Method for testing and evaluating the design bearing capacity of pile foundations on offshore oil platforms

Abstract

The invention discloses a method for detecting and evaluating design bearing capacity of a pile foundation of an offshore oil platform. The method comprises the following steps of: (1) installing a plurality of pairs of force and acceleration sensors on the detection section of the pile foundation before piling; (2) performing first re-piling detection after piling, and evaluating the bearing capacity of the pile foundation at the moment; (3) performing second re-piling detection, and evaluating the bearing capacity of the pile foundation at the moment; and (4) detecting the design bearing capacity of the pile foundation of the platform. According to the method disclosed by the invention, with the help of field high strain dynamic test and theoretical analysis and calculation, the time-based change law of the bearing capacity of the pile foundation is obtained and serves as the basis of detecting and judging the design bearing capacity of the pile foundation; whether the bearing capacity of the pile foundation before load is applied to the platform meets the requirements on the design bearing capacity is evaluated scientifically; the method has the characteristics of operation simplicity and convenience, low investment cost, short detection period and high reliability; in the aspect of hammering energy, a processing method under the action of lower energy hammering is provided; and therefore, the evaluation result is closer to the objective reality.

Description

Technical field [0001] The invention relates to a method for detecting bearing capacity, in particular to a method for detecting and evaluating the design bearing capacity of offshore oil platform pile foundations. It belongs to the field of offshore oil engineering. Background technique [0002] During the piling process of offshore oil platforms, due to the complexity and variability of the marine geological environment, even if the pile is successfully driven to the design penetration depth, it cannot be guaranteed that the bearing capacity of the pile foundation will meet the design requirements. Therefore, it is necessary to check the bearing capacity of the pile foundation. At the same time, in the process of piling, there will be a phenomenon of hammer rejection. The so-called hammer rejection means that the number of hammer strokes has reached or exceeded the control standard, and the pile body cannot continue to penetrate to reach the design depth. Once the hammer is r...

AI Technical Summary

Problems solved by technology

[0006] ①. This method can only detect the bearing capacity of pile foundation under the action of "certain hammer energy".

However, it is difficult to accurately grasp the "certain hammering energy", so there is an error between the pile-soil interaction state and the ultimate bearing capacity state of the pile foundation at the time of hammering

[0007] ②, this method can only detect and judge the pile foundation bearing capacity at the "hammering moment"

Since the bearing capacity of the pile foundation is constantly recovering with time, if the selected "hammering time" of re-driving is short from the end of piling, it is likely to draw a wrong conclusion that the bearing capacity of the pile foundation has not reached the design bearing capacity; If the "hammering moment" is too long from the end of piling, it may delay the offshore construction period and cause economic losses

Therefore, the method of high strain measurement to detect the design bearing capacity of pile foundation has the disadvantages of low accuracy, blind detection time, long detection cycle and high economic cost

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