基于数据及计算的村镇聚落个体空间形态特点研究——以张家口市下花园区四个村落为例

本研究旨在对村镇聚落个体空间形态进行量化研究.通过对河北省张家口市下花园区四个样本村庄的调研得到现状影像图,在此基础上进行平面绘制、处理,分别计算四个村庄的聚落边界形态指数、聚落密度及公共空间维度,评述数据,得到村镇聚落个体空间形态的量化特征,并结合不同地文区特征,对上述指标及方法进行思考与展望.     

上行式移动模架法现浇箱梁施工技术研究

作为一种较为先进的现浇箱梁施工技术,上行式移动模架法施工不受制梁场地的限制,具有施工便捷、安全、质量突出的优势.以重庆轨道交通4号线二期普福站～桐梓林站区间(高架段)TMS40上行式移动模架应用为例,在阐述上行式移动模架法施工技术特点以及原理的基础上,就其在现浇箱梁具体施工项目中的应用情况展开分析,并指出项目施工过程中的质量控制手段,期望能进一步提升上行式移动模架法应用水平,保证现浇箱梁施工质量,促进桥梁工程的有效发展.     

Experimental study on the influence of soluble salt content on unsaturated mechanical characteristics of undisturbed Ili loess

Bulletin of Engineering Geology and the Environment - Due to the perennial influence by west wind climate, the loess in Ili, China, is obviously different from that in the loess plateau of the...     

连续梁桥静载试验研究

论述了连续梁桥静载试验的方法、内容和实际加载方案,对有关测试项目（挠度、应力等）理论值的计算方法进行了讨论,通过将实测值与理论值进行对比研究,得出了试验桥梁的评价结果。     

基于车辆荷载的锈损公路桥梁疲劳性能试验研究

采用湿盐砂锈蚀方法获得腐蚀环境钢筋混凝土劣化试件,选取与车辆荷载作用下公路桥梁实际承受的疲劳应力水平,通过8根锈蚀钢筋混凝土梁的弯曲疲劳试验,分析了锈蚀钢筋混凝土梁的疲劳破坏形态及应力水平和钢筋锈蚀率对梁疲劳性能的影响规律。试验结果表明,锈蚀梁的疲劳破坏形态为主筋脆性断裂;在设计应力水平作用下,疲劳加载满足规范200万次要求;在桥梁实际应力水平作用下,未锈蚀试验梁的平均疲劳寿命较规范值减少6.71%;锈蚀较严重的试验梁疲劳寿命较规范值减少13.57%,较同应力水平的未锈蚀梁疲劳寿命减少42.54%,锈蚀对试验梁的疲劳寿命影响显著。随着疲劳循环次数的增加,锈蚀梁钢筋内部出现疲劳损伤、抗弯刚度逐渐退化,混凝土残余应变累积,裂缝演变基本符合快速增加、稳定发展、急剧变化的“三阶段”发展规律。根据试验结果,建立S-N疲劳寿命方程,提出了锈蚀钢筋混凝土梁疲劳寿命计算方法,研究结果为桥梁结构疲劳性能评估提供理论依据。     

Characteristics of soft marine clay under cyclic loading: a review

Soft clay forms a big proportion of the seabed ground. In a marine environment, waves, wind, and earthquakes, often known as cyclic loads, are a main contributor to the loading of the seabed. The safety of offshore structures relies on the response of soft marine clay to these cyclic loadings. Its very fine-grained composition, and hence low permeability, is the defining factor for soft marine clay showing a very different response to cyclic loading than sand. The responses of soft marine clay subjected to cyclic loading range from degradation in soil strength and stiffness to principal stress rotation, excess pore pressure generation, and deformation accumulation. These dynamic characteristics of soft marine clay are strongly influenced by several factors, including loading level (amplitude, frequency, and number of cycles), loading history, and path. The purpose of the present paper is to present an overview of the research results on the characteristics of soft marine clay under cyclic loading in the past decades. Some remarks on future research for improving the understanding of dynamic characteristics of soft marine clay are also provided based on the results of up-to-date research.     

Identification of structural domains by considering multiple discontinuity characteristics: a case study of the Songta Dam

Discontinuities formed by different geological processes strongly affect the inhomogeneity of a rock mass. Demarcation of statistically homogeneous regions is useful to speculate the tectonic evolution history. Therefore, a new method is introduced to divide the homogeneous structural domains based on multiple discontinuity characteristics. The new method is divided into three steps. Firstly, the 34-patch network on the lower-hemisphere Schmidt projection and the correlation coefficient are adopted to quantify the similarity of discontinuity orientation. Secondly, the Wald–Wolfowitz runs test is utilized to identify the similarity for trace length and trace type. Thirdly, the structural domains are comprehensively identified based on the similarity of discontinuity orientation, trace length and trace type. The comprehensive method is subsequently adopted to divide the structural domains within the Songta right abutment rock mass. The results illustrate that the rock mass around PD222 and PD234 belongs to the same structural domain D1 and the rock mass around PD224 and PD236 belongs to the other structural domain D2. The D2 located at the high elevation suffers longer and stronger unloading effect of the river valley, which is more likely to form the long discontinuities. However, the D1 located at the low elevation develops mainly the short discontinuities. Hence, it is reasonable and consistent with geological development background that the abutment rock mass is divided into two structural regions along the vertical direction using the new method.     

Development of Suburban New Towns in Shanghai: Jobs-Housing Spatial Relationship Analysis

This paper identifies the employment and housing locations of residents in Shanghai based on mobile phone signaling data, so as to obtain the employment density and commuting data and analyze the development of nine suburban new towns from the perspective of jobs-housing spatial relationship. Firstly, the paper defines employment-intensive areas and gets the average employment density of each new town according to the employment density data. Then it marks out the scope of the employment influence through analyzing the sources of workers in each new town in accordance with the commuting data. Finally, it analyzes the jobs-housing balance of each new town using independence index, finding that suburban new towns in Shanghai have become main clusters of economic activities, while the scope of employment influence in each new town is still concentrated in its administrative area, with less attraction to residents in other areas. The independence index demonstrates a law that the suburban new town which is farther from the central city sees a higher degree of jobs-housing balance. Among them, new towns located in the outer suburbs with a low independence index indicate their special development situation, the reason of which is worth further study.     

Nutrients transport in the bare urban redeveloped soil system during runoff process

Stormwater pollution in redeveloped soils mixed with construction wastes imposes a serious impact to receiving waters. The transport and distribution of rainfall water and nutrients in the surface-flow and subsurface-flow (including side-flow and down-flow) of bare redeveloped soil runoff system were determined. Results indicated that the flow patterns and pollutants transport of surface-flow were different from those in subsurface-flow. The flowrate of surface-flow increased at the beginning and reached to a stable state, and then disappeared immediately after the rainfall stopped. While the flow rate of subsurface-flow was persisted and decreased gradually artery the rainfall. Most of the pollutants were carried in the surface-flow, which directly results in polluting the surface-receiving waters. And the pollutants distribution percent in side-flow was higher than that in down-flow. Results obtained in this study will provide information for the management of stormwater pollution in the bare redeveloped soil mixed with construction wastes.     

基于神经网络预测误差修正的广义预测控制

针对建模误差对预测控制的影响,提出一种基于神经网络预测误差修正的广义预测控制算法.被控对象采用递推最小二乘法(RLS)辨识其线性模型;预测误差由前馈神经网络进行建模,并用Powell快速优化方法训练网络.该方法无需预先离线训练神经网络,即可投入闭环控制,并具有理想的稳定性、跟踪性能和鲁棒性.仿真结果表明该算法能够有效地控制复杂系统.