城市配电网采用预制分支电缆改进高层建筑供电方式

本文就城市配电网预制分支电缆使用的必要性，及对目前太原市区高层建筑的几种供电方式进行了技术经济比较，论述了预制分支电缆的特性及应用范畴，并结合具体工程设计作出了结论，采用预制分支电缆是高层建筑供电的经济实用方案。     

三(明)-福(州)高速公路K196+425～+640段路堑右侧边坡滑坡治理

三(明)-福(州)高速公路三明段为国道G104主干线京-福高速公路在福建省三明市境内的一期工程。是一条在山岭重丘区修建的高速公路。三-福高速公路三明段SA7合同段K196 425~ 640段路堑右侧边坡原设计为6级半高边坡,并在第2和第3级设计了锚索地梁锚固。待施工至第1级时,高边坡产生较大规模滑坡,估计体积约12.5万m3。滑坡产生的主要原因是坡体工程地质和水文地质条件差。其次是源于区内连续降雨。再其次是设计锚固深度不足。后经中铁西北科学研究院论证制定了一套较完整的包括刷方减载、放缓边坡、加宽平台、分台整治、预应力锚索框架加固、仰斜坡体排水孔疏水以及地表完善的截排水系统等综合治理方案。所有加固工程完成后,在该高边坡共布置监测断面6条。至今已分别进行了4次深孔位移监测,并经1a多的检验,治理效果良好。     

公路路基支挡结构物加固技术研究

近年来,国内各地相继出现了公路路基支挡结构物失稳事件,对相关路桥的运营安全造成了严重威胁。由于条件特殊及环境制约,此类工程加固难度很大。结合山东省G104界河立交桥加筋土挡土墙和G205高峪铺公铁立交桥坡间挡土墙的加固,对此类工程失稳的特征、原因及相应的工程对策从理论到实践展开了深入研究,并得到了具有一定推广价值的结论。     

光电复合缆绞车牵引系统力学分析

针对深海光电复合缆绞车牵引系统的复合缆和卷筒的设计缺乏理论依据的关键问题,根据光电复合缆的特性和大容量收放的特点,运用微积分和MATLAB仿真的方法对复合缆在双卷筒上的受力进行详细分析,得到牵引卷筒上复合缆力学模型,进而讨论了牵引卷筒上复合缆的张力衰减情况。最后,基于ANSYS软件对复合缆进行有限元分析验证缆绳应力变化。仿真结果证明,所建立的牵引卷筒上缆绳的力学模型符合条件,为大载荷绞车的牵引系统设计提供了理论依据,有一定的工程意义。     

Evaluation of the uplift behavior of plate anchor in structured marine clay

The uplift behavior of a plate anchor in a structured clay (soft Ariake clay) is investigated through a series of laboratory tests and method of finite element analysis. The tests are adopted to identify the factors influencing the behavior of the anchor, including the thixotropic nature of Ariake clay, consolidation time, and embedment ratio of the anchor. A finite element method (FEM) is used to analyze and predict the uplift behavior of the anchor plate well in the elastic region and the yield load. The results from both the laboratory tests and the FEM analysis suggest that the embedment ratio for a deep anchor in Ariake clay is close to 4. Further increase in embedment ratio improves the capacity to a lesser extent. FEM overestimates the failure load of the uplift anchor in soft Ariake clay by about 20%. This may be ascribed to the hypothesis in the FEM analysis that there is continuous contact between the clay and the anchor until failure. Vesic’s theory for deep anchors, which may be used to predict the ultimate pullout resistance of the plate anchor in reconstituted Ariake clay, is verified to be applicable. In this paper, the plastic flow zone around the anchor is discussed using FEM which makes the behavior of anchor more understandable during the design stage.     

高地应力地下厂房预应力锚索预紧系数

为了有效控制围岩大变形,避免围岩破坏,常常对围岩变形突出的高边墙、洞室交叉口区域采用预应力锚索加固。目前,对于具有时效变形特征的高地应力、低强度应力比的地下厂房锚索预紧力相关研究尚较少报道。以锦屏一级水电站地下厂房为代表的高地应力地下厂房,在围岩开挖过程中表现出显著的时效变形特征,从而导致锚索、锚杆内力持续增加,甚至内力超出强度极限而破坏。为合理设置锚索预紧力,基于围岩时效变形特征,提出了围岩时效释放荷载计算方法,并推导了预应力锚索预紧系数计算公式。该公式可以解释不同地应力环境以及不同支护强度、不同施锚时间对锚索预紧力的影响。与锦屏一级地下厂房锚索预紧系数实际采用值对比分析可见,所提出的预紧系数公式较为合理,具有工程实践指导作用。     

拉压分散型锚索锚固机制及工程应用研究

近年来,结合拉力型、压力型以及荷载分散型锚索特点于一体的拉压分散型锚索在工程中有一定的应用,但内锚固段锚固机制以及设计方法研究尚不成熟。基于Kelvin解,分别推导拉力分散型锚索和压力分散型锚索的内锚固段与周围岩土体之间的剪应力解析解,再根据叠加原理得到了拉压分散型锚索内锚固段剪应力简化计算方法;基于理论成果将拉压分散型锚索应用于工程实例中,分别进行了拉压分散型锚索的基本性能试验及与拉力分散型锚索的预应力损失对比测试。通过算例分析结果表明,单元锚固体的两端剪应力较大,中间较小,剪应力的分布特征与现有文献资料模型试验及数值模拟结果相吻合;根据锚索的基本性能试验结果,按照本文计算方法得到了压力段和拉力段剪应力峰值强度,与已有的研究成果根据岩石单轴抗压强度得到的压力型和拉力型锚杆锚固段剪应力峰值强度结果基本吻合;经对锚索预应力损失测试结果分析及工程的长期监测,拉压分散型锚索在工程应用中荷载传递稳定可靠,工程应用效果良好。     

Dynamic investigation of a hybrid suspension and cable‐stayed bridge

Ambient and forced vibration tests were carried out on the Beauharnois bridge, a unique, 177‐m combined suspension and cable‐stayed structure near Montreal, Canada. A rehabilitation program was completed on the bridge during which the deck was completely rebuilt with an orthotropic slab on two steel trusses. The rehabilitation program also included the addition of two pairs of stay cables on both towers, creating a hybrid suspension system. The paper presents a series of dynamic tests performed to evaluate the dynamic properties and the dynamic amplification factor (DAF) for the rehabilitated bridge. The experimental program involved the measurement of vertical, transverse, and longitudinal acceleration responses of the deck and tower under ambient and controlled traffic loads. Displacement, strain, and integrated acceleration DAFs were computed under different loading conditions. Modal properties were evaluated and used to correlate a three‐dimensional finite element model for the bridge, including non‐linear cable behaviour. The paper discusses the experimental setup as well as the techniques used to evaluate vibration frequencies, mode shapes, and the DAF. Correlation of numerical dynamic properties and experimental results is also presented. Copyright © 2000 John Wiley & Sons, Ltd.     

西客站管理委员会办公楼基坑支护工程问题分析及处理

文章简要分析和论证了在第三系砾岩、粘土岩中施工时遇到的问题和处理方法,以及地下水对边坡稳定性的影响。对今后在该地区施工有参考和借鉴价值。     

土层锚杆抗拔力的影响因素及其计算公式的修正

通过对土层锚杆抗拔力影响因素的探讨,得出土层锚杆抗拔力设计值的较为准确的计算公式进而可以节省锚杆材料或使锚杆工程更安全。