Influence of size of granulated rubber and tyre chips on the shear strength characteristics of sand–rubber mix

Use of scrap tyres in isolation systems for seismic damping, requires a knowledge of the engineering properties of sand–rubber mixtures (SRM). The primary objective of this study is to assess the influence of granulated rubber and tyre chips size and the gradation of sand on the strength behaviour of SRM by carrying out large-scale direct shear tests. A large direct shear test has been carried out on SRM considering different granulated rubber and tyre chip sizes and compositions. The following properties were investigated to know the effect of granulated rubber on dry sand; peak shear stress, cohesion, friction angle, secant modulus and volumetric strain. From the experiments, it was determined that the major factors influencing the above-mentioned properties were granulated rubber and tyre chip sizes, percentage of rubber in SRM and the normal stress applied. It was observed that the peak strength was significantly increased with increasing granulated rubber size up to rubber size VI (passing 12.5 mm and retained on 9.5 mm), and by adding granulated rubber up to 30%. This study shows that granulated rubber size VI gives maximum shear strength values at 30% rubber content. It was also found that more uniformly graded sand gives an improved value of shear strength with the inclusion of granulated rubber when compared to poorly graded sand.     

基于Landsat和Sentinel-2时间序列影像的海南西部橡胶林龙卷风灾情评估

风害是影响中国天然橡胶产业发展最严重的自然灾害之一,它短时间内对橡胶林造成严重的物理伤害(大量落叶、枝条和主干折断等),严重影响后期生长和产量.传统地面调查虽然精度高,但耗时费力、经济成本高,利用遥感快速评估对指导灾后生产恢复、保险赔付和科学研究等具有重要意义.本研究以2019年8月1912号热带风暴“杨柳”在海南西部...     

基于ANSYS的液压卡盘胶筒的应力分析与优化

针对以往液压卡盘的胶筒在设计中用经验方法确定的安全系数难于保证胶筒结构的可靠性问题,通过有限元分析方法,对胶筒式液压卡盘的胶筒进行了应力分析,确定了对胶筒应力、应变有较大影响的因素。结果表明,在保证足够夹紧力的前提下,减小胶筒外直径,胶筒长度相应增加,并适当增加胶筒肩部倒角,可以有效改善胶筒的受力条件,提高胶筒使用的可靠性,从而可简化卡盘的结构,提高卡盘的可靠性。      

地缘政治经济背景下中老-中越边境地区橡胶林时空扩展特征研究

国家间地缘政治经济关系正在驱动区域土地利用变化,边境地区首当其冲。20世纪90年代以来,全球橡胶市场的强劲需求以及中南半岛与域外国家40多个地缘经济合作机制的实施,引起了包括中国与老挝(以下称“中老”)-中国与越南(以下称“中越”)边境地区橡胶林扩展种植在内的显著土地利用变化。基于此,利用Landsat影像构建的橡胶林落叶-新叶萌生期内植被-水分指数(Renormalized Vegetation Index, RNVI)组合算法,获取中老-中越边境地区1990年代以来中老、中越地缘政治经济关键节点的橡胶林种植信息,进而揭示中老、中越地缘政治经济关系对其边境地区橡胶林扩展的影响及其国别差异。结果表明:(1)在“替代种植”与边境农林合作等地缘政治经济影响下,中老-中越边境地区橡胶林种植面积由1992年的995.5 km²增加至2018年的5537.7 km²,增长近4.6倍,且呈明显的沿边性和跨境性;(2)随着中老磨憨-磨丁口岸开通、中老北部九省合作机制构建等,1992—2018年,中老边境沿线30 km缓冲区内橡胶林种植面积从244.7 km...