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51.
Jiunn-Shyang Chiou Zhi-Wei Xu Cheng-Chang Tsai Jin-Hung Hwang 《Marine Georesources & Geotechnology》2018,36(5):554-563
Lateral cyclic load tests were performed on an aluminum model pile in dry sand. Two levels of loading were adopted to represent different service load conditions. The maximum number of loading cycles was 1,000. From the test results, it was found that the even though in the service load condition, the pile response was still affected by cyclic effects and a larger load level would produce more significant influence. In a global point of view, the lateral displacement and maximum moment increased with loading cycles, while the secant stiffness within a cycle decreased with cycles. The cyclic effect was more significant on the lateral displacement than on the moment. In a local point of view, cyclic loading would degrade the equivalent subgrade stiffness for the soil shallower than about seven times diameter. In addition, the secant subgrade stiffness within a cycle increased with loading cycles. Some experimental relationships of lateral pile response and loading cycles were built and compared with those in the literature. 相似文献
52.
Reliable,with high data rate,acoustic communication in time-varying,multipath shallow water environment is a hot research topic recently.Passive time reversal communication has shown promising results in improvement of the system performance.In multiuser environment,the system performance is significantly degraded due to the interference among different users.Passive time reversal can reduce such interference by minimizing the cross-correlated version of channel impulse response among users,which can be realized by the well-separated users in depth.But this method also has its shortcomings,even with the absence of relative motion,the minimization sometimes may be impossible because of the time-varying environment.Therefore in order to avoid the limitation of minimizing the cross-correlated channel function,an approach of passive time reversal based on space-time block coding (STBC) is presented in this paper.In addition,a single channel equalizer is used as a post processing technique to reduce the residual symbol interference.Experimental results at 13 kHz with 2 kHz bandwidth demonstrate that this method has better performance to decrease bit error rate and improve signal to noise ratio,compared with passive time reversal alone or passive time reversal combined with equalization. 相似文献
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This article presents a method for the nonlinear analysis of laterally loaded rigid piles in cohesive soil. The method considers the force and the moment equilibrium to derive the system equations for a rigid pile under a lateral eccentric load. The system equations are then solved using an iteration scheme to obtain the response of the pile. The method considers the nonlinear variation of the ultimate lateral soil resistance with depth and uses a new closed‐form expression proposed in this article to determine the lateral bearing factor. The method also considers the horizontal shear resistance at the pile base, and a bilinear relationship between the shear resistance and the displacement is used. For simplicity, the modulus of horizontal subgrade reaction is assumed to be constant with depth, which is applicable to piles in overconsolidated clay. The nonlinearity of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The validity of the developed method is demonstrated by comparing its results with those of 3D finite element analysis. The applications of the developed method to analyze five field test piles also show good agreement between the predictions and the experimental results. The developed method offers an alternative approach for simple and effective analysis of laterally loaded rigid piles in cohesive soil. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
55.
大陆岩石圈和大洋岩石圈有着深刻的差别,运用板块构造理论和模式研究大陆岩石圈会遇到许多特殊的问题。本文从陆缘演化和多个板块构造旋回叠加两方面做了初步探讨,提出岩浆型被动陆缘是独立的一类古陆缘;在辨认后续板块构造旋回叠加中,新构造成分和格局的确定有重要意义。本文还讨论了汲取大陆地质研究经验,在新的学科水平上重新解释传统大地构造学中一些有用概念的意义。 相似文献
56.
被动椭圆形标志物应变分析的计算机模拟 总被引:1,自引:0,他引:1
本文采用计算机数学模拟的方法更深入地探讨了椭圆形标志物应变分析技术(R_f/Φ去应变法、Shimamoto等提出的代数法、调和平均值法和算术平均值法)的适用条件。一共形成了十一组有代表性的应变前数组,四种变形路径:纯剪、单剪、纯剪加单剪和体变。当应变前数组在(-90°,90°)内均匀分布或随机分布时,无论变形路径是哪一种(共轴的还是非共轴的),上述的所有方法都是适用有,且以代数法最佳。当应变前数组具有优选方位(单峰分布)且变形路径为共轴递进变形时,在一定条件下,R_f/Φ法能用来估计应变。经分析发现当应变足够大时,调和平均值法是一种简单快速的应变计算法。 相似文献
57.
滑坡治理方法及其应用实例 总被引:11,自引:1,他引:11
对目前国内外滑坡治理方法进行总结综述,例举了滑坡治理的几个实例,指出了滑坡治理的优先考虑方法。 相似文献
58.
本文研究了土-结构动力相互作用对采取不同控制措施的结构控制效果的影响。文中首先建立了主动调谐质量阻尼器(ATMD)、半主动磁流变阻尼器(MR)和被动多重调谐质量阻尼器(MTMD)等三种结构控制措施在时域中的控制算法和控制律,然后基于子结构法,采用间接边界元方法,通过傅里叶变换,推导了分别安装三种结构控制措施的受控结构在频域中的运动方程,数值仿真分析了某36层高层建筑的地震反应及其控制效果。结果表明,当采用ATMD或MTMD控制时,考虑土-结构动力相互作用后结构地震反应有所减小;当采用MR控制时,考虑土-结构动力相互作用后结构地震反应有很大程度的减小。由此看来,在设计软土地基上高层结构的结构控制措施时,不考虑土-结构动力相互作用对结构控制效果的影响是偏于安全的。 相似文献
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从水泥土的固化机理出发,结合水泥搅拌桩桩身标准贯入试验和水泥土配合比试验,分析讨论了土性指标、土质条件和地层性质对水泥搅拌桩成桩质量的影响。 相似文献