Static load test method for foundation piles

Abstract

The invention discloses a foundation pile static load test method, and particularly relates to a foundation pile static load test method applied to the field of large-tonnage foundation pile static bearing capacity detection engineering. The foundation pile static load test method has the advantages that the loading height can be decreased, and meanwhile the uplift bearing capacity of an engineering pile can be reasonably utilized. The method comprises the steps of a, determining the value of the loading working load Q and the value of the uplift force P; b, calculating the maximum deflection ymax generated by a secondary beam under the effect of 1.6Q; c, calculating the total uplift deformation amount s of an anti-anchor system; and d, determining the pre-loading load in the locking process of the anti-anchor system according to the maximum deflection ymax of the secondary beam of a loading platform and the total uplift amount s of the anti-anchor system. According to the foundation pile static load test method, the effect that loading and the anti-anchor system form the combined action can be guaranteed, meanwhile, the uplift bearing capacity of the engineering pile can be fully utilized so as to decrease the loading height, and therefore the safety of static load test for the large-tonnage foundation pile can be guaranteed.

Description

technical field [0001] The invention relates to a static load test method for foundation piles, in particular to a static load test method for foundation piles used in the engineering field of detecting the static bearing capacity of large tonnage foundation piles. Background technique [0002] Pile static load test is a kind of geotechnical engineering in-situ test method. It is a common test method used to test whether engineering piles can meet the design requirements. It is also required by JGJ94 "Technical Specifications for Building Pile Foundations". A test method. [0003] With the increase of the building height, the requirements for the bearing capacity of the building foundation are also increasing. In the foundation engineering, the pile foundation is an important foundation type. According to the different bearing capacity requirements, the design parameters of the pile foundation can be flexibly set, etc. advantages and are widely used. Affected by the differ...

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Problems solved by technology

[0004] The existing static load test methods for foundation piles mainly include single surcharge method, single anti-anchor method and self-balancing method. In the static load test of large-tonnage foundation piles, the single surcharge method requires more concrete blocks , the height of the stacked load is high, so that the center of gravity of the stacked load moves upwards. During the test, a little carelessness will cause the stacked load to collapse, forming a serious safety hazard

The anti-anchor method generally uses the uplift force of engineering piles (the piles that already exist in the foundation design and directly bear the building load in the later stage) as the counter force. It is easy to cause the engineering pile to be pulled out and damaged, and even the accident that the engineering pile is pulled out, so that the engineering pile cannot continue to be used, and the pile needs to be re-formed at the original pile position, which increases the project cost

The self-balancing method is a new type of static load test method for foundation piles. Its principle is to use the weight of the foundation pile itself and the frictional resistance of the soil around the pile above the neutral point of the pile to provide the load. The piles are poured together with the foundation piles. This method does not require a large amount of surcharge, nor does it require reaction piles, but the hydraulic loading system is for one-time use. After the test is completed, the parts of the hydraulic loading system must be grouted twice , the cost is high and the installation is cumbersome. It is suitable for the situation where the soil around the pile is good and can provide sufficient frictional resistance, so the scope of application is limited

[0005] As mentioned above, in the static load test of large-tonnage foundation piles, there is no static load test method for foundation piles in the existing technology that can reduce the height of the piled load and at the same time make reasonable use of the uplift bearing capacity of engineering piles

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