Numerical analysis of deformation behaviour of quay walls under earthquake loading

In the last 50 years, there have been many incidences of failure of gravity quay walls. These failures are often associated with significant deformation of liquefiable soil deposits. Gravity quay wall failures have stimulated great progress in the development of deformation-based design methods for geotechnical structures. In this paper, the effective-stress analysis method has been used in conjunction with a generalised elasto-plasticity constitutive model implemented into a finite element procedure. Various monotonic and cyclic triaxial paths are simulated in order to demonstrate the capabilities of the constitutive model. The FEM is validated by back analysis of a typical Port Island PC1 caisson type quay wall, which was damaged during the 1995 Hyogoken-Nanbu earthquake. The numerical results are compared with the observed data obtained consisting of seaward displacement, settlement and tilting. In addition, both the influence of permeability, on the generation of pore water pressure and the influence of the relative density of the backfill and foundation layers, on the residual deformation of gravity quay walls are investigated.     

Seismic active thrust on cantilever walls with short heel

This note presents an analytical solution of the thrust on retaining walls with short heel, where the seismic action is simulated through the pseudo-static approach. The critical shape of the thrust wedge is assumed to be that minimizing the safety factor against wall sliding. This procedure is also congruent with the original method of Coulomb. The problem is mathematically expressed by a system of two equations, the first cubic and the second quadratic, whose solution converges quickly.     

The inspection of retaining walls using GPR

In hilly regions, retaining walls along roads, motorways and railway lines are numerous. In some cases the knowledge of the details of the construction is limited. If rehabilitation work becomes necessary, a detailed knowledge of the construction is desirable for the improved planning of maintenance and repair. This paper describes the application of Ground Penetrating Radar (GPR) for the inspection of retaining walls. The work was carried out in two steps. First, an investigation was carried out on large retaining walls at a Swiss motorway within the framework of a service contract. This included the development of an apparatus enabling high precision positioning of the antennas on the walls. Second, a pilot study was performed on a smaller wall with optimized acquisition and processing parameters. This included the use of antennas with different orientations and the fusion of the two corresponding datasets as well as true 3-D data processing. This paper describes the approaches to data acquisition and processing in the form of the two case studies. Results from different acquisition and processing strategies are compared and the benefits and limits are discussed.     

切方边坡悬臂桩桩间土稳定性研究

在调查分析切方边坡悬臂桩桩间土破坏模式的基础上,指出在桩间净距不大的情况下,桩间土多表现为局部滑塌现象。通过分析斜坡切方前的初始应力状态及桩间土滑塌失稳的临界判据,结合岩土强度理论建立了考虑三维土拱效应及切方卸荷的桩间土稳定性分析模型。以襄－渝二线施工过程中某路堑边坡为研究对象,通过计算分析,结合现场施工的观测情况,指出桩间土滑塌曲面的后缘线一般位于桩顶土拱作用的拱圈内侧区域,桩间土多呈拉-剪破坏模式。工程实践表明,采用土钉对桩间土进行加固取得了良好的效果。数值模拟发现,土钉的钻进应穿越桩间土拱有效作用的区域,土颗粒的楔紧挤密效应在一定程度上对土钉起到等效锚固的作用。     

In-plane soil–structure interaction in layered,fluid-saturated,poroelastic half-space I: Structural response

Linear in-plane soil–structure interaction in two dimensions (2D) is studied in fluid-saturated, poroelastic, layered half-space using the Indirect Boundary Element Method (IBEM). The structure is a shear wall supported by a rigid embedded foundation. Exact stiffness matrices for the soil layer and half-space, and Green׳s functions of uniformly distributed loads and pore pressure on an inclined line are derived. Results of the system response in the frequency domain are presented for the special case of single soil layer over bedrock, semi-circular foundation and zero seepage force. The effects of water saturation, soil porosity, depth of soil layer, rigidity contrast between layer and bedrock are investigated in the frequency domain for incident plane P- and SV waves. The results suggest that water saturation may cause increase of the system frequency by more than 10%.     

Implications of the spandrel type on the lateral behavior of unreinforced masonry walls

Seismic response of unreinforced masonry (URM) buildings is largely influenced by nonlinear behavior of spandrels, which provide coupling between piers under in‐plane lateral actions. Seismic codes do not appropriately address modeling and strength verification of spandrels, adapting procedures originally proposed for piers. Therefore, research on spandrels has received significant attention in some earthquake‐prone countries, such as Italy and New Zealand. In the last years, the authors of this paper have performed both monotonic and cyclic in‐plane lateral loading tests on full‐scale masonry walls with single opening and different spandrel types. Those tests were carried out in a static fashion and with displacement control. In this paper, experimental outcomes for two as‐built specimens are presented and compared with those obtained in the past for another as‐built specimen with a wooden lintel above the opening. In both newly tested specimens, the masonry above the opening was supported by a shallow masonry arch. In one of those specimens, a reinforced concrete (RC) bond beam was realized on top of the spandrel, resulting in a composite URM‐RC spandrel. Then, the influence of spandrel type is analyzed in terms of observed damage, force–drift curves, and their bilinear idealizations, which allowed to compare displacement ductility and overstrength of wall specimens. Furthermore, effects of rocking behavior of piers are identified, highlighting their relationship with hysteretic damping and residual drifts. Copyright © 2014 John Wiley & Sons, Ltd.     

基于IDA法与Pushover法的混凝土核心筒抗震性能对比分析

足够数量地震输入的增量动力分析方法（IDA方法）是目前最为真实和先进的模拟结构抗震性能手段,而静力推覆分析方法（Pushover Analysis方法）操作简单,更为实用,可以较好揭示结构从弹性到屈服直至倒塌过程中构件的工作状态。采用2种方法对钢筋混凝土核心筒算例进行评估,并作对比分析。结果表明,采用IDA方法得到的4个性能水平与Pushover方法得到的指标限值有一定误差,但均在一定范围之内,采用IDA方法得到顶点位移角限值偏大;采用单一侧力模式的Pushover方法无法完全体现高阶振型及地震动等因素的影响,造成Pushover方法分析结果与结构实际弹塑性地震响应有一定差异。     

Calibration of a hysteretic model for glass fiber reinforced gypsum wall panels

Glass fi ber reinforced gypsum(GFRG) wall panels are prefabricated panels with hollow cores, originally developed in Australia and subsequently adopted by India and China for use in buildings. This paper discusses identifi cation and calibration of a suitable hysteretic model for GFRG wall panels fi lled with reinforced concrete. As considerable pinching was observed in the experimental results, a suitable hysteretic model with pinched hysteretic rule is used to conduct a series of quasi-static as inelastic hysteretic response analyses of GFRG panels with two different widths. The calibration of the pinching model parameters was carried out to approximately match the simulated and experimental responses up to 80% of the peak load in the post peak region. Interestingly, the same values of various parameters(energy dissipation and pinching related parameters) were obtained for all fi ve test specimens.     

Performance-based analysis and design for internal stability of MSE walls

ABSTRACT

Mechanically stabilized earth (MSE) walls must be designed with adequate margins of safety against internal stability failure described by tensile strength and pullout limit states. Probabilities of failure (or reliability index) will vary strongly with the accuracy of the underlying models that appear in limit state performance functions. In this paper, prior work by the authors and co-workers on this topic is reviewed. Relative performance is explored in the context of the reliability (or probability of failure) of steel and polymeric reinforcing elements in MSE walls using limit state performance functions with load and resistance models having different accuracy.     

瑞利面波在防渗墙施工质量检测中的应用

阐述了瞬态多道瑞利面波探测的原理和方法,并将其应用到水泥土防渗墙施工质量的检测中,取得了一定成效.测试结果与施工观测结果相对比,相互吻合,为类似工程的质量检测提供了一种可行的检测方法.