Stress variation of soil surrounding tunnel and grouting reinforcement effect based on stress release

With FLAC, a criteria of stress release ratio （SRR）, i.e., about 10% of the relative difference of the ground settlement before and after the supporting system is installed, is incorporated into stress release method （SRM）. At the same time, the Mohr-Coulomb Criterion is used to analyze stress changes around the tunnel induced by excavation. It shows that the surrounding soil around shallow tunnels can be partitioned by loosened zones （unloading zones） and plastic zones among which the shear stresses in the soil are less than 10 kPa below the M-C yield line. Both types of zones are separated. With the increasing of the SRR, the areas of plastic zones and loosen zones gradually increase. The surrounding soil is equally divided into 24 regions in order to study the influence of different grouting regions on the ground settlement. The reinforcing effect of grouting can be modeled by enhancement of the soil strength around the tunnel. By the approach of the SRM, numerical analysis indicates that, in the upper area （top of the surrounding soil about 210°）, the reinforcing effect gradually decreases as the reinforcing region moves from arch springing to the vault of the crown; when reinforcing regions lie in the upside of the surrounding soil, the influence on the ground settlement is generally greater than in the lower part; at the same time, with the increase of the SRR, the influential differences are more and more obvious.     

便携式干式变压器导线材料原位无损检测装置的研制

研制出一款便携式干式变压器导线材料的原位无损检测装置。介绍了该装置的整体结构和主要电路。对装置的检测能力进行测试,结果表明,该装置可在不破坏干式变压器的条件下,对导线材料实现无损鉴别。     

交通荷载作用后粉质黏土不排水强度特性试验研究

利用动三轴仪,对京津高速铁路沿线典型的饱和粉质黏土经历交通荷载长期作用前后的强度进行对比试验,研究排水条件、施工扰动及超固结等因素对土体振后不排水强度的影响.研究结果表明:长期交通荷载作用下产生的累积轴向应变和孔压均可作为试样结构破坏程度的表征,且存在临界值.当应变或孔压超过其临界值时,振后强度会发生衰减.若施工扰动破坏了土体天然结构性,两者的临界值均将大大降低,地基振后强度均发生衰减,且衰减程度也比天然地基大.地基中存在良好的排水途径将有效提高正常固结地基振后承载能力;交通荷载的往复作用及排水条件对预压处理后的超固结地基强度影响较小.     

地基不均匀沉降时埋地管涵纵向力学模型探讨

地基不均匀沉降是影响埋地管涵纵向力学性状的主要因素之一。针对Winkler地基模型的缺陷,采用Pasternak双参数地基模型建立了较为合理的考虑地基差异沉降的埋地管涵纵向力学模型,得到了沉陷区埋地管涵的挠曲线表达式,进而对埋地管涵的纵向力学性状要素进行分析,表明管涵结构的挠度、转角、弯矩、剪力均在差异沉降处有突变,且各要素受不均匀沉降的影响范围有限。     

进一步加强PVC塑钢门窗施工安装质量的控制

塑料门窗经过型材及其配件的采购,门窗的组合、装配、门窗的施工安装这三个过程中,塑料门窗的施工安装是最后一个非常重要的环节。本文通过塑钢门窗的特性、施工安装特点等的论述,指出了PVC塑钢窗工艺程序及工艺要点的控制,最后指出了PVC塑钢窗常见质量通病及防治措施。     

飞来峡水利枢纽大坝安全监测自动化系统及其升级完善设想

介绍飞来峡水利枢纽大坝安全监测自动化系统的组成情况,并根据运行以来所面临的新问题加以总结,提出认为必要和可行的升级完善设想。     

密炼机终炼温度对白炭黑胶料性能的影响

针对白炭黑胶料,采用高温（100℃）和传统低温（50℃）终炼法在密炼机中分别进行湿法混炼胶和干法混炼胶的终炼,研究终炼温度对胶料性能的影响。结果表明,相较于低温终炼,高温终炼会使混炼胶的门尼粘度和混炼能量消耗降低,混炼胶的t10和t90略微延长,硫化胶的邵尔A型硬度、100%定伸应力和300%定伸应力增大,拉伸强度和拉断伸长率减小。     

上海老厂房“点石成金”

青海省住房和城乡建设厅切实把保障扩大内需投资建设项目质量和效益作为当前的重要工作来抓，近日，该厅下发通知要求各地建设主管部门加强建筑市场监管和服务，确保扩大内需投资建设项目的质量和效益。     

龙潭湖甲藻水华应急处置的研究

为消除龙硿洞龙潭湖甲藻水华,选用二氧化氯、漂白粉和生石灰等安全、廉价、易得的常规消毒、除藻剂。检测结果表明,湖水中叶绿素由139.05μg/L降至3.60μg/L,减少97.4%,甲藻由11.1×106cells/L降至0cells/L,佩氏拟多甲藻(Peridiniopsis penardii)和颗粒直链藻极窄变种(Melosira granulate var.angustissima)均被漂白粉、二氧化氯杀死漂白,叶绿体被完全破坏,底泥样品悬浮后观察,均未检出活体拟多甲藻,甲藻水华被彻底消除。     

几种常见元器件疑难问题的巧妙处理方法

1.巧妙判断高频硅堆的好坏将模拟万用表置于直流250V档,把硅堆与万用表按图接好,然后通入220V交流电,见图1所示,如果万用表指针发生偏转(大概≥30 V范围内),说明该硅堆是