岩体的渗透系数是渗流场分析与工程渗控设计的重要参数,钻孔压水试验是获取该参数的主要方式之一.针对地下水面下有界渗流区域中倾斜钻孔压水试验数据解析问题,基于Darcy定律和镜像法建立了岩体渗透系数解析模型,并对该模型进行了数值验证.该解析模型形式简洁,物理意义明确,且在钻孔试段离地下水位较远时可退化为现行钻孔压水试验规程推荐的Hvorslev公式,是现行压水试验数据解析方式的理论拓展,可作为钻孔压水试验规程修订的重要依据.

抗滑稳定是软弱地基上土石坝坝基安全的关键问题之一,其抗滑稳定计算及加固处理技术也一直是学者研究的热点.以深厚覆盖层软弱地基上的仙女山水库土石坝为背景,针对软弱土层抗剪能力低、坝基深层抗滑稳定安全系数低于规范要求的问题,通过渗流和抗滑稳定计算,并进行加固措施对比分析,提出了在大坝下游坡脚设置压重体的处理措施.计算结果表明:在大坝下游设置压重体后,坝基深层抗滑稳定安全系数满足规范要求,且压重体结构简单、施工快捷,可为类似工程的坝基抗滑稳定加固处理提供借鉴.

云龙河三级水电站碾压混凝土拱坝坝址为典型的"V"形狭窄河谷,由于采用了通仓碾压和连续上升的施工方式,合理的分缝设计对改善坝体应力条件、保证大坝安全尤其重要.结合云龙河三级水电站拱坝的特点,首次提出了"下诱上横"的碾压混凝土拱坝分缝新技术,该分缝设计可保证施工期低高程坝体联合抵挡汛期洪水,浇筑完成后在预定位置张开成缝以利于后期封拱灌浆.经计算分析,并通过实际施工过程及运行阶段验证,该分缝设计是合理的,可为类似工程提供借鉴.

Taking Xiannvshan Reservoir with deep overburden under the reservoir basin for example, we carried out a nonlinear finite element calculation on the stress and deformation of composite geomembrane used as the seepage prevention for the whole reservoir basin to analyze the safety of composite geomembrane.The result indicate that under the water pressure during operation period,settlements occur in overburden under the reservoir basin.Meanwhile, horizontal deformation from both banks slope towards the center of the reservoir.The deformation are well-distributed.According to the influence of the deformation, the composite geomembrane at the both banks slope is in tension,while composite geomembrane at the center of reservoir is in compression.The tensile safety factor and strain safety factor are both more than 5.0.The composite geomembrane can fit the deformation of overburden and be with a certain safety margin.

采用冷却管通水冷却降温是现行大体积混凝土施工期行之有效的主要温控措施,但在某些地区和部位的混凝土采用通水冷却降温存在施工困难,代价高,水资源浪费大的情况.通过数值计算分析方法,探讨了以冷却空气作为介质的大体积混凝土施工期温控措施.计算结果表明,对于某一特定的混凝土结构,可以找到一组通风冷却的温度控制参数,使得通风冷却与通水冷却达到近似相同的冷却效果,但与通水冷却相比,通风冷却效果会随着管长的增加而减弱较快,不适宜在混凝土中布置过长的冷却管线.

Oyuk坝是世界上仅有的两座百米级硬填料坝之一.在宏观均质假定的基础上考虑硬填料较为明显的细观非均匀性的影响,基于损伤本构模型对Oyuk坝在正常运行工况以及地震工况下的大坝工作性态进行了分析,采用水荷载与地震荷载超载法,探讨了Oyuk坝在静动条件下的破坏模式与安全度,并与弹塑性本构模型的计算结果进行了对比.研究结果表明:在正常运行工况以及OBE地震工况中,Oyuk坝基本全断面受压,坝体强度安全系数与抗滑稳定系数均较高,坝体基本处于弹性工作状态;大坝存在静力整体失稳的破坏模式,但对水荷载的超载安全度高,且抗震性能好;采用考虑细观非均匀性的损伤本构模型所得大坝的破坏过程与破坏形态比弹塑性模型的模拟结果更贴近实际.

The concrete faced rockfill dam(CFRD) of Myitsone Hydropower Station is built in an extra-wide valley,and little seismic engineering experience is available in the anti-seismic design.In view of the problems such as large permanent deformation in the CFRD and face slab breakage in a strong earthquake,quasi-static method and FEM time-history method are applied to analyze the dynamic response of acceleration and stress of rockfill dam,face slab stress,joint deformation,and residual deformation of dam body and dynamic stability of dam slope.And the anti-seismic safety of dam is evaluated.The results show that in the case of design and check earthquake,the dam slope stability meets the requirements of specification;the dam permanent deformation is at an equivalent level comparing with other similar projects;the face slab stress status meets the seismic safety requirements;the joint deformation of face slab is within the permissible range of sealing structure.

Inversion parameters are used to calculate and predict long-term deformation of high concrete face rockfill dam (CRFD). Since the construction process and deformation mechanism of rockfill are complex, it is difficult to separate the instantaneous deformation and rheological deformation, and hence it is necessary to carry out the integrated inversion of static constitutive and rheological model parameters. Based on the measured displacement data, static constitutive and rheological model parameters sensitive to the deformation of rockfill dam are selected for inversion. Additionally, a modified particle swarm optimization algorithm ( MPSO) based on particle migration and radial basis function neural network (RBF-ANN) are adopted. What is more, by using the trained neural network to describe the relationship between model parameters and displacements, shorts computing time of parametric inversion. The inversion result of Shuibuya CRFD shows that the calculated settlements agree well with the measured data; and dam deformation is within a reasonable range and tending towards stability.

The spillway of Shuibuya project is of big flood discharge capacity and high head,consequently,the stress state of the bucket lip is very complex under high water pressure,and it is difficult to arrange the reinforcement in the bucket lip because of large reinforcement quantity calculated by conventional mechanical method.The three-dimensional finite element analyses focusing on the stress and deformation of the bucket lip with different structural measures are performed here by ANSYS.Based on the finite element analysis,the reinforcing principle of the side wall and bottom plate is proposed.The research may provide a reference for similar projects.

Recently, increasing attention has been given to hydraulic fracturing phenomena in core wall of rockfill or soil dams. However, most of the studies are carried out from the macro prospective, and the fracturing mechanism is still disputable. In this paper, the hydraulic fracturing problem is analyzed using the particle flow code (PFC) from the micro prospective. The occurrence and development of hydraulic fracturing is simulated. Results show that the fracturing pressure Pf increases with the increasing of the vertical stress in an approximately linear way, which agrees well with experimental results. Under the high hydraulic gradient condition, the maximum principal stress near crack tip is decreased because of the wedge effect of water. Hydraulic fracturing will probably occur when the maximum principal stress is less than or close to the water pressure of upstream of core wall. In addition, it is also illustrated that the main reason of hydraulic fracturing in core wall is that the tension stress exceeds the tensile strength of the soil.

Settlement is one of the most important deformation characteristics of a high concrete-face rockfill dam (CFRD) and is regarded as a key indicator of dam safety. The time-dependent settlement behavior of the Shuibuya CFRD is studied on the basis of in situ settlement-monitoring records and displacement back-analysis. The goal of this work is to characterize actual deformation of the dam and to verify the back-analysis method used in this paper. The settlement-monitoring records were from seven control stations at the crest and 38 monitoring points inside the body of the dam and covered the construction period, the initial filling of the reservoir and 2years of operation. A displacement back-analysis for parameters is performed by hybrid generic algorithms (HGAs) and finite element method (FEM). Comparative studies of monitoring data and back-analysis show good agreement between measured settlements and computed settlements. Furthermore, the deformation in the next 3years is predicted on the basis of back-analysis. Overall, it is demonstrated that the deformation of the Shuibuya CFRD is basically stable and that the technique used to control the dam deformation is successful.

An attempt has been made to investigate the scale effect on the creep deformation property of rockfill. Two kinds of specimens with different size (Phi 50 cm x 100 cm and Phi 30 cm x 60 cm) are subject to stress controlled triaxial creep tests, which aim to study the scale effects on creep deformation of rockfill. The maximum grain diameter of the large specimens is 10 cm, while 6 cm for the small one. It reveals that scale effect has significant influence on creep property of rockfill. Larger specimens give more creep deformation, but no clear law is found about the scale effect on the factor of creep rate lambda.

Creep deformation is an important feature of high rockfill dams.Excessive settlement may endanger the stability of the dam or impair its normal operation.3D FEM analysis based on power function creep constitutive model was used to predict the long term deformation of a 300 m high rockfill dam named Shuangjiangkou.Furthermore,a preliminary attempt was made to study the impact of scale effect on the long-term deformation of high rockfill dam.It was demonstrated that the deformation of Shuangjiangkou core rockfill dam becomes stable 3 years after full-filling,and under control.The scale effect research indicated that the specimens for laboratory testing have smaller long-term deformation than the real rockfill,which will influence the precision of numerical simulation.

Firstly,scale effect on instantaneous deformation of rockfill is studied by experimental data in former studies and numerical tests base on stochastic granule discontinuous deformation(SGDD) model. It is demonstrated that larger specimen shows higher shear strength and initial modulus of elasticity under the same axial stress and confining pressure without considering creep deformation of rockfill. Secondly,two kinds of specimens with different sizes(φ50 cm×100 cm(maximum grain diameter is 10 cm) and φ30 cm×60 cm(maximum grain diameter is 6 cm)) are subjected to stress control triaxial creep tests,which aim to study the scale effects on creep deformation of rockfill. It reveals that scale effect has significant influence on creep property of rockfill. Larger specimens give more creep deformation,but no clear law is found about the scale effect on the factor of creep rate λ . Finally,based on the synthetical analysis of scale effect on total deformation including instantaneous and creep deformations of rockfill,the total deformation of big specimen is larger than that of the small one as a whole.

The deformation of anti-seepage structure of a high rock-fill dam mainly depends on the rock-fill deformation,particularly in the case of large rock-fill deformation,cracks on the structure could easily appear that deteriorate the anti-seepage performance and even harm the dam stability.With a wide use of rock-fill dam in recent years,creep deformation of high rock-fill dam receives a special concern.This overview covers a broad scope of research advances in rock-fill creep of high dams,such as constitutive model,creep mechanism and numerical simulation,with a discussion on the prospective studies.

The establishment of limit state function is the first step to analyze the reliability of the stability of gravity dam foundation.The four limit state functions are compared and the reasonability of the four is discussed as well.The results indicate that the same reliability index β could be obtained by the three limit state functions which are established by remaining push force method,passive resisting force method and equal K method.The three functions can be uniformly expressed as limit state function composed of safety factor.The result got by the so called equal β method which aims to make the two blocks have the same β overestimates the failure probability.Therefore,it is unreasonable to evaluate the reliability of gravity dams with deep slide problems by equal β method.

In order to simplify the construction procedure and shorten the construction period,the concrete crushing-type side wall(CSA) technology is widely adopted during constructing many concrete face rockfill dams(CFRD),in which the CSA replaces the traditional cushion as the contact interface with concrete slab.The construction specificity of CSA decides that the larger difference will exist between the contact relation between CSA and concrete slab and the one between cushion and concrete slab.Although recent construction technology has greater development than before,concrete slabs’ cracks of a few CFRD still occur seriously.Distributing rule of cracks for CFRD with CSA is not same with ones which adopt traditional cushion.The cracking of concrete slab has great relation with its stress state during construction period.At present the whole computation method of concrete slab stress analysis exists more simplification assume,which results in pour stress accuracy of concrete slab from computation results.Submodeling method is presented to compute the stress and deformation of concrete face slab considering CFRD constructed by stages.A contact friction element with no thickness based on coulomb friction model is applied to simulate the special boundary between CSA and concrete face slab.The actual project analysis result shows that the temperature decrease and the intense constrain with not flattening of upstream slope at some altitude bring about cracking of concrete slab.