EGB123 Civil Engineering Systems in Inner Urban Environments

Introduction

Write a brief one paragraph statement about what your geotechnical engineering investigation is about and its needs.

The Kurilpa Point Urban Investigation Zone is located at the South Brisbane region in the south east region of Queensland State. It is approximately four kilometres west of East Brisbane on the Brisbane River (Figure 1). The whole area is surrounded by Brisbane River which separates the North and South of Brisbane. The Go Between Bridge separates Kurilpa Point from the North area of Brisbane and being one of the only two bridges in the area, it serves residents coming from the south too as far as Queensland University. This is all shown in the Map screenshot of the area (Figure 1) and in the MyMaps page indicated in section2 below.

Figure 1: Kurilpa Area Map

There has been an increasing pressure for further development as evidenced by the Brisbane City Council’s website and plans are underway to optimize the land use for both residential and tourism purposes. The development is within the coastline and in surrounding areas. In a bid to analytically understand future environmentally sensitive land uses, Riverbend Public Private Partnership purposes to carry out urban study area investigations for the whole Kurilpa Point area. To facilitate the preparation of this Plan, Gosford City Council commissioned Webb, The urban study area investigation is bounded generally by Brisbane River, M3 Highway on the East and Brisbane Corso on the South East.

Aim

The aim of this investigation is to establish the ground conditions at the Kurilpa area and in a bit to determine whether there will be any hindrances to construction. The investigation also intends to ascertain the environmental impact of the development.

Objectives

Using a numbered list, prepare four objectives of your geotechnical engineering investigation.

• To analyse the site conditions around the southern abutment of the Go Between Bridge.
• To analyse the design requirements and drivers of the southern abutment of the Go Between Bridge.
• To analyse the relationship between the southern abutment of the Go between bridge and surrounding engineering systems.
• To propose a construction plan and schedule for the Go Between Bridge.

Scope And Limitations

The investigation will be limited to offsite research going by going through secondary information recorded in the Brisbane planning authority libraries, reports and articles.

Sources Of Information

The information regarding to this region will be obtained from Brisbane’s planning records, previous reports, textbooks, journal articles and news articles and stories.

About Yourself

Write a one paragraph biography about yourself with particular emphasis on your aspirations as an engineer.

Geotechnical Engineering Investigation

Matters About The Bridge Southern Abutment

An abutment is a structure on which the bridge’s structure rests. It is found at the edges of the bridge where it connects with the land surface. It is important in dispersing the lateral and vertical forces of the bridge and it works in collaboration with the columns. It is especially essential to Go Between bridge because it only has 2 support structures at the edges with a lot of traffic generated weight concentrated at the mid span and the edges. The southern abutment is susceptible to a considerable vertical loading as it experiences both live loads in the form of vehicles wheel loading and the dead load of the bridge structure itself.

The diagrams below show the cross section of an abutment and its map view in a bid to show the design components.

Figure 2: Cross Section of an Abutment

Figure 3: Birds Eye View of the Southern Abutment of the Go Between Bridge

Figure 4: Perspective view of the Southern Abutment of the Go Between Bridge

The type of loads being borne by the southern abutment of the Go Between Bridge are both vertical and lateral forces. The lateral forces are forces generated by the exertion of downward loading forcing the bridge down into a straight shape (Das & Sobhan, 2013). This action pushes the edges outwards towards the landmass creating lateral stress on to the abutment. They can also be generated by breaking force of the vehicles. The vertical forces are generated by direct traffic loading. This is usually the weight of the car transmitted onto the bridge as tire pressure. It acts downwards on the bridge as live load which acts directly on downwards, on to the abutment. The dead load generated by the weight of the bridge itself acts on the bridge abutment directly (Das & Sobhan, 2013).

Geotechnical Design Drivers

The geotechnical design of this abutment includes applying basic soil mechanics principles in the design and analysis of sloping land mass, retaining wall and foundation. It is done with references to the Australian Standard codes of practice. In designing the abutment, one of the drivers would be the strength. The abutment needs to be able to carry the loads described above (Sivakugan & Das, 2009). Therefore, considerations must be made for the settlement of soils and the bearing capacity and how to effectively design an abutment that is within the required limits of these properties. Another driver would be the environmental impact. Owing to the fact that it would be constructed next to the water, it would be important to provide for a structure that does not have adverse effects on the bordering water mass (Valley, 2009).

The serviceability of the bridge necessitates a proper geotechnical design too as the bridge’s functionality too. It is important to design the abutment in a way that will control the deflection, cracking, overall stability, durability and fire resistance. The aesthetic component of the abutment also controls the geotechnical design as, to attain the required beauty, serviceability should also match the design necessitating a geotechnical design that considers the shape (Baecher & Christian, 2005).

The southern abutment of the Go Between Bridge falls under a bridge structure and therefore its design is governed by the bridge design code. The recently modified Bridge Code AS (/NZS) 5100:2017 is a collaboration between the bodies Standards Australia and Austroads which cuts across every state and territory (SAI Global, 2011). It is also governed by the Road Design Guide by Austroads. The Go Between Bridge is a box girder bridge that uses the cantilever design. This type of technology employs a cantilever or more situated back to back. They are supported on one end with an extension to balance the weight.

Integration Considerations

The southern end of the Between Bridge is connected to Merivale Streets, Boundary Street and Montague Road. The abutment borders Riverside Drive with a portion of the bridge passing above it. The abutment borders the buildings on 3 Lanfear Street and 23 Bouquet Street. While it has not direct structural effect on the streets and road, it affects their transport capacity and management directly meaning that poor construction and management may affect the traffic flow (Blanchard, 2008). The excavation would directly affect the surrounding structures as the soil is susceptible to expansion leading to instability and poor settlement and should therefore be controlled.

Construction

The construction process would include site clearing, sheeting, demolitions and excavation, concreting, backfilling and compacting then landscaping. The site clearing process would include redirecting traffic flowing into both ends of the bridge and putting up barricades. It also includes clearing of surrounding vegetation and any non-structural elements including signs and boards etc. Safety walls made of sheet metal and signage should be put in place at this stage to avoid non-personnel interference. Sheeting follows where sheets are driven into the ground. They could be precast piles and sheets or bored piles. It is done to retain soil to control soil expansion. From here, the process of demolition of the existing structure and excavation of the ground begin. Excavation is done by an excavator and dozer while demolition is done using a wrecking ball.

Following clearing and excavation, the process of concreting begins. It can be done in situ, precast or incorporate both types of elements. The foundation in this case is to be done offsite as it would be piles driven into the ground. A pile cap is to be cast either on site or precast. The wing walls, sleeper pad, slab, pavement and approach of the abutment and bridge would be done in situ while the deck and deck girder should be cast offsite in order to prestress them. This would require a hammer for driving the piles, concreting equipment and steel for the in situ concreting. The labour sub-trades required are concreters, steel fabricators, scaffolders, masons, excavators, moving and mixing plant operations and unskilled labourers.

Governance and Values Considerations

Standards Australia’s technical committee BD-090, Bridge Design and Austroads under the Road Design Task force are in charge of the southern geotechnical abutment structure to the Go Between Bridge on a national level. On a state level, the Queensland Department of Transportation and Main Roads are responsible at a state level. Their main aim is the management of transportation systems and by making policies and effecting the current policies.

These bodies are also responsible for maintenance of roads and bridges should any need it. In collaboration with the Brisbane City Council planning department, they can suggest new construction or renovation plans. The main values observed are the adherence to codes and local area policies in order to provide a safe and serviceable system of transportation that meets the required design criteria. These matters are important to the geotechnical engineer in this field as they provide a guiding principle in the investigation and designing of geotechnical structures.

Engineering Systems Interrelationships

The geotechnical system of the southern geotechnical abutment structure to the Go Between Bridge is in direct contact with a road network. This means that if any failure occurred, it would affect the region’s transportation flow. It borders a ferry and a Bikeway too although not in direct contact. However, if it were to be dysfunctional for one reason or the other, it would case a traffic congestion on the road network and a volume surge on both the nearby William Jolly Bridge and ferry. This means that successful completion of the abutment and the bridge itself would provide traffic pressure relief to those transport systems (Blanchard, 2008).

While it is situated next to buildings, it does not directly affect their structural properties but if it were to collapse, it might affect the soil on which they are built and hence their structural stability. As such, the design engineer would be responsible for liaising with the transport engineers and local area planning authorities to ensure fast response action would be provided in case of an emergency (Blanchard, 2008)?

Conclusions

Summary of remarks of your investigation

The geotechnical engineering investigation carried out on the southern abutment of the Go Between Bridge reveal a heavy linkage of the geotechnical component of the built environment with the other engineering systems. It shows that geotechnical design is fundamental in ascertaining and providing the structural integrity of the elements of the built environment. The investigation reveals that a geotechnical engineer must also be prepared to work with other professionals in order to establish a fully serviceable geotechnical structure and as their interrelationships mean that a failure in one component could mean strain or total failure in the rest too.

Engineering systems context in inner urban environments

Geotechnical engineering would be incorporated to a large extent on the southern abutment as it is a subsurface feature. This is one of the 4 bridges across the river in that region and so it experiences significant loading, wear and tear. This means that, design of other systems should be done in such a way that it helps alleviate this pressure on to the abutment. For elements of the built environment and structures coming up in the inner urban environment around this region proper geotechnical investigation should be done in order to ascertain their structural properties and allow for serviceable design.

Observations of geotechnical and broader civil engineering professional practice in inner urban environments

Geotechnical design paves the way for a lot of other engineering systems to be implemented. One can actually say that that is where construction of the built environment begins. Geotechnical engineering offers the information accumulated through investigations and tests to other engineering disciplines in order enable accurate designs and management of the systems. It also provides for design of substructures over which other engineering systems can construct on. This makes them interdependent on each other and all equally important.

Observations for those embarking on a profession in civil engineering

Civil engineering is a profession with many specifications, all of which are interrelated and it is important for a prospective engineer to learn to collaborate with other professionals in any project. It is important as a civil engineer to be knowledgeable in the policies and design frameworks that govern the design and implementation of these infrastructural systems. The field of Civil Engineering is one that carries the full weight of the responsibility of infrastructural systems and their management. As such, care must be taken to provide outcomes that can match the level of safety, integrity and durability required to ensure serviceability and human protection.

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