What are the common problems encountered in the construction of precast piles 10

Pile sinking is difficult. Because of excessive pile sinking, the elevation of the pile top is lower than the design elevation.

The construction is completed and the piles are extruded.

The pile is tilted. Pile failure.

Pile head failure.

1. The mixture is loose and not easy to bond;

2. The mixture has high cohesion, clumps, and is not easy to pour;

3. The cement mortar in the mixture does not fill the pores between the stones;

4. Layered segregation of mixtures in the process of transportation and pouring;

5. After the concrete is poured, it will not be condensed and hardened locally or for a long time;

6. The surface of the concrete structure that has been poured is bulging, commonly known as the surface "flowering";

7. The surface of the concrete is rough due to lack of slurry, or there are many small pits, but no steel bars are exposed;

8. The main reinforcement, auxiliary reinforcement or stirrups in the reinforced concrete structure are not exposed by the concrete wrapping surface;

9. The concrete is partially loose, the mortar is less, and there are many stones, and there are gaps between the stones, forming honeycomb-shaped holes;

10. Poor concrete compactness and large local porosity; There are honeycombs, holes, inner wall collapses, etc.

The piling regulations with precast piles are to ensure the safe construction and excellent quality of precast piles, and also to ensure the stability and safety of structural buildings. Here's why:

1.Improve pile quality. Precast piles have excellent reinforced concrete quality in the factory, which is more stable and higher than the quality of piles poured on site, which can improve the structural strength and safety of the whole building.

2.Save time on site construction. The prefabricated pile can be completed in advance in the factory, and when the front wheel pile needs to be installed on site, only the pile needs to be hoisted to the designated position, which greatly shortens the on-site construction time and improves the construction efficiency.

3.Reduce the difficulty and cost of construction. The use of prefabricated piles can reduce the limitation of site distance and special environmental conditions, and also reduce the demand for machinery and manpower on the construction site, which helps to reduce the consumption of manpower and material resources and reduce construction costs.

4.Facilitate quality supervision and acceptance. Precast piles are manufactured in-house and are able to go through strict quality control and acceptance procedures to ensure that the product meets the requirements, and there is a clear product identification and traceability system. This helps to improve the quality and safety of the construction on site.

Therefore, it is necessary to have piling regulations for precast piles to ensure the quality and safe construction of precast piles and ensure the stability and safety of the building structure.

1. Due to the unreasonable survey method or the sampling spacing is too large, the ups and downs of the bearing layer are not clarified, so although the design requirements are required to adopt dual control, it is difficult for the construction unit to grasp it, and the design depth is often controlled, and the hammer penetration or oil pressure value cannot be reached; The dust or hammer penetration or oil pressure value is reached, but the design depth is not reached. As a result, the pile length does not match the actual pile.

2. Prestressed concrete pipe piles can be divided into post-tensioned prestressed pipe piles and pre-tensioned prestressed pipe piles. The pre-tensioned prestressed pipe pile is a kind of hollow cylinder slender concrete prefabricated component made by pre-tensioning prestressing process and centrifugal molding method, which is mainly composed of cylindrical pile body, end plate and steel hoop annihilator.

3. There are many methods of sinking pipe piles, and the methods that have been constructed in China are: hammering method, static pressure method, vibration method, water injection method, pre-drilling method and middle excavation method, etc., and the static pressure method is the most used. Due to the violent vibration and loud noise of diesel hammer piling, in order to meet the needs of urban construction, in recent years, the process of pressurizing prestressed pipe piles by large-tonnage static pile drivers has been developed in various parts of China.

4. Because the soil structure around the pile is disturbed when the pile is sunk, the stress state of the soil is changed, and the soil squeezing effect is produced; The welding time is too long during the construction of the pile driver; There are many joints of the pile, and the welding quality is not good, or the pile end is stopped in the hard interlayer; The construction method and construction sequence are improper, the number of piles formed every day is too much, the pile pressing rate is too fast, and the piles are too dense and too dense, which aggravates the soil squeezing effect, and the floating of the pile body will cause the deformation of the engineering pile test pile to be too large and the bearing capacity to be reduced.

In pile foundation engineering, the treatment measures for common problems of piling include pre-drilled pile sinking, setting up bagged sand wells or plastic drainage boards, and digging anti-vibration ditches.

1. Pre-drilled pile sinking.

If there is a hard formation or difficult to penetrate geological conditions under the pile position, the method of pre-drilling pile sinking can be adopted. By drilling under the pile in advance, the pile body is sunk into the hole in advance to reduce the force on the pile body and ensure the stability of the pile.

2. Set up bagged sand wells or plastic drainage boards.

In the soft soil layer or the stratum with high water content, the pile body is prone to problems such as pore water or mud, which leads to the decline of the bearing capacity of the pile. In order to solve this problem, bagged sand wells or plastic drainage boards can be set up next to the piles to help remove pore water and mud, and improve the bearing capacity of the high piles of the combustion chain.

3. Dig anti-vibration ditches.

In the process of vibrating piling, it may cause greater vibration impact on the surrounding soil and structure, and even cause settlement and damage. In order to reduce the impact of vibration on the surrounding environment, an anti-vibration trench can be dug next to the pile to absorb and slow down the transmission of vibration waves by filling it with soft soil or other anti-vibration materials.

Classification of piling:

1. Bored piles.

The hole is drilled first, and then concrete is poured into the hole to form the pile. This method is suitable for soft soil conditions, which can improve the bearing capacity and lateral force resistance of the pile.

2. Prefabricated piles.

The piles are prefabricated at the factory and then transported to the construction site for installation. This method is suitable for deep pile foundations, which can improve the construction efficiency and quality.

3. Steel pipe piles.

The steel pipe is driven into the soil layer, and then the concrete is poured into the steel pipe to form a pile body. This method is suitable for deep pile foundations, which can improve the bearing capacity and lateral force resistance of the pile.

4. Immersed pipe pile.

The steel pipe or concrete pipe is sunk into the soil layer, and then the soil inside the pipe is dug out to form a pile hole, and finally the concrete is poured into the pipe to form a pile body. This method is suitable for renting sections under soft soil conditions, which can improve the bearing capacity and lateral force resistance of the pile.

1. Spraying blockage: the reason may be that the cement is damp and agglomerated or the filter screen of the pulping tank is damaged or the slurry is not completely cleared. Treatment measures: improve the on-site cement storage environment, remove slag in time, and check the damage of the filter screen from time to time.

2. Insufficient spraying: the reason may be that the slurry pipeline is bent, external pressure, leakage or the slurry pipeline is too long, and the pressure loss along the way is large. Treatment measures should be timely inspection, maintenance of pipelines and selection of appropriate locations to excavate the pulping pool. When the site conditions are not available, the pumping pressure can be appropriately increased.

3. Footage is blocked: the reason may be that there are lonely stones, tree roots or other things that have not been removed underground. The treatment measures should be stopped to remove obstacles or shifts.

4. The speed of the sun shed is unstable: the reason may be that the equipment itself has a control system problem or the crew is not standardized or unskilled, and the equipment that does not meet the requirements of the treatment measures shall not enter the site, formulate and improve a clear responsibility system and do a good job in pre-job training.

The construction of cement mixing pile is a concealed project, if the construction quality is not good, once it is covered by structures such as embankments, it will constitute hidden dangers and is not easy to inspect and remedy. Therefore, pay close attention to all aspects of construction, and strictly cement mixing pile construction belongs to concealed engineering, such as poor construction quality, once covered by embankments and other structures, it constitutes a hidden danger and is not easy to inspect and remedy. Therefore, it is very important to pay close attention to all aspects of construction and strictly manage the construction process.

The control of construction quality is a meticulous technical work. It is best to establish a quality assurance system for self-inspection and mutual inspection of the construction team, sampling inspection by the technical person in charge and supervision by the supervision of the side station.