钢结构管道穿越西山断层安全性分析     

栾骏  唐新军  胡明祎 《内陆地震》2008,22(2):129-134

根据乌鲁木齐市西山发震断层的有关资料,针对西山地区两种主要地层岩土工程数据,利用有限元理论,采用大型通用有限元分析软件ANSYS对天然气管线穿越西山断层的反应进行了分析和研究。通过分析穿越断层地下管线的应力与变形情况,得出了在使用年限内钢结构管道以粉土层为地基持力层和覆土材料将处于安全状态的结论。  相似文献   

光生物反应器的组建   总被引：1，自引：0，他引：1  

刘建国  张京浦  殷明炎  孟昭才 《海洋与湖沼》1998,29(1):109-110

于１９９７年４月在借鉴国外资料基础上,组建成了一种适用于实验室培养光自养生物（如光合细菌,微藻和单克隆无性繁殖系）的气升式螺旋管道串联的光生物反应器,该装置内可插入ｐＨ值电极,溶解氧电极,温度电极,细胞密度电极,粘度电极等,通过传感器获得的电信号,进一步传导入微机,实现按程序化自动记录和控制有关参数,进行一次性,间歇和连续浮培养,以红球藻为材料进行培养和初步结果表明,培养时间较常规方法缩短了一半,  相似文献   

Soil reaction to lateral harmonic pile motion     

《Soil Dynamics and Earthquake Engineering》2016

The analytical representation of dynamic soil reaction to a laterally-loaded pile using 3D continuum modeling is revisited. The governing elastodynamic Navier equations are simplified by setting the dynamic vertical normal stresses in the soil equal to zero, which uncouples the equilibrium in vertical and horizontal directions and allows a closed-form solution to be obtained. This physically motivated approximation, correctly conforming to the existence of a free surface, was not exploited in earlier studies by Tajimi, Nogami and Novak and leads to a weaker dependence of soil response to Poisson's ratio which is in agreement with numerical solutions found in literature. The stress and displacement fields in the soil and the associated reaction to an arbitrary harmonic pile displacement are derived analytically using pertinent displacement potentials and eigenvalue expansions over the vertical coordinate. Both infinitely long piles and piles of finite length are considered. Results are presented in terms of dimensionless parameters and graphs that highlight salient aspects of the problem. A detailed discussion on wave propagation and cutoff frequencies based on the analytical findings is provided. A new dimensionless frequency parameter is introduced to demonstrate that the popular plane-strain model yields realistic values for soil reaction only at high frequencies and low Poisson's ratios.  相似文献   

1st Ishihara Lecture: An overview of the behavior of pile foundations in liquefiable and non-liquefiable soils during earthquake excitation     

《Soil Dynamics and Earthquake Engineering》2015

The seismic response of a pile foundation is usually analyzed by approximate methods in practice. These methods typically neglect one or more of the important factors that affect seismic response such as inertial interaction, kinematic interaction, seismic pore water pressures, soil nonlinearity, cross stiffness coupling and dynamic pile to pile interaction. A nonlinear 3-D analysis is used to show how all these factors affect pile response, to demonstrate some of the consequences of using various approximate methods and to provide a comprehensive overview of how pile foundations behave during earthquakes in liquefiable and non-liquefiable soils.  相似文献   

Quasi-3D analysis: Validation by full 3D analysis and field tests on single piles and pile groups     

《Soil Dynamics and Earthquake Engineering》2015

A quasi-3D method for the analysis of single piles and pile groups is presented. The method includes an equivalent linear constitutive model for nonlinear analysis, an 8-node pile element that simulates the effects of pile volume and energy transmitting boundaries which are especially important for the analysis of high frequency loading of machine foundations. The quasi-3D formulation and equivalent linear model result in orders of magnitude decreases in computational time. The accuracy and reliability of the approximate approach was validated by comparing results with 3D analytical results from MIT and by data from field tests on single piles and pile groups from Taiwan. The computed results compared very favorably with the analytical and field test data.  相似文献   

利用有限元方法模拟力学拉伸试验以钢纤维混凝土为例   总被引：1，自引：0，他引：1  

孙玉军  Kwang Ik Kim  张怀  石耀霖 《地震》2013,33(4):145-152

力学试验是获取岩石等许多工程材料力学性能的主要方法之一。 但是对某些特殊材料, 由于影响其力学性能的因素众多, 单纯通过试验来获取其力学性能, 成本高, 过程复杂。 如工程抗震中目前普遍使用的钢纤维混凝土(SFRC), 很难单纯通过力学试验来获取钢纤维的分布对其力学性能的影响。 本文基于随机方法对钢纤维混凝土建立有限元模型, 利用数值模拟的方法来估计钢纤维的分布和体积率对钢纤维混凝土拉伸性能的影响。 通过与试验结果比较验证了其可行性, 结果表明钢纤维的分布对钢纤维混凝土屈服前的力学性能影响较小, 对屈服后的应力-应变特征影响较大。 当钢纤维体积率从1%变化到2%, 钢纤维混凝土的屈服强度与体积率大致为线性关系, 强度随之增加。  相似文献   

Mitigation of the seismic motion near the edge of cliff-type topographies using anchors and piles     

Constantine A. Stamatopoulos  Maria Bassanou 《Bulletin of Earthquake Engineering》2009,7(1):221-253

Concentration of damage of buildings near the edge of cliff-type topographies has been observed during a number of recent earthquakes and interpreted by numerical dynamic analyses that illustrate the amplification of the horizontal acceleration and the generation of parasitic vertical acceleration near the tip of slopes. The paper performs a detailed parametric numerical analysis to investigate the ability of mitigating this topographic effect using anchors and piles. A typical field case, the Aegion slope of Greece, is considered. Different input motions are applied. The results illustrated that anchors and piles can be effective in mitigating the topographic effect. The main issue is that if the part of the slope in which topographic amplification occurs is connected to that at larger depths, in which the acceleration is smaller, then the accelerations at the top of the slope have to become more uniform and smaller. For typical diameter and material properties of anchors/piles the effectiveness of the mitigation depends on the length, inclination, location and number of anchors/piles. An optimum configuration of anchors/piles mitigating the topographic effect is proposed.  相似文献   

A simplified method for unified buckling and free vibration analysis of pile-supported structures in seismically liquefiable soils     

S. Bhattacharya  S. Adhikari  N.A. Alexander 《Soil Dynamics and Earthquake Engineering》2009

In seismic-prone zones with liquefiable deposit piles are routinely used to support structures (buildings/bridges). In this paper, a unified buckling and dynamic approach is taken to characterize this vibration. The pile–soil system is modelled as Euler–Bernoulli beam resting against an elastic support with axial load and a pile head mass with rotary inertia. The emphasis here is to obtain a simple expression that can be used by practicing engineers to obtain the fundamental frequency of the structure–pile–soil system. An approximate method based on an equivalent single-degree-of-freedom model has been proposed. Natural frequencies obtained from the exact analytical method are compared with approximate results. Proposed expressions are general as they are functions of non-dimensional parameters. It is shown that this simplified method captures the essential design features such as: (a) the continuous reduction of the first natural frequency of the structure–pile–soil system due to progressive reduction of soil stiffness due to liquefaction; (b) the reduction in the axial load-carrying capacity of the pile due to instability caused by liquefaction. The results derived in this paper have the potential to be directly applied in practice due to their simple yet general nature. An example problem has been taken to demonstrate the application of the method.  相似文献   

装配式钢结构被动房在岛礁工程独立房屋中的应用探讨          下载免费PDF全文

商亦蓝  高屹 《海洋开发与管理》2018,35(3):67-71

装配式钢结构被动房是一种新型的节能环保建筑,具有轻质高强、施工快捷简便、抗震性能好、对环境影响小等许多突出优点,因而在独立房屋等岛礁建筑上有广阔的应用前景。文章对装配式钢结构被动房的概念进行了简要介绍,对其优点进行了针对性分析,并在此基础上提出了装配式钢结构被动房在岛礁独立房屋中应用的设想;针对岛礁的特殊地理位置和恶劣的环境特征,从运输、施工、使用和维护4个环节出发,讨论了装配式钢结构被动房在岛礁工程实际应用中应注意的运输困难、能源匮乏、锈蚀严重、台风多发等主要问题,并给出了装配式轻钢结构体系结合模块化、小型化运输的整体方案和锈蚀防护、冷桥阻断等构造措施。  相似文献   

Wave-induced vibration control of offshore jacket platforms through SMA dampers     

《Applied Ocean Research》2019

Since permanent wave-induced vibrations of offshore jacket platforms reduce the service life of the jacket structure and deck equipment and increase the fatigue failure of the welded connections, this research has used SMA (shape memory alloy) dampers to control the jacket platform oscillations. Superelasticity, high durability, and energy dissipation capability make SMA elements good nominees for the design of vibration control devices. In this research, to model the force-displacement hysteretic behavior of SMA elements their idealized multi-linear constitutive model has been implemented and the time history responses of vibration equations have been evaluated by direct integration method. To analyze the SMA damper effects on the vibration suppression of the jacket platforms, a 90 (m) high jacket located 80 (m) deep in water has been selected as a case study. Numerical results have shown that optimized SMA dampers with constant-geometry SMA bars will improve the dynamic behavior of the jacket platform under the action of an extreme regular wave. However, under the action of two irregular waves, SMA dampers with varying-geometry SMA bars will cause significant reduction in the dynamic responses of the jacket platform. The power spectral density function of the deck displacements have shown that the previously mentioned SMA dampers avoid resonance by shifting the natural frequencies of the jacket structure away from the excitation frequencies.  相似文献