Abstract
Shallow foundations are very distinctive in Bhutan since construction of buildings are regulated to 7-8 story and the superstructure loads are not very high compared to high-rise buildings elsewhere. However, the safety of the buildings depends primarily on the stability of the subsoil. This can be evaluated by estimating Ultimate Bearing Capacity (UBC) and it is the measure of the subsoil strength. In the current study, field test such as Plate Load Test (PLT) and Standard Penetration Test (SPT) are conducted in the study area which are most common conventional methods adopted in Bhutan given the typology of infrastructures. Detail analysis is performed for PLT and SPT data collected from southern parts of Bhutan to assess the shear stability characteristics of the subsoil. The field exploration was carried out at embedment depth of 1.5 m in both the tests. PLT directly provides UBC through load and settlement plot. With SPT N-values, UBC are estimated for square footing using empirical correlations proposed by Terzaghi 1943 and Meyerhof 1963. The results are compared to comprehend the design parameters. Both in-situ test resulted close estimation of UBC. In SPT, analysis results indicate Meyerhof's correlation more conservative suggesting safe and economical foundation design. The parametric analysis was performed to deduce and validate correlations among the parameters used. The subsoil lithology was reviewed to validate the subsoil characteristics for the southern belt of Bhutan to which resistivity profiles of the underlying strata of the subsoil in the region have been reported similar to the investigation conducted in this study.
Highlights
Bhutan is located in seismically active Himalayan fringe with several moderate to high earthquake histories in the past such as 2009 Mongar earthquake (Mw 6.1) and 2011 Sikkim-Bhutan earthquake (Mw 6.9)
Geotechnical investigation becomes a part of Detail Project Report (DPR) under strategic planning to study the technical feasibility and suitability of the area to be developed which is a pre-requisite for construction [4] and to predict the potentially problematic soils in the area for future precautions to the damages and reduce maintenance cost [5]
The criterion on bearing capacity ensures that the foundation does not undergo shear failure under loading, while settlement requirement ensures that settlement of the structure is within the tolerance limit of the superstructure [9]
Summary
Bhutan is located in seismically active Himalayan fringe with several moderate to high earthquake histories in the past such as 2009 Mongar earthquake (Mw 6.1) and 2011 Sikkim-Bhutan earthquake (Mw 6.9). The major shear zones of the Himalayan arc are the Main Himalaya Thrust (MHT), the Main Boundary Thrust (MBT), the Main Central Thrust (MCT), the South Tibetan Detachment System (STDS), and the Indus-Tsangpo Suture Zone (ITSZ). These features span the entire Himalayan arc including the Bhutan Himalaya [1,2]. In any infrastructure development projects, geotechnical site investigation (GSI) plays an important role in assessing the soil properties which are important parameters for architectural and structural design of structures [7] in relation to behavior of buildings to seismic responses [8] and most importantly strength characteristics of the foundation subsoil [4]. Correlation among the soil parameters such as N-value, bulk unit weight, angle of internal friction and bearing capacity factors are presented to demonstrate the influence on UBC
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
