Method for calculating vertical ultimate bearing capacity of bridge pile foundation in underlying karst development area

Abstract

The invention discloses a method for calculating the vertical ultimate bearing capacity of a bridge pile foundation in an underlying karst development area, which is characterized in that the end resistance of a pile foundation is corrected under the condition of considering the variation conditions of the height, span and top plate thickness of a karst cave according to a calculation formula for the ultimate bearing capacity of a rock-socketed cast-in-place pile in a common empirical formula method based on a numerical simulation result; and finally, the corrected vertical ultimate bearing capacity of the underlying karst development area bridge pile foundation is obtained. The accuracy and applicability of calculating the vertical ultimate bearing capacity of the bridge pile foundation in the underlying karst development area are high; meanwhile, the method can be applied to the conditions of different underlying karst heights, spans and roof thicknesses, the problem of calculation of the bearing capacity of the bridge pile foundation in the karst area can be solved, and the calculation result is accurate and reliable.

Description

technical field [0001] The invention belongs to the technical field of design and construction of bridge pile foundations in geotechnical engineering, and in particular relates to a calculation method for the vertical ultimate bearing capacity of bridge pile foundations in an underlying karst development area. Background technique [0002] With the rapid development of my country's traffic construction, highway bridges inevitably cross the karst development area. The function of the bridge pile foundation is to transmit the upper load to the deep underground soil layer with good bearing capacity, so as to meet the requirements of bearing capacity and settlement. Pile foundations can not only bear vertical loads and horizontal loads, but also resist uplift loads and withstand vibration loads. The vertical bearing capacity of pile foundations under vertical loads is mainly provided by pile side friction resistance and pile tip resistance. At present, the calculation methods f...

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Problems solved by technology

[0003] The special geological conditions in the karst development area have brought many uncertain factors to the design and construction of the bridge pile foundation, and the existence of the underlying karst caves has caused problems such as insufficient bearing capacity of the highway bridge pile foundation, and even caused quality defects in the pile body, causing safety hazards

[0004] Among them, the size of the underlying karst cave and the thickness of the roof are the key factors that significantly affect the vertical bearing capacity of the pile foundation in engineering design. So far, there are few studies on the influence of the size of the underlying karst cave and the thickness of the roof on the vertical bearing capacity of the underlying karst pile foundation. , so a series of problems have been caused: ①The phenomenon of displacement, inclination and stress concentration in special positions of the bridge pile foundation will affect the normal operation of the pile foundation; ②The influence of different sizes and roof thicknesses of the underlying karst caves on the vertical bearing capacity of the pile foundation In the engineering design and construction stages, the influence of different influencing factors on the vertical bearing capacity of pile foundations was not fully considered; ③The current design technical specifications lack targeted design methods and parameter values ​​for bridge pile foundations in underlying karst development areas , the design and calculation of the bridge pile foundation often does not match the actual force, resulting in certain hidden dangers in the bridge structure

[0005] The existence of the underlying karst seriously threatens the stability and bearing characteristics of the bridge pile foundation, and affects the normal operation of the pile foundation. The actual force does not match, which will easily cause a lot of waste in the cost of bridge pile foundation engineering and hidden safety hazards during bridge operation

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