Geophysical surveys have been proven to reduce the risk of experiencing unexpected subsurface conditions by 70%. Construction costs as well as delays have seen a decline due to these surveys. Conducting geophysical surveys can save approximately 10-15% on the total costs of the project. This is owing to the fact that there will be a curb in interruptions. This will also contribute to more informed decision making.
Let’s explore some ways in which geophysical surveys help ensure safety and efficiency.
Geophysical surveys are known to play a role in hazard detection. They work efficiently in detecting buried objects or structures, such as buried utilizes, underground cavities, or archaeological artifacts. They are also used to detect and assess landslides. These surveys have been proven to reduce the impact of landslides on the environment and public safety. As they can accurately identify potential landslide zones and early warning systems, they can facilitate more efficient land-use planning and improve disaster.
An instance where geophysical surveys were helpful in hazard detection was the Alaskan Way Viaduct Replacement Program. The Alaskan Way Viaduct was an elevated section of State Route 99 in Seattle. This structure was built in the 1950s. Due to the decades of wear and tear, the structure was weakened during the Nisqually earthquake in 2001. As a result of this, it was impertinent to replace it for the sake of the public’s safety. The program consisted of 30 projects which would replace the viaduct and provide safety and improvements in mobility to Seattle’s central waterfront.
“Geophysical surveys are indispensible in construction, they provide critical information about subsurface conditions that can make or break a project. By uncovering hidden risks early, thee surveys help us design safer structures and execute projects more efficiently, avoiding costly surprises down the line” says Dr. Richard J. Finno, Professor of Civil Engineering, Northwestern University.
New efforts are now being made to improve the design and installation techniques to achieve enhanced system efficiency and reduced ‘first costs’. The recently developed surveys have proved to be cost and time-efficient. This method was used to map mid- and large-scale tunnel alignments to plan and integrate detailed soil investigations efficiently. It can also be used in road construction. Considering the hydrological point of view, geophysical methods can be helpful in identifying the water table, geological strata, pollution arising from the road and the movement of the pollution before, during and after construction.
The Hyderabad Metro Rail Project is one case that emphasizes this point. While the planning and construction of this project was underway, geophysical surveys were conducted to understand the underlying conditions across Hyderabad. The data extracted from these surveys were used to help engineers make decision about certain elements of the rail system. This was used to identify potential obstacles which were the used by the project team to avoid delays.
“Geophysical surveys were the backbone of our planning for the Mumbai Coastal Road Project. The insights they provided allowed us to foresee challenges and optimize our construction methods, which significantly enhanced the efficiency of the project” said Dr. N.K. Patil, Chief Geotechnical Engineer at L&T Infrastructure Engineering while he was participating in a technical seminar on Coastal Infrastructure Development in Mumbai.
The optimal ground for construction can be determined through geophysical surveys. Geophysical surveys can produce valuable information on subsurface structures. These surveys, combined with other direct methods, are widely recognized as reliable for determining subsurface structure.
According to research conducted by M Zoghi, B.H Richard, P.J Wolfe, E.C Hauser and JD Hicks, The risk of similar failures due to unsuspected features beneath the roadway was highlighted by a collapsed coal mine under Interstate 70 in eastern Ohio. These failures occurred for various reasons, like uncharted features beneath roadways, which can lead to catastrophic disruptions and high repair costs. The study aimed to help mitigate these risks. It aimed to develop a cost-effective reconnaissance geophysical survey technique to identify potential failure zones. Various geophysical methods were tested, namely seismic refraction, resistivity imaging, and surface wave profiling. As indicated by the results, these techniques are promising in detecting problem areas that need more detailed investigation.
Dr. P.K Jain, a Senior Geotechnical Engineer from the India Institute of Technology says “Geophysical surveys provide the critical data needed to tailor foundations designs to the unique subsurface conditions of a site. By understanding soil and rock properties in detail, engineers can optimize foundation structures, ensuring both stability and cost-effectiveness.”
The field of geophysical surveys is rapidly evolving. This is being done due to the constant and rapid growth of new technologies. As geological exploration develops, it will require certain science and technology. Technology helps with obtaining more accurate results from these surveys. Geophysical surveys are more modern than we thought.
An instance where innovative techniques were used to ensure safety and efficiency in construction is the integrated Geophysical Survey System in the Bangalore Namma Metro Project. As Bengaluru’s Namma Metro is moving into Phase 3 expansion, the Bengaluru Metro Rail Corporation (BMRCL) is set to launch a crucial geophysical investigation where they will analyze the soil stability as well as the geological factors throughout the proposed routes. This is being done to ensure safe construction.
Dr. Ashok Kumar, Director of Geotechnical Services, RITES LTD says “By incorporating innovative geophysical techniques, such as survey systems and advanced imaging method, we can significantly enhance safety and efficiency in construction. These technologies allow us to accurately assess subsurface conditions and address potential challenges before they impact the project.”
Geophysical surveys play a key role in ensuring safety and efficiency. With the help of these methods, one can make sure that construction takes place is a safe manner while also maintaining efficiency and a good pace.
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