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Xiang T.,CAS Wuhan Institute of Rock and Soil Mechanics | Xiang T.,HydroChina Kunming Engineering Corporation | Feng X.,CAS Wuhan Institute of Rock and Soil Mechanics | Jiang Q.,CAS Wuhan Institute of Rock and Soil Mechanics | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

On the basis of system analysis and summary of the existing research results of failure mode classification, analysis methods and controlling measures of surrounding rock for underground engineering, a new failure mode classification method for surrounding rock of large-scale underground cavern group is proposed. The special features such as large span, high sidewall and cross of multi-cavern influencing on failure modes have been concerned in the method. Based on the three levels: control factors, failure mechanism, generation conditions, 18 typical failure modes have been summarised. The corresponding stability analysis methods and control measures are recommended for each failure modes. Furthermore, a new method is also proposed for dynamic recognition of failure modes and the corresponding control measures according to dynamic updating of geological conditions and characters of surrounding rock revealed during excavation. The new methods have been applied to dynamic construction of Jinping II hydropower station. The potential failure modes and corresponding stability analysis methods as well as control measures on excavation and support design are recommended before the construction of powerhouse. During the excavation layer by layer, the failure modes, excavation and support strategies are calibrated, recognized and modified according to the revealed actual geological conditions and characters of surrounding rocks. The procedure is continued until complete of the construction. The practice indicates that the methods are applicable, scientific and systematic, so as to provide an effective way for excavation and support design optimization during construction and avoid occurrence of local instability problems.

Zhang Y.,China University of Petroleum - East China | Zhang Y.,Hohai University | Xu W.-Y.,Hohai University | Zou L.-F.,Hohai University | Sun H.-K.,HydroChina Kunming Engineering Corporation
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

The large-scale landslides, widely distributed in southwest mountains and canyons, are prone to produce instability due to rainfall. In Gushui hydropower station, not only is the extremely large volume of Zhenggang large landslide accumulation body up to more than 4 750×104 m3, but also the thicknesses of many ultra-deep landslide are over 50 m. Under the influences of the heavy rainfall in 2008, the landslide started to deform again and even more seriously. According to the results of field engineering geological investigation and analysis of geologic structure characteristics and hydrogeology conditions, the mechanism of rainfall infiltration and stability in the current situation was qualitatively analyzed first. Then the whole landslide was transfixed slipping surface in the state of creep deformation; so it should be treated such as excavating and reinforcing. Combined with the analysis result, quantitative study of the seepage properties of landslide showed the dynamic sliding mechanism that water infiltration caused deformation, evaluated the stability and treatment, thus proposed effective drainage measures before and after the treatment under the rainfall. The results also showed that the saturation line and backwater was formed due to saturated soil by infiltration. Before the treatment, the backwater was seriously persisted in local landslide and slip surface; and the worst stability came out 4 days later after the rain stopped; and the maximum thickness of backwater increased up to 6 m. However, with backwater reduced obviously, the stability was significantly increased by the treatment. The results truly reflected the situations and laws of the stability of landslide, which were consistent with the results of field exploration. The results were significantly improved by the treatment. Drainage measures proposed would keep the landslide's stability efficiently. The research results will be useful and meaningful in the same projects as reference.

Zhao E.F.,Hohai University | Zhang L.B.,Hydrochina Kunming Engineering Corporation
Applied Mechanics and Materials | Year: 2013

Reservoir basin deformation monitoring data of some high arch dams has shown that the upstream of the dam subsided while the downstream warped upward slightly. Therefore, combining reservoir basin with high arch dam and foundation, the widespread finite element model is built and the reservoir basin deformation and its influence factor weight are determined through the simulation of the bedrock depth, the extending length of the upstream and downstream and different water levels based on an improved entropy method. The engineering simulation model has proved the reservoir basin deformation mechanism. Moreover, the reservoir basin deformation will tend to converge when the simulation model expands to certain extent. The research can provide suggestions for deformation doubts occurring during the high arch dam operation. © (2013) Trans Tech Publications, Switzerland.

Chen D.-H.,Hohai University | Du C.-B.,Hohai University | Yuan J.-W.,Hohai University | Hong Y.-W.,HydroChina Kunming Engineering Corporation
Journal of Earthquake Engineering | Year: 2012

Two input models of seismic excitation, the nonlinear contact characteristics of contraction joints, were presented. The influence of the damping ratio on the seismic response of a high arch dam was then investigated. A new element (the viscous-spring boundary element capable of reflecting the radiation damping effects of an infinite foundation), the external source wave input subroutine, and the dynamic contact models, including the characteristics of normal opening-closing and radial sliding, were developed in this paper. The nonlinear contact behavior of contraction joints was simulated using a nonlinear exponential dynamic contact model, and the radial nonlinear characteristic was simulated using the Mohr-Coulomb criterion. Linear elastic and nonlinear seismic response analyses for a 300-m high concrete arch dam under construction were performed. The results showed that the damping ratio greatly influenced the seismic response of a high arch dam using a massless foundation model, and the damping ratio between 3-5% resulted in a conservative seismic response. The results of the viscous-spring boundary input model were in good agreement with those given by the massless foundation model when a damping ratio of 10% was used, but the openings of joints near the crown cantilever varied significantly. The effects of radiation damping of the foundation on the seismic response could be simplified to some extent by increasing the material damping of the dam in this study. © 2012 Copyright A. S. Elnashai & N. N. Ambraseys.

Chen Q.,University of Sichuan | Duan B.,HydroChina Kunming Engineering Corporation
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

The gravelly clayey soils are commonly used as seepage resistant materials in high embankment dams. The core of the high embankment dam may crack owing to the layered construction placement or arch effect of the core. However, the filter design criteria for cracked gravelly clayey soils are not found. The filter tests are conducted using cracked gravelly clayey soils with different gravel contents and filters with different gradations and dry densities. The existing filter criteria for gravelly clayey soils are summarized and compared with the test results. The results show that the existing filter criteria cannot fully satisfy the need of filter design for cracked gravelly clayey soils. Based on the results of the tests and comparative analyses, the filter criteria for cracked gravelly clayey soils are proposed considering the combination seepage resistant mechanism of cracked gravelly clayey soils and the filters. The verification using the filter test results shows that the proposed filter criteria can be used for the filter design of cracked gravelly clayey soils with different gravel contents.

Zhao Y.,HydroChina Kunming Engineering Corporation | Li Q.,HydroChina Kunming Engineering Corporation | Chen J.,HydroChina Kunming Engineering Corporation | Li W.,HydroChina Kunming Engineering Corporation
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

With the development of large-scale hydropower projects and the underground space constructions, the rock stress measurement and the influence of stress on engineering rock masses and constructions attract more and more attentions. Based on in-situ stress measurement of Huangdeng dam, the elastic moduli are obtained from the core confining pressure test, the interior compression modulus test and bearing plate test; and the elastic moduli are different. Therefore, the phenomena of difference are analyzed according to rock damage mechanics and rock mass properties under high confining pressures. Besides, stress relief process of measurement is analyzed based on unloading rock mass properties; and the effect of expansion on stress measurement is determined. The results show that with the increase in confining pressure, the elastic modulus of rock mass may grow positively mainly due to the compression of rock fractures; unloading rock mass may appear the phenomenon of serious expansion with the mechanical vibration. Considering the above analyses, a selecting principle of elastic modulus in aperture deformation method in in-situ stress measurement is proposed; and it would offer a reference to other similar projects.

Zhang Z.,HydroChina Kunming Engineering Corporation
14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering | Year: 2011

The engineering practice of 200 m high concrete face rockfill dams in China is introduced in this paper. Innovative ideas and techniques involved in engineering design, construction and operation are highlighted during construction of four 200 m high dams, i.e. Tianshengqiao 1st cascade, Hongjiadu hydropower project, Sanbanxi hydropower project and Shuibuya hydropower project. Key issues and countermeasures in the development of super-high dam are addressed including section zonings, design of rockfill materials, deformation control and seepage control.

Luo Y.,Hydrochina Kunming Engineering Corporation Ltd
Shuikexue Jinzhan/Advances in Water Science | Year: 2015

The research methods of hydraulics are diverse and each method has its characteristics. It is more concerned for the similarities and differences of reached achievements from all kinds of methods. Based on the bottom outlet of flood discharge with high water head in one hydropower station, the simulation and observation are carried through for the hydraulic issues by applying the physical modeling experiment, the prototype measurement of hydraulics and the time-averaged turbulence mathematical model. The adaptable scope and degree of three kinds of methods are identified. It is identical well for the simulated results of three methods with the macroscopic hydraulic flow state, bottom flow velocity, time-averaged pressure and aerated cavity. Meanwhile, there is a certain difference in the simulation of flow profile. The fluctuation prototypical water surface and longitudinal diffusion of water jets are larger. The achievement can be used to lead the selection of research method and correction of achievement for this type of hydraulic issues. ©, 2015, China Water Power Press. All right reserved.

Luo Y.,Hydrochina Kunming Engineering Corporation
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2016

In this study, physical model tests and numerical simulations of 3-D turbulent flows have been used to optimize the shape of a stilling basin downstream of the tunnel spillway at the Guanyinyan hydropower station through a series of shape modification, and a satisfactory new shape with a backward step and diffusing walls was obtained. Detailed analysis on major hydraulic characteristics, fluctuating pressure in the slab joints, and slab uplift force, shows that protective works should focus on an area at the basin bottom in a distance of 60 m behind the step. A significant correlation exists between surface fluctuating pressure and joint fluctuating pressure, and the max uplift force on a unit area of the slabs is 0.4-1.6 times the rms value of surface fluctuating pressure. The test results provide technical support to design and operation of stilling basins. © 2016 All right reserved.

Fu S.,Hubei Engineering University | Zhang S.,Hubei Engineering University | Xie M.,HydroChina Kunming Engineering Corporation | Chen S.,Hubei Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Temperature control and crack prevention are one of the key problems for high concrete arch dam. Taking Xiaowan project for example, the most important technologies of temperature control and crack prevention are studied systematically, which include material property, theory and methodology, construction and engineering measures etc.. The reasonable and scientific technology route for the temperature simulation feedback analysis is presented; the simulation feedback analysis system and dynamical information-based design methodology of temperature control design for arch dam are established. Limited value of safety degree for anti-cracking, reasonable scheme of temperature control are recommended for engineers. Therefore, the dynamical design based on simulation feedback analysis of arch dam is implemented well in Xiaowan project. The practical effect indicates that the achievements of this paper provide the theoretical supports and scientific information for the design and construction of Xiaowan arch dam project.

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