Influence of soil nail orientations on stabilizing mechanisms of loose fill slopes

2013 ◽  
Vol 50 (12) ◽  
pp. 1236-1249 ◽  
Author(s):  
C.Y. Cheuk ◽  
K.K.S. Ho ◽  
A.Y.T. Lam
Keyword(s):  
Earth Pressure ◽  
Slope Movement ◽  
Numerical Analyses ◽  
Soil Nails ◽  
Soil Nail ◽  
Static Liquefaction ◽  
Liquefaction Failure ◽  
Loose Fill ◽  
Typical Design

Soil nailing has been used to upgrade substandard loose fill slopes in Hong Kong. Due to the possibility of static liquefaction failure, a typical design arrangement comprises a structural slope facing anchored by a grid of soil nails bonded into the in situ ground. Numerical analyses have been conducted to examine the influence of soil nail orientations on the behaviour of the ground nail–facing system. The results suggest that the use of steeply inclined nails throughout the entire slope could avoid global instability, but could lead to significant slope movement especially when sliding failure prevails, for instance, due to interface liquefaction. The numerical analyses also demonstrate that if only subhorizontal nails are used, the earth pressure exerted on the slope facing may cause uplift failure of the slope cover. To overcome the shortcomings of using soil nails at a single orientation, a hybrid nail arrangement comprising nails at two different orientations is proposed. The numerical analyses illustrate that the hybrid nail arrangement would limit slope movement and enhance the robustness of the system.

Sonic echo and impulse response tests for length evaluation of soil nails in various bonding mediums

2008 ◽  
Vol 45 (7) ◽  
pp. 1025-1035 ◽  
Author(s):  
Shu-Tao Liao ◽  
Chin-Kuo Huang ◽  
Chung-Yue Wang
Keyword(s):  
Nondestructive Testing ◽  
Impulse Response ◽  
Field Tests ◽  
Drilled Shafts ◽  
Driven Piles ◽  
Soil Nails ◽  
Soil Nail ◽  
Testing Techniques ◽  
Nondestructive Testing Methods

The objective of this paper is to present the results of research for evaluating the installed lengths of soil nails with nondestructive testing methods. Two closely related methods, the sonic echo test and the impulse response test, both of which had been widely applied to assess the integrity of drilled shafts and driven piles, were evaluated to test their capabilities on soil nails. To carry out this study, soil nails of various lengths were embedded in different surrounding materials in the laboratory and then tested with both methods to predict their lengths. The surrounding materials studied in this research included soil and cement grout. Finally, field tests for in situ soil nails were carried out. The results indicated that the relative stiffness of the soil nail to the bond material plays a very important role in the success of testing. It is hoped that through this kind of study, the capability and limitation of using these nondestructive testing techniques to determine the installed lengths or to evaluate the bonding conditions of soil nails can be better understood.

Failure by corrosion in PC bridges: a case history of a viaduct in Italy

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Piero Colajanni ◽  
Antonino Recupero ◽  
Giuseppe Ricciardi ◽  
Nino Spinella
Keyword(s):  
Prestressed Concrete ◽  
Design Methodology ◽  
Progressive Collapse ◽  
Numerical Analyses ◽  
Existing Structures ◽  
History Of ◽  
Progressive Collapse Analysis ◽  
Practical Implications ◽  
Post Tensioned

Purpose The paper illustrates a viaduct collapse due to corrosion phenomena. Moreover, a contribution to the issues related to both the control of existing structures and design methods to be followed for the construction of new buildings is provided. Design/methodology/approach The objectives were achieved by in situ observations and numerical analyses. The effects of corrosion phenomena are investigated, and the progressive collapse analysis is provided to be helpful in this case. Findings The damages induced by corrosion phenomena have caused the collapse of the viaduct taken in to account. The performed numerical analyses were able to reproduce the effects of corrosion in terms of reduction of wires diameter. Research limitations/implications The research is limited to prestressed concrete viaduct with post-tensioned cables. Practical implications A monitoring plan, subdivided in several phases, is suggested, to avoid critical situations as these described. Originality/value The case study brought useful information on the effects of corrosion on the decks section, showing how the technology in post-tensioned cables is usually insidious and prone to the issues relating to corrosion of the wires

On Numerical Simulation of the Stepped Soil-Nail Wall

2013 ◽  
Vol 353-356 ◽  
pp. 692-695
Author(s):  
Chang Zhi Zhu ◽  
Quan Chen Gao
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Internal Force ◽  
Numerical Results ◽  
Analysis Model ◽  
Foundation Pit ◽  
Soil Nails ◽  
Soil Nail ◽  
Soil Nail Wall ◽  
Design And Construction

Based on an Engineering Example which was supported by the stepped soil-nail wall, a numerical analysis model was established by FLAC3D,and the process of the excavation and supporting was simulated, and the numerical results of the soil nails internal force and foundation pit deformation were obtained. The simulated result was consistent with the measured results. It shows that the method of FLAC3D numerical analysis can be used to the numerical analysis of foundation pit excavation and supporting, and it will provide the basis for the design and construction of practice project.

scholarly journals In-Situ Measurement of Internal Earth Pressure During Landslide Movement

1998 ◽  
Vol 38 (3) ◽  
pp. 97-107 ◽  
Author(s):  
Kiminori Araiba ◽  
Akira Suemine
Keyword(s):  
Earth Pressure ◽  
In Situ Measurement ◽  
Landslide Movement

Critical Insights in Laboratory Shear Wave Velocity Correlations of Clays

2021 ◽  
Author(s):  
Dania Elbeggo ◽  
Yannic Ethier ◽  
Jean-Sébastien Dubé ◽  
Mourad Karray
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Earth Pressure ◽  
Dynamic Parameter ◽  
Clay Deposits ◽  
Sample Disturbance ◽  
P Rat

Shear wave velocity is an important mechanical/dynamic parameter allowing the characterization of a soil in the elastic range (γ < 0.001 %). Thirty five existing laboratory correlations of small strains shear modulus or shear wave velocity were examined in this study and are grouped into different general forms based on their geotechnical properties. A database of 11 eastern Canadian clay deposits was selected and used for the critical insights. The effect of the coefficient of earth pressure at rest was also examined. A range of variation for each general form of correlation was determined to take the plasticity index and void ratio values of investigated sites into account. The analysis shows a significant scatter in normalized shear wave velocity values predicted by existing correlations and raises questions on the applicability of these correlations, especially for eastern Canadian clays. New correlations are proposed for Champlain clays based on laboratory measurement of shear wave velocity using the piezoelectric ring actuator technique, P-RAT, incorporated in consolidation cells. An analysis of P-RAT results reveals the sample disturbance effect and suggests an approach to correct the effect of disturbance on laboratory shear wave velocity measurements. The applicability of the proposed correlations, including the disturbance correction, is validated by comparison with in situ measurements using multi-modal analysis of surface waves (MMASW).

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