映不同沥青混合料的低温性能;对于低温蠕变试验,采用0℃、10%破坏荷载应力水平更适用于不同沥青混合料,利用0℃压缩应变能作为沥青混合料低温抗裂性能评价指标,方法简便易于推广.  相似文献   

9.
纤维加筋沥青混凝土断裂性能试验   总被引:1,自引:1,他引:1  
应用断裂潜能和临界应力强度因子KIC的概念,研究了在开裂的沥青路面上加铺沥青面层时的抗裂性能,分析了玻璃纤维加筋沥青混凝土(GFRAC)、普通沥青混凝土以及抗滑面层的开裂行为。采用马歇尔试验与3点弯曲试验,选取有预切缝和无切缝两种试件进行试验,利用断裂潜能的概念评估沥青混凝土抑制裂缝产生的能力,并且测定了材料的临界应力强度因子。研究表明,加入玻璃纤维能有效地提高沥青混合料稳定度,改善沥青混凝土的高温抗变形能力。  相似文献   

10.
应力吸收层沥青混合料的路用特性   总被引:1,自引:0,他引:1  
通过对自主研发的Sampave特种改性沥青的应力吸收层混合料进行低温弯曲试验,分析沥青结合料对应力吸收层沥青混合料低温抗裂性能的影响;采用拉伸与拉压疲劳试验,比较不同沥青结合料的应力吸收层混合料抗拉伸变形与抗拉压疲劳性能.结果表明,研发的Sampave特种改性沥青混合料具有优良的低温抗裂、抗拉伸和抗拉压疲劳性能,但单一改性剂SBR改性沥青并不能达到应力吸收层沥青结合料的性能要求.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

16.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

17.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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