Search results for: Free PDF Quiz 2024 High Hit-Rate EMC D-PM-IN-23 Latest Test Report 🍂 Search for ✔ D-PM-IN-23 ️✔️ and download exam materials for free through [ www.pdfvce.com ] 🦞Questions D-PM-IN-23 Exam
-
Analysis, design and construction stages of Milad geosynthetic-reinforced soil bridge abutment in Tehran – Iran
Reinforced soil walls are one the most cost effective options for retaining structures, and are being increasingly used in recent years around the world. They have also proved that they have performed to an acceptable level under earthquake loading conditions. This paper presents the analysis, design and construction stages of the first major geosynthetic reinforced soil bridge abutment built in Iran. The bridge abutment was designed, analysed and constructed by BPI Company in Tehran, Iran in 2009. This abutment is analysed using both the Limit Equilibrium Method (LEM) for stability analysis and Finite Element Method (FEM) for deformation analysis under static and seismic loads. The design has been carried out according to the Federal Highway Administration Manual (FHWA-NHI-00-43, 2001) and National Cooperative Highway Research Program Report 556-2006 (NCHRP) as a guideline. Deformations of the abutment were monitored with an accuracy of ±1mm before and after the construction of the concrete sill and are compared with the outputs from the numerical methods. This project was undertaken on behalf of the Tehran Municipality with the aim of bringing this new method of abutment construction to the country. This project is likely to be the first of many to adopt this cost effective solution.
-
Approach For Assessing Time Of Preload And Surcharge Removal Of Embankments On Soft Soils
The process of preload release involves a review of the instrumentation and monitoring data. Back analysis is carried out to match field measurements with numerical predictions by adjusting relevant geotechnical model, parameters and construction sequence. Once a match is achieved, the calibrated geotechnical model is used for the prediction of long- term settlement. The removal of preload and surcharge fill is only allowed via the release of a Hold Point, when the predicted long term settlement satisfies the design criteria. This paper provides technical advice and guidance to undertake geotechnical review of preload performance as part of the Hold Point release process.
-
Geotechnical Stability Analysis
51st Rankine Lecture
-
Melbourne’s Southbank interchange – A permanent excavation in compressible clay
The Southbank Interchange of the Melbourne City Link Project links major freeways and access roads. The permanent excavation covers an area of three hectares and extends to a maximum depth of 9 m, which is 6 m below the groundwater table.
Design and construction approaches were developed firstly to control seepage into the excavation to limit groundwater lowering beyond the site, and secondly to limit the effects of potentially damaging base heave during construction. Lateral flow of groundwater into the excavation was controlled by a cut-off wall extending through the compressible clay with a surrounding line of closely spaced recharge wells. Analyses showed the recharge wells in combination with the wall would be effective in limiting drawdown outside the site. Monitoring showed that pore water pressures were maintained within the design criteria, with the assistance of deep recharge of an underlying aquifer to control vertical seepage. Survey showed settlements outside the site were minimal.
Shallow pressure relief drains were installed to limit uplift pressures and control base instability in the deepest parts of the excavation. Monitoring of the groundwater levels in the underlying aquifer and comparisons with results from flow models were used successfully to control uplift pressures during construction.
-
Comparing Performance Of Geocomposite Filter-Drains And Granular Filters Under Canal Lining
In many irrigation projects where the groundwater table is high part of the canals may be located below the water table. In this situation groundwater applies uplift pressure to the bottom and side panels of the canal lining. This phenomenon may cause deformation, displacement and or rupture of the concrete panels or other damage which results in high maintenance costs to the project. The most effective way to control the uplift pressure under the canal lining is to provide a filter-drainage system under the lining. Up to the present, granular filters have been the most common material in use. In some cases application of granular materials is not an easy task due to high costs involved and/or environmental impacts. In recent years geosynthetic materials (geocomposites) have been employed as replacement for granular filters. In the present study the behaviour of geocomposite material as a filter drainage layer under canal lining has been investigated using a physical laboratory model. The results of the experiments showed that a geocomposite layer of adequate thickness can fully relieve the uplift pressure and discharge the drained water effectively. Also the efficiency of the filter-drainage under bottom concrete panels only and both bottom and side concrete panels were studied. The results showed that providing a filter under the side panels has no significant effect on the drainage capacity of the system. As the weight of the concrete panel on a geocomposite layer would cause some deformation of the material its effect was also considered in the physical model. The results of this part of the experiments showed that by applying the weight of the concrete lining the effective thickness and thus permeability of the geocomposite is reduced and its effect should be considered in the design of geosynthetic filters.
-
The Design And Construction Of Very Deep Excavations – Recent Developments
Technical advancements in construction plant, materials and numerical analysis tools have made possible a step change in the achievable depth of excavations required for infrastructure, building and mining projects. This has been in response to an increased complexity in such projects particularly in connection with rail, water and power infrastructure sectors around the globe. Such advances do not come without some risks and a clear understanding of the limitations of the techniques, capabilities of construction monitoring and the benefits of practical design details are key to successful execution. In addition, a sound knowledge of the behaviour and testing of materials particularly fresh concrete and support fluids is essential in the minimisation of defects in deep earth retaining structures, which can be extremely costly to remediate.
This paper considers the state of the art in the construction of very deep and complicated excavations by making reference to a number of recent case histories, where records have been broken and new technologies have been deployed. The construction of diaphragm walls to depths well in excess of 100 m and with wall thickness of 1800 mm and using concrete with a 28-day cube strength in excess of 60 MPa are now possible, provided great care is taken. Improved verticality tolerances of better than 1 in 400, coupled with precise monitoring and advanced design techniques, means that the structural capacity of earth retaining walls in shaft construction have increased significantly which has led to the realisation of deeper excavations, together with deep openings which may be necessary for associated tunnels.
The author will also include the presentation of recent improvements in safety both in cage lifting, handling and splicing as well as around open diaphragm wall excavations. A better understanding of the causation of defects in concrete which has been placed under support fluid via a tremie, has been gained through painful experience and has greatly benefitted from the recent publication of useful guidance in Australia, UK and by the EFFC (European Federation of Foundation Contractors). This has led to a number of new site tests on fresh concrete for mix stability and bleed potential which are gaining increasing traction in the industry. In addition, the introduction of more stringent testing on support fluid such as bentonite during excavation means that instances of defects including leaks, inclusions and areas of poor concrete cover can be reduced. However, despite the availability of extensive guidance on good reinforcement cage detailing for diaphragm cages, examples of poor practice still remain, with great potential to lead to extensive defects such as mattressing which may compromise the durability of permanent works. The author will highlight examples of good and bad practice.
-
Development of Horizontal Soil Mixed Beams as a Shallow Ground Improvement Method Beneath Existing Houses
Following the 2010-2011 Canterbury Earthquake Sequence (CES), the vulnerability of residential houses in some areas of Christchurch to liquefaction-induced damage was realised. As a result of the ground surface subsidence caused by the CES, the liquefaction vulnerability has also increased in some parts of Christchurch (Russell et al., 2015). The liquefaction-induced damage resulted in a large number of residential houses in Christchurch that were uneconomic to repair. They are being demolished and rebuilt on stiffer and stronger foundation systems and in some areas which are particularly vulnerable to liquefaction, the stiffer and stronger foundation systems are being used in conjunction with shallow ground improvements. There are also a large number of houses that have liquefaction-induced damage, but are economic to repair. Until recently there was no practical ground improvement solution that could be economically constructed beneath existing repairable residential houses to decrease their liquefaction vulnerability. However, during a shallow ground improvement trial research project, commissioned by the New Zealand Earthquake Commission (EQC) in 2013, a method was developed to improve ground beneath residential houses, known as Horizontal Soil Mixing (HSM). HSM involves the mechanical mixing of injected grout into in situ soils using a modified directional drill and a specifically designed soil mixing tool to construct a series of HSM beams to improve the thickness and stiffness of the non-liquefying crust and decrease the vulnerability of the existing house to future liquefaction-induced damage. This paper describes the development of the HSM construction methodology, including constraints and issues that were encountered and overcome.