PARAPHRASING (ENGINEERING REPORT)
Jess-93
100_report.docxIntroduction
1.1 Project Background
The Leprechaun Heights civil earthworks development project has been assigned toThe Matrix Engineers Company by the Gold Coast City Council. The development of the new urban retirement community will be based on the beachfront of the southern end of Gold Coast, Queensland. Matrix Engineers have been approached to evaluate the downscaled model of the development land (scale: 1:200), which has been provided by the developer. The model will be analysed to locate the possible locations (based on budget) of the highland and to design the foundation earthworks for the project. Results and data are to be analysed prior to the closure of the project.
1.2 Aim and objectives 1.2.1 Aim
Find the most cost effective locations of the earthworks within the area of the scale model.
Build a geometric scale model of the stage on the downscaled site.
1.2.2 Objectives
Analysing preparatory measurements of the scale model
Create a digital illustrated model using preliminary data
Find possible locations to undergo further analyses based on the cost of purchasing and moving sand.
Take precise measurements to analyse the possible locations
Finding the most cost effective locations to develop construction platform.
Create a digital illustrated model
Compare and analyse the digitally illustrated construction platforms locations
Provide the preliminary design based on the most cost effective model
1.2.3 Design Constraints
When determining the ideal construction location for this development the following design constraints were considered.
In general to keep the total construction cost at minimum
Aim to keep platform construction costs within the initial civil earthworks budget which is set at $150,000.00 AUD.
There is 40,000m3 of sand available at no cost. However, any extra sand required will cost delivery fees of $12.50 per m3. In addition disposing of any extra sand will cost $20.00 per m3.
Constructed platform must sit at reduced level (RL) of 21.0 m AHD (Australian Height Datum)
The platform has to be designed as a truncated pyramid with a rectangular site of 40m x 40m in prototype and the batters on the side are to be constructed at 1 Vert : 3 Hor.
Table 1 lists the full design parameters for the scale mode and the real scale equivalent information which was provided by the developer.
Table 1. project parameters and costs
|
|
Model Scale (1:200) |
Real Scale |
|
Area of platform |
20 cm x 20 cm = 400 cm2 |
40 m x 40 m = 1,600 m2 |
|
Repose angle |
32 degrees |
32 degrees |
|
Available sand for construction |
5,000 cm3 |
32,000 m3 |
|
Cost of purchasing sand |
$100 per cm3 |
$12.5 per m3 |
|
Cost of disposal of excess sand |
$160 per cm3 |
$20 per m3 |
|
Cost of buying land (footprint) |
$80 per cm2 |
$20 per m2 |
|
Height of surrounding edge |
20 cm |
40 m |
|
Truncated pyramid height |
Platform is 2 cm below surrounding top edge |
4 m below surrounding top edge |
Note. Retrieved from Leprechaun Heights Project Guidance Lecture Notes (p.02) Griffith University
METHODOLOGY
This section of the report discusses the strategies that were applied to analyse the most cost effective positions for the proposed development site. This process was broken down into 3 key tasks of data collection, pyramid calculations and MATLAB simulations.
Raw data collection and analysis
A team of engineers surveyed the proposed development site which can be described as “table
4” at Griffith University, Building G09, and room 1.43 as represented by figure 1. The survey
was conducted on the afternoon of Wednesday 21st of August 2014. A restricted time window of 2 hours was provided to the site with no further access to be granted.
The collection of the raw data was done by measuring along the x-axis for every 2.5cm and whilst having the adjustable y-axis perpendicularly along every mark of 2.5cm respectively. The Vernier callipers end was then to be placed inside a hole on the 100cm ruler. The raw data was first recorded by hand on to grid paper with the axis labelled along the grid paper prior taking measurements. This was more time efficient than going through the process of directly typing the queries of typing the values down. The recorded values on the grid paper values were then typed into a Microsoft Excel spread sheet.
By observing Figure 2, which represents the survey data plotted in Microsoft Excel. It can be noticed that some errors occurred in the data measurements thus the coarseness of the terrain. Due to the restricted access of 2 hours there was no availability to re-measure to inconsistencies in the raw data
A similar process was also done when constructing the truncated pyramid DEM, however the pyramid measurements were calculated within the constraints of the project. Calculations were made by using trigonometry identities.
All the results of the pyramids heights were put in a survey in excel to demonstrated in a colour scale, as shown in figure 7, where the base and the top of the pyramid stands. Darker colours represent the base and lighter colours represent the top of the pyramid.
Figure 7. Pyramid DEM Heights in cm
MATLAB was used to determine the ideal location this was achieved by modelling each pyramid location on the surveyed surface. Figure 9 shows the general principles of the method used. By observing figure 9, it can be noticed that the area of importance is only where the pyramid is above the surface. When the pyramid is below the surface the area will not be calculated. The foot print cost is when the surface level intersects the pyramid.
Figure 8. General method of calculation.
Note. Retrieved from Week 3: Leprechaun Heights Lecture Notes (p.12) Griffith University.
Figure 10. General program flow.
Figure 10 above, describes the general method of calculation and equation 6 describes the general function used to generate the values of the SurveyOverlay matrix.
Construction of the pyramids.
At the construction site, a difference in position was noted and the pyramid was fitted in a slightly different angle and coordinates compared to the computer simulation figure for a most
optimal location. This was due to a tolerance of uncertainties of the measurements.
After the pyramid was shifted, a new footprint area had to be calculated. On the day of the construction model the coordinates of the four corners of the area were taken and with these coordinates interpreted as single vectors, as shown in figure 11 and the corresponding coordinates were collected and are presented in table 2.
As a result of the measurement and analysis of the data collected, between design and construction stages of the Leprechaun Heights civil earthworks development project have produced different results regarding the most cost effective locations.
Figure 15 represents the average survey DEM calculated in MATLAB when comparing this to figure 2 on page 6 within this report. It can be notice that the inconsistencies of the data measurements has reduce to an insignificance amount. Therefore due the averaging of the 4 survey points into one point. It could be suggested that this method has allowed for error is measurement to be mitigated.
For a more accurate set of locations, calculations were done based on a 2.5x2.5cm measurement. As a result, the three possible locations have being assigned in order to optimise the final result as shown in table 3. Note that the x and y coordinates provided in
Table 3 are for the bottom right corner of the pyramid.
1.1 Construction Results
As a result of shifting the position in a different angle and slightly moving it horizontally and vertically a new and final result was produced, this new result includes a best optimisation of the use of sand granted and total cost is under the planned budget. Table 4 shows the final coordinates of the position of the pyramid including the footprint cost at $106,872.00 and volume of sand used 0cm3. The actual positon of the pyramid on the construction site was determined to be on the x (146.1) and y (46) coordinates.
Table 4 lists the calculated costs when determining the optimal locations for the 2.5cm DEM. The optimal location was determined to be at location 158cm,58cm with a total cost of $AUD 104,439.10.
3.2 Discussions
Although the 2.5 cm resolution computer simulation provided more accurate result then the 5 cm resolution it still contained uncertainties due to the averaging of the four heights to produce an average volume, at the construction site it was noted that a 10 cm shifting would provide the optimal location “table 4”. When comparing these results it can be noticed that the location for the ideal cost is shifted around 10 cm on the vertical direction and 10cm on the horizontal direction which fall within the expected tolerance.
When determining the cost of the ideal location firstly the volume of sand required for construction and the foot print at this location was determined as shown on section 2.2 Construction of the pyramid pg.8. Note that, although a location that used the least amount of sand it may not necessary be the best location based on the foot print cost.
After comprehensive measurements, computer simulated models and calculations done in the downscale model, a final position with optimal use of sand provided and footprint cost within determined budget was decided. Other engineering aspects that is not included in this final report. Once this model is approved, the construction of the platform will take place and the final report will be delivered within the time frame stipulated earlier in this report.
