Looking for a construction plan for piles in water? Introduction to the construction technology of u

When it comes to the underwater pile foundation construction process, at this stage, what is the basic situation of the construction enterprises carrying out the construction of the water pile foundation? What is the basic overview? The following is the relevant content of Zhongda Consulting to sort out the relevant water pile foundation construction, and the basic situation is as follows:

Underwater pile foundation construction process:

Cast-in-place pile construction.

The cast-in-place pile is made of a hole directly on the source rock of the pile position, and then the reinforcement cage is placed in the hole and poured concrete. Cast-in-place piles can adapt to various strata, no need to connect piles, no vibration, no soil compaction, low noise during construction, and should be used in densely populated areas. However, its operation requirements are strict, and a long curing period is required after construction to bear the load, and a large amount of soil slag or mud is discharged when the hole is formed.

According to the different hole-forming processes, it can be divided into cast-in-place piles with holes in dry operations, cast-in-place piles with mud wall protection, cast-in-place piles with casing holes and cast-in-place piles with blasting and expanding holes. In recent years, the construction technology of cast-in-place piles has developed rapidly, and some new processes such as ramming and expanding immersed pipe cast-in-place piles and drilling and grouting piles have also appeared.

Cast-in-place pile construction - dry operation into holes.

The dry operation of the hole-forming pile is suitable for the soil with low groundwater level and no groundwater in the depth of the hole, and the soil can be directly taken into a hole without the need for wall protection. At present, auger drilling rigs are commonly used to form holes.

Construction process.

Site cleanup, measurement and setting of the pile position, pile driver in place, drilling and soil into holes, removing sediment at the bottom of the holes, quality inspection and acceptance of holes, hoisting the reinforcement cage, pouring concrete in the holes.

Construction precautions.

When starting to drill, the drill pipe should be kept vertical and in the correct position to prevent the expansion of the hole diameter and the increase of the empty soil at the bottom of the hole caused by the shaking of the drill pipe.

When it is found that the drill pipe is shaking, moving, deflecting or difficult to drill, the drill should be checked to eliminate underground obstacles and avoid deflection of the pile hole and damage to the drilling tool.

During the drilling process, the clay at the orifice should be cleaned up at any time, and the drilling should be stopped in case of abnormal conditions such as groundwater, collapsed holes, and shrinkage holes, and the relevant units should be studied and treated.

When the drill bit enters the hard soil layer, it is easy to cause the borehole to deviate, and the drill bit can be lifted up and down to sweep the drill several times repeatedly in order to cut off the hard soil. If the correction is ineffective, the clay can be partially backfilled in the hole to more than 0 5m at the deviation hole, and then re-drilled.

After the hole reaches the design depth, the orifice should be protected, accepted according to the regulations, and the construction record should be made.

The virtual soil at the bottom of the hole can be cleared as much as possible, and the rammer can be used to ram the virtual soil at the bottom of the hole or carry out pressure injection cement slurry treatment, and then quickly hoist the reinforcement cage and pour concrete. Concrete should be poured in layers, and the height of each layer should not be more than 1 5m.

First, the general situation of the project.

**Overpass is a four-layer intersecting structure composed of two main line viaducts and eight ramps, the bridge area has the Yongding River running through the north and south, the bridge structure has crossed the Yongding River many times, and some pile foundations are laid in the Yongding River.

Judging from the hydrological survey, Yongding River is an important flood drainage channel in the flood season, in order to ensure that the Yongding River has sufficient water crossing area during the flood control period, the construction unit decided to use the construction plan of erecting a working platform in the water, arranging a drilling rig and drilling piles in the water on the working platform.

Second, the construction method.

1. Set up a working platform, according to the hydrological survey, the water depth of the Yongding River is generally 2-3m, and there is a silt layer at the bottom of the river of 4-5m in the flood season, and the following is a rich sub-sandy soil with underground.

First, carry out construction lofting, determine the specific pile foundation position and the outer edge line of the operating platform, lay the control pile, according to the positioning of the control pile, lay 325mm steel pipe column, as the supporting pile of the working platform, the steel pipe column is selected with a length of 10m, and the spacing is arranged (see detailed drawings for specific arrangement).

The steel pipe column is pressed by a vibrating machine or an excavator, and the pressing depth is not less than 3m below the silt layer at the bottom of the river, and then the D36 type I-beam is welded above the steel pipe column, and the vertical and horizontal platform is arranged to leave a pile space of not less than 2m in diameter.

2. Suppress the long casing.

It is proposed to use a long casing with a length of 7m and a diameter, which is directly pressed by a vibrating machine or excavator to ensure that it is not less than 2m below the old soil at the bottom of the river, and the upper mouth of the casing is not less than 50 cm above the water surface.

3. Drilling rig layout.

After the working platform is erected, the casing is positioned, and after the burial is completed, the GPS-15 drilling rig is laid on the platform, and the reverse circulation drilling rig can also be used, and the mud pool is located on the edge of the river cliff, and the mud pool and the casing are connected with a 180 steel pipe to ensure that the mud is a**.

4. Concrete irrigation.

After the pile foundation is formed, the lifting of the reinforcement cage is carried out, and the concrete pump truck is used to convey the conduit to clean the hole, and the underwater concrete is poured.

During the construction of the pile foundation, it is the dry season, the elevation of the top surface of the steel trestle and the steel platform is: the construction water level (the steel trestle steel pipe pile is based on 30cm steel pipe, and the depth of driving is determined according to the actual situation when the pile is sunk, and two rows are set up in the direction of the cross bridge, and the main beam is made of I25B steel in the longitudinal direction, and the secondary beam is made of I20B I-beam in the transverse direction, and the spacing is used. The trestle is only used for the installation of pump pipes and the transport of small tools.

The structure of the steel platform is shown in the attached drawing: schematic diagram of the structure of the main bridge water drilling pile construction platform. Before the construction of the platform and trestle bridge, we have reported to the relevant departments of waterway, maritime affairs, water conservancy and other departments for approval, issued construction notices, and set up corresponding navigation and navigation aid signs.

During and after the completion of construction, night warning lights will be set up at appropriate locations to guide the passage of passing ships and ensure the navigation safety and construction safety of passing ships.