Cracking of RC School Building Due to Soil Expansion

The geotechnical investigations, the structural analyses and the remedial measures of a cracked reinforced concrete school building are presented in this paper. The building is located in Irbid, Jordan, where the soil is highly expansive and the volume change of the soil causes major destruction in the buildings in the area. Field and laboratory tests were performed on the foundation soil of the building to determine its swell potential and other engineering properties. The school building is modeled as a 3-D finite element model using Sap2000 code. The model is built based on results of geotechnical investigation. The results revealed structural deficiencies in building members (columns, beams and footings) due to the swelling gradient. Remedial measures were proposed and implemented to rehabilitate and strengthen the overstressed members. The repaired school has been under service since 2003. The school building performance is being under monitoring since then and has shown reliable performance

Crack simulation for the cover of the landfill – A seismic design

The stability of the landfill is an environmental issue. The collapse of the landfill causes environmental pollution and influences human life. In the present study, the crack on the cover of the landfill was simulated. Rankine’s theory and the Phantom Node Method were used for the simulation length of the crack and the mechanism of the crack propagation in the nonlinear extended finite element method (NXFEM). Artificial Neural Networks (ANNs) based on Levenberg-Marquardt Algorithm and Abalone Rings Data Set mode were used to predict displacement in critical points of the model. The vibration mechanism of the landfill was changed in each model. During applying seismic load on the model, the optimized thickness of the clay cover on the landfill was discussed. The thickness of the landfill cover controls the seismic response of the landfill. The numerical simulation shows differential displacement of the landfill impacts on the crack propagation and the need for the appropriate design of the cover thickness of the landfill

Crack simulation for the cover of the landfill – A seismic design

The stability of the landfill is an environmental issue. The collapse of the landfill causes environmental pollution and influences human life. In the present study, the crack on the cover of the landfill was simulated. Rankine’s theory and the Phantom Node Method were used for the simulation length of the crack and the mechanism of the crack propagation in the nonlinear extended finite element method (NXFEM). Artificial Neural Networks (ANNs) based on Levenberg-Marquardt Algorithm and Abalone Rings Data Set mode were used to predict displacement in critical points of the model. The vibration mechanism of the landfill was changed in each model. During applying seismic load on the model, the optimized thickness of the clay cover on the landfill was discussed. The thickness of the landfill cover controls the seismic response of the landfill. The numerical simulation shows differential displacement of the landfill impacts on the crack propagation and the need for the appropriate design of the cover thickness of the landfill

Crack simulation for the cover of the landfill – A seismic design

The stability of the landfill is an environmental issue. The collapse of the landfill causes environmental pollution and influences human life. In the present study, the crack on the cover of the landfill was simulated. Rankine’s theory and the Phantom Node Method were used for the simulation length of the crack and the mechanism of the crack propagation in the nonlinear extended finite element method (NXFEM). Artificial Neural Networks (ANNs) based on Levenberg-Marquardt Algorithm and Abalone Rings Data Set mode were used to predict displacement in critical points of the model. The vibration mechanism of the landfill was changed in each model. During applying seismic load on the model, the optimized thickness of the clay cover on the landfill was discussed. The thickness of the landfill cover controls the seismic response of the landfill. The numerical simulation shows differential displacement of the landfill impacts on the crack propagation and the need for the appropriate design of the cover thickness of the landfill

Impact of earthquake’s epicenter distance on the failure of the embankment – A seismic prediction

Cracks in clayey soil cause a reduction in the seismic loading capacity which can lead to structural failures. Seismic acceleration is the primary cause of crack propagation and damage to the earth's structure. This study investigated the impact of the earthquake's epicenter distance on the embankment model with a pre-existing crack in the embankment's core. The research adopted the numerical modeling method of soil categorized as a no-tensile material to explain displacement in selected points of the model using the extended finite element method (XFEM). Artificial Neural Networks (ANNs) were used to predict displacement obtained by XFEM. It was observed that the failure pattern and the maximum displacement time of the model change with the associated distance of the earthquake's epicenter. The key study objective is to understand the model's failure mode and introduce a new classification in earthquake damage prediction

Geological discontinuity persistence: Implications and quantification

Persistence of geological discontinuities is of great importance for many rock-related applications in earth sciences, both in terms of mechanical and hydraulic properties of individual discontinuities and fractured rock masses. Although the importance of persistence has been identified by academics and practitioners over the past decades, quantification of areal persistence remains extremely difficult; in practice, trace length from finite outcrop is still often used as an approximation for persistence. This paper reviews the mechanical behaviour of individual discontinuities that are not fully persistent, and the implications of persistence on the strength and stability of rock masses. Current techniques to quantify discontinuity persistence are then examined. This review will facilitate application of the most applicable methods to measure or predict persistence in rock engineering projects, and recommended approaches for the quantification of discontinuity persistence. Furthermore, it demonstrates that further research should focus on the development of persistence quantification standards to promote our understanding of rock mass behaviours including strength, stability and permeability

Failure Mechanisms and Strength of Non-Persistent Rock Joints

256 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.Jennings method which assumes full shear strength along joint and rock bridge is a useful reference condition. The Bridge Mobilized Strength Ratio, BMSR, provides a means of assessing how much of the reference strength along the bridge is mobilized. The MBSR is the ratio of (mobilized shear strength minus shear strength of joint) to (Jennings shear strength minus shear strength of joint), for the average normalized stress at failure. Conditions causing BMSR to be different from the reference value include: (a) for mode 1, shear failure in the plane of the joints through bridge and non-persistent joints, BMSR decreases, as the ratio of normal stress, \sigma\sb{\rm n}, to compressive strength, \sigma\sb{\rm n}/\sigma\sb{\rm c}, decreases below 0.2. (b) for mass stiffness $<$ bridge stiffness, and as number of bridges increases, progressive failure can develop reducing BMSR. (c) for the case of \phi\sb{\rm j} \ll \phi\sb{\rm i}, it was observed for single joints that the BMSR was above one. It is concluded that the higher value was due to concentration of the normal stress on the stiffer bridge, thus giving a higher shear strength than computed by Jennings method, which assumes a uniform normal stress distribution. (d) offset of joints reduces confinement and increases tensile stress conditions between joint segments causing a reduction of strength.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Failure Mechanisms and Strength of Non-Persistent Rock Joints

256 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.Jennings method which assumes full shear strength along joint and rock bridge is a useful reference condition. The Bridge Mobilized Strength Ratio, BMSR, provides a means of assessing how much of the reference strength along the bridge is mobilized. The MBSR is the ratio of (mobilized shear strength minus shear strength of joint) to (Jennings shear strength minus shear strength of joint), for the average normalized stress at failure. Conditions causing BMSR to be different from the reference value include: (a) for mode 1, shear failure in the plane of the joints through bridge and non-persistent joints, BMSR decreases, as the ratio of normal stress, \sigma\sb{\rm n}, to compressive strength, \sigma\sb{\rm n}/\sigma\sb{\rm c}, decreases below 0.2. (b) for mass stiffness $<$ bridge stiffness, and as number of bridges increases, progressive failure can develop reducing BMSR. (c) for the case of \phi\sb{\rm j} \ll \phi\sb{\rm i}, it was observed for single joints that the BMSR was above one. It is concluded that the higher value was due to concentration of the normal stress on the stiffer bridge, thus giving a higher shear strength than computed by Jennings method, which assumes a uniform normal stress distribution. (d) offset of joints reduces confinement and increases tensile stress conditions between joint segments causing a reduction of strength.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Scale Effect on Mode of Failure and Strength of Offset Rock Joints

As a sustainable construction material, the use of rock has increased significantly. In this experimental study, the scale effect on failure mechanisms and compressive strength of rock blocks was investigated. Samples of rock with non-persistent offset joints were subjected to uniaxial loading. The angle of orientation of the rock bridge with respect to the applied axial load and the size of the block were studied. Two different block sizes, having dimensions of (63.5 × 28 × 20.3) cm and (30.5 × 15.24 × 10) cm, were tested. The joint inclination angle was maintained at 22.5° in both cases. Also, degree of persistence was kept constant at 0.3 for all tested blocks. However, the offset angle which connects the inner tips of the joints was changed from 30°-90° with an increment of 15°. The results showed a reduction in strength with increasing the size of the sample. This reduction is becoming more significant as the bridge inclination angle increases. This behavior is due to the fact that as the bridge inclination angle increases the mode of failure shifted from shear to tension mode which is more dependent on the size of sample due to the presence of more micro flaws. No effect of block size was noticed on mode of failure for the tested blocks