| Karst areas account for more than one-fifth of China’s land area,and various types of karst landforms and cave forms are widely distributed in the strata of karst areas.The construction of pile foundation engineering in karst areas cannot avoid hidden caves in the strata.Since the stability of the hidden karst caves under the pile foundation in the karst area is crucial to building safety,and most of the karst caves are approximately elliptical in shape,it is necessary to give an analysis method for the stability of the elliptical karst caves underlying the pile foundations,which can be used for pile foundations.Providing a reference for the stability analysis and pile foundation design of the elliptical cave.On the basis of summarizing the analysis methods of the stability of karst caves underlying pile foundations,theoretical calculations are carried out,and the stability analysis methods of elliptical karst caves underlying pile foundations are deduced.First,considering the load-bearing characteristics of rock-socketed piles in karst areas and the location of elliptical karst caves,a calculation model is established,and the additional stress under the uniform load at the pile tip is deduced;combining the complex variable function and the superposition principle,the uniform load at the pile tip and the gravity Under the joint action,the stress components of the elliptical cave boundary are calculated,and then the Griffith failure criterion was introduced to judge the stability of the elliptical cave,and the generalized Hoek-Brown criterion was used to quantitatively analyze the stability of the cave boundary.Comparing the theoretical analysis results with the numerical simulation results,the analysis shows that the theoretical analysis is in good agreement with the numerical results,which verifies the reliability of the analysis method for the stability of elliptical caves.Secondly,through the finite element numerical analysis of the stability of the double karst caves underlying the pile foundation and the elliptical karst caves underlying the double piles in various working conditions in the karst area,the pile side karst caves,the double karst caves underlying the pile foundation and the double karst caves under the pile foundation are given.Simplified analysis conditions for elliptical karst caves underlying piles.Finally,the feasibility of the analysis method for the stability of elliptical karst caves underlying pile foundations is verified by two engineering examples,and the applicability of the simplified analysis method for double karst caves underlying pile foundations is discussed. |
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