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Problem soils
Published in F.G. Bell, Geological Hazards, 1999
Subsurface structures should be designed to be stable with regard to the highest groundwater level that is likely to occur. Structures below groundwater level are acted upon by uplift pressures. If the structure is weak this pressure can break it and, for example, cause a blow-out of a basement floor or collapse of a basement wall. If the structure is strong but light it may be lifted, that is, subjected to heave. Uplift can be taken care of by adequate drainage or by resisting the upward seepage force. Continuous drainage blankets are effective but should be designed with filters to function without clogging. The entire weight of structure can be mobilized to resist uplift if a raft foundation is used. Anchors, grouted into bedrock, can provide resistance to uplift.
Uplift control and remedial measures with waterproofing drained synthetic membranes
Published in J.A. Llanos, J. Yagüe, F. Sáenz de Ormijana, M. Cabrera, J. Penas, Dam Maintenance and Rehabilitation, 2017
In gravity dams, in absence of drains the uplift pressure at the base is considered acting on 100% of the base, and varying in a linear way between headwater and tailwater. In presence of foundation drains, the design uplift can be reduced based on the effectiveness of the drainage system, that is to say on depth, size, and spacing of the drains; on the character of the foundations; and on the facility with which the drains can be maintained (US Army Corps of Engineers 1995). The uplift pressure at the base will vary linearly from the undrained pressure head at heel, to the reduced pressure head at the line of drains, to the undrained pressure head at toe.
Groundwater Problems for Excavations in Soils
Published in Pat M. Cashman, Martin Preene, Groundwater Lowering in Construction, 2020
If the risk of buoyancy uplift is a concern, geotechnical analyses (allowing for the undrained shear strength of the soil and the cylindrical tunnel geometry) should be carried out – an example is described in Soler et al. (2016). The objective should be to determine whether the thickness of clay below tunnel invert is adequate to resist upward groundwater pressures from the confined aquifer.
A new approach for Modelling pile settlement of concrete piles under uplift loading using an evolutionary LM training algorithm
Published in Ships and Offshore Structures, 2021
Ameer A. Jebur, William Atherton, Zeinab I. Alattar, Rafid M. Al Khaddar
Pile foundations have been widely used as an effective system to deliver essential structural integrity for offshore structures such as oil platforms and wind turbines (Doherty et al. 2015; Jebur et al. 2017). The accurate geotechnical evaluation of the load carrying capacity of a pile subjected to uplift loads is an important safety aspect; it plays a key role in the pile foundation design process and continues to gain growing attention in the field of geotechnical engineering (Fattah and Al-Soudani 2016; Jebur et al. 2018b). In the offshore environment, to address issues around uplift loads, it is recommended that piles are driven deeper into the ground in order to develop sufficient resistance to uplift loads. Uplift loads have a substantial effect on the supporting piles if heavy structures like offshore structures, basements, pumping stations and dry docks are constructed in situ in the presence of a water table. Furthermore, transition tower, masts, tall chimneys, jetting structures, etc., are commonly design to resist uplift loads induced form the overturning moments and/or changing in water table level (Reddy and Ayothiraman 2015).
Tsunami mitigation by combination of coastal vegetation and a backward-facing step
Published in Coastal Engineering Journal, 2018
Ghufran Ahmed Pasha, Norio Tanaka, Junji Yagisawa, Fuadi Noor Achmad
According to FEMA (2008), a structural failure by overturning is mostly due to hydrodynamic forces of the incoming or returning flow. However, in the 2011 Japan tsunami, failure of wooden houses due to displacement of the entire house was also widespread. The uplift loading is mainly applied to the underside of floor systems and is blamed for the collapse of elevated floor levels in structures like parking garages, although most failures of this type did not result in collapse of the entire structure (FEMA 2008).
An experimental and numerical comparative study on the uplift capacity of single granular pile anchor and rough pile in sand
Published in International Journal of Geotechnical Engineering, 2022
Jerin Joseph, Shailendra Kumar, Vishwas A Sawant, Jignesh B Patel
The uplift of a structure may take place due to buoyancy and wind force or when the structure is constructed on expansive soils. The buoyancy force acts under structures like underground storage tanks, basements, and dry docks due to the high groundwater level. Lightweight structures like transmission and microwave towers, chimneys, and tall buildings are subject to wind forces. The presence of expansive soils under shallow foundations can cause uplift due to an increase in the soil volume when it comes in contact with moisture. The damage caused due to uplifting leads to substantial financial loss during rectification and may also be irreparable. The uplift due to the presence of expansive soil under the structure can be prevented by mechanical, physical, and chemical alterations or by adopting special foundation techniques like pad foundations and under-reamed piles (Phani Kumar and Rao 2000). In sandy soils, bored concrete piles as tension piles and micropile of sufficient length can counter the uplift forces. Tension pile resists uplift owing to its self-weight, the pile skin friction (Das 1983; Meyerhof 1973), and also the shearing resistance in the failure zone formed in the surrounding soil mass (Chattopadhyay and Pise 1987; Dewaikar, Deshmukh, and Choudhury 2010; Hong and Chim 2015; Shanker, Basudhar, and Patra 2007). Micropiles are long and slender piles that can resist high uplift forces (Hong and Chim 2015). A recently suggested method, granular pile anchor (GPA), is found to be very useful in controlling the heave and resist uplift force in expansive soil (Muthukumar and Shukla 2020; Phani Kumar and Rao 2000; Phanikumar and Muthukumar 2014; Rao et al. 2007; Srirama Rao, Phanikumar, and Suresh 2008). The GPA is a modified granular column in which a steel anchor rod passes through the centre and is attached to a rigid circular steel plate/concrete pedestal at the bottom of the column (Rao et al. 2007) (Figure 1). The steel anchor rod is connected to the footing/shallow foundation, which rests on the GPA. The uplift force is resisted by the self-weight of the GPA material and its interaction with the surrounding soil. The GPA resists the uplift force and, at the same time, improves the bearing capacity of the soil.