The amount of water seepage allowed for the concrete of the manually dug pile

We generally operate like this, before pouring off the concrete, the water is pumped dry first, put into the reinforcement cage, some piles underground water seepage is more serious, so then carry out a pumping, after draining, immediately pour the concrete, at the same time the construction site conditions are good can be pumped and smashed, then the amount of general water seepage is not very much, and the pile of pouring and pounding generally does not affect the quality of concrete because of water seepage; If the construction conditions do not allow pumping, the problem is relatively big, we use the tower crane to hoist the concrete has also been constructed, the construction time is long, when pouring and smashing, we require the concrete company to control the concrete to the minimum slump, as long as it can be transferred out of the mixer truck, then when pouring and smashing, part of the infiltrated water is absorbed by the concrete when vibrating, so as to reduce the amount of water seepage, if the amount of water is large, the dry cement is also placed to absorb water, In addition, more than 200 PVC pipes are placed in the center of the pile to increase synchronously with the height of concrete pouring, and a small mud pump is placed in the PVC pipe to intermittently absorb water and drain a part of the water volume to control the amount of seepage. Because no one knows how much water seeps in the ground, but it is found that there is more seepage during construction.

In the pouring concrete, there is water in the holes. Groundwater is constantly seeping into the hole piles. If the amount of seepage reaches a certain level, it will affect the pouring quality of concrete. Must be controlled.

What is the allowable amount of permeability? There are no specific provisions, so let's follow the above qualitative provisions. As long as it does not affect the quality of the concrete, it is acceptable.

1) The vertical deviation is large: the verticality of the pile hole exceeds the deviation, because the verticality of the pile well is not checked according to the hanging line drop of each excavation section during the excavation process, resulting in the verticality exceeding the deviation after digging. It is necessary to dig a section every time, that is, according to the axis of the center line of the well, the hanging line pendant, with a ruler rod to measure the trimming, so that the arc of the well wall is kept straight up and down.

2) There are too many residual virtual soil at the bottom of the well: after the hole is formed and trimmed, a large amount of virtual soil is accumulated at the bottom of the well, which is not carefully removed. After digging to the specified depth, in addition to carefully removing the virtual soil, check again after placing the reinforcement cage, and the virtual soil at the bottom of the hole must be cleared.

If necessary, use cement mortar or concrete to seal the bottom.

3) Excessive water accumulation at the bottom of the hole: water accumulates at the bottom of the hole after the hole is formed, and the drainage measures taken during the excavation process are improper, and the seepage of groundwater accumulates at the bottom of the well. In areas with high groundwater levels and large seepage, precipitation measures should be taken to reduce the groundwater level below the bottom of the pile and then excavate.

When a small amount of stagnant water is watered, semi-dry hard concrete can be used for the first plate.

4) Concrete vibrating is not real: due to the difficulty of the concrete pouring and vibrating operation conditions of the pile body, no effective auxiliary vibrating measures are taken, resulting in loose and unreal concrete of the pile body, cavities, necking, soil clamping and other phenomena. Technical disclosure should be carried out before concrete pouring and vibration operation, and layered pouring, layered vibration and continuous operation should be adhered to.

The thickness of layered pouring should be 300 500mm in height, and if necessary, iron pipes, bamboo rods, and steel bars should be used to assist in inserting and pounding, so as to supplement the lack of mechanical vibration.

5) Twisted and deformed steel cage: the steel cage is processed and produced, the spot welding is not firm, and the supporting stiffeners are not used, which is easy to deform and twist when transported and hoisted. The reinforcement cage should be machined on a dedicated platform.

The spot welding of the main reinforcement and stirrups should be firm, the support reinforcement should be reliable, and the lifting should be vertical, so that it can be smoothly put into the well and keep the skeleton intact.

Manually dug piles.

The phenomenon of excessive groundwater is often encountered, and there are many ways to do it:

First, the soil part.

1. Try to reduce the height of each wall protection (the soil quality is generally not more than 1 meter, and the soil is easy to collapse can be pressed by meters, meters, etc.);

2. If the amount of groundwater is too large, you can use a wooden wedge to drive into the hole wall with serious water seepage, and then use water glass.

The mortar is sealed, and then ordinary concrete is poured. Concrete can be stirred and poured, and after solidification, it is excavated according to the hollowing diameter;

3. For the fluid soil, you can first use fiber fabrics, straw, etc. to enclose, and then use cement concrete to stabilize the covering surface.

2. The part with rocks.

1. For digging holes to the rocky part, when there is a large amount of water inflow, you can take the water inrush to naturally reach a standstill, and then use pouring underwater concrete.

Method; The perfusion depth can be based on the size of the scale, generally not more than 3 meters; After the concrete reaches a certain strength, water is pumped and excavated;

2. It can be considered not to pour underwater concrete, but to use the drilling and grouting method: that is, the geological drilling rig is used to punch holes around the excavated holes (not in the holes that have been dug) to punch holes (the holes are punched to the estimated rock layer, and then the conduit is inserted to press the cement slurry in); After the cement slurry reaches a certain strength, start pumping and digging holes.

Third, for the quicksand part.

If there is quicksand under the digging hole, no matter how you dig it is difficult to dig down, you can temporarily process a steel casing (the diameter of the steel casing is slightly less than the diameter of the hole dug), put the steel casing into the hole, and slowly lower it. Generally, when it comes to the quicksand section, due to the pressure of the quicksand, the steel casing can only sink slowly, and once the quicksand is blocked, it can be excavated normally.

(1) When the amount of groundwater is not large. In this case, generally adopt submersible pump pumping, excavation while pumping, keep the inner foundation of the column hole without water accumulation, the concrete retaining wall of the corresponding pile section must be poured in time after the pile hole is formed and the bearing capacity meets the design requirements, and then the construction of the next section of pile foundation is carried out.

2) When the amount of groundwater is large. If the use of submersible pump pumping can not make the pile hole in the water pumping, it is inconvenient to carry out excavation and concrete wall construction, it should be considered from the construction plan, the construction sequence of each pile hole should be reasonably arranged, and the surrounding pile hole is pumped at the same time, so that the groundwater level of the construction section is temporarily reduced, so as to reduce the water inflow in the excavation hole, and adopt the method of alternate cycle construction, reasonable organization, arrangement, can receive good results. When the depth of the manually dug pile is not deep, the precipitation diversion of the unified light tube well can generally be reasonably arranged around the site, and when the foundation plane occupies a large area, the number of rows of the precipitation tube well can also be increased, which can generally be solved.

In addition, there is a special circumstance, which is also the situation that the frequency encountered in the construction of the project is relatively high, in the construction process of the artificial digging pile, sometimes it will be affected and restricted by the surrounding environment, one is that the surrounding environment of the construction site, the infrastructure and so on do not allow the construction to pump out the groundwater without restrictions; Second, there are streams, ponds, pools, etc. around the construction site, and it is impossible to achieve the purpose of pumping and precipitation without limit. The most effective way to deal with this type of problem is to cut off the water source and close the waterway. When the pile hole is shallow, the method of sealing the steel sheet pile can be used; When the pile hole is deep, the drilling pressure grouting is used to form a curtain to retain water, so as to ensure that the purpose of normal construction can be achieved during normal pumping.

This question is multiple-choice and the answer is: BStrongly weathered rocks.

The unsuitable range of artificially dug piles is strong weathered rock above the water table. Manually excavated pile, engineering term, reinforced concrete pile excavated by manpower and poured on site. The diameter of the manually dug pile is generally coarse, and the thinnest is more than 800 mm, which can carry the main body of the structure with fewer floors and greater pressure, and the application is more common.

The cushion cap is arranged on the top of the pile, and then the cushion cap beam is used to tie and connect together, so that the stress of each pile is evenly divided and grinded, and the whole building is used to support the whole building. Manually excavated cast-in-place pile refers to the pile hole made by manual excavation method, and then placed the steel bar blind cage and poured concrete pile.

Features:The construction of manual digging piles is convenient, the speed is fast, and there is no need for large cherry blossom type machinery and equipment, and the excavated piles are stronger than the seismic ability of wooden piles and concrete driven piles, and the cost is more economical than that of punching cone punching, impact cone punching, impact drilling rig punching, rotary drilling rig drilling, and caisson foundation. Therefore, it has been widely used in highways and civil buildings.

However, the underground working conditions of the excavated piles are poor, the environment is harsh, and the labor intensity is high, so safety and quality are particularly important. When it is necessary to take a small area of water pumping due to construction, attention should be paid to the observation of the surrounding strata and buildings, and the relevant units should be notified in time to deal with abnormal conditions.

Answer]: Mode disturbance A

When the concrete is poured by manual digging pile, when the concrete drop exceeds 3m, the chute should be used to pour jujube, and the height of the end of the string barrel from the bottom of the hole should not be greater than 2m; The concrete should be dismantled by a plug-in vibrator to prevent the delamination and segregation phenomenon caused by too high a height.

According to the engineering geology, the whole process of hole formation must drain precipitation, and the organization should be complete and effective.

Drainage system, the discharge of water in the pile hole adopts a two-stage drainage system, and the water in the hole pile is first pumped and discharged to the ground.

The water system is discharged into the municipal pipe network after treatment.

The ground drainage system in the construction area is arranged along the perimeter of the site.

In addition to the construction area, the living area should also be provided with drainage ditches to drain rainwater and.

Domestic sewage. Second, precipitation.

This project adopts well point precipitation, and the construction process arranges special personnel to dewater the surrounding precipitation wells.

The groundwater level is kept below the construction soil layer.

Ensure that the rock and soil at the bottom of the hole are dredging and the hole is safe during the underground operation.

Complete, the wall protection proceeded smoothly. In the process of hole pile excavation, the water seepage in the pile well can be used to depreciate the pile hole itself.

The method is: 1, a small amount of seepage can be dug in the pile hole to dig a small collection pit, with the excavation with the bucket hanging.

2. If the amount of seepage is slightly larger, a deep water collection well can be dug in the pile hole, pumped out with a small submersible pump, and followed by the soil.

Deepening of the catchment well.

3. When the amount of seepage is large, a pile can be selected in each area to excavate in advance as the surrounding pile hole.

Precipitation wells. Third, the construction quality and technical requirements of precipitation wells.