高温高压下凝析气压缩因子计算方法的对比

高温、高压凝析气由于重组分的存在,临界参数偏差较大,导致其压缩因子的计算精度较低.以状态方程和经验关联式为基础,结合SSBV以及WA校正方法对SRK、DPR、DAK、HY、Cranmer 5种模型计算精度进行对比分析.研究结果表明:SRK状态方程在计算轻质气体时,误差最小,适应性最好.随着C7+含量及压力的不断增大,经验关联式DPR、DAK、HY和Cranmer模型通过与SSBV与WA校正方法结合,适应性增强,优于SRK状态方程,相对而言,DAK方法和DPR方法误差分布更加稳定.但是由于考察范围有限,因此研究方法相较研究结论更有意义,为凝析气压缩因子的计算提供了新的研究思路.     

含水率和压缩频率对秸秆开式压缩能耗的影响

为了减少生物质秸秆压缩能耗,优化压缩工艺,以小麦秸秆（品种：农大211）,玉米秸秆（品种：农大108）为研究对象,模拟生物质秸秆压缩成型实际工况,利用INSTRON 3367材料试验机和自制压缩筒组件进行了“开式”压缩试验,研究了含水率分别为15%、35%和55%的小麦秸秆以及25%、45%和65%的玉米秸秆在3个不同压缩频率0.5、0.75和1次/min下的成型压缩比能耗。结果表明：小麦秸秆在含水率55%和压缩频率0.5次/min时压缩比能耗最小;玉米秸秆在含水率65%和压缩频率为0.5次/min时压缩比能耗最小。统计结果表明,秸秆压缩比能耗随着含水率的增高和压缩频率的降低而减少;含水率和压缩频率对压缩比能耗影响均显著。     

温度对揉碎柠条可压缩性的影响

揉碎柠条的可压缩性对其压缩设备的设计和压缩生产工艺的选择有重要影响。该文通过对揉碎柠条在22～140℃范围内4个不同温度下的压缩试验,建立了柠条在压缩过程中压力与体积应变、压力与压缩密度以及体积模量与压缩密度的数学模型,获得了温度对揉碎柠条可压缩性的影响规律。研究结果表明：揉碎柠条在压缩过程中存在松散、过渡和压紧3个阶段,在松散阶段可压缩性较好,过渡阶段可压缩性逐渐降低,压紧阶段可压缩性迅速降低。同时,柠条的可压缩性与温度有关,在所选温度范围内,可压缩性随温度的升高而提高;且随压缩密度的增加,温度对其可压缩性的影响逐渐增强。研究结果为柠条压缩设备的设计及其加工工艺的合理选择提供了参考。     

基于气体溶解与油液可压缩性的油气悬架性能研究

基于气体溶解效应和油液可压缩性建立了矿用自卸车使用的混合式油气悬架的非线性数学模型.通过求解非线性数学模型方程组,分析了油气悬架中气体溶解和油液可压缩性对系统内部压力变化的影响,并与试验结果进行了对比分析.结果表明建立的模型能较准确地描述油气悬架的输出力特性,而且气体溶解效应和油液可压缩性在油气悬架设计研究过程中不可忽略.同时,压缩行程中气体溶解和油液可压缩性对油气悬架特性的影响大于伸张行程时的影响.     

哈尔滨绕城西线高速公路软土地基沉降的计算及其分析

根据现场勘察结果,用现代土力学理论对哈尔滨绕城高速公路软土地基试验段路基的沉降量进行了计算和分析,对未来将会发生的不均匀沉降做出了预报,为工程施工提供参考。     

巴西塞拉都(Cerrado)地区氧化土土壤紧实性评估研究

The Cerrado region of Brazil, one of the fastest-growing agricultural areas in the world, is undergoing very rapid mechanization; this development is good for the country’s economy but may also snowball into substantial loss of agricultural land and other environmental degradation if the soil susceptibility and vulnerability to compaction is not well understood. In this study we explored different techniques for estimating soil intrinsic abilities to withstand applied pressure using the prevalent Oxisols of the Cerrado region under native vegetation. Undisturbed samples were collected from three sites within the region and subjected to 1) compressibility test: 2) manual penetration resistance test; 3) automated penetration resistance test; and 4) packing density analysis. The four methods produced analogous results. Our results showed the significant influence of soil structure on the inherent strength and compaction susceptibility of the soils. We also established the association of soil structure with the mineralogy of the soil. It is noteworthy that the packing density which was developed from very simple and easily obtained parameters could give a picture of the tendency of the soil to compact. Thus, this approach would be useful in developing compaction susceptibility maps for the region. It could be concluded that most of the Oxisols in the Cerrado region would support mechanized agricultural production very successfully. However, there is need for careful management of the mechanization process to avert degradation. The management techniques should include conservationist practices such as no till in order to maintain as much as possible the favorable structure and drainage of these very old soils.     

Modified Hyperbolic Model of High Compressibility Clay Considering Strain Strengthening Effects

The elasto plastic constitutive relation of high compressibility clay in Wuhan was investigated. On the basis of the framework of Duncan E~v model, an elasto plastic constitutive model was derived by fitting the data of triaxial compression tests under CTC stress path on isotropic consolidation condition. With the average slope of unload reload curves as unload modulus, the loading unloading function was introduced as the loading unloading criterion. Moreover, the comparison was made among the stress strain relation curve simulated by the proposed model and those with Duncan model and test curve. It was shown that the proposed model was more reasonable, which can reflect the stress strain relation of normally consolidated soils under CTC path. Especially, the model can reflect the strain strengthening effect. The maximum relative error was no more than 5%.     

植被恢复对典型黑土表层土壤压缩性和承载能力的影响

以恢复年限分别为14、36、50 a的落叶松人工林及相邻耕地表层土壤(0~10 cm)为研究对象,采用快速固结试验法,对土壤孔隙比、压缩指数、先期固结压力等指标进行测试,分析植被恢复对典型黑土表层土壤压缩性、承载能力的影响。结果表明:土壤孔隙比、压缩指数、先期固结压力,均随恢复年限的增加而增加,压缩指数、先期固结压力变化范围分别为0.231~0.399、4.2~100.0 k Pa。落叶松林地土壤压缩指数、先期固结压力,均显著高于耕地土壤(p0.05);随植被恢复年限的增加,典型黑土表层土壤压缩性、承载能力逐渐提高,耕性有所增强。土壤力学性质指标与理化性质之间,表现出显著的相关性(p0.05);压缩指数与土壤黏粒比例、有机质质量分数之间关系更为紧密(p0.01);先期固结压力与土壤黏粒比例呈极显著负相关(p0.01)。植被恢复导致土壤有机质质量分数的增加;土壤密度和黏粒比例的降低,是黑土表层土壤压缩性增加、土壤承载能力增强的重要原因。