A Simplified Procedure to Evaluate Earthquake-Induced Residual Displacements of Conventional Type Retaining Walls

This study attempts to develop a simplified procedure to evaluate earthquake-induced residual displacements of conventional retaining walls (e.g., gravity, leaning, and cantilever retaining walls). Based on the results from a series of shaking table model tests, the study found that subsoil and backfill deformations could be significant even in cases of dense model ground that cannot be evaluated by using Newmark's rigid sliding block analogy. In the proposed method, therefore, the effects of subsoil and backfill deformation were taken into account as well as the movement of the wall as a rigid mass, which was evaluated using Newmark's method. The deformation properties of the subsoil and backfill were modeled based on results from a series of laboratory soil tests and moment load tests. Simulations of shaking table model tests using the proposed method revealed that computed residual displacements agreed well with the measured ones even though the model tests were conducted under a wide variety of conditions.     

土石坝地震永久变形的危险性分析

本文将地震地面运动模拟为零均值平稳高斯随机过程,以Newmark滑块模型为基础,建立了土石坝地震永久变形的概率分析模型,利用Monte-Carlo数值模拟检验,证明了在随机地震作用下土石坝永久位移服从正态或对数正态分布,通过大量综合计算,给出了永久位移概率分布参数与可能滑动体平均地震加速度功率谱参数之间的经验关系,针对一个算例,对土石坝地震永久位移进行了危险性分析。     

Microcomputer-Aided Instruction of Structural Steel Design

An innovative approach is reported for teaching structural steel design in a civil engineering undergraduate curriculum. It is based on the interactive environment and graphic capabilities of inexpensive microcomputers. Ten BASIC interactive microcomputer-aided design programs have been developed and used in a senior-level structural steel design course at the Ohio State University. The approach of interactive design and the interactive microcomputer-aided design programs make the learning of structural steel design more exciting and result in more effective training of future designers. Students can gain experience and develop insight in structural design while they are still in an academic environment.     

永久性岩钉支护结构在某边坡工程中的应用

镇江高等专科学校理工座东侧为山体,山体顶至山体底高差3.3～13.7 m,山体表面松散的岩石及整体是否稳定直接影响学校师生安全。另外,山体治理方式直接影响山体与校园绿化的整体和谐性。通过分析对比,设计人员放弃了采用承重型垂直挡土墙的设计思路,并大胆尝试永久性岩钉支护结构,通过削方、加固、培土、绿化等措施,有效满足了学校师生安全及校园内绿化美观要求。     

某边坡稳定性评价

通过对某边坡的工程现状,并结合专业软件及监测数据对其稳定性做出评价,评价结果对确保周边人民生命财产的安全具有重要的实际意义。     

Microcomputer-Aided Design and Drafting of Moment-Resisting Connections in Steel Buildings

A microcomputer-aided system has been developed for interactive design and drafting of connections in steel buildings made of standard. rolled-I sections, called STEELCON. The basis of design is AISC specification. In addition to interactive design, STEELCON can displaylplot any isometric view of the connection plus three orthographic views, i.e., front, side, and top face views. The orthographic views show all the necessary details for fabrication and construction of the connections. Interactive design and drafting of two different moment resisting connections are presented. They are the shop welded and field bolted framed flange plate connection and the shop and field welded flange plate connection.     

建筑基坑与永久边坡一体工程的锚固优化设计

针对一兼具临时基坑与永久边坡于一体的特殊高大锚固工程 ,探讨了其最优化设计方法 ,结合工程特点对优化参数的选取、目标函数的建立、锚杆的锚固机理以及施工期和使用期的设计验算内容与方法等问题作了深入分析 ,并成功应用于该锚固工程 ,获得了良好的技术经济综合效益。     

岩质深大基坑永久护坡施工技术

依山而建的岩质深大基坑永久护坡,相较于一般的临时护坡有着更加严苛的要求.如何因地制宜、科学地组织施工,避免安全事故的发生,逐渐成为项目管理中的重点.通过创新监测手段,如利用微震监测、三维激光扫描等新技术,实时掌握和预测护坡变形的趋势.同时,在施工过程中结合具体实际,做到动态设计和施工方案动态优化,确保了岩质深大基坑永久...     

Evaluation of Long-Term Displacements of Pile Foundation Using Coupled FEM and Centrifuge Model Test

Recently the introduction of performance-based design into infrastructure including pile foundation is on process. For performance-based design, it is necessary to develop a practical prediction method for long-term displacements of pile foundation. In this paper, soil-water coupled analyses with FEM-FDM method are conducted to evaluate the long-term displacements of pile foundation installed in soft clayey ground. The analytical target is the actual pile foundation of road viaduct planned to be constructed in Niigata Prefecture, Japan. As constitutive model for ground, subloading t_ij model is adopted, which is a simple elasto-plastic model for normally and over consolidated soils. Further more, centrifuge model tests are conducted to verify the validity of the numerical analyses. As the conclusion of a series of analyses and centrifuge model tests, following aspects are clarified; 1) the long-term behaviour of pile foundation; 2) the influence of the thickness of bearing layer to the behaviour; 3) the mechanism of pile-soil-pile system, especially about how the load is allotted to each pile, how the migration of excess pore water pressure occurs, migrates and dissipates, and how the uneven settlement is caused.     

狮子包滑坡稳定性分析

狮子包滑坡是位于三峡库区的一个典型的顺层滑坡,随着三峡水位不断上涨,地下水位上升对滑坡稳定产生不利影响,此外,可能的水库诱发地震也给狮子包滑坡带来了安全隐患。因此,需要对其进行稳定性计算和分析,在计算方法的选取上采用了传递系数法,通过计算结果,建议采取相应的防护工程对其进行治理。     

宁波申菱交流永磁同步直拖门通过科技成果评估

2007年12月26日，建设部科技发展促进中心在宁波象山组织举行了宁波申菱电梯配件有限公司交流永磁同步直拖门系统建设行业科技成果评估会。该产品采用无减速装置扁平化结构，速度、电流双闭环矢量控制设计，低速输出转矩大、运行平稳、低噪、高效、节能等特点得到了建设部科技发展促进中心组织的评估委员会的一致肯定。     

Earthquake-Induced Flow Slides of Fills and Infinite Slopes

Earthquake induced flow slides of saturated or partially saturated sloping ground have taken place in man-made earth structures during past earthquakes. Two series of dynamic centrifuge model tests (1:50 scale) were conducted to simulate the behavior of embankment fills and infinite slopes resting on a stiff sloping base. Conditions that yield earthquake-induced flow slide were investigated. The test parameters included soil density, slope angle, level of phreatic water and shaking intensity. The test results showed that downward deformation increased with decreasing soil density, increasing phreatic water elevation and shaking intensity, and that there existed a threshold soil density below which flow slides occurred. Undrained monotonic loading torsional simple shear tests were also conducted. Conditions inducing very large deformation or flow slide that were obtained by the undrained shear tests were consistent with those observed in the model tests.     

地震引发青川县地区主要地质灾害浅析

以四川省汶川县为震中的地区发生了里氏8级地震,造成大批的人员伤亡,引发了大量的地质灾害.本文以地震引发青川县地区地质灾害为背景,介绍了地震引发的滑坡、泥石流、堰塞湖与地下水污染等主要地质灾害,并对主要地质灾害给出了相应的防治措施.汶川地震表明:在山区环境中,应加强地震诱发地质灾害的防治工作.     

矿区岩质斜坡稳定性评价与研究

以某矿为例,采用不平衡推力法和统计矩法等方法对矿区斜坡稳定性进行了评价,给出了各种算法下斜坡的安全系数和可靠指标;同时采用FLAC3D有限差分数值计算方法,对斜坡的位移场、速度场和稳定性做出综合评价,得出了斜坡安全系数;最后运用瑞典法、Bishop法、Janbu法等其他方法也对斜坡的安全系数进行了计算;比较研究结果表明:工程地质环境等随机变量对斜坡稳定性影响较大;FLAC3D与其他方法计算值基本一致,在矿区特殊的地质环境下,统计矩法能够有效地避免不确定因素过多产生的误差,其简便的计算和合理的结果显示了很大的优越性;对斜坡稳定性分析要求严格时,应采用多种方法进行综合比较.     

某工程边坡稳定性分析与评价

基于某土岩质边坡的详细岩土工程勘察工作,对拟建工程场地边坡稳定性做出评价,为边坡支护设计、施工提供必要的岩土设计参数,以期为今后类似工程提供参考和借鉴。     

竖向地震效应下近断层边坡永久位移预测模型

利用改进的能量法从美国NGA数据库的4 669条地震记录中量化识别出305条近断层速度脉冲地震动。脉冲具有方向性效应,所有地震动均转换到最强脉冲方向。基于Newmark刚塑性理论模型,考虑竖向地震效应,输入拟合后的地震动,计算了边坡永久位移值。根据大量计算结果统计发现,竖向地震效应对近断层内的边坡永久位移有显著影响,既有边坡地震位移预测模型的预测值离散性较大。通过相关性分析,发现竖向效应作用下,边坡永久位移值与近断层地震动的峰值速度相关性显著。采用统计学回归分析方法,建立了基于峰值速度(PGV)、Arias强度(I_a)、临界加速度(a_c)的预测模型,该模型简单实用,可应用于近断层区域的边坡滑坡地质灾害风险评估。     

巫山高切坡稳定性评价及防治措施研究

结合巫山县殡仪馆西侧高切坡的工程地质特点,在对高切坡现状和破坏模式分析的基础上,选取了不利工况下的典型坡面进行边坡的稳定性分析。结果表明:计算剖面在不加支护措施下处于稳定状态,考虑到安全储备及外界不利因素影响,对边坡采取了支护措施,支护后的高切坡稳定性已得到提高,可为类似工程提供参考。     

三峡永久船闸高边坡锚索预应力状态监测分析

三峡永久船闸高边坡使用了250束1000kN和3873束3000kN的预应力锚索进行加固,并安装了113台锚索测力计对锚索的受力状态进行长期监测,在使用锚索的数量及安测力计台数上均属世界少有。在对锚索测力计监测资料系统整理和分析的基础上,重点分析了高边坡锚索的受力状态、加固效果及预应力损失,为船闸高坡稳定安全状态的判别提供依据,并为今后其他工程提供可资借鉴的实际应用资料。     

Effects of Sand Permeability and Weak Aftershocks on Earthquake-Induced Lateral Spreading

Centrifuge research conducted at Rensselaer Polytechnic Institute (RPI) is summarized focusing on the effect of sand permeability and of weak aftershocks on earthquake-induced lateral spreading. One-dimensional shaking tests were conducted in a laminar box at a centrifugal acceleration of 50 g, simulating a 10 m thick homogeneous layer of clean Nevada sand of relative density 40-45% inclined a few degrees to the horizontal. Seven centrifuge experiments were done using either water or a viscous pore fluid fifty times more viscous than water, thus varying the soil permeability by a factor of fifty and simulating either a coarse prototype sand or a fine sand in the field. These seven tests were subjected to the same shape of base input excitation but with peak input accelerations ranging from 0.18 g to 0.46 g between tests. An additional special centrifuge test of a similar model with viscous pore fluid was subjected to a strong base “main shock”, followed after a few seconds by two “weak aftershocks”. Excess pore pressures, accelerations, settlements and lateral ground deformations were measured. The results are discussed in detail and several correlations are presented between testing and measured parameters such as thickness of liquefied soil, ground surface settlement, lateral ground displacement and input peak acceleration. The results of the special test, together with other evidence, provide strong support to the hypothesis that reported continued ground deformations from lateral spreads in the field are often caused by continued weak vibration or aftershocks occurring after the main shock.     

边坡病害评价分析及治理方案设计

公路边坡病害问题严重影响公路安全运营,以井冈山市茨坪南西侧I区AB边坡为例,从地质、地形、气候及水文条件等出发,研究区域环境,实地调查了边坡的形态以及病害特征,定性评价边坡稳定性,并提出相应治理的建议。