Analysis and treatment of common quality problems

Analysis and treatment of common quality problems in pile foundation construction

the analysis and treatment of quality problems and hidden dangers in pile foundation construction will affect the structure of buildings from limit to emergency stop, which have the same functional safety. This paper mainly introduces the categories, cause analysis and common treatment methods of common quality problems in pile driving (pressing) construction

there are many construction procedures and high process requirements in pile driving (pressing) engineering, and there are many factors affecting the quality of pile foundation, generally including:

1. The engineering geological survey report is not detailed and accurate

2. Reasonable value of design

3. Various reasons in construction

the analysis and treatment of quality problems and hidden dangers in pile foundation construction will affect the structural safety of buildings. This paper mainly introduces the categories, cause analysis and common treatment methods of common quality problems in pile driving (pressing) construction

1 common quality problem categories and cause analysis

common quality problems in pile driving (pressing) engineering include: the bearing capacity of a single pile is lower than the design value, and the pile is inclined. Japan's chemical fiber company has not done this too much, broken pile, broken pile joint, and excessive deviation of pile position. Reasons for the above problems:

1.1 common reasons why the bearing capacity of a single pile is lower than the design requirements are:

1.1.1 insufficient pile sinking depth

1.1.2 the pile end does not enter the bearing layer specified in the design, but the pile depth has reached the design value

1.1.3 the final penetration is too large

1.1.4 others, such as excessive pile inclination, fracture and other reasons lead to the decline of single pile bearing capacity

1.1.5 the stratum profile, foundation bearing capacity and other relevant data provided in the survey report are inconsistent with the actual situation

1.2 common reasons for excessive pile inclination:

1.2.1 the quality of prefabricated piles is poor, in which the pile top surface is inclined and the pile tip position is not correct or deformed, and the most · power - 40W is easy to cause pile inclination

1.2.2 the pile driver is not installed correctly, and the pile frame is not perpendicular to the ground

1.2.3 the center lines of pile hammer, pile cap and pile body do not coincide, resulting in eccentric hammering

1.2.4 the pile end meets stones or hard obstacles

1.2.5 the pile spacing is too small and the pile driving sequence is improper, resulting in strong soil squeezing effect

1.2.6 improper excavation of foundation pit earthwork

1.3 common reasons for pile breaking:

in addition to the pile breaking caused by excessive inclination, there are three other reasons:

1.3.1 the fulcrum or lifting point for pile stacking, lifting and transportation is improper

1.3.2 during pile sinking, the pile body bends too much and breaks. For example, the bending caused by the quality of pile fabrication, or the bending caused by hammering when the pile is slender and meets a harder soil layer

1.3.3 too many blows. For example, some design requirements of pile hammering are too heavy, and the design penetration is too small. No matter how large the diameter is, it is rarely used in industrial and civil construction, resulting in excessive hammering and pile fracture during construction

1.4 common reasons for pile joint disconnection:

when the design pile is long, due to the needs of construction technology, the pile is prefabricated and sunk in sections. Steel welded connectors are often used as pile joints between sections. The disconnection of pile joints is also common. In addition to 1.2.1-1.2.5 in section 1.2, the central lines of the upper and lower piles are not coincident; Poor construction quality of pile joint, such as insufficient weld size and other reasons

1.5 common causes of excessive pile position deviation, measurement and setting out errors; The pile sinking process is poor, such as the inclination of the pile body, resulting in large deviation of the completed pile position