Pine pile construction scheme, pine pile construction method

Abstract:Treating soft foundation with pine pile is a foundation treatment method that is easy to obtain, low cost and easy to construct. Pine piles are suitable for working in environments below the groundwater table, and are suitable for projects with shallow thickness of soft soil foundations.

CLC Number: U445 Document Identification Code: A

Article Number:1674-1145(2009)14-0139-02 Weak soil refers to silt, silty soil, partially alluvial soil, miscellaneous fill and other high compressibility soil, which is widely distributed in the southeast coastal areas of China and around inland rivers and lakes, commonly known as soft soil. A foundation consisting of soft soil is a soft soil foundation.

In recent years, more and more projects have been built on soft soil, but there are many disadvantages to using soft soil as the foundation of buildings. Because the strength of soft soil is very low, the compressibility is higher, can not bear the larger building load, the settlement and uneven settlement of the building foundation are often relatively large, so the construction of buildings on the soft soil foundation requires that the soft soil foundation must be treated.

Pine wood is rich in pine resin and has good antiseptic ability. There is an ancient proverb that "the water is a thousand years of cedar, and the water is a thousand years of pine", and when using wooden piles to treat soft soil foundations, pine piles are generally used. As an ancient foundation treatment method, pine piles have been widely used in Guangxi, especially in the mountain engineering area, because of its advantages of easy material, simple and easy construction technology and low cost.

It is regrettable that pine piles, as an effective foundation treatment method, are not mentioned in the technical specifications such as "Technical Code for Building Foundation Treatment", "Code for Design of Building Foundation Foundation", "Code for Design of Highway Bridge and Culvert Foundation and Foundation". Combined with the practical experience of engineering, the author makes some summaries on the design and construction of soft soil foundation treated with pine piles for reference.

First, the general situation of the project.

A mountain highway project in Wuzhou, Guangxi, covers the culvert, separated foundation, and the single foundation area is 32m2 (b=, l=11m). The average buried depth of the groundwater level, the buried depth of the culvert foundation h=1m, and the design foundation stress is 200kpa. The geology of the project site is silty clay, soft plastic, rich in groundwater, high water level, and the actual buried depth of the bearing layer is about 4m.

After analysis and comparison, it was determined that pine piles were used to treat the foundation.

Surveying and pay-off, digging and filling the working face, pile lofting, driving pine piles, sawing flat pile heads, rubble piles and C10 concrete cushion construction, bearing cap construction.

Wooden piles are mainly purchased in the local timber market, and are transported to the site warehouse by car, and the wood pile should be purchased with attention to the wood material, and the pile length should be slightly larger than the design pile length. The pile wood used must be of uniform material and must not be excessively bent. When the two ends of the pile are connected in a straight line, the deviation between the center of each section and the straight line shall not exceed the relevant regulations; In addition, the pile shall not have cavities, cracks or other defects that can damage the strength.

Precautions for using pine piles.

1. Pine piles are made of logs, do not be sawn into other shapes, especially can not be sawn in half into a semicircle, the semi-circular pile is quickly bent strongly, so that it loses its effectiveness.

2. Do not promote pine piles as fir piles or other piles. Most common woods are water-avoidable, and can quickly blacken, deform, and decay in the water, especially fir wood, which should never be used.

3. The design method of pine pile composite foundation is similar to that of ordinary composite foundation, but the pile core distance is often very small.

1. Handle pine piles.

1) Sawn the top of the pine pile flat, and sawing it according to the design height (it can be slightly longer).

2) The small end of the pine stake can be used to cut into a 30cm long tip.

3) The pile body should be specially protected during handling construction, and the pile head can be tied with iron wire.

2. Determine the pile length.

If the pile is too long and the pile is too short, it may affect the whole effect, so before piling, you can use a wooden pile to test the place to be driven to determine the length of the wooden pile in each area. The actual pile length used is longer than the test pile. According to the design drawings, the pine piles of the required size are prepared in each area of the construction, and the pile position of the pine piles is determined.

3. According to the pile position, the pine pile corresponding to the pile length is driven into the soil layer.

1) If the chain acorn soil layer is soft, the back of the excavator's bucket can be compacted with the soil.

2) After the soil bag is stable, the back of the excavator bucket can be used to vertically drive the wooden pile into the bearing layer or the person next to the shed uses the pile driver to lift the wooden pile in place, and then manually vertically drive into the bearing layer.

3) Considering that the upper end of the pine pile is prone to horizontal displacement, a stone layer is generally laid between the pine piles for reinforcement.