Rock mass utilization for the foundation surfaces of high arch dams in medium or high geo-stress regions: a review

Bulletin of Engineering Geology and the Environment - The complex geological conditions of high arch dam sites could increase the difficulty in the design and construction processes, making the...     

Vibration analysis of a beam with partially distributed internal viscous damping

In this paper, governing equations of vibration for a beam with distributed internal viscous damping are established by using Timoshenko beam theory and Hamilton's principle. Then, the transfer matrix method is applied to obtain the frequency equations for the beam. The results reveal, when the internal viscous damping fully distributes along the beam, that the natural frequency decreases with the increasing damping and drops to a zero value at a certain critical damping. While the damping is locally distributed, damped frequency, mode shape and transient response time are affected most significantly by locating the damped segment at the position with maximum bending moment. The flexural amplitudes and phase angles of a beam excited by the resonant harmonic load can be effectively predominated by tuning the damping value.     

基于温度应力仿真分析的碾压混凝土重力坝诱导缝开裂研究

考虑彭水水电站碾压混凝土坝的实际碾压浇筑过程，采用混凝土钝裂缝带模型，在三维瞬态有限元温度应力仿真分析的基础上，对大坝诱导缝的开裂及裂缝扩展进行了跟踪计算。计算结果表明，坝体的上游面诱导缝缝端应力强度因子局部超过混凝土的断裂韧度而发生开裂，且诱导缝的开裂明显减小了坝段中部区域的拉应力。根据诱导缝的开裂分析结果，建议诱导缝的设置长度为4．5m。     

基于动态多步流动法的非饱和土水力特性测试研究

非饱和土水力特性在非饱和土的研究中起重要作用。鉴于传统的测试方法耗时较长,提出能够快速测定非饱和土水力特性的动态多步流动方法。该方法基于WeiDewoolkar提出的多孔介质热动力学混合物理论模型,推导出能够描述非平衡态的非饱和土饱和度的演化方程,通过对粉土和粉质黏土两种试样开展动态多步流动试验,并根据动态试验结果求解饱和度演化方程,得出试样处于平衡状态时的土水特征曲线和渗透函数。该方法不需要求解初边值问题,仅仅需要动态多步流动的试验数据求解饱和度的演化方程,进而得出试样的水力特性参数,与其它方法相比,该方法更加简单有效。     

我国大陆实测深部地应力分布规律研究

深埋地下工程往往面临着高地应力的环境,在研究"深部"及"深部工程"概念的基础上,通过搜集我国大陆地区600多组深部岩体地应力实测资料,绘制出我国大陆地区埋深大于500 m的实测垂直主应力、最大水平主应力、最小水平主应力以及侧压力系数随埋深分布图,参照Hoek-Brown方法对深部岩体地应力特征进行初步分析,回归分析深部岩体垂直应力与埋深的关系、最大和最小水平主应力随埋深的分布规律以及侧压力系数随埋深的分布规律;采用分段函数的形式拟合侧压力系数分布图的包络线。     

旋挖挤扩灌注桩设计方法探讨

桥梁和房屋建筑受力特点不同,因此铁路、公路以及工民建行业在桩基承载力计算上有着不同的认识和理解,特别是在桩端阻力的处理上很不一样。三岔双向挤扩灌注桩是近年来兴起的一种多点支承的新型变截面桩,其盘阻力占到了总承载力较大的比例,往往超过30 %。在设计该桩型时,采用不同行业规范将出现较大的差异。通过研究不同规范中的计算方法,并依据已有详细准确资料的18个工程,对DX桩在铁路工程中的设计方法进行了研究。     

基于并层单元的大体积混凝土水管冷却温度场热-流耦合精细计算

热-流耦合精细算法能准确反映冷却水管附近温度梯度,从而精确计算大体积混凝土水管冷却温度场,然而该方法在有限元计算中存在前处理规模大、计算效率低的缺点;依据混凝土的热力学参数随龄期变化特性和混凝土水管冷却温度场分布规律,开发了一整套热-流耦合精细计算的前、后处理程序,在计算过程中依据龄期特性对混凝土单元不断进行并层处理,从而实现了大体积混凝土水管冷却温度场整体-局部一致模型的快速建立和高效精确数值模拟。数值计算算例表明该方法能在保证计算精度的同时,极大地降低有限元计算过程中的单元规模,有效地节约了计算时间,提高了计算效率,使得大体积混凝土温度场全过程精细数值仿真得以实现。     

软粘土的模型参数试验求解方法

目前国内外对岩土类材料的理论研究建立了很多的模型，应用较为广泛的有修正的剑桥模型、Lade-Duncan模型，和Matsuoka模型等双屈服面模型，现对建立在双屈服面模型基础上的殷宗泽模型进行了试验研究，研究结果表明该模型对于软粘土具有较好的适用性。     

High quality information extraction and query-oriented summarization for automatic query-reply in social network

In this paper, we propose a new method for automatic query-reply in social network. Information extraction and query-oriented summarization method are applied here to reply people’s query. There are few effective and commonly used methods on filtering the redundancy and noise of the raw data, which results in the poor quality of the reply. Due to the characteristics of social network messages, we pay more attention to reducing the noise and eliminating the redundancy of the messages to ensure the quality of the final reply. First, we propose an information extraction method to extract high quality information from social network messages, which is based on time-frequency transformation. Second, query-oriented text summarization is implemented to generate a brief and concise summary as the final reply, which is based on the scoring, ranking and selection of sentences of high quality social network messages produced by previous step. Experimental results show that the research is effective in filtering the redundancy and noise of social network messages, the final query-reply results outperform other commonly used methods’ results in both automatic evaluation and manual evaluation. Through our approach, noise and redundancy of social network messages are effectively filtered. Certainly, our method improves the quality of the reply for people’s query.     

Supplier selection using AHP methodology extended by D numbers

Supplier selection is an important issue in supply chain management (SCM), and essentially is a multi-criteria decision-making problem. Supplier selection highly depends on experts’ assessments. In the process of that, it inevitably involves various types of uncertainty such as imprecision, fuzziness and incompleteness due to the inability of human being’s subjective judgment. However, the existing methods cannot adequately handle these types of uncertainties. In this paper, based on a new effective and feasible representation of uncertain information, called D numbers, a D-AHP method is proposed for the supplier selection problem, which extends the classical analytic hierarchy process (AHP) method. Within the proposed method, D numbers extended fuzzy preference relation has been involved to represent the decision matrix of pairwise comparisons given by experts. An illustrative example is presented to demonstrate the effectiveness of the proposed method.