What is the self balancing method pile foundation detection?

Hello! We specialize in the research and promotion of "self-balancing method" pile measurement technology.

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At present, because the "self-balancing method" pile measurement technology is not mature at present, it is still in the stage of argument, practice and perfection, so not only you encounter such a problem, but also many other engineering and technical personnel in the industry are also confused.

Of course, this is also an opportunity for us, if there are no technical difficulties, what else are we developing? What to promote?

Like you, in our long-term pile measurement work practice, we have also encountered many detailed problems in the implementation process, and there are also many technicians who consult and discuss with us through various ways (**, forum, email).

In order to better promote this new practical technology, we have gathered all kinds of problems encountered (including different ones) together and made a technical discussion garden in the space, in order to provide a place for everyone to communicate. The questions that have been summarized so far are as follows, so please comment!

16: How to determine the position of the load box when the self-reaction force (self-balance) pile measurement method is implemented?

15: How to understand and solve the problem of pile breakage by implementing the self-reflexive force (self-balancing) pile measurement method?

14.Implement the self-reaction force (self-balancing) pile measurement method, displacement rod or displacement wire for displacement monitoring?

13.How to understand and solve the Q-S curve conversion problem by implementing the self-reaction force (self-balancing) pile measurement method?

12.Why should we use a professional load box to load the self-reflexive (self-balancing) pile measurement method?

11.Can I use the self-reflexive method (self-balancing method) to test the static load of the pile?

9.What are the key technologies of self-reaction (self-balancing) pile measurement method?

8.Is there a standard implementation plan for the self-reflex (self-balancing) pile measurement method?

7.What is the current development status of self-reflexive method (self-balancing method) pile measurement technology?

5.How to recognize the value of self-reflexive method (self-balancing method) pile measurement technology?

4.What are the advantages and disadvantages of self-reflexive (self-balancing) pile measurement technology?

3.What are the similarities and differences between the self-reflexive pile measurement method (self-balancing method) and the traditional static load test loading method?

2.How to correctly understand the technical characteristics of the self-reflexive force method (self-balancing)?

1.What is the self-reflexive method (self-balancing method) pile measurement technology?

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Self-balancing methodPile test, first of all, calculate the balance point. The pressure box is placed here, and the bearing capacity of the upper section pile and the lower section pile is equal, that is, balanced, and the sum of the bearing capacity of the upper and lower sections of the pile measured at this time is the bearing capacity of the single pile. Of course, taking into account the following reasons, the reduction factor is usually multiplied by the ultimate load of the pile in the upper section.

In the usual pile test, the load is added to the top of the pile. For friction end-bearing piles, the axial direction of the pile is due to the gradual decrease of the pile pressure with the depth of the pile.

The compression also decreases with depth, so when the upper part of the pile reaches the limit value of side friction, the side friction of the lower part of the pile is far from reaching the limit value. Therefore, the self-balancing method, for friction piles controlled by deformation.

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Precautions for pile detection.

It is necessary to pay attention to the implementation of low-energy transient or steady-state excitation on the top surface of the pile, so that the pile can do elastic vibration in the elastic range, and thus produce the longitudinal propagation of stress waves, and at the same time, the integrity of the pile is evaluated by using the wave and vibration theory. The main use of pile low strain detector.

High strain method. It is a detection method to determine whether the vertical compressive bearing capacity of a single pile meets the design requirements and evaluates the integrity of the pile by measuring and calculating by carrying out a heavy hammer on the top of the pile, so that the dynamic displacement of the pile is close to the settlement of the conventional static load test pile, so that the rock and soil resistance around the pile can be fully exerted. The main use of pile high strain detector.

The self-balancing method is different from the traditional stacking method and the anchor pile method, the technology is to place the load box made according to the requirements of the pile bearing capacity parameters at the bottom of the pile body in the construction process, connect the pressure tubing and the displacement measurement device at the top of the pile, and after the concrete is cured to the standard age, the bottom load box is pressurized by the top high-pressure oil pump to obtain the bearing capacity of the pile end and the total friction resistance of the pile side.

Technical advantages – simple test environment.

The self-reaction method no longer requires an external loading force, so it can complete the test that cannot be completed or is difficult to complete by the traditional loading method when facing some pile foundations (difficult piles) where the test environment is very difficult.

Here, difficult piles refer to super-large tonnage pile foundations, pile foundations in slope, water, deep excavation and other environments, as well as some other pile foundations that do not have stacking and anchoring pile conditions.

The advantage of the self-reaction method makes it possible to complete the pile foundation test, which makes an irreplaceable contribution to the quality assurance of architectural design and construction, and reflects its huge technical value and social value.

Technical disadvantage – complex technical details.

Compared with the traditional method, the self-reflexive method has a short development history and low technical maturity and popularity, so there are still many problems in the details of experimental implementation and key technologies. For example: the determination and selection of pile test methods, the selection and installation of load boxes, the safety protection and repair measures of pile bodies, the accuracy assurance of displacement measurement methods, etc., these technical details need to be continuously developed and improved through a lot of practice and research.

Summary. 2.In the usual pile test, the load is added to the top of the pile.

For friction end-bearing piles, because the pile pressure gradually decreases with the depth of the pile, and the axial compression of the pile also decreases with the depth, when the upper part of the pile reaches the limit value of side friction, the friction resistance of the lower part of the pile is far from reaching the limit value. Therefore, the self-balancing method is not suitable for friction piles controlled by deformation; For load-controlled end-bearing piles, such as rock-socketed piles, the accuracy will be better. The sum of the lateral friction resistance of the upper and lower pile sections measured above will be greater than the actual situation, so the reduction factor mentioned above appears.

The self-balancing method is not the same as the traditional stacking method and the anchor pile method of carrying the sail bend, the technology is to place the load box made according to the requirements of the pile bearing capacity parameters at the bottom of the pile body in the construction process, connect the pressure oil pipe and the displacement measurement device at the top of the pile, and after the concrete is cured to the standard age, the bottom load is pressurized by the top high-pressure oil pump, and the bearing capacity of the pile end and the total friction resistance of the pile side are obtained.

1.To test the pile by the self-balancing method, the first thing to do is to calculate the balance point. The pressure box is placed here, the bearing capacity of the upper section of the pile and the lower section of the pile is equivalent, that is, the balance, and the sum of the bearing capacity of the upper and lower sections of the pile measured by Xiangyu Xun at this time is the bearing capacity of the single pile.

Of course, taking into account the following reasons, it is common to consider the reduction factor multiplied by the ultimate load of this section of the pile.

2.In the usual pile test, the load is added to the top of the pile. Because the pressure of the pile gradually decreases with the depth of the pile, and the axial compression of the pile also decreases with the depth, when the upper part of the pile reaches the limit value of the side friction, the friction resistance of the lower part of the pile is far from reaching the limit value.

Therefore, the self-balancing method is not suitable for friction piles controlled by deformation; For load-controlled end-bearing piles, such as rock-socketed piles, the accuracy will be better. The sum of the lateral friction resistance of the upper and lower pile sections measured above will be greater than the actual situation, so the reduction factor mentioned above appears.

At present, the static load test of pile foundation mainly includes the following types of loading methods: stacking method, anchor pile method and self-balancing method or self-reaction method.

Among them: the stacking method, which is to pile enough counterweight on the ground to provide the loading reaction force to achieve the loading of the pile foundation. It is a traditional test method.

The anchor pile method is a traditional test method that uses the auxiliary pile near the test pile as the reaction support, and the load test on the pile foundation.

The self-reaction method is a method of self-loading in the pile foundation with its own bearing capacity as the loading reaction force and realizing self-loading, which is a new experimental technology developed in recent years.

Of course, in practice, the "comprehensive method" can also be used, i.e. a combination of the above test methods.

The detection principle is to --- a special loading device into the load box, bury it in the corresponding position in the pile together with the reinforcement cage before the concrete is poured, and lead the pressurized pipe of the loading box and other test devices required from the pile body to the ground, and then pour into the pile. There is a pressurized pump in the ground like a load box pressurized loading, so that the pile body inside the load force, through the calculation and analysis of the relationship between the load force and these parameters, we can not only obtain the bearing capacity of the pile foundation, but also can obtain a series of data such as the lateral resistance coefficient of each layer of soil, the side resistance of the pile, the bearing force at the end of the pile, etc., this method can be used to provide data basis for the design, and can also be used for the inspection of the bearing capacity of the engineering pile. This method is called the self-balancing method or the self-reflex method.