挤压破碎带原位岩体高压渗透变形试验方法

某大型水电工程重力坝坝基为发育规模较大的挤压破碎带,为准确了解挤压带的渗透变形特性,现场模拟电站建成后的水力条件,采用原位高压渗透变形试验,研究挤压破碎带岩体渗透变形破坏形式和程度,确定挤压带的渗透坡降(临界坡降、破坏坡降)及破坏类型。     

Soil seismic analysis for 2D oblique incident waves using exact free-field responses by frequency-based finite/infinite element method

The seismic analysis of a viscoelastic half-space under two-dimensional (2D) oblique incident waves is carried out by the finite/infinite element method (FIEM). First, the frequency-domain exact solutions for the displacements and stresses of the free field are derived in general form for arbitrary incident P and SV waves. With the present formulation, no distinction needs to be made for SV waves with over-critical incident angles that make the reflected P waves disappear, while no critical angle exists for P waves. Next, the equivalent seismic forces of the earthquake (Taft Earthquake 1952) imposed on the near-field boundary are generated by combining the solutions for unit ground accelerations with the earthquake spectrum. Based on the asymmetric finite/infinite element model, the frequency-domain motion equations for seismic analysis are presented with the key parameters selected. The results obtained in frequency and time domain are verified against those of Wolf’s, Luco and de Barros’ and for inversely computed ground motions. The parametric study indicated that distinct phase difference exists between the horizontal and vertical responses for SV waves with over-critical incident angles, but not for under-critical incident angles. Other observations were also made for the numerical results inside the text.     

岩质边坡最危险滑裂面的GA-Sarma算法研究

 基于现有国内外边坡极限平衡法稳定性分析软件在岩质边坡滑裂面搜索中的局限性,将遗传算法(GA)和Sarma法相结合,提出岩质边坡最危险滑裂面的GA-Sarma算法。GA-Sarma算法解决以折线形为滑面形态、以层面等结构面为边界任意条分并满足条块间边界力平衡原理、滑裂路径可追踪顺坡向不连续结构面的岩质边坡最危险滑裂面的全局优化问题。     

全球化背景下遗失的场所精神

结合批判性地域主义的内涵以及场所与场所精神的概念,从场所精神这个角度对当今全球化的冲击所带来的城市无个性、千城一面的问题进行了思考,指出场所及场所精神正是批判的地域主义的核心概念,进而明确了人们寻求特殊性、地域性、差异性的实质是对场所精神的寻求。     

Optimizing parameters of tuned mass damper subjected to critical earthquake

Tuned mass damper (TMD) has been proposed as one of the vibration control methods for rehabilitation of buildings. Because the parameters of TMD can significantly affect the seismic performance of structures, many researches focused on finding the optimum parameters. Because earthquakes are random phenomena and future earthquakes in comparison with past earthquakes may be more destructive, the optimum design of TMD subjected to selected earthquakes can be nonconservative. Hence, the main contribution of this paper is to present the optimal design of TMD for the seismic vibration control of a structure subjected to a critical earthquake that produces the most severe response of a structure. In order to achieve this purpose, the parameters of TMD are optimized through minimizing the maximum displacement of the roof. First, three optimization methods are used to obtain the optimal parameters of TMD for a 10‐story shear building subjected to the critical earthquakes. Finally, the responses of the controlled and uncontrolled buildings such as the roof displacement, strokes, transfer function, and different forms of energy are compared. Results show that the optimum designs of TMD not only effectively reduce the roof displacement but also improve the seismic performance of the building.     

Applying critical chain buffer management theory in location-based management

Guidelines for prioritizing buffers on location-based management (LBM) projects are established through the use of critical chain theory (CCT). Buffer management theory in LBM has gained little attention from the research community. CCT builds on the assumption that each task is, either consciously or unconsciously, given a certain time buffer with which to cope with unpredicted events, and that these buffers become a large part of the project lead time. However, CCT suggests that these buffers entail inherent waste within schedules and fail to protect both critical activities and projects. CCT assumes that time estimates become self-fulfilling prophecies, as practitioners tend to procrastinate, and the buffers are often wasted. In addition, excess time rarely benefits the project if activities do finish early, because succeeding activities are unlikely to begin before the planned date. Although the criticisms by CCT also apply to LBM projects, CCT is based on the critical path method, and the guidelines from CCT must be adapted to the criticality principle of LBM theory. Accordingly, the contribution to the body of knowledge of this article is guidelines of buffer placement and prioritization in LBM that are based on critical chain buffer management theory.     

中国BT项目关键成功因素研究

中国不少地方政府采取BT模式建设公共项目,但许多BT项目最终并未取得成功,因此有必要对BT项目关键成功因素进行研究。首先梳理BT项目实施流程及工作内容,结合BT项目成功标准,初步归纳影响BT项目成功的关键因素,然后用问卷调查方法对初步关键成功因素进行修正和确认,得到关键成功因素清单,然后扩大问卷调查范围确定各关键成功因素的重要性,并对重要性的调查结果从整体和按角色进行对比分析,所得结果对BT项目中的业主、实施方、监理等各参与方都有借鉴作用。     

钢梁弯扭屈曲临界弯矩通用公式研究

为研究钢梁弯扭屈曲总势能方程中的各势能项对临界弯矩M_cr通用公式中各系数取值的影响,由总势能方程推导临界弯矩M_cr的通用公式及3种典型总势能方程下各系数的计算式,揭示各势能项与各个系数的联系,计算无侧向支撑简支钢梁临界弯矩M_cr通用公式中各系数的数值,并分别分析现行国家标准GB 50018-2002和GB 50017-2003的整体稳定系数φ_b设计公式存在取值各异的问题。结果表明：系数C₁、C₂和C₃的取值除都与非线性正应变能和非线性剪应变能有关外,系数C₁的取值还与圣维南扭转应变能有关,系数C₂的取值还与外荷载势能有关,而影响系数C₃取值的势能项则因总势能方程而异;现行国家标准GB 50018-2002和GB 50017-2003的φ_b设计公式应采用统一的形式,且应统一φ_b设计公式中系数C₃的取值。     

高寒地区铁路客站混凝土结构冬期施工技术

哈大高铁哈尔滨西站工程所在地纬度高,结构施工跨越冬季;通过采用综合蓄热法与暖棚法相结合的双重技术方法,研究负温高性能混凝土配合比、渗透性能、抗冻性、受冻临界强度,过程中实施温控和防裂控制技术,成功进行了新建哈西客站工程轨道层结构混凝土的冬期施工,解决了单一暖棚法成本高、控制难和单一综合蓄热法无法保证混凝土质量的难题,填补了高铁工程结构混凝土-30℃以下严寒气候条件下冬期施工空白,为保证高铁站房工程质量提供了技术支撑,具有显著经济效益与社会效益。     

带软弱夹层的土质边坡稳定性分析研究

在简化方法的基础上,拟定破裂面为曲线形式,推导了深度不大位置存在软弱夹层的均质边坡的安全系数,并搜索了最危险滑动面,通过对比分析,反映了软弱夹层对边坡稳定的影响,可为带软弱夹层的实际边坡工程的分析和设计提供参考。