Abstract
Soil nailing technique is being widely used for stabilization of vertical cuts because of its economic, environment friendly and speedy construction. Global stability and lateral displacement are the two important stability criteria for the soil nail walls. The primary objective of the present study is to evaluate soil nail wall stability criteria under the influence of in-situ soil variability. Finite element based numerical experiments are performed in accordance with the methodology of 23 factorial design of experiments. Based on the analysis of the observations from numerical experiments, two regression
models are developed, and used for reliability analyses of global stability and lateral displacement of the soil nail wall. A 10 m high prototype soil nail wall is considered for better understanding and to highlight the practical implications of the present study. Based on the study, lateral displacements beyond 0.10% of vertical wall height and variability of in-situ soil parameters are found to be critical from the stability criteria considerations of the soil nail wall.
Abstract
Sliding within the dam foundation is one of the key failure modes of a gravity dam. A twodimensional (2-D) physical model test has been conducted to study the sliding failure of a concrete gravity dam under overloading conditions. This model dam was instrumented with strain rosettes, linear variable displacement transformers (LVDTs), and embedded fiber Bragg grating (FBG) sensing bars. The
surface and internal displacements of the dam structure and the strain distributions on the dam body were measured with high accuracy. The setup of the model with instrumentation is described and the monitoring data are presented and analyzed in this paper. The deformation process and failure mechanism of dam sliding within the rock foundation are investigated based on the test results. It is found that the horizontal displacements at the toe and heel indicate the dam stability condition. During overloading, the cracking zone in the foundation can be simplified as a triangle with gradually increased height and vertex angle.
Key Words
concrete gravity dam; rock foundation; overloading; physical model test; sliding failure; fiber Bragg grating (FBG).
Address
Hong-Hu Zhu: Dept. of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
Jian-Hua Yin: Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University,Chengdu, Sichuan, China Jian-Hua Dong and Lin Zhang: State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University,Chengdu, Sichuan, China
School of Water Resources and Hydropower Engineering, Sichuan University, Chengdu, Sichuan, China
Abstract
Ground settlements and pore pressure changes were monitored around a shallow tunnel constructed in clay till during the excavation and primary lining installation. The settlements above the tunnel continued to develop for up to 100 days after the primary lining installation. Triaxial compression tests were carried out to estimate the short-term and long-term deformation characteristics of the till. Numerical simulation was conducted to history match the field measurements, and thus, to quantify the settlements induced by ground stress relief, consolidation and creep. It was found that the surface settlements due to ground stress relief, consolidation and creep are 17, 12 and 71% of total settlement (about 44 mm), respectively. In addition, early installation of rigid concrete lining could be an effective
means to reduce the settlement due to creep.
Key Words
shallow tunnel; clay till; consolidation; creep; settlement.
Address
Z. Wang and R.C.K. Wong: Dept. of Civil Engineering, Schulich School of Engineering, The University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada
H. Heinz: Thurber Engineering Limited, Calgary, Alberta, Canada
Abstract
Slope stability analysis of the right abutment of a railway bridge proposed at about 350 m above the ground level, crossing a river and connecting two huge hillocks in the Himalayas, India is presented in this paper. The site is located in a highly active seismic zone. The rock slopes are intensely jointed and the joint spacing and orientation are varying at different locations. Static slope stability of the rock slope is studied using equivalent continuum approach through the most commonly used commercial numerical tools like FLAC and SLOPE/W of GEOSTUDIO. The factor of safety for the slope under static conditions was 1.88 and it was reduced by 46% with the application of earthquake loads in pseudostatic analysis. The results obtained from the slope stability analyses confirmed the global stability of the slope. However, it is very likely that there could be possibility of wedge failures at some of the pier locations. This paper also presents the results from kinematics of right abutment slope for the wedge
failure analysis based on stereographic projections. Based on the kinematics, it is recommended to flatten the slope from 50o to 43o to avoid wedge failures at all pier locations.
Key Words
jointed rock mass; static slope stability; pseudo-static analysis; kinematic analysis and wedge failure.
Address
Gali Madhavi Latha and Arunakumari Garaga: Dept. of Civil Engineering, Indian Institute of Science, Bangalore, India
Abstract
In the framework of meshfree methods, a new methodology is developed based on radial point interpolation method (RPIM). This methodology is applied to a one-dimensional contaminant transport modelling in the saturated porous media. The one-dimensional form of advection-dispersion equation involving reactive contaminant is considered in the analysis. The Galerkin weak form of the governing equation is formulated using 1D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Numerical examples representing various phenomena, which occur during migration of contaminants, are presented to illustrate the applicability of the proposed method and the results are compared with those obtained from the analytical and finite element solutions. The proposed RPIM has generated results with no oscillations and they are insensitive to Peclet constraints. In order to test the practical applicability and performance of the RPIM, three case studies of contaminant transport through the landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.
Key Words
contaminant transport; meshfree method; radial point interpolation method; thin plate spline radial basis function; saturated porous media.
Address
R. Praveen Kumar: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia 5095, Australia
G.R. Dodagoudar: Dept. of Civil Engineering, Indian Institute of Technology Madras, Chennai - 600 036, Tamil Nadu, India
