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jelod

2011-07-28 08:54

2011年第2期电子版文档

Formation, distribution and risk control of landslides in China

Runqiu Huang^*, Weile Li

State Key Laboratory of Geohazards Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, 610059, China

Received 18 March 2011; received in revised form 8 May 2011; accepted 16 May 2011

Abstract: China is a country with a large population as well as frequent landslides. The formation and distribution of landslides in China are determined by its special topography, complex geological environment, active earthquake environment and unusual climate features. This paper analyzes the main features and distribution of 200 catastrophic landslides that occurred in China since 1900. The relationships among the distribution of landslides and topographic conditions, geological structure, climate features and strong earthquake environment are analyzed. The features of landslide-triggering factors and critical conditions in different areas have also been considered. Based on the above-mentioned work, the authors have undertaken the studies of landslide susceptibility assessment. The study is performed according to the topographic and geological features, which are the main triggering factors that affect the landslides. The Mainland China can be divided into 12 zones, including 4 high susceptibility zones, 7 medium susceptibility zones and 1 low susceptibility zone, according to landslide proneness. Considering the number of life loss and extent of property loss caused by landslides in those 12 zones, the risk evaluation results are listed as follows: 2 extremely high-risk zones, 5 high-risk zones, 2 medium-risk zones and 3 low-risk zones. Taking the number of life loss caused by landslides as the standard of risk level, the paper also analyzes the change in landslide risk level and main risk control measures in China since 1990s. Based on the risk level of landslides in other countries or regions, the acceptable landslide risk level in China has been proposed.

Key words: landslides; risk control; distribution of landslides in Mainland China

jelod

2011-07-28 08:55

Safety monitoring and stability analysis of left abutment slope of Jinping I hydropower station

Shengwu Song, Dewen Cai, Xuemin Feng, Xiaopeng Chen, Dikai Wang
Chengdu Hydroelectric Investigation and Design Institute, China Hydropower Engineering Consulting Group Corporation, Chengdu, 610072, China
Received 19 November 2010; received in revised form 6 May 2011; accepted 15 May 2011

Abstract: Safety monitoring and stability analysis of high slopes are important for high dam construction in high mountainous regions or precipitous gorges. In this paper, deformation characteristics of toppling block at upper abutment, deforming tensile rip wedge in the middle part and deep fractures are comprehensively analyzed based on the geological conditions, construction methods and monitoring results of left abutment slope in Jinping I hydropower station. Safety analyses of surface and shallow-buried rock masses and the corresponding anchorage system are presented. The monitoring results indicate that the global stability of the large wedge block in the left abutment is effectively under control, and the abutment slope is stable in a global sense. After the completion of excavation, the deformations of toppling block at the top of the slope and deep fracture zone continue at a very low rate, which can be explained as “rock mass creep”. Further monitoring and analysis are needed.
Key words: Jinping I hydropower station; left abutment slope; safety monitoring; analysis and evaluation; stability analysis

[attachment=207328]

jelod

2011-07-28 08:56

Design, construction and mechanical behavior of relics of complete large Longyou rock caverns carved in argillaceous siltstone ground

Zhifa Yang1, Zhongqi Yue2, Lihui Li1
1 Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
2 Department of Civil Engineering, the University of Hong Kong, Hong Kong, China
Received 17 February 2011; received in revised form 27 May 2011; accepted 5 June 2011

Abstract: This paper presents a comprehensive summary of data, analyses and findings from the investigations over the past twelve years about the relics of large Longyou rock caverns carved about 2 000 years ago at shallow depths in argillaceous siltstone. The paper presents the typical features associated with the rock caverns. They include structures, large spans, portals, extreme shallow-buried depths, imprints, drainages, inclined ceiling, inclined sidewalls, slender rock pillars, rock staircases, site and strata selections, caving lighting, carving method, and underground construction surveying. They are used to reconstruct and highlight the design and construction methods adopted by the ancients. The paper further demonstrates that the relics of the complete large rock caverns are a consequence of coincidental combinations of ancient human effort and natural factors. The full occupation of water with weak acidity in the large rock caverns with the soft surrounding rocks of weak alkalinity is found to be the main factor ensuring and preserving the caverns to have been stable and integral over 2 000 years. However, the five unwatered complete rock cavern relics have been experiencing various deteriorations and small failures including cracks, seepage, small rock falls and delaminating ceiling rocks. Although these deteriorations have been repaired and stabilized effectively, the paper demonstrates that an entire roof collapse failure is highly possible in the near future to each of the five unwatered rock cavern relics. The findings presented in this paper are also invaluable both to the long-term protection and preservation of the large rock cavern relics of national and international interests and importance, and to extend and enrich our experience and knowledge on the long-term stability and integrity of man-made underground rock cavern engineering projects.
Key words: rock cavern; rock mechanics; rock engineering; long-term stability and integrity; argillaceous siltstone; environment

[attachment=207329]

jelod

2011-07-28 08:56

jelod

2011-07-28 08:57

A non-Archimedean number system to characterize the structurally inhomogeneous rock behavior nearby a tunnel

S. V. Lavrikov, O. A. Mikenina, A. F. Revuzhenko*
Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Received 15 February 2011; received in revised form 12 May 2011; accepted 1 June 2011

Abstract: The development of mathematical models of structurally inhomogeneous media leads to the necessity to consider structure of space itself where deformation occurs, i.e. change of mathematical apparatus itself. The space, whose coordinate axes are non-Archimedean straight lines, has been considered. Refusing the fulfillment of Archimedes’s law allows to describe multi-scaling of the space, and so to consider deformation processes on different scale levels. The construction of two-scale mathematical model of rock masses has been considered as an example. The constitutive equations have been formulated on micro- and macro-levels and interaction condition between different levels as well. On micro-level, the elastic behavior of grains and plastic sliding between grains with possible softening are taken into account. On macro-level, the model represents a nonlinear system of equations describing the anisotropic rock mass behavior. On the basis of model, the numerical algorithm and code have been carried out to solve the plane boundary value problems. Examples of numerical simulations of stress-strain state of structural rock masses nearby a tunnel opening are presented. The deformation contours and isolines of stresses are plotted.
Key words: rock mass; inhomogeneity; mathematical model; non-Archimedean analysis; constitutive equations

[attachment=207331]

jelod

2011-07-28 08:58

Strength and damage of marble in ductile failure

Mingqing You*
School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, 454010, China
Received 20 January 2011; received in revised form 28 April 2011; accepted 3 May 2011

Abstract: To study the effects of loading paths and stress states on rock strength and deformation, marble specimens were axially compressed to various displacements under a confining pressure (CP) firstly, and then the damaged specimens were recompressed under another CP. The bearing capacity of a marble specimen depends merely on CP at the stage of ductile deformation, and it has no relation with the loading history when CP keeps constant or increases. However, the damaged specimen turns into brittle when it is recompressed uniaxially or at a lower CP, and the Young’s modulus and strength are lower than those of a dense specimen. The increasing ratio of triaxial strength to CP has a close relation with the areas of fissures in the damaged specimens but not the internal friction angle. Material strength and bearing capacity are two different conceptions for rocks. Material strength decreases continually as the plastic deformation increases; however, the bearing capacity is determined by both the stress state and the material strength.
Key words: rock mechanics; brittle-ductile; damage; strength; Young’s modulus

[attachment=207332]

jelod

2011-07-28 08:58

Study on embedded length of piles for slope reinforced with one row of piles

Shikou Yang, Xuhua Ren, Jixun Zhang
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, 210098, China
Received 26 January 2011; received in revised form 7 May 2011; accepted 9 May 2011

Abstract: The embedded length of anti-slide piles for slope is analyzed by three-dimensional elastoplastic shear strength reduction method. The effect of embedded pile length on the factor of safety and pile behavior is analyzed. Furthermore, the effects of pile spacing, pile head conditions, pile bending stiffness and soil properties on length and behavior of pile are also analyzed. The results show that the pile spacing and the pile head conditions have significant influences on the critical embedded length of pile. It is found that the critical embedded length of pile, beyond which the factor of safety does not increase, increases with the decrease in pile spacing. The smaller the pile spacing is, the larger the integrity of the reinforced slope will be. A theoretical analysis of the slip surface is also conducted, and the slip surface determined by the pressure on piles, considering the influences of both soil and piles for slope, is in agreement with the ones in previous studies.
Key words: slope stability; factor of safety; embedded pile length; strength reduction method; slip surface
[attachment=207333]

jelod

2011-07-28 08:59

Tempo-spatial characteristics and influential factors of rockburst: a case study of transportation and drainage tunnels in Jinping II hydropower station

Lipeng Liu1, 2*, Xiaogang Wang1, Yizhong Zhang3, Zhixin Jia1, Qingwei Duan1
1 Department of Geotechnical Engineering, China Institute of Water Resources and Hydropower Research, Beijing, 100048, China
2 School of Engineering and Technology, China University of Geosciences, Beijing, 100083, China
3 Beijing Vibroflotation Engineering Co., Ltd., Beijing, 100102, China
Received 4 January 2011; received in revised form 25 March 2011; accepted 19 April 2011

Abstract: Jinping II hydropower station is located in a high in-situ stress region in Southwest China. During the excavations of the transportation and drainage tunnels, more than 460 rockburst events were recorded in the transportation tunnel and 110 in the drainage tunnel, which has a serious and negative influence on the tunnels’ construction and the safety of staff and equipment. In the paper, the characters of rockburst patterns are analyzed for the transportation and drainage tunnels. The results are illustrated as follow: (1) Most of intensive rockbursts occur in the layer T2b, and continuous occurrences of rockbursts are more frequently observed than those in other layers. (2) The critical overburden depth of rockburst in the transportation tunnel is 600 m, and the length of the continuous occurrence section of rockburst is smaller than 25 m. The damaged depth of the rockburst has the tendency to increase with the increasing overburden depth, and the maximum damaged depth is over 3.5 m. (3) From east to west (west to east) in Jinping II hydropower station, the rockburst usually takes place in the right (left) side of tunnel working face, and then the left (right) or roof of the tunnel. The total length of the continuous occurrence section of rockburst is 57.4%–62.2% of the overall rockburst length, followed by the rockbursts of flake-splitting type and other types. (4) Compared with the transportation tunnel, the intensity of rockburst in the drainage tunnel is higher while the length of the continuous occurrence section of rockburst is smaller. The rockburst section with length less than 10 m and depth of 1 m mainly occurs in the layer at a depth of 1 800–2 000 m. The influences of opening geometry and excavation method on the characteristics of the adjacent zone are great, but the influence of the stress among the tunnel group induced by excavation is relatively low.
Key words: Jinping II hydropower station; rockburst; developing pattern; influential factor

[attachment=207334]

jelod

2011-07-28 08:59

Stress-strain analysis of Aikou rockfill dam with asphalt-concrete core

Chaoyang Fang, Zhenzhen Liu
State Key Laboratory of Water Resources and Hydropower Engineering Sciences, Wuhan University, Wuhan, 430072, China
Received 13 December 2010; received in revised form 4 March 2011; accepted 24 March 2011

Abstract: Aikou rockfill dam with asphalt-concrete core is situated in a karst area in Chongqing City, China. In order to study the operative conditions of the rockfill dam, especially those of the asphalt-concrete core, the Duncan model is adopted to compute the stress and strain of both the rockfill dam and the asphalt-concrete core after karst grouting and other treatments. The results indicate that the complicated stress and deformation of both the dam body and the core are within reasonable ranges. It is shown that structure design and foundation treatment of the dam are feasible and can be used as a reference for other similar projects.
Key words: asphalt-concrete core; rockfill dam; Aikou reservoir; stress and deformation

[attachment=207335]

jelod	2011-07-28 09:01
有点晕啊，“o n s”竟然是屏蔽的词汇，所以很多自动变成***了，呵呵

丹江水好	2011-07-28 14:43
有些大牛的文章吆，林老师辛苦了，顶一个。

jelod	2011-07-28 16:51
引用第10楼丹江水好于2011-07-28 14:43发表的 : 有些大牛的文章吆，林老师辛苦了，顶一个。应该做的，为大家服务。呵呵

94178640	2011-07-29 09:28
多谢楼主分享啊：）

toyboldi	2011-08-26 16:05
谢谢

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