A dual mortar contact method for porous media and its application to clay-core rockfill dams

The clay-core rockfill dam is a multibody contact system in which the hydromechanical response of the clay core plays a crucial role. This complex problem is highly challenging to model numerically. We present a numerical approach that considers the multibody contact, consolidation, and strong geometric and material nonlinearities for the modeling of clay-core rockfill dams. Within the framework of the dual mortar finite element method, the presented approach considers the contact bodies as independent porous media continuums. The nonlinear contact conditions are derived based on the effective contact traction on contact interfaces and pore pressure continuity. The weak forms are obtained by introducing Lagrange multipliers as additional unknowns, which are then condensed through an extended general transformation. The presented method is first validated with a patch test considering the contact between two porous media. Then, a three-dimensional analysis of the Rumei clay-core rockfill dam is performed. The main numerical analysis concerns are the two observation galleries planned for construction inside the clay core. The galleries consist of dozens of tunnel-like concrete blocks, giving rise to complex concrete-concrete and concrete-clay contacts. The discontinuous separation and sliding between concrete blocks are investigated. For the concrete-concrete contact, both hard and soft joint approaches are evaluated and compared. The pore pressure results of the concrete structures are also analyzed.     

坝料流变对高面板堆石坝的应力变形影响研究

在高应力状态下坝料的流变较为明显。为研究坝料流变对混凝土面板坝应力变形的影响,采用长科院九参数幂级数流变模型及其试验参数,对某高混凝土面板堆石坝进行应力、变形分析。结果表明,坝料流变使坝体变形明显增加,坝体应力有所减小。考虑坝料的流变特性后的面板法向位移(挠度)明显增加,面板坝轴向和顺坡向应力极值增加。对于分期浇筑面板和分期蓄水的高混凝土面板堆石坝,选用合适的流变本构模型正确地模拟堆石体的流变特性,可以为大坝填筑进度及面板分期浇筑时间的确定提供参考,并有助于正确地预测大坝的应力变形。     

东升电站堆石混凝土重力坝固结灌浆工程

东升水电站挡水建筑物采用堆石混凝土重力坝,基础固结灌浆过程中发现钻孔施工难度较大,采用了先对抛石段灌浆,后钻孔,再整体固结灌浆的方法,解决了这一问题,提高了整体的施工效率,经检验,固结灌浆效果明显,达到了设计要求。     

高土石坝震害与抗震措施评述

目前,我国西部地区正建或拟建一大批高土石坝,这些高坝都位于地震高烈度区,做好抗震设计非常重要。本文总结了地震荷载作用下土石坝常见的几种破坏形式,包括地震永久变形、滑坡失稳、液化、防渗体破坏、次生破坏;针对这些破坏形式,总结了地震高烈度区高土石坝的抗震措施,包括预留超高、坡脚压重、坝顶加固、抗液化措施、防渗体处理等;提出了现阶段高土石坝抗震的计算方法和抗震措施存在的缺点和不足,并对我国今后的高土石坝抗震稳定研究提出了建议。     

土坡体系可靠度分析方法及在高土石坝工程中的应用

针对土坡稳定体系可靠度分析问题,提出了一种分析方法框架,包括采用缩减方差抽样技术生成随机变量样本值、采用全局优化算法搜索边坡最小安全系数、采用Monte-Carlo法计算边坡体系可靠度3个主要部分。在此框架下,建立了一种较为简便实用的高土石坝坝坡稳定体系可靠度分析方法。该方法采用拉丁超立方抽样技术生成随机变量的样本值,再用商业软件STAB搜索相应的坝坡最小安全系数,最后用可靠指标法或Monte-Carlo法计算坝坡体系可靠度。工程算例表明,筑坝材料强度参数的随机不确定性对坝坡临界滑弧的位置影响较大,坝坡稳定体系可靠度小于单一滑动面的坝坡稳定最小可靠度,提出的方法可用于实际工程坝坡稳定体系可靠度分析。     

A novel interface element with asymmetric nodes and its application on concrete-faced rockfill dam

Based on the Goodman element, the Guyan reduction method is introduced to develop the interface element with asymmetric nodes, which accomplishes the coarse-fine mesh transition between soil and structure in finite element models by providing a different number of nodes on the two sliding surfaces. The number of Gauss points is greater than that of the traditional Goodman element, which ensures its accuracy. The developed interface element is employed in the dynamic elasto-plastic analysis of CFRDs. The results indicate that the use of the constructed interface element can significantly decrease the number of elements with little influence on the accuracy.     

Response surface and genetic method of deformation back analysis for high core rockfill dams

High core rockfill dams exhibit complex deformation mechanisms because of complicated geological conditions, many material partitions and severe weather conditions. When realistic parameters cannot be obtained through laboratory tests or engineering analogies because of effects of size or time, back analysis is necessary to predict deformation characteristics. This paper proposes a method of deformation back analysis based on the response surface method and genetic optimization theory. The parameters of the creep and Duncan–Chang models for the Pubugou gravelly soil core rockfill dam are sequentially calculated. Back analysis performed using this method efficiently yields more precise results than those obtained from laboratory-determined parameters.     

沿海地区复杂地层抗拔桩在深基坑中的试桩实例

通过沿海地区复杂地层中抗拔桩试桩实例,介绍了抗拔试验桩试验参数与方法以及深基坑中的抗拔桩施工技术：填石夹填土层成孔技术、桩端岩心取样技术与桩基清孔技术。试验表明,抗拔试验参数较为可靠且能满足结构设计的抗拔要求,为抗拔桩在深基坑中的应用研究提供了数据支撑。     

细石混凝土砌石坝质量控制问题研究——杜河水电站细石混凝土砌石重力坝施工实践

本文阐述了细石混凝土砌石重力坝的施工方法和特点，施工中的质量控制所采取的组织措施和技术措施，特别是技术措施，从施工前原材料的检查和检验、施工中施工方法和工艺监督及控制、施工后抽查和检测都进行了详尽的阐述，并就施工中需要特别注意的问题提出了具体的解决办法。     

高心墙堆石坝地震变形与稳定分析

针对西部强震区一300m级高心墙堆石坝,采用三维非线性有效应力动力有限元分析方法,在地震反应分析基础上,应用所建立的分析方法,重点研究了高心墙堆石坝的地震残余变形、坝体单元抗震安全性和坝坡的抗震稳定性,得出了大坝地震残余变形和动力稳定的有关规律和结论,可供工程建设参考.