Abstract
The thickness of a karst cave roof at the bottom of a socketed pile plays an important role in the vertical bearing capacity of the socketed pile in the karst region. In practice, its thickness is simply recommended to be not less than 3 times the diameter of the socketed pile, regardless of the geological conditions and the size of the cave itself. In this study, we present an approach for calculating the critical thickness‐to‐diameter ratio of a karst cave roof η (η = h/d, the ratio of karst cave roof thickness to pile diameter) based on the generalized Hoek–Brown criterion by virtue of the limit analysis method, which considers the pile tip load, hardness degree of the intact rock, and rock mass quality. The analysis results show that less load at the bottom of the pile, higher quality of rock mass, and more hard rock all lead to a smaller critical thickness‐diameter ratio, whereas the critical thickness‐to‐diameter ratio is greater. The validity of the proposed method is verified through a physical model test.
Highlights
Pile foundations have been widely used in engineering construction in karst areas because of their strong load transfer capacity, which can effectively reduce the uneven settlement of the foundation and reduce the adverse impact of a karst cave on the foundation to a certain extent [1]. e key problem with pile foundations in karst areas is the calculation of their vertical bearing capacity
E quantitative analysis method for karst cave roofs is generally established on the theory of structural mechanics, by which the karst cave roof is simplified into a beam or slab structure according to the fracture distribution around the roof and the pile bottom load
We present an approach for quantitatively calculating the roof thickness based on the generalized Hoek– Brown failure criterion by virtue of the limit analysis method, which comprehensively considers the effects of the pile tip load, the hardness degree of the intact rock, and the rock mass quality on the roof thickness
Summary
Pile foundations have been widely used in engineering construction in karst areas because of their strong load transfer capacity, which can effectively reduce the uneven settlement of the foundation and reduce the adverse impact of a karst cave on the foundation to a certain extent [1]. e key problem with pile foundations in karst areas is the calculation of their vertical bearing capacity. E quantitative analysis method for karst cave roofs is generally established on the theory of structural mechanics, by which the karst cave roof is simplified into a beam or slab structure according to the fracture distribution around the roof and the pile bottom load. Based on this simplified model, the bending, shear, and punching stability of the roof are checked to determine the vertical bearing capacity of the pile [5]. Bai [7] improved the calculation method for the safety thickness of karst cave roofs by considering the influence of the weight
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