New method for applying boron neutron lifetime well logging technology to detect quality of pile foundation post pressure grouting

Abstract

The invention discloses a new method for applying the boron neutron lifetime well logging technology to detect the quality of pile foundation post pressure grouting. The new method comprises the following steps that firstly, boric acid used for capturing thermal neutrons is added in cement grout; secondly, an underground neutron generator and a gamma ray detector are placed in the bottom of a detection pipe reserved in a pile foundation, the underground neutron generator starts to repeatedly transmit high-energy pulse neutrons, the high-energy pulse neutrons are gradually elevated upwards, the gamma ray detector synchronously records the relative change of the number of thermal neutrons in media, the number of the thermal neutrons is attenuated in the exponential form at the measuring stage, and a base line is measured; fourthly, grouting is conducted; and fifthly, after grouting, the detecting detection manner is the same as the detection manner in the third step, and a boron water curve is measured. According to the new method, the base line measured before grouting and the boron water curve measured after grouting are compared, the upward movement height and the distribution position of the post-pressure grout can be visually recognized, and accordingly the distribution situation of the post-pressure grout in a pile end soil layer and a pile periphery soil body is judged.

Description

technical field [0001] The invention relates to a new method for detecting the grouting quality of a pile foundation by applying the boron neutron lifetime logging technology, and belongs to the field of bridge pile foundation detection. Background technique [0002] The post-pile grouting technology refers to that after the cast-in-situ pile is piled and reaches a certain strength, the grout that can play the role of cementation and solidification is injected into In the soil layer at the pile tip and the soil around the pile, the sediment at the bottom of the pile, the bearing layer at the pile tip and the mud skin around the pile use the effects of grout penetration, filling, compaction, splitting and consolidation to change the physical properties of the original soil. The properties and mechanical state of the pile can improve the strength of the pile tip soil and the pile side soil, increase the resistance of the pile tip and the friction force of the pile side to vary...

AI Technical Summary

Problems solved by technology

[0003] However, since the pile foundation is a concealed project, it is difficult to judge the quality of the grouting construction after the pile foundation, and the geological conditions are changeable and complex. , it is very difficult to evaluate the specific grouting effect. Up to now, it is mainly to evaluate whether the pile meets the design requirements by measuring the ultimate bearing capacity of a single pile. The engineering application of grouting quality inspection, and the effect of grouting cannot be directly evaluated, but can only indirectly reflect the effect of grouting

Among the existing detection methods, there is no good quality detection method for the reinforcement effect of the grout in the bottom of the pile body and the soil around the pile.

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