Groundwater and geotechnical aspects of deep excavations in Hong Kong

Forth, R. A.

doi:10.1016/j.enggeo.2003.09.003

Cited by 49 publications

(24 citation statements)

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“…Pumping groundwater using Pattern 4 inevitably causes a decrease in the groundwater level outside the pit, resulting in settlement of the surroundings (Hsi and Small, 1992;Forth, 2004;Gue and Tan, 2004;Roy and Robinson, 2009;Pujades et al, 2014a). In general, ground settlement around the foundation pit is mainly caused by dewatering as well as by the excavation.…”

Section: Introductionmentioning

confidence: 97%

Environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer

Shen

et al. 2015

Engineering Geology

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Section: Introductionmentioning

confidence: 97%

Environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer

Shen

et al. 2015

Engineering Geology

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“…The issue on the calculation and design of excavation dewatering has attracted the attention of many researchers [6][7][8][9], especially a great deal of literature on dewatering for deep excavations with partially penetrating curtains has been published in recent years [10][11][12][13][14][15][16]. Deep excavations are conducted in China's coastal cities, where the aquifers have a very large thickness (sometimes as large as 60-70 m).…”

Section: Introductionmentioning

confidence: 99%

A Simplified Approach to Design Jet-Grouted Bottom Sealing Barriers for Deep Excavations in Deep Aquifers

2019

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This paper presents a simplified methodology for the design of jet-grouted bottom sealing barriers (temporary water-tightness structures) for deep excavations that was undertaken in deep aquifers. The bottom sealing barriers are usually required to prevent uplift failure against the water head below. Additionally, jet-grouted bottom sealing barriers are never perfect due to the uncertainties of jet grouting columns at the site, so the design must carefully consider the analysis of seepage. For these reasons, the proposed calculation procedure focuses on two different failure mechanisms (i.e., "instability failure" and "seepage failure") of massive bottom sealing barriers. Subsequently, the design parameters of the jet-grouted bottom sealing barriers (e.g., depth and thickness) for an excavation case were determined while using the proposed design procedure. The field pumping test results show that the water-tightness performance of bottom-sealing barriers performed at site is good, which ensures that the water level inside the excavation can reach the desired level and the groundwater drawdown outside can be minimized. The leakage flow rate of bottom-sealing barriers is lower than the designed maximum allowable seepage when the water level inside stabilizes at the final period of the pumping test.

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“…However, dewatering reduces the piezometric head that may produce ground subsidence (i.e., pumping settlements) (Terzaghi, 1943;Corapcioglu, 1981a, 1981b). This subsidence is of high risk (especially in urban areas) because it may damage nearby buildings and structures (e.g., see Hsi and Small, 1992, Gue and Tan, 2004, Forth, 2004, Roy and Robinson, 2009. Consequently, when pumping is mandatory, pumping settlements are predicted in advance to avoid unexpected events; if they are deemed not acceptable, then corrective measures (sometimes over-dimensioning) are adopted to minimize the settlements (Vázquez-Suñé et al, 2004;Pujades et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

Leveling vs. InSAR in urban underground construction monitoring: Pros and cons. Case of la sagrera railway station (Barcelona, Spain)

Serrano-Juan

Pujades

Vàzquez-Suñé

et al. 2017

Engineering Geology

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Monitoring is required when dewatering underground construction sites to anticipate unexpected events and preserve nearby existing structures and/or buildings. The most accurate and widespread monitoring method to measure displacements is leveling, a point-like surveying technique that typically allows for tens of discrete in situ sub-millimeter measures per squared kilometer. Another emerging technique for mapping soil deformation is the interferometric synthetic aperture radar (InSAR) method, which is based on SAR images acquired from orbiting satellites. This remote sensing technique can provide better spatial point density than leveling, more extensive spatial coverage and lower-cost acquisitions. This paper analyses, compares and discusses leveling and advanced multi-temporal InSAR measurements when they are used to measure the soil deformation induced by the dewatering associated with underground constructions in urban areas. This comparison, which has not been considered in previous works, is of paramount importance to ascertain the most suitable technique (or combination of techniques) in these contexts. To do so, an experiment was performed in the future railway station of La Sagrera, Barcelona (Spain), in which leveling and advanced multi-temporal InSAR were used to quantify ground deformation by dewatering. The results showed that soil displacements measured by leveling and InSAR were not always consistent. In the context of soil deformation measurements produced by dewatering in urban areas, InSAR measurements appear to be more accurate for investigating soil deformation, whereas leveling was more appropriate for quantifying the real impact on the nearby buildings.

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Groundwater and geotechnical aspects of deep excavations in Hong Kong

Cited by 49 publications

References 1 publication

Environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer

Environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer

A Simplified Approach to Design Jet-Grouted Bottom Sealing Barriers for Deep Excavations in Deep Aquifers

Leveling vs. InSAR in urban underground construction monitoring: Pros and cons. Case of la sagrera railway station (Barcelona, Spain)

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