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Trial discussion on the application of concrete technology in the construction of pile foundation of building engineering

The characteristics of concrete in the construction of pile foundation of building engineering

Building pile foundation, is composed of foundation pile connected to the top of the foundation pile bearing platform together, bearing platform and bearing platform are generally interconnected with bearing beam. If all the piles are buried in the soil and the bottom of the bearing platform is in contact with the soil, it is called low bearing pile foundation; when the upper part of the pile is exposed to the ground and the bottom of the bearing platform is above the ground, it is called high bearing pile foundation.

If only one pile (usually large diameter pile) is used under the bearing platform to bear the load of superstructure (usually column), such pile foundation is called single pile foundation; pile foundation with 2 and more piles under the bearing platform is group pile foundation.

The construction quality of building pile foundation is related to the engineering quality of the whole building, so in the process of pile foundation construction, the construction standard should be strictly followed. In the construction of building pile foundation, it is more common to use concrete.

Concrete is extremely widely used in the construction of building pile foundation, and it can be said that it is indispensable. In the construction of building pile foundations, cement concrete is by far the most commonly used concrete.

Concrete is made of aggregate, aggregate, cementitious materials and water in a certain ratio to prepare, after concrete mixing equipment pounding molding, in a certain temperature and humidity (China uses the standard maintenance conditions: temperature of 20 ± 3 ℃; humidity of not less than 90%) under the maintenance of artificial stone.

With many characteristics of low price, abundant raw materials and simple production process, concrete is now used more and more in the construction of pile foundations. In addition to some of the previous characteristics, concrete also has the advantages of good durability, high compressive strength, a wide range of strength levels.

Application of concrete technology in pile foundation construction of construction projects

With the rapid development of China’s economy, various construction projects have also stimulated the rapid development of the construction industry. Through a large number of engineering practice experience, the infill pile technology has also been developed rapidly and is widely used in engineering construction.

In the process of designing the infill pile, the strength should be taken into consideration. There are certain requirements for the strength of concrete for grouted piles, which should basically be higher than C15, the aggregate should be less than forty millimeters, and the slump should basically be between fifty millimeters and seventy millimeters. And for underwater concrete filling, it should be ensured that the strength of concrete is higher than C20 and the slump should be basically within the range of one hundred and sixty millimeters to two hundred millimeters.

1、Conduit

Construction pile concrete infill construction should be selected for the construction of vertical conduit, whether the quality of the conduit is good will directly affect the overall quality of engineering construction.

In the choice of conduit, should ensure that it has a smooth inner wall, in general, the inner diameter should be controlled between 20 cm to 30 cm. To avoid the emergence of problems such as collision of steel skeleton, the flange should be avoided at the lower end of the bottom section of the pipe.

The distance between the bottom position of the funnel and the position of the orifice must be more than the length of an intermediate section of pipe, while the ball plug is passed through the test, and the concrete filling is selected for construction by the chopping ball method.

Between the funnel and the conduit using wire for valve ball suspension operation, to ensure that the distance between the conduit and the bottom of the hole is between 30 and 40 cm. The valve ball should be cut off after the filling funnel is filled with concrete and accompanied by the filling funnel mixture for the drop, and then the concrete mixer unloading switch will be opened to ensure the continuity of the concrete filling operation, and the concrete thickness measurement through the measuring rope to ensure that the first batch of concrete filling is over and the depth of the conduit meets the construction regulations with the conduit internal no regrouting phenomenon occurs, then the concrete filling construction is carried out, when the conduit buried depth between 2 meters to 6 meters and more than 6 meters, according to the actual situation of construction should be 1 to 2 sections of the catheter removal, and ensure that the catheter buried depth greater than 2 meters, repeated construction, to ensure that the top height of concrete with the construction of the situation.

2、Clear hole

The hole clearing operation should be carried out after the borehole meets the design elevation, analyzed from its slag thickness, the support pile should be above the design provisions, the friction pile must ensure that it is in line with the design requirements, when the design requirements cannot be met, should ensure that the pile diameter is more than 1.5 meters and the length is more than 40 meters, the slag thickness should be controlled below 500 mm, the hole clearing construction can be carried out through the slurry exchange method for the amount of sediment ground Check.

3、Grouts

Underwater concrete grouting construction of construction projects is mainly used in the construction of the conduit method, in the construction should pay attention to the amount of concrete reserves and liquidity to avoid the emergence of plugging. Concrete grouting construction should ensure that the depth of the conduit buried in more than 1 meter, in the construction must pay attention to the chopping ball, open material door.

4、Pouring

Concrete pouring construction should pay attention to its continuity, to ensure that the conduit in any case has a sufficient amount of concrete. Concrete pouring should be combined with the specific circumstances of the construction, in the case of conduit removal frequency is controlled, should prevent the emergence of problems such as conduit buried too deep and stuck pipe. In the concrete pouring 2 meters below the location of the bottom of the conduit buried to avoid water influx in the conduit, but its depth should be controlled within 6 meters.

If it is difficult to lift the concrete in the conduit up and down, the conduit should be lifted upwards, and in this case, if it is difficult to drop the concrete, the conduit should be pumped in a smaller extent. In the accurate determination of the top surface position of concrete, the probe hammer can not be selected for construction, based on this, in the construction of the final link should be selected to use the bamboo rod to determine the top surface position of the pile, while checking the amount of concrete filling.

Concrete technology considerations in the construction of pile foundations of construction projects

Construction is an important project related to the growth of the national economy, with the development of China’s construction business construction requirements continue to improve, concrete construction technology as one of the important technology of construction pile foundation construction, its construction process selection of scientific and reasonable will be directly related to the quality of the entire project, related to the safety of people’s lives.

Due to the direct effect of atmospheric factors and geological conditions, construction projects often have various disease problems under the long-term influence of various factors. Concrete construction technology as the main technology of pile foundation construction, only to ensure the standardization of its construction process and fully grasp its technical points, in order to effectively improve its overall quality.

1, at present, the main way of pile foundation construction includes: mud wall protection method and a full set of pipe construction.

These two construction methods are necessarily related and have certain differences, and establish and improve the road and bridge pile foundation construction system. In the construction of road and bridge pile foundation, the main raw material of concrete is cement, and its auxiliary materials are sand and gravel, and according to the corresponding proportion and water for mixing.

Under the action of external forces, concrete in general will have various deformation, when the temperature is affected, it may appear temperature deformation and other problems. In the actual construction, in order to ensure the effective control of shrinkage, a series of link control is required, in which the appropriate drilling rig should be selected, and this rig should meet the actual needs of engineering construction, which is the basic premise of bored pile construction.

In this process, we should pay attention to the utilization of the type of drill bit, appropriately increase the diameter of the drill bit, etc., combined with other specific links to strengthen the detection and control. The following measures can be used to effectively achieve effective control of shrinkage in the process of bored pile drilling Shorten the time from hole formation to concrete placement.

In the geological environment prone to shrinkage, the time for hole formation, hole cleaning and cage welding should be shortened appropriately, shortening the empty hole time is an important measure to reduce shrinkage, and increasing the length of reinforcement sections as much as possible during construction to reduce the number of welding heads. Strengthen the detection and control of hole diameter.

2.In the daily construction process, the sediment layer link is of great significance to the bearing capacity of the pile foundation.

In order to ensure the smooth progress of the whole project, the sediment layer thickness before pouring needs to be strictly standardized, and it is to meet the needs of engineering construction. In order to avoid the problem of insufficient sediment layer thickness in construction, we need to improve the specific requirements about the mud performance index.

The specific gravity, viscosity, sand content and other parameters of the mud should be adjusted accordingly according to the specific geological conditions of the construction, and slurry formation can be carried out when necessary. Supervisors should carry out acceptance after the drilling is completed and take corresponding methods to check the final hole depth; guarantee the accuracy of the side rope and safeguard the quality of the project to achieve effective control of the sediment layer, which is conducive to the smooth progress of the overall project.

Conclusion

To sum up, with the continuous improvement of the development speed of China’s construction engineering career, whether the pile foundation construction is effective in the construction of building projects is becoming more and more important, in order to meet the requirements of social and economic development, concrete construction technology as the main component of construction pile foundation engineering construction, its technical level will directly affect the overall quality of the project.

For this reason, the construction unit must understand the characteristics of concrete construction of construction pile foundation project, based on the choice of pile foundation with which to improve its technical level, in order to promote the development of construction enterprises.