Scenario A: The extension of the Swansea University Bay Campus.
Geological Survey is a branch of building engineering that has been gaining popularity in the construction industry. The process involves research and evaluations of geological conditions of construction sites, including tests, mapping, explorations, and experiments (Fuis et al., 2017). The application of geological survey has been of great benefit to project managers as it results in an effective construction process involving minimal risks. One project that needs a geological survey is the extension of the Swansea University Bay Campus. A successful geological study of the site will require a consideration of potential problem conditions that may be encountered and the methods that can be applied in making the project safe and successful.
Potential Problem Conditions
Water Table Level
The site had no tall structure constructed before. As a result, the underground conditions are unknown to the engineers and construction contractors. One problem that the extension site can have is with the water table level. The presence of limestone at the site makes this process important due to the high probability of having high amounts of water below and above the water table. Groundwater flows through limestone using networks of underground channels that end up storing water underground (Abd El-Karim, Mosa El Nawawy& Abdel-Alim, 2017). Thus, it is critical to determine whether the problem exists before the construction process commences.
The Nature of Fissures, Voids, and Faults
The presence of voids, fissures, and faults in the underground can limit the nature of a construction project in an area. Since the bedrock is made up of limestone and coal measures, there is a big probability that it has voids and fissures, mostly in areas where the two materials combine. The flow of water through conduits in limestone results in the creation of channels that end up being voids (Fuis et al., 2017). As a result, the bedrock posing a big threat if a tall building is constructed above them as it cannot hold buildings that exceed a certain height. Similarly, the presence of water in the coal measures may create fissures, limiting the ability of bedrock to support a large building.
Ground Layer Thickness
Another problem that may prevent the expansion of the university’s facilities on the site is the thickness of the ground layer. Besides having limestone and coal, the bedrock might not be thick enough to support the tall buildings that need to be constructed in the area. Additionally, the ground layer might have structural features that make it unfavorable for such a project. The process of the geological survey should determine whether any of these problems exist before approving the project to proceed. The expansion project will continue at the site only if the ground layer’s structural features are favorable, and the ground layer is of the required thickness.
Techniques to be Used in a Geological Survey
Window Sampling
Window sampling is one of the best shallow-depth methods used in the geological survey. The process is quick and economical, thereby taking little time and resources to undertake the study. The process involves an analysis of soil samples collected from the ground through the insertion of tubes of different lengths into the ground (Designing Buildings Ltd., 2019). Tubes with longitudinal openings are inserted into the earth using tracked percussive samplers or hand-held pneumatic samplers through which ground properties at different lengths are determined. Sample tubes used in this case are one-meter-long and are driven using drill rods that adjust their lengths. The drop and weight heat are adjusted from time to time to ensure that dynamic probing and standard penetration testing is achieved together with soil sampling. Although the technique is most commonly used in areas where the construction process is to be undertaken with minimal disturbance to the ground, it is still applicable. The expansion is to include underground facilities in which the bedrock or underground soil materials will not be affected. For this reason, the process will require the use of a method that can be applied in determining characteristics of the soil at depths not exceeding ten meters, thus the use of window sampling.
Rotary Boreholes
Another technique that can be used is rotary boreholes. The method involves an analysis of samples from depths of up to 100 meters, thereby giving more detailed information about the lower layers of the soil. The technique is used where exploration involves drilling through stable geological formations such as dense gravel or rocks. The method aims at analyzing two main factors, namely the presence of voids and structural details of the soil. Rotary-hole boreholes are drilled when the main target of analysis is determining if there are voids in the underground structure. The technique is suitable in areas with a likelihood of mining activities due to the high probability of the area to have voids in the bedrock. Determining structural details of the bedrock is achieved through the use of rotary cored boreholes. In this case, air, water, or mist is sprayed into a drilled hole via a core barrel after which a flush is circulated. Samples are then collected and examined in a laboratory through which structural details are identified.
The technique is the most suitable for this project because it can collect samples from deeper lengths in the ground. The expansion project will have the construction of tall buildings hence a need for ensuring that the bedrock can support the structures. The use of rotary boreholes is also suitable in the analysis process due to the presence of limestone as a part of the bedrock, which makes other techniques unable to collect samples within and below the bedrock (Designing Buildings Ltd., 2019). Hence, the surveying process will result in having samples from all layers of the underlying rock through which detailed information regarding the project site will be obtained. Besides being efficient in determining the structure of the bedrock and the underlying layers of the soil, the method must complement the use of window sampling to ensure that in-depth is provided for both the shallow and deep layers of the ground.
Conclusion
A geological survey is essential in determining the suitability of a construction site. Some of the problems that the site might have to include the presence of water in and below the bedrock, presence of fissures, voids, and faults as well as a less thick ground layer. The main techniques that can be applied in the geological survey include window sampling from shallow depths and rotary boreholes for more extended depths. Although the methods are used individually, it is essential to combine their findings to ensure that the site meets all project requirements. Thus, the success of the expansion project will be determined by the accuracy and effectiveness of the findings from the use of the two techniques.
References
Abd El-Karim, M. S. B. A., Mosa El Nawawy, O. A., & Abdel-Alim, A. M. (2017). Identification and assessment of risk factors affecting construction projects. HBRC Journal, 13(2), 202-216. Retrieved from: https://www.tandfonline.com/doi/full/10.1016/j.hbrcj.2015.05.001
Designing Buildings Ltd. (2019). Designing buildings wiki. designing buildings Ltd. Retrieved from: https://www.designingbuildings.co.uk/wiki/Ground_investigation
Fuis, G. S., Bauer, K., Goldman, M. R., Ryberg, T., Langenheim, V. E., Scheirer, D. S., … & Graves, R. W. (2017). Subsurface geometry of the San Andreas fault in southern California: Results from the Salton Seismic Imaging Project (SSIP) and strong ground motion expectations. Bulletin of the Seismological Society of America, 107(4), 1642-1662. Retrieved from: https://pubs.geoscienceworld.org/ssa/bssa/article/107/4/1642/354067