树根桩加固地基的实践   总被引：1，自引：0，他引：1  

王振福  王波 《陕西地质》1997,(2)

树根桩加固处理地基是一种简单有效的方法，结合树根桩施工实践，论述了树根桩施工工艺及施工质量控制措施等问题。  相似文献   

Circulating planning ideas from the metropole to the colonies: understanding South Africa's segregated cities through policy mobilities     

Astrid Wood 《Singapore journal of tropical geography》2019,40(2):257-271

In the early part of the twentieth century, South African cities were segregated in accordance with British city planning concepts that embodied the belief that social order can be manipulated through the urban form. This paper surveys the history of South African planning practices to understand the spread of segregation policies and practices. Whereas scholars tend to agree that the apartheid city (post?1948) is a more highly organized and structured version of the colonial city (pre?1910), the literature lacks consensus on the development of the segregated city (1910?1948) within South Africa. How did concepts of segregation circulate and why was it implemented with such consistency? Accordingly, this paper employs concepts of policy mobilities to trace historical configurations in South Africa to international influences. The focus on the circuits of knowledge explains how concepts and designs transplanted from elsewhere helped create the form of South African cities today. Understanding the movement of planning ideas through policy mobilities furthers geographical understandings of historical circulation processes, the role of the local actors, and policy mobilities failure. This history of learning also challenges the assumption that South African cities are unique and in so doing opens the doors for knowledge sharing between postcolonial cities.  相似文献   

Analysis of Multiple Tourist Agents’ Symbiotic Relationship on the View of Tourist Enterprises Based on a Grey Correlation Model: A Case Study of Qinghai Lake,China     

XIANG Cheng  TANG Zhongxia  LIU Menglin  SHAO Li 《资源与生态学报(英文版)》2019,10(3):335-344

Tourism symbiosis is a social phenomenon consisting of many complex factors, and the reciprocal cooperation among multiple tourist agents at tourist destinations is the crux of the sustainable development of tourism. This study is from the perspective of tourist enterprises, and introduces the Symbiosis Theory of genecology. A quantitative evaluation is used to analyze both the equilibrium state of the combined symbiotic behavior routes and the behavior patterns of tourist enterprises with local governments, community residents, tourists and tourist enterprises around Qinghai Lake. The findings reveal: (1) the symbiotic behavior routes of the multiple tourist agents “E→G-R-T-E” in the Qinghai Lake area are constituted of intense symbiotic indications, while the maximum dimensionality of symbiotic interest of “E→G-R-T-E” is still in the state of disequilibrium and dissymmetry; (2) the symbiotic model of multiple tourist agents “E→G-R-T-E” in the Qinghai Lake area is an asymmetrically positive symbiotic model. It is proposed that, by establishing symbiotic mechanisms for guidance, decisions, supervisory control and profit distribution, the participation mechanism for multiple agents “E-G-R-T” can be further standardized. Moreover, tourist enterprises should be regarded as the primary agents to optimize the symbiotic model for “E→G-R-T-E” through the reinforcement of integrative supply and the construction of integrative effect, and finally promote the integrative symbiotic model of symmetrical reciprocity of the E-R-G-T model “driven by scenic areas, responsive to community residents, affected by local governments and enjoyed by tourists.”  相似文献   

浅议高压喷射注浆技术     

周苍松 《湖南地质》1992,11(4):324-329

高压喷射注浆技术是近年发展起来的一种基础处理新技术,它是利用高压载能介质将软弱土体冲切破碎后注入固结浆液在原位混合凝固,达到强化地基的目的。该技术多用于深层软土地基加固,建造堤坝防渗帷幕及高强度的防渗挡土墙等。本文就这项新技术及其机具设备与安装、施工程序、应用前景作了概括介绍。  相似文献   

Formation and evolution of sand deserts in Xinjiang,Northwest China：Ⅰ. Provenances of desert sands     

ZHU Bingqi  YU Jingjie  QIN Xiaoguang  Patrick RIOUAL  LIU Ziting  XIONG Heigang 《地理学报》2014,24(1):177-190

Sandy desert landscape is a geological product of arid climate and abundant sand materials supply in natural conditions, therefore the formation of sandy desert is an ideal studying object for understanding the interaction between various stratigraphic/epigenetic spheres of the earth system. However, until now, the knowledge about the provenance and formation of these deserts in Xinjiang, Central Asia is diverse and inconsistent, a systematic review is necessary. Ancient aeolian sand sediments in the internal areas of these deserts and their twin dust deposits in the Cenozoic strata surrounding the Xinjiang deserts are direct and indirect clues reflecting the provenance of sand materials and the formation and evolution of deserts. Based on the geochemical, mineralogical and isotopic evidences of desert sands and relevant deposits in the peripheral regions, this paper reviews the research progress on the development of the sandy deserts in Xinjiang, Northwest China. Many proofs proposed that desert sands in Xinjiang were mainly sourced from the ancient pluvial, alluvial and fluvial sediments and were eventually achieved because of the local sand supply. It pointed out that the settings of tectonic structure in Xinjiang had made sediments both in the Tarim Basin and the Junggar Basin being influenced greatly by regional hydrological system and aeolian processes originated from the planetary wind system of westerly, the East Asian winter monsoon and the topographical mountain-valley winds. However, the directions of transportation paths are different between the hydrological dynamics and the aeolian dynamics, which are decided by the slantwise structures of the basins tectonics and the regional atmospheric circulation routes, respectively, and have determined anisotropies of the transport pathway of these sediments delivered by different agents. This results in a geological cycle of detrital sediment transportation in the two large basins and thus largely increases the degree of sediment mixing, alternation and recycle between younger and older sediment sources, as well as the complexity and diversity of sand provenances.  相似文献   

干湿循环与初始静偏应力耦合作用下城市污泥固化土动力累积变形特性     

杨爱武  袁腾云  杨少朋  张卫 《工程地质学报》2022,30(1):117-126

城市污泥固化土用作路基填料,对于节约工程成本、保护环境等具有重要意义。本文以城市污泥固化土为研究对象,利用DDS动三轴仪,从干湿循环次数、初始静偏应力、动应力3个方面研究其对累积塑性应变及动强度特性的影响。试验结果表明:在干湿循环单独作用下,土体累积塑性应变随干湿循环次数的增加先增大后趋于稳定,但与初始静偏应力耦合作用下对土体累积塑性应变的影响不太显著。动应力对其影响较大,且存在临界值:当动应力小于临界值时,累积塑性应变呈现出先增大后逐渐稳定的趋势; 当动应力大于临界值时,累积塑性应变在达到某一振次后快速增大,土体迅速产生变形破坏。干湿循环与初始静偏应力都会降低土体的动强度,但干湿循环在达到10次后,动强度将趋于平稳,不再受其影响。通过回归分析,建立了考虑干湿循环次数、初始静偏应力及动应力等因素影响的城市污泥固化土稳定型累积塑性应变模型,并验证了其可行性。  相似文献   

冻融作用下污泥固化轻质土动力特性及结构演化          下载免费PDF全文

杨爱武  王斌彬  钟晓凯 《水文地质工程地质》2022,49(1):57-65

冻融作用会影响污泥固化轻质土动力特性和结构特性。为研究不同冻融循环次数和冻结温度下的污泥固化轻质土动力特性及结构演化,对冻融循环作用后的污泥固化轻质土进行动三轴试验和固结试验。试验结果表明:在冻融循环作用下,污泥固化轻质土动应力-应变曲线呈弱应变硬化型。污泥固化轻质土动强度和变形随着冻融次数（n）的增加和冻结温度（T）的降低而减小。经历前4次冻融作用后,对固化土变形和动强度影响较大,经历8次冻融循环后基本趋于稳定。冻融循环对土体动力特性的影响本质上是对土体结构性的影响。固化土冻融结构势（m_dσn）的变化规律与动强度类似,随冻融次数的增加和冻结温度的降低而下降。冻融循环次数是影响污泥固化轻质土动力特性和结构性的主要因素,冻结温度为次要因素。  相似文献   

黄豆脲酶诱导碳酸钙沉淀多变量试验研究     

崔猛  符晓  郑俊杰  吕苏颖  熊辉辉  曾晨  韩尚宇 《岩土力学》2022,43(11):3027-3035

植物源脲酶诱导碳酸钙沉淀（enzyme induced carbonate precipitation,简称EICP）可以显著改善砂土的工程力学特性,但在具体操作时,参数取值无对应规范,固化效果有待提升。基于黄豆脲酶,研究了温度、脲酶浓度、尿素浓度、钙浓度、pH值、钙源种类等变量对脲酶活性与碳酸钙沉淀的影响,并进行了沉淀物（碳酸钙晶体）的扫描式电子显微镜（scanning electron microscope,简称SEM）与X射线衍射（X-ray diffraction,简称XRD）测试,在此基础上开展了黄豆脲酶固化砂的无侧限抗压强度与固化效果试验研究。结果表明：脲酶活性随脲酶浓度的增加而线性增长,但存在温度阈值,温度超过阈值后,脲酶将完全失活,且阈值随脲酶浓度的增大而降低;尿素浓度与pH值共同影响脲酶活性,二者存在一个最优组合,当尿素浓度在0.1～1.0 mol/L时最优pH值为7,当尿素浓度在1.0～1.5 mol/L时最优pH值为8。脲酶是沉淀反应的催化剂,脲酶浓度越高,反应越完全,碳酸钙沉淀率越高;尿素与钙溶液则主要通过掺入量影响碳酸钙沉淀量,掺量比例宜为1:1,且二者浓度与pH值可通过影响脲酶活性来影响碳酸钙的沉淀情况;不同钙源对碳酸钙沉淀量的影响幅度不大。不同钙源沉淀碳酸钙晶体的成分与密度基本相同,但晶体结构差异较大,氯化钙沉淀碳酸钙晶体以块状为主,表面分布球状、类球状晶体,胶结面大,可作为EICP技术中较为理想的钙源。基于黄豆脲酶和氯化钙钙源固化砂的无侧限抗压强度约为掺粉煤灰砂样的6倍,通过SEM图像可发现,沉淀碳酸钙晶体包裹并黏结砂粒成为整体,固化效果非常理想。  相似文献   

马海盐湖高含泥、低品位地表固体钾矿矿浆絮凝沉降试验研究          下载免费PDF全文

李海民  马金元  张全有  边红利 《盐湖研究》2012,20(1):34-39

研究了非离子聚丙烯酰胺、阴离子聚丙烯酰胺、阳离子聚丙烯酰胺、聚氧化乙烯、聚合氯化铝等絮凝剂对马海盐湖泥湖高不溶物矿浆的絮凝沉降效果,给出了研究结果。此项研究对高不溶物可溶盐矿物母液的回收利用有一定的参考价值。  相似文献   

机载粉剂催化剂播撒设备的研制及其在奥运和残奥消云中的应用     

金华  张蔷  何晖  马新成  黄梦宇  田海军  刘力威 《气象》2012,38(11):1443-1448

人为引发的下沉气流可以抑制对流云的发展,这一现象已在试验中得到验证。用“人工下沉气流法”实施人工消云试验时,需在云顶大剂量的播撒粉剂催化剂。北京市人工影响天气办公室研制了能完成此类大剂量播撤任务的设备,并通过外场飞行试验对设备进行检验和改进。这是国内人工影响天气领域首个采用空投播撒法的粉剂催化剂播撤设备;可减少催化剂对飞机和播撤设备的污染。分析发现,新设备能够满足人工消云作业中播撒大剂量粉剂催化剂的需要。该设备在北京奥运会、残奥会开闭幕式当日的消云试验作业中投入使用,共实施消云飞行作业9架次,累计利用新设备播撒吸湿性粉剂催化剂34吨。  相似文献