地下连续墙“三合一结构”的施工技术

阐述了＂三合一结构＂地连墙与传统地连墙相比的优势;介绍了地连墙在作为＂三合一功能结构＂时,在技术与施工方面主要应严格控制的几个关键环节;论述了在实际工程中的应用效果和趋势远景。     

竖向预应力锚杆加固抗滑挡土墙工程

结合竖向预应力锚杆加固重力式抗滑挡土墙治理滑坡的工程实例,重点阐述了竖向预应力锚杆＋抗滑挡土墙构造及其施工工艺流程,指出竖向预应力锚杆＋抗滑挡土墙新型结构在基岩山区滑坡治理中的应用前景。     

护壁桩作为塔吊基础的理论设计及应用

通过鞍山第一高楼——鞍山国际明珠大厦深基坑护壁桩作为塔吊基础的理论设计及成功应用的工程实例,详细介绍了深基坑支护中护壁桩在作为基坑支护的主要结构的同时,又可以通过理论与实际的相互转化,从而又能承担塔吊基础载体的这一大胆设计,成功解决了许多狭小地带修建高层时塔吊安置的难题。以此理论计算为依据,可以举一反三,解决集中荷载在基坑设计中如何取值并且转化成模型,为今后类似工程提供经验。     

青海省日月山断裂对公路工程的致灾机理研究

通过对青海省内一条北北西向右旋走滑断裂对公路工程危害现象的野外实地调查和室内有限元分析,对其蠕滑运动下的致灾机理进行了讨论。结果表明。断层蠕滑作用下的灾害多分布在上盘,且上盘公路南半侧多发张剪性破裂,北半侧多发压扭性破裂,交汇位置的先期破裂是由南侧路沿开始并向路内扩展的。     

闭合型地下连续墙基础竖向承载性能数值模拟

基于室内模型试验,就闭合型与单片地下连续墙基础在竖向承载性能上的差异进行了对比分析,并采用FLAC-3D软件进行数值分析来丰富室内模型试验,探讨了土体变形模量、密度、内聚力以及内摩擦角对闭合型地下连续墙竖向承载力的影响。结果表明：闭合型地下连续墙基础外侧摩阻力的发挥过程与单片地下连续墙基础大致相同,但由于土芯的存在,其内侧摩擦阻力发挥机理更复杂;闭合型与单片地下连续墙基础均可视为端承摩擦型基础;随着墙周土变形模量的增加,闭合型地下连续墙基础竖向位移显著减少,墙体轴力也减少;密度对闭合型地下连续墙基础沉降的影响不显著;内聚力对侧摩擦阻力的影响程度受地下连续墙和土体之间相对位移量的控制;只有闭合型地下连续墙基础的沉降量超过20 mm时,土体内摩擦角才对基础的竖向承载力有较大影响。     

从挡墙滑塌谈较陡不稳定斜坡和填方边坡的主动支撑

本文结合某挡墙滑塌地质灾害的工程实例,通过简单力学分析认为,应将受拉力的锚杆锚索变为可承压的隐地梁,并尽量使其与滑动结构面近直交,通过主动支撑支挡使整个抗滑工程系统更为稳固。通过对挡墙结构的改进,可使其在对山区高速公路、大型场地建设高切方边坡、较陡潜滑坡和不稳定斜坡,以及高填方边坡的治理中更能发挥长效作用。     

Numerical studies of anchored sheet pile wall behavior constructed in cut and fill conditions

The construction of sheet pile walls may involve either excavation of soils in front or backfilling of soils behind the wall. These construction procedures generate different loading conditions in the soil and therefore different wall behavior should also be expected. The conventional methods, which are based on limit equilibrium approach, commonly used in the design of anchored sheet pile walls do not consider the method of construction. However, continuum mechanics numerical methods, such as finite element method, make it possible to incorporate the construction method during the analyses and design of sheet pile walls. The effect of wall construction type for varying soil conditions and wall heights were investigated using finite element modeling and analysis. The influence of construction method on soil behavior, wall deformations, wall bending moments, and anchor forces were investigated. The study results indicate that walls constructed by backfill method yield significantly higher bending moments and wall deformations. This paper presents the results of the numerical parametric study performed and comparative analyses of the anchored sheet pile walls constructed by different construction methods.     

Study on the action of the active earth pressure by variational limit equilibrium method

Within the framework of limiting equilibrium approach, the problem of active earth pressure on rigid retaining wall is formulated in terms of the calculus of variations by means of Lagrange multipliers. It is transcribed as the functional of extreme‐value problem by two undetermined function arguments, and is further transformed into determining the minimax solution of restrained functions incorporating the geometrical relations of the problem. The function of (fmincon) in the optimization toolbox of MATLAB 6.1 can be used to find the minimax solution. Computation results show there exist two kinds of modes of failure sliding along plane surface and rotating around log‐spiral cylinder surface when the soil behind the walls reaches the critical active state. The magnitude of active earth pressure in the case of translational mode is less than that in the case of rotational mode. The location of action point of earth pressure in the case of translational mode is at or below $\frac{1}{3}$ height of the wall, and in the case of rotational mode, is above $\frac{1}{3}$ height of the wall. Preliminary study indicates a pair of numbers by two theoretical modes can be regarded as an interval estimation of active pressure. Copyright © 2009 John Wiley & Sons, Ltd.     

The influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey ground

Conventional numerical predictions of deep excavations normally neglect the construction process of the retaining structure and choose the earth pressure at rest as initial condition at the beginning of the simulation. The presented results of simulation and measurements during the construction process of the Taipei National Enterprise Center show, that such an assumption leads to an underestimation of the horizontal wall deflection, the surface ground settlements as well as the loading of the struts in case of normally to slightly over‐consolidated clayey soil deposits. The stepwise installation process of the individual diaphragm wall panels results in a substantial modification of the lateral effective stresses in the adjacent ground. Especially the pouring process of the panel and the fresh concrete pressure causes a partial mobilization of the passive earth pressure and a distinct stress level increase in the upper half of the wall. As a consequence of the increased stresses prior to the pit excavation, up to 15% greater ground and wall movements are predicted. Moreover, the increased stress level due to the installation process of the diaphragm wall leads to substantial higher strut loadings during the excavation of the pit. Copyright © 2006 John Wiley & Sons, Ltd.     

缘于任意自旋场的Vaidya黑洞的熵(英文)

用在brick模型基础上发展起来的membrane模型 ,计算了缘于任意自旋场的非静态黑洞———Vaidya黑洞的自由能和熵。结果表明 ,玻色子场 (自旋s =1,2 )和费米子场 (自旋s =1/2 )的熵都恰好与黑洞的视界面积成正比 ,这与静态和稳态的情况相同。而且 ,玻色子和费米子场的熵具有相同的形式 ,二者相差一个系数