沈阳市方形广场地下通道工程施工技术          下载免费PDF全文

寇俊峰  方德平 《探矿工程》1998,(5):52-53

通过地下通道施工实例,介绍了小导管超前注浆预加固的施工及注浆材料、注浆参数的确定方法。  相似文献   

差分GPS水下地形测绘关键技术研究     

杨豪强  袁秋林 《全球定位系统》2005,30(3):12-15

简要介绍了将差分GPS技术用于水下地形测绘的方法，重点研究了平面坐标转换和水深数据修正两个关键技术，给出了平面定位的坐标转换方法和考虑水温、含盐度等对声速的影响，以及海水潮位变化等因素后的水深测量修正方法。  相似文献   

Adaptive bang–bang control for the vibration control of structures under earthquakes     

C. W. Lim  T. Y. Chung  S. J. Moon 《地震工程与结构动力学》2003,32(13):1977-1994

An adaptive method based on the modified bang–bang control algorithm is proposed for the vibration control of structures subjected to unexpected severe seismic loads greater than the design loads. A hydraulic‐type active mass damper was made and experiments were carried out in the laboratory using a one‐story test structure and a five‐story test structure with the active mass damper. Through numerical simulations and experiments it was confirmed that the proposed method works well to suppress the vibration of structures subjected to unexpected severe seismic loads greater than the design loads without causing any unstable situations. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

从一则工程实例析<建筑地基处理技术规范>地基承载力深度修正的合理性     

李自停  李志侃 《地质灾害与环境保护》2003,14(2):60-62

通过-工程实例指出，《建筑地基处理技术规范》JGJ79—9l地基承载力深度修正系数取1．0致使粗颗粒土在超过一定临界深度时地基处理是“无效”的，因而也是不合理的。  相似文献   

改性尿素的结构变化及其肥效的盆栽试验研究   总被引：1，自引：0，他引：1       下载免费PDF全文

吴平霄  廖宗文冯新 《岩石矿物学杂志》2003,22(4):442-444

利用有机-无机(矿物)控释材料对尿素进行改性，制成改性尿素。盆栽试验结果显示，在等重条件下，改性尿素较普通尿素有较大幅度的增产效果。运用X射线衍射及红外光谱分析对改性尿素的结构进行研究，发现其晶体结构发生了较大变化，增加了改性尿素的稳定性，从而延长了其肥效并提高了氮的利用率。  相似文献   

考虑时效作用的桩基承载力计算方法研究   总被引：1，自引：0，他引：1  

彭劼  施建勇  娄亮  郑少军 《岩土力学》2003,24(1):118-122

采用空间轴对称固结有限元结合修正剑桥模型，用柱形孔扩张对沉桩过程进行模拟，求出不同时期桩周土中的应力，从而得到不同间歇期桩侧的最大摩擦力。应用荷载传递法对桩基承载力进行计算，结合桩周土体剪切强度、应力状态的变化，得到了考虑时效影响的桩基承载力的计算方法。实例计算表明，结果较合理。  相似文献   

高速公路路基膨胀土填料改性处理及应用   总被引：3，自引：0，他引：3  

石坚  陈宝义  刘大军 《吉林地质》2002,21(4):64-68

膨胀土能否作为高速公路路基填料一直是个有争议的问题。本文在前人理论的基础上，对宁靖盐高速公路在施工中所遇到的膨胀土进行了一系列的改性处理试验，总结出膨胀土改性的具体办法，并对具体的施工技术作了相应的研究。  相似文献   

柱撑蒙脱石改性磷铵及其增效机理研究   总被引：1，自引：0，他引：1  

冯新  宋波  吴平霄  廖宗文 《矿物岩石地球化学通报》2002,21(4):238-241

本通过Keggin离子制备了柱撑蒙脱石，并对其进行了酸化处理。盆栽试验研究表明，利用柱撑蒙脱石和酸化柱撑蒙脱石对磷酸二铵进行改性试验处理，生物量显高于磷铵对照，氮素和磷素利用率显提高。X射线衍射技术和红外光谱对改性磷铵进行结构研究表明，其晶体结构发生了较大的变化，这种变化减少了氮的损失和磷在土壤中的固定，从而提高磷铵氮磷的生物有效性。  相似文献   

Locally modified surface winds on linear dunes as derived from directional raingauges     

David Sharon  Adina Margalit  Simon M. Berkowicz 《地球表面变化过程与地形》2002,27(8):867-889

The study deals with local airflow patterns induced by 12–16 m high, partly vegetated dunes, under various prevailing wind conditions. Detailed empirical data were derived by means of an unconventional use of directional raingauges. The utility and accuracy of the method have been previously tested in a combined empirical and numerical study over ridges on a similar scale. Results are presented on the nature, extent and intensity of locally modified patterns of surface flow and on their dependence on wind conditions and slope inclination. Results may serve to verify or refine existing perceptions or models of the flow affecting sand movement over dunes. For example, deflected surface wind flow and even stationary vortices were found to form under winds with resultant angles of incidence of only 5–10° relative to the axes of the dunes, and on slopes inclined only 12–15°, i.e. lower angles than often assumed in previous studies of dune morphology. Various effects of the resulting surface flow on the dune ecosystem are also referred to, e.g. the distribution of settling dust and seed dispersal. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Barrier jets around the Southern Alps of New Zealand and their potential to enhance alpine rainfall     

Michael J. Revell  Jeff H. Copeland  Howard R. Larsen  David S. Wratt 《Atmospheric Research》2002,61(4)

We use new data from the SALPEX'96 campaign to examine the evolution of orographically modified flow over and around New Zealand's Southern Alps. We consider prefrontal situations for which the larger-scale synoptic pattern generates an incoming northwesterly flow perpendicular to the mountain axis, calculate the nondimensional parameters which control the wind flow and determine how long it takes orographic modifications to become established. We place flows over the New Zealand Alps in a Rossby number/Blocking number parameter space and compare them with flows over other mountain ranges on the globe. Using model and aircraft data, we show the region of modified flow extends over 100 km upstream of the Southern Alps.We show 2D model simulations represent many aspects of the flow modification satisfactorily, although they tend to overdevelop the final state of the Barrier Jet flow. In 3D, using real data to force the boundaries, the migratory nature of the weather systems in the area would generally limit the time available for a modified steady state to develop. In addition, in situations where there is significant lateral variation of initial fields, the 2D results may only be applicable for a few hours.From the point of view of potential to influence alpine rainfall processes, for the case studied, the gradual uplift associated with the modified flow between 1 and 2 km above sea level extended far enough upstream in saturated air to enable cloud drops to grow to drizzle drops before reaching the much more substantial updrafts at the foot of the Alps. This allows vigorous prefrontal precipitation to occur over the foothills and mountains due largely to warm rain processes.  相似文献