Several renowned foreign and Pakistani professional experts presented thought-provoking technical papers on 'Tunnelling, Deep Excavations and Sub-structures" here on Friday at a seminar organised by the Pakistani Geotechnical Engineering Society and stressed the need for preserving precious lands.
Nespak Geotech expert engineers, Sohail Kibria, Junaid Ahmed, Sohail Majid and Miss Sadaf Saeed, in their joint paper on "Deep Excavations in Lahore" said that the recent hike in prices of land in urban areas had compelled the owners, builders, architects and engineers to rely on vertical buildings.
They said that the skyline of Lahore, a city with rich cultural heritage, is experiencing swift change from traditional low buildings to high-rise construction and added that tall buildings are quickly finding their way with multi-level basements to get benefits of excavation relief and to meet the demand for parking areas.
They recommended that in deep excavations, strict supervision is necessary for all operations such as piling, deep excavation and grouting and stressing is very important to the success of the system. Poor design and construction procedures may result into catastrophic failure, they remarked.
They gave a presentation about the different stages of 64 feet deep foundation excavation for a 28 storey I T Tower structure, which included 5 basements. The President of International Society for Soil Mechanics and Geological Enginering, Professor Pedre Simao Pinto of Portugal in his paper remarked that in spite of the impressive progress made during the last few years on tunnelling, it was necessary to understand tunnels structures behaviour during static and seismic conditions. He strongly recommended continued study of fast developments in earthquake geological engineering and in underground soil structures.
Professor In-Mo Lee of Korean University in his paper remarked that tunnelling engineers should have good knowledge of fundamental concepts of ground structure interactions to successfully accomplish the task of tunnelling projects. Referring to his experience of Korean peninsula, he said that the decomposed residual soils and weathered rocks, depending on the degree of weathering, are abundantly encountered.
Wasif Ahmed Siddqiui, a Pakistani expert in geotechnical engineering, stressed the need for starting training programmes for geologists and tunnel engineers to ensure better communication on tunnelling projects. He stressed the need for systematic documentation of tunnel case histories for comparison of rock conditions, support design and construction experiences.
From Taiwan, Chi H Chen, Chairman of Taipei Professional Civil Engineers Association and Wei F Lee, a Research Fellow, in their joint paper described the forensic investigation of a construction failure at the subway station of a Mass Transit in their country. They said that the major cause of construction failure was the uncontrollable ground water leakage, which occurred at the bottom of the shield tunnel, machine face and vibration during diaphragm wall breaking operation. They said that investigation process and data assessment presented in their paper would provide a helpful reference to engineers engaged in forensic practices.
M H Chughtai, a Pakistani expert while talking on 'Tunnelling, Rock Supports, Open and Box Cuts, Slope Stabilisation" described in details the tunnelling methods and support systems in the mountainous areas in the north of Pakistan where avalanches and huge landslides occur.
Referring to the 7.6 magnitude earthquake of October 2005 in AJK and parts of Hazara, which killed thousands of people, he stressed the need to acquire the tunnelling techniques to plan and construct underground passages and tunnels. Tunnelling work is very hazardous and expensive, therefore, extensive planning and investigation is required and proper procedures must be followed in the pre-excavation period, he recommended.
'Organisers of the seminar told Business Recorder that the foreign and Pakistani delegates will visit high-rise I T Tower, in Gulbgerg, which has 64-feet deep foundation with five basements as well as Mubarik Centre on Ferozepur Road on Saturday.
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