共查询到20条相似文献，搜索用时 93 毫秒
1.
本文对一般河流中钻(冲)孔施工过程中出现的坍孔问题,结合多年的实际经验进行了详细论述,并且提出了坍孔处理与防治方法。 相似文献
2.
3.
随着桥梁建设的发展,桥梁钻孔桩已被广泛采用。由于桥址处的水文和地址条件复杂,桥孔施工普遍存在流砂层坍孔,卵砾石成孔与护壁困难,基岩钻进破岩效率很低,严重影响了桥梁钻孔的技术经济效益。在钻孔桩施工中工序较多,工艺流程互相衔接,主要工序都在水下及地下进行,不便监视,经常出现各种坍孔现象。本文对一些技术问题进行探讨。 相似文献
4.
软土地基钻孔灌注桩工程施工质量通病主要有：缩径、断桩、桩顶冒水、桩身孔洞、钢筋笼＂上浮＂、＂烂桩头＂、桩孔坍孔、孔位倾斜等。就其形成原因逐一进行剖析,并提出了相应的防治措施。 相似文献
5.
6.
日本《共同通讯新闻速报》2007年1月23日报道，在大阪府坍市建成世界首家以建筑废材为原料的生物乙醇商业生产设施，1月16日举行了竣工仪式。[第一段] 相似文献
7.
由于我国林产品最主要出口国的美国林产品市场全面复苏,加上欧洲、南美、南非和亚洲在内的许多国家的经济形坍趋好,对木质家具等产品需求量增加,使我国木质家具、人造板和木质地板等产品出口量增加,从而带动了木材和各种人造板产品进口量的全面大幅度增长。 相似文献
8.
浅谈不良地质地段路基病害的综合治理 总被引：1，自引：0，他引：1
浅谈不良地质地段路基病害的综合治理黑龙江省林口林业局闫世成众所周知，路基在水、风、冰冻等自然因素的长期作用下，经常发生变形和破坏，例如：边坡的表土剥落，形成冲沟，土体滑坍沉降及翻浆、冰湖等等，为保证路基的强度和整体稳定性，必须因地制宜的对不良地质地段... 相似文献
9.
酸刺沟隧道出口水平旋喷桩施工技术 总被引：1，自引：0，他引：1
主要介绍水平旋喷桩在隧道软弱围岩中施工工艺及加固效果的应用。酸刺沟煤矿铁路专用线隧道出口施工时,经现场核实均与设计图纸相符,泥岩与粘性土经地下水长期浸泡饱和后形成稳定性极差的软塑-流塑状地层,即形成泥岩与粘土的互化层,隧道在开挖施工中极易滑坍。为解决通过这种隧道地质的施工方法,保证隧道永久质量和施工中的安全,采取新工艺、新材料和新方法,着重考虑隧道超前预加固,通过对超前小导管、超前小导管预注浆、大管棚、深孔注浆、水平旋喷桩、水平搅拌桩和水平固结等方案比选,决定采取水平旋喷桩施工技术,主要研究软弱围岩隧道施工中如何应用水平旋喷桩,初步拟选桩直径、桩长、外插角和循环距离等技术参数,通过现场施工,顺利通过该隧道软弱围岩段,在该隧道软弱围岩段成功地应用了水平旋喷桩,值得推广和借鉴。 相似文献
10.
11.
木材皱缩评价指标的研究 总被引：8，自引：1，他引：7
近年来 ,国内外学者对木材皱缩缺陷开始关注 ,澳大利亚学者Ｔ .ＣＩｎｎｅｓ( 1 995,1 996)、中国学者王喜明 ( 1 989)、刘 元 ( 1 994)等分别研究了澳大利亚产桉木如多枝桉、细叶桉和赤杨、山杨等木材的干燥皱缩缺陷。他们从调湿处理对皱缩的作用 ;皱缩材组织结构的变化 ;皱缩机理 ;皱缩极限温度 ;预冻处理对皱缩的作用等方面做了大量深入而细致的工作。所取得的成果公开发表后得到同行学者的认可 ,对进一步研究避免皱缩的干燥工艺打下了较好的基础。但在众多有关木材皱缩的研究报告中 ,普遍遇到一个同样的问题就是如何定量地去评价和测量… 相似文献
12.
13.
Shrinkage and collapse in thin sections and blocks of Tasmanian mountain ash regrowth 总被引：2，自引：0，他引：2
Summary Total collapse values from the green condition to various equilibrium moisture contents (EMC) were obtained by comparing shrinkage before reconditioning in matched blocks and sections of the wood of Eucalyptus regnans. It was shown that while collapse to 17% EMC comprised the largest portion of total collapse, a significant component, apparently caused by drying stress, developed below 17% EMC. Between 5% EMC and 0% moisture content a collapse recovery of some 1% occurred, seemingly because of changes in drying temperature. After reconditioning, collapse recovery was only partial and a high level of residual collapse remained. It was shown that collapse recovery was highest near the sapwood-heartwood boundary, while residual collapse was highest near the heartwood centre. While residual collapse was weakly negatively correlated with specific gravity, this relationship was not significant after adjustment was made for change in shrinkage after reconditioning in sections. All types of collapse were positively correlated with R-ratios calculated for blocks. However, relationships were not as well defined when R-ratios for sections were employed, the exception being for collapse below 17% EMC which was highly negatively correlated with R. The difference between shrinkage before reconditioning and shrinkage after reconditioning in sections, while totalling near zero, was positively correlated with specific gravity. It was demonstrated that this quantity could not constitute collapse in the traditional sense of collapse of the cell lumens. A possible association with moisture content of the material was discussed. 相似文献
14.
平武县清漪江沟泥石流物源现存量分析 总被引：1，自引：0，他引：1
清漪江沟为涪江上游平通河的一条支沟,位于四川省平武县境内,曾多次发生泥石流灾害.2010年8月12日清漪江流域降雨112 mm,由此引发山洪和泥石流.泥石流发生后的第16天,调查了宽坝林场场部至锁江乡立石沟19.73 km长的两岸汇水沟、侵蚀沟和不同类型崩塌体的发生数量及其泥石流物源的现存量.结果表明,调查区段内,两岸有大小汇水沟54条,密度2.7条·km-1,在林地和耕地上新形成了65条侵蚀沟,密度3.3条·km-1,沟口的物源现存量达1 264 m3,密度为64 m3·km-1;有394处大小不同的崩塌体,数量密度为20处·km-1;现存的崩塌体量共7 324 m3,现存量密度达371 m3·km-1.南坡和北坡的崩塌数量和现存量存在很大的差异,南坡崩塌了286处,数量密度为14.5处·km-1,占河流两岸崩塌数的72.6％;崩塌现存量5 486 m3,现存量密度为278.1 m3·km-1,占崩塌现存总量的74.9％;北坡崩塌了108处,数量密度为5.5处·km-1,占河流两岸崩塌数的27.4％;崩塌体现存量1 838 m3,现存量密度为93.2 m3·km-1,占崩塌体现存总量的25.1％.分析还表明,人为活动是泥石流物源的主要来源,尤其是耕地.因此,在泥石流灾害治理中,应重视和引导农村调整产业结构,改善生态环境,提高防灾减灾的综合治理能力. 相似文献
15.
Shrinkage of green cane (Arundo donax L.) was measured during air-drying at room temperature. The cane began to shrink at 150% moisture content due to a remarkable collapse of parenchyma cells. The collapse recovered after boiling in water, but more serious collapse (recollapse) was induced by the following drying. On the other hand, the collapse recovered almost completely after steaming with saturated water vapor at 92°–96°C without recollapse. By comparing the thickness of cane specimens before and after steaming, the degree of cell collapse remaining in dry cane was evaluated. When the green cane was frozen prior to drying, the degree of collapse was reduced whereas the drying rate remained unchanged. The effect of prefreezing was interpreted as the generation of air bubbles in the cell lumen which hinder the effective loading of liquid tension on the cell wall. Even when the cane was carefully dried using a conventional method used by reed manufacturers, the degree of collapse was very large and it increased with elevating internode position. 相似文献
16.
17.
18.
To improve the drying method in the manufacture of woodwind reeds, green canes (Arundo donax L.) were dried under various humidity–temperature conditions and the intensity of cell collapse was evaluated from the swelling due to steaming during the recovery of collapse. At 30°C, the intensity of collapse was increased by slower drying. It was considered that: (1) slower drying resulted in higher sample temperature in the early stage of drying and acted to increase the collapse; (2) rapid drying stiffened the surface of the sample and such a shell prohibited the following collapse; (3) slower drying i.e., longer loading of liquid tension caused more remarkable and/or frequent viscoelastic yields of cells. Consequently, the intensity of collapse increased when the cane was dried from its waxy outer surface or in the presence of node: both of them retarded drying. On the other hand, higher drying temperature caused greater intensity of collapse in spite of faster drying. It was suggested that the thermal softening of cane cells leads to easier yielding of the cell wall, and at the same time the rapid drying does not allow the recovery of collapse after the disappearance of free water. These results indicated that faster drying at lower temperature is preferable for drying cane with less collapse. 相似文献
19.
20.
刘元 《中南林业科技大学学报(自然科学版)》1994,(2)
本文从理论上探讨了木材干燥皱缩的机理．并通过对红柳桉和多枝桉进行干缩性试验，阐述了木材干燥皱缩的特征、特性及其影响因子．揭示了木材干燥皱缩受外界环境影响的规律，对在生产中克服和防止木材干燥皱缩有一定的参考价值． 相似文献