【作者】 陈亮亮；

【导师】 冯德成；

【作者基本信息】 哈尔滨工业大学 ， 道路与铁道工程， 2010， 硕士

【摘要】 水泥稳定砂砾作为路面基层,在我国各地都有着广泛的使用。水泥稳定砂砾的压实度是水泥稳定砂砾施工必须做到的一个重要技术指标。通常的做法是通过室内试验,在标准击实功(一般为重型击实)的作用下得到混合材料的最大干密度与最佳含水量,并以此作为评定施工现场压实度的标准。对于水泥稳定砂砾材料最大干密度的确定方法是按照《公路无机结合料稳定材料试验规程》(JTG E51-2009)规定的重型击实的方法来确定,由于砂砾很难得到类似粘土的击实曲线,进而来确定密度与最佳含水量。在采用重型击实的方法对水泥稳定砂砾进行击实时,干密度在一定凡范围内随加水量的增大而增大,不存在最佳含水量的概念。同样使用哈工大第三代振动击实仪对水泥稳定砂砾进行击实试验,得到的结果与重型击实的结果相近,干密度依然随加水量的增大而增大。当砂砾饱和之后,击实之后试样当中的含水量比较稳定。为解释砂砾材料的击实特性,本文系统分析了砂砾材料的矿物组成、颗粒组成、水与颗粒之间的相互作用、砂砾材料的透水性对击实特性的影响。砂砾材料的当中的矿物成分主要是石英、长石等原生矿物,自身硬度大,击实功作用下不存在土土颗粒的压缩;黑龙江省北黑高速所用的五种砂砾的筛分试验结果表明:砂砾材料当中95%以上都是粗粒(0.075mm以上),而起到粘聚作用的粉粒与粘粒成分很少,因此砂砾和粘土具有不同的击实特性。结合文献说明砂砾材料自身粗颗粒含量多,呈透水性,其渗透系数要远远大于粘土;砂砾材料当中毛细压力随材料颗粒粒径的增大与材料饱和度的增大都在减小。说明了在饱水状态下砂砾材料中,击实功作用下,水分起到润滑作用而不会产生大的孔隙压力,同时毛细压力对击实功的影响降到最低,因而饱水状态为砂砾材料的最佳击实状态。在明确砂砾击实成型的机理与最佳击实状态的基础上,提出了水泥稳定砂砾最大干密度的确定方法——“饱水振动+水泥填充修正”的方法。在水泥浆填充集料之间的空隙,而不改变击实之后试样体积的前提下,试样的干密度增大。通过在实体工程配合比设计与现场压实度的检验的实践,证明该方法简便实用,结果稳定可靠,解决了公路试验工作者水泥稳定砂砾击实试验中得不到“凸型”曲线,修饰试验数据以满足规范规定要求的难题。通过工地现场基层压实度的检验证明,本文建立的方法所确定的干密度更适合作为当前重型压路机与振动压路机具施工水平下基层压实度的控制指标。更多还原

【Abstract】 Cement stabilized sand gravel (CSSG)is widely paved as the base course in China. The mix must reach a certain degree of compaction, and the compactness is one of the most important requirements. Generally, Modified Proctor Compaction Test (MDCT) is used to get the maximum dry density (MDD) and optimum water content, the former is used as the standard to evaluate the degree of compaction in construction field.The method to determine the maximum dry density is according to The Methods of Materials Stabilized with Inorganic Binders for Highway Engineering (JTG E51-2009).For sand gravel, it is difficult to get the similar compaction curves as clay which can be used to determine the maximum dry density and optimum moisture content. When doing the MDCT, the MDD increased with the amount of water added to the mix,and the vibrating compaction tests done by the 3rd -Generation Vibrating Compactor shows the similar result done by MDCT, and the moisture content of the compacted saturated samples is stable.In order to explain the compaction property, the paper do analyses as follows:the mineral constituent of the sand gravel , grain composition、the interaction between water and grain、the permeability’s influence on compaction property. The main minerals of the sand gravel are quartz, feldspar etc, which are difficult to deform during compaction. Meanwhile, the content of the fines that make the material cohesive is very small, according to the sieving test results of the 5 kinds of sand gravel used in Bei(an)Hei(he) expressway construction, almost 95 percent of sand gravel is coarse grain (larger than 0.075mm),it makes the sand gravel have the different compaction property compared with clay soil.According to the relevant reference ,for sand gravel having high content of coarse grain, the permeability parameter is 100 thousand times of clay soil; the capillary pressure decrease with both the grain diameter’s augmentation and saturation aggrandizement. When the sand gravel is under saturation condition, the water lubricates the grain surface without high pore water pressure for the good permeability of sand gravel. To sum up, the saturation condition is defined as the best compaction condition for sand gravel.On the basis of understanding the compaction property of sand gravel and the best compaction condition, the paper establish a new method to determine cement stabilized sand grave’s maximum dry density——“Saturated Sand Gravel Compaction”+”Cement Filling Correction”. The cement slurry fills the void between the aggregate grain, without changing the volume of compacted samples, therefore the dry density of CSSG increases. When the method is applied in the mix design ,it shows that the method is not only accurate but also easy to use. The method solve the problems that confuses the highway tester personal ,which make them cannot but fabricate data in order to get the appointed compaction curves. The maximum dry density determined by the method is more applicable to control the degree of compaction and it is better suited the current construction technology and vibrating roller’s application.更多还原