scholarly journals Geotechnical Characteristics and Stability Analysis of Rock-Soil Aggregate Slope at the Gushui Hydropower Station, Southwest China

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Jia-wen Zhou ◽  
Chong Shi ◽  
Fu-gang Xu
Keyword(s):  
Limit Equilibrium ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Soil Aggregate ◽  
Equilibrium Analysis ◽  
Hydropower Station ◽  
Small Scale ◽  
Rock Masses ◽  
Geological Processes ◽  
Toppling Failure

Two important features of the high slopes at Gushui Hydropower Station are layered accumulations (rock-soil aggregate) and multilevel toppling failures of plate rock masses; the Gendakan slope is selected for case study in this paper. Geological processes of the layered accumulation of rock and soil particles are carried out by the movement of water flow; the main reasons for the toppling failure of plate rock masses are the increasing weight of the upper rock-soil aggregate and mountain erosion by river water. Indoor triaxial compression test results show that, the cohesion and friction angle of the rock-soil aggregate decreased with the increasing water content; the cohesion and the friction angle for natural rock-soil aggregate are 57.7 kPa and 31.3° and 26.1 kPa and 29.1° for saturated rock-soil aggregate, respectively. The deformation and failure mechanism of the rock-soil aggregate slope is a progressive process, and local landslides will occur step by step. Three-dimensional limit equilibrium analysis results show that the minimum safety factor of Gendakan slope is 0.953 when the rock-soil aggregate is saturated, and small scale of landslide will happen at the lower slope.

Convergence aspect of limit equilibrium methods for slopes

1990 ◽  
Vol 27 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R. N. Chowdhury ◽  
S. Zhang
Keyword(s):  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Solution Process ◽  
Iterative Solution ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Negative Slope ◽  
Slip Surfaces ◽  
Geological Discontinuity

This note is concerned with the multiplicity of solutions for the factor of safety that may be obtained on the basis of the method of slices. Discontinuities in the function for the factor of safety are discussed and the reasons for false convergence in any iterative solution process are explored, with particular reference to the well-known Bishop simplified method (circular slip surfaces) and Janbu simplified or generalized method (slip surfaces of arbitrary shape). The note emphasizes that both the solution method and the method of searching for the critical slip surface must be considered in assessing the potential for numerical difficulties and false convergence. Direct search methods for optimization (e.g., the simplex reflection method) appear to be superior to the grid search or repeated trial methods in this respect. To avoid false convergence, the initially assumed value of factor of safety F0 should be greater than β1(=−tan α1 tan [Formula: see text]) where α1 and [Formula: see text] are respectively the base inclination and internal friction angle of the first slice near the toe of a slope, the slice with the largest negative reverse inclination. A value of F0 = 1 + β1, is recommended on the basis of experience. If there is no slice with a negative slope for any of the slip surfaces generated in the automatic, search process, then any positive value of F0 will lead to true convergence for F. It is necessary to emphasize that no slip surface needs to be rejected for computational reasons except for Sarma's methods and similarly no artificial changes need to be made to the value of [Formula: see text] except for Sarma's methods. Key words: slope stability, convergence, limit equilibrium, analysis, optimization, slip surfaces, geological discontinuity, simplex reflection technique.

Pseudo-Static Analysis of Slope Considering Circular Rupture Surface

2014 ◽  
Vol 5 (2) ◽  
pp. 37-43 ◽  
Author(s):  
Sima Ghosh
Keyword(s):  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Failure Surface ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Seismic Slope Stability ◽  
Slide Mass ◽  
Critical Circle ◽  
Seismic Forces

In this present paper, a circular failure surface passing through the toe is assumed for a homogeneous soil, and the Fellenius line is used to locate the centre of the most critical circle. Using limit equilibrium analysis under the influence of static forces such as weight of potential slide mass and surcharge along with the pseudo-static seismic forces are considered to obtain the factor of safety of the slopes. Factor of safety is found through the application of force equilibrium. The effects of variation of different parameters like slope angle (i), soil friction angle (F) and seismic acceleration coefficients both in the horizontal and vertical directions (kh and kv respectively) on the factor of safety are presented. Finally, the present results are compared to the existing solutions available in literature and found to give minimum values of factor of safety using the present approach for seismic slope stability analysis.

Study on Stability of Unstable Rock Masses on Right Bank Slope of JinPing I Stage Hydropower Station, Southwestern China

2011 ◽  
Vol 243-249 ◽  
pp. 3036-3042 ◽  
Author(s):  
Da Huang ◽  
Yong Xing Zhang ◽  
Run Qiu Huang
Keyword(s):  
Failure Mode ◽  
Calculation Method ◽  
Limit Equilibrium ◽  
Rock Block ◽  
Southwestern China ◽  
Hydropower Station ◽  
Rock Masses ◽  
Limit Equilibrium Theory ◽  
Earthquake Force ◽  
Unstable Rock

A lot of investigations showed that unstable rock masses (URM) could be classified into four failure modes：whole slide，rock block landslide，whole shear fall，and compress-rip-slide. Unloading cracks forming URM failure boundary don¢t store water usually，so the main loads to cause URM failure in dam region are weight and earthquake force. According to limit equilibrium theory, Authors put forward different calculation method of stability and criterion of stability state class to different failure mode. The corresponding treatments and cure to URM of different scale and stability state are presented, too.

Formation and Stablity of the Sky Pond Landslide Dam, China

2011 ◽  
Vol 243-249 ◽  
pp. 3189-3200 ◽  
Author(s):  
Yan Hui Song
Keyword(s):  
Yellow River ◽  
Limit Equilibrium ◽  
Landslide Dam ◽  
Equilibrium Analysis ◽  
Qualitative Assessment ◽  
Hydropower Station ◽  
The Yellow River ◽  
Geological Conditions ◽  
Dammed Lake ◽  
The Stability

The Sky Pond landslide dam is located in Muchang valley, a branch of the Yellow River branches. From this point it is about 6Km to the mouth of the valley from where the Yellow River flows 0.8Km downwards to the planned Jishi gorge hydropower station. The Sky Pond landslide dam is actually formed by two landslides from both the left and right bank slopes and completely blocks the seasonal river channel. The volume of the landslide dam is about 14 millions m3 with 2.37 millions m3 water stored in the dammed lake under the condition of perennial mean water level. Because (1) the dam body is large in width and thickness; (2) the dammed lake water is small both in volume and weight compared to the landslide dam; (3) recharge to the dammed lake is basically the same as the discharge every year; and (4) there is a natural spillway in the dam body, the landslide dam is present at least 750 years after its formation. Although landslide dams which have existed for several hundreds to thousands of years are generally considered as stable, there are remains which may fail catastrophically. In order to analyze the stability of the Sky Pond landslide dam and provide justification for the future engineering decisions, this paper describes the engineering geological conditions near the landslide dam and the characteristics of the dam body, and a detailed discussion of the formation mechanism of the landslide. Based on engineering geology investigation, a qualitative assessment of the stability of the dam and an analysis of the probability of dam overtopping and piping is carried out. Limit equilibrium analysis has been used to calculate the stability of the dam slope under various operational conditions. Results of the stability analyses indicate that the Sky Pond landslide dam should remain stable and does not present a potential theat to the planned hydropower station.

A limit equilibrium solution for bearing capacity of strip foundations on sand

2003 ◽  
Vol 40 (2) ◽  
pp. 351-361 ◽  
Author(s):  
Vincenzo Silvestri
Keyword(s):  
Bearing Capacity ◽  
Equilibrium Solution ◽  
Limit Equilibrium ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Published Data ◽  
Strip Foundation ◽  
Limit Equilibrium Analysis ◽  
Dilatancy Angle ◽  
Minimization Procedure

A limit equilibrium analysis is used in this paper to obtain the bearing capacity of a strip foundation on sand. Bearing capacity factors Nq and Nγ are determined for a practical range of friction angles, using a minimization procedure. The dilatancy angle Ψ of the sand coupled with the apparent friction angle ϕ allows the use of a modified friction angle ϕ*, which is in turn employed in the analysis. Comparisons with previous published data indicate that the proposed analysis gives adequate results. It is also shown that consideration of a dilatancy angle Ψ < ϕ leads to a bearing capacity value that is lower than that obtained for the case with Ψ = ϕ.Key words: limit equilibrium, bearing capacity, sand, dilatancy, strip footing, Nq and Nγ factors.

Research on Landslide Accumulation Mass Stability at a Hydropower Station

2012 ◽  
Vol 212-213 ◽  
pp. 981-984
Author(s):  
Jing Du ◽  
Yan Xi Zhao
Keyword(s):  
Limit Equilibrium ◽  
Friction Angle ◽  
Unit Weight ◽  
Hydropower Station ◽  
Safety Factors ◽  
Natural Unit ◽  
Landslide Stability ◽  
Large Landslide ◽  
History Of ◽  
Specification Requirement

Landslide stability is very important to the hydropower station construction. The volume of landslide accumulation mass in a hydropower station was more than 47, 500, 000 m3, it was a large landslide accumulation body rarely in the history of hydropower engineering. As a research object, the landslide accumulation mass in this hydropower station was divided into three parts by geologic ingredient, which included bedrock, slip soil and accumulation mass. According to mechanical parameters such as internal friction angle, cohesion, natural unit weight and saturated unit weight obtained by some research, limit equilibrium method was adopted to analyze the slope stability. Accumulation mass safety factors in different parts were calculated, the destruction style was illustrated and landslide accumulation mass stability was also analyzed. The results show under normal condition, rainstorm and earthquake condition, the safety factor cannot meet the specification requirement. The research provides meaningful reference to design and construction in similar hydropower station.

scholarly journals A Simple Three-Dimensional Failure Criterion for Jointed Rock Masses under True Triaxial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yaohui Gao ◽  
Chunsheng Zhang ◽  
Zhaofeng Wang ◽  
Jun Chen
Keyword(s):  
Failure Criterion ◽  
Triaxial Compression ◽  
Three Dimensional ◽  
Friction Angle ◽  
Failure Criteria ◽  
Jointed Rock ◽  
Rock Masses ◽  
True Triaxial ◽  
Jointed Rock Masses ◽  
Triaxial Strength

The joint configuration and the intermediate principal stress have a significant influence on the strength of rock masses in underground engineering. A simple three-dimensional failure criterion is developed in this study to predict the true triaxial strength of jointed rock masses. The proposed failure criterion in the deviatoric and meridian planes adopts the elliptic and hyperbolic forms to approximate the Willam–Warnke and Mohr–Coulomb failure criterion, respectively. The four parameters in the proposed failure criterion have close relationships with the cohesion and the internal friction angle and can be linked with the joint inclination angle using a cosine function. Two suits of true triaxial strength data are collected to validate the correctness of the proposed failure criterion. Compared with other failure criteria, the proposed failure criterion is more reasonable and acceptable to describe the strength of jointed rock masses.

scholarly journals A limit equilibrium analysis of progressive failure in the stability of slopes

1978 ◽  
Vol 15 (1) ◽  
pp. 113-122 ◽  
Author(s):  
K. Tim Law ◽  
Peter Lumb
Keyword(s):  
Slip Surface ◽  
Progressive Failure ◽  
Limit Equilibrium ◽  
Friction Angle ◽  
Soil Mass ◽  
Local Failure ◽  
Equilibrium Analysis ◽  
Stability Of Slopes ◽  
The Stability ◽  
Definition Of

A limit equilibrium method of analysis is proposed for the study of progressive failure in slope stability under a long-term condition. Based on effective stresses, the formulation of the method is derived from consideration of force and moment equilibrium within the soil mass above a prospective slip surface. By dividing the soil mass into a number of vertical slices, recognition of local failure can be made. Once local failure takes place, post-peak strength is assumed to be operative. This then initiates a redistribution of interslice forces and leads to some further local failure. Thus realistic available strengths along the slip surface can be evaluated. This permits the definition of a final safety factor, which is expressed in terms of the actual available reserve of strength. The proposed method has been applied to three well documented case records and encouraging results have been obtained. Based on the assumption that post-peak strengths are given by a friction angle equal to the peak value and a zero cohesion, stability charts have been prepared for design purposes.

scholarly journals Sensitivity Analysis on Stability Parameters in Landfill

2015 ◽  
Vol 9 (1) ◽  
pp. 108-111 ◽  
Author(s):  
Sun Hong-Jun ◽  
Fan Yan-Chao ◽  
Zhao Li-Hong
Keyword(s):  
Safety Factor ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Stability Parameters ◽  
Limit Equilibrium Analysis ◽  
Sensitivity Curves ◽  
Overall Stability ◽  
The Stability

To study the stability of waste body failure in landfill, the landfill was divided into two parts: an active wedge and a passive wedge. A limit equilibrium analysis was used to calculate the safety factor of stability in landfill. The parameters which affected the stability of the landfill were discussed. Sensitivity curves of each parameter were proposed and effect trends of various parameters on safety factor were analyzed. Cohesion c and internal friction angle фs increases linearly with the safety factor. The safety factor decreases with increasing slope angle β and filled height H. The safety factor of after landfill settlement was higher than the safety factor of settlement which did not occur. It increases the overall stability about 16%.

Analysis of Unstable Rock-Mass Stability Based on Limit Equilibrium Method and Strength Reduction Method

2016 ◽  
Vol 858 ◽  
pp. 73-80
Author(s):  
Ying Kong ◽  
Hua Peng Shi ◽  
Hong Ming Yu
Keyword(s):  
Rock Mass ◽  
Failure Mode ◽  
Posterior Margin ◽  
Reduction Method ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Rock Masses ◽  
Unstable Rock

With the slope unstable rock masses of a stope in Longsi mine, Jiaozuo City, China as the target, we computed and analyzed the stability of unstable rock masses using a limit equilibrium method (LEM) and a discrete element strength reduction method (SRM). Results show that the unstable rock masses are currently stable. Under the external actions of natural weathering, rainfall and earthquake, unstable rock mass 1 was manifested as a shear slip failure mode, and its stability was controlled jointly by bedding-plane and posterior-margin steep inclined joints. In comparison, unstable rock mass 2 was manifested as a tensile-crack toppling failure mode, and its stability was controlled by the perforation of posterior-margin joints. From the results of the 2 methods we find the safety factor determined from SRM is larger, but not significantly, than that from LEM, and SRM can simulate the progressive failure process of unstable rock masses. SRM also provides information about forces and deformation (e.g. stress-strain, and displacement) and more efficiently visualizes the parts at the slope that are susceptible to instability, suggesting SRM can be used as a supplementation of LEM.

Sign in / Sign up

Export Citation Format

Share Document