CN100564695C - The job practices of carrier pile - Google Patents

Abstract

The job practices of carrier pile, sentence in the stake position and to ram the mode pore-forming in the single tube to projected depth, in institute pile hole, insert solid filler and ram and form enlarged footing carrier and closely knit pile concrete, wherein adopt by comprising foundation end sealing and being externally connected with the inner tamping tube of pore-forming element of construction and interior hammer ram in the bottom at interior pore-forming structural system through syndeton, by interior hammer ram at the tamping force of the closed bottom end portion of inner tamping tube with pore-forming element of construction substep or directly ram in the soil, until making the rammer pipe sink to soil layer, in institute pile hole, carry out carrier construction and closely knit pile concrete then to projected depth.This worker's method has that noise is little, the immersed tube ability is strong, adapt to that soil layer is wide, pile quality good, the bearing capacity of stake is high and advantage such as the part solid building waste of can dissolving, be particularly suitable for the construction of plain concrete rigid pile and broken stone pile in the composite foundation, also can be used for the construction of reinforced concrete pile.

Description

Construction method of carrier pile

technical field

The invention relates to a construction method of a carrier pile in a bottom-expanded cast-in-situ pile in the field of building foundation construction.

Background technique

In-situ pouring concrete piles are one of the construction methods of building foundation concrete piles. There are many kinds of construction methods. There are different construction equipment and construction techniques for different ground conditions. Among them, the hole forming methods of the pile body include drilling, punching, Digging holes, spiral holes and immersed tube holes and so on.

In order to increase the bearing capacity of the pile end, an enlarged head is often formed at the bottom of the pile end of the cast-in-place pile, which is called an expanded-bottomed cast-in-situ pile. There are also various types of bottom expansion methods such as drilling expansion, explosion expansion, compression expansion, tamping expansion, injection expansion and excavation expansion.

At present, in the construction of the enlarged head of the bottom-enlarged cast-in-situ pile, the main purpose is to control the concrete volume or the area of the enlarged bottom of the enlarged head. The purpose is to increase a certain end-bearing area to improve the bearing capacity of the pile end. There is no requirement for the height, so the bearing capacity of the pile is not greatly improved, and the material of the enlarged head is the same as that of the pile body, so it cannot be used to the fullest.

In order to increase the bearing capacity of single piles more significantly, a new type of pile has been developed - carrier pile, which is a pile composed of two parts: concrete pile body and pile end carrier, and its pile length includes the concrete pile body. length and carrier height. The pile end carrier is composed of tamped concrete (dry hard concrete), tamped filling material (including broken bricks, broken concrete blocks, cement mixture, crushed stone, pebbles and minerals that are rammed into the foundation soil at the pile end for compaction). Ballast and other materials) and a pile end bearing body composed of three parts of compacted soil. Different from the control index of pile end expansion head construction in general bottom expansion grouting piles, carrier pile construction mainly controls the penetration of the carrier when the filling material is compacted, and the difference in penetration will directly affect the bearing capacity of the pile and the deformation of the pile .

Since the pile end carrier is composed of three parts whose compressive modulus gradually decreases, the pile end stress gradually spreads from large to small through the rammed concrete, rammed filler expansion head, and compacted soil, and has already dropped relatively in the lower foundation soil. Low. Therefore, not only the force on the pile tip is reasonable and the material can be used to the fullest, but also it can be used as the bearing layer of the carrier pile in some strata where the conventional pile foundation is not suitable for the pile tip bearing layer, so that the pile length can be shortened and the cost of the pile foundation can be saved. At the same time, because there is a large carrier formed by strong tamping under the pile end, its single pile has a high bearing capacity, and is most suitable for the construction of plain concrete rigid piles (CFG piles) and gravel pile reinforcements in composite foundations. The construction of reinforced concrete piles has good economic benefits.

The construction process of the carrier pile is divided into three steps, namely pile hole construction, carrier construction and pile body construction. Among them, the construction methods of the carrier and the pile body are roughly the same, but the hole forming methods of the pile holes are different, resulting in different construction methods.

The patent (application) No. is that Chinese patent documents such as 98101041.5, 98101332.5, 99100566.X and 00106288.3 have all disclosed the relevant composite carrier tamping pile construction method respectively. The hole-forming process of the construction method is to ram the bottom of the pipe to a certain depth with a slender rammer inside the pipe and then press it into the pile pipe. This process is repeated continuously. After reaching the designed depth, the carrier and pile body concrete construction is carried out. Since the rammer is in direct contact with the soil layer during pile hole construction, the soil often adheres to the surface of the rammer when it encounters a wet and sticky soil layer. The hammering force is greatly weakened, the speed of the immersed tube is low, and the soil will splash from the inside of the tube, which will affect the surrounding environment; when constructing in a stratum with good groundwater permeability, the rammer directly rams the water body in the hole, and the water hammer The effect will greatly weaken the hammering force, making it difficult to form a hole, and the water will splash out from the pipe. When a hard formation is encountered within the design depth, it will be difficult or even impossible to sink the tube. In addition, since this construction method belongs to the compaction hole-forming method, when construction is carried out in a stratum with severe soil compaction effect, the ground will bulge, and serious quality problems such as broken piles, necking and hanging feet will occur.

Contents of the invention

In view of the above situation, the present invention will provide a new construction method for carrier piles, so that it can be constructed in a variety of different strata, and has the advantages of low noise, strong pipe sinking ability, wide adaptability to soil layers, good pile body quality, and It has the advantages of high bearing capacity and can absorb part of solid construction waste. It is especially suitable for the construction of plain concrete rigid piles and gravel piles in composite foundations, and can also be used for the construction of reinforced concrete piles.

The construction method of the carrier pile of the present invention is to form a hole to the design depth by adopting a single-tube internal tamping method at the pile position, then fill the pile hole with solid filler and tamp to form an enlarged head carrier and a dense pile body concrete, Among them, a pore-forming structure system consisting of an internal ramming pipe with a closed bottom and a pore-forming structural unit connected outside the bottom through a connecting structure and an internal rammer (such as the current 3500-5000kg internal ram) is used. The tamping force of the internal rammer on the closed bottom of the internal ramming tube rams the hole-forming structural unit into the soil step by step or directly until the ramming tube sinks into the soil layer to the designed depth, and then carries out carrier construction in the formed pile hole and dense pile concrete.

In the above construction method, the earth taker is directly rammed into the soil during the construction of the pile hole. During the tamping process, according to the stratum conditions encountered during the tamping process, corresponding methods can be adopted respectively, that is, the earth taking method can be used to form holes in the hard soil layer. , in the non-hard soil layer, the compaction method can be used to form holes.

When encountering the hard soil layer and adopting the method of taking soil to form a hole, the above-mentioned hole-forming structural unit connected to the end of the internal ramming pipe closed at the bottom can be an earth-taking device structure, such as the various forms currently in use. soil extractor. The earth taker is rammed into the soil layer by the tamping force of the closed bottom end of the inner ramming tube by the internal rammer, and then the earth taker is lifted out of the pile position and the soil inside is removed, and then reinserted into the original pile hole to continue tamping. Repeat this operation until the earth taker is sunk into the soil layer to the design depth.

If there is no hard soil layer in the hole-forming stratum, the above-mentioned hole-forming structural unit that is connected to the end of the internal ramming pipe that is closed at the bottom can be the above-mentioned soil extractor, or a pointed ram head or a flat-bottomed ram head, The ramming tube is sunk into the soil layer to a design depth by the ramming force of the closed bottom end of the inner ramming tube by the internal rammer.

According to the specific conditions of the construction site strata, the above-mentioned two construction methods of taking soil to form holes in the hard soil layer and compacting holes in the non-hard soil layer can be used separately, alternatively or mixed. For example, all or part of the soil can be used to form holes in the stratum with severe soil squeezing effect.

In order to further improve the scope of application and flexibility of the above-mentioned construction method of the present invention, the internal ramming pipe with closed bottom end can adopt a combined ramming pipe with at least two pipe section structures connected to each other by a connecting structure, and the length can be adjusted according to construction needs And/or connect with appropriate mating structural members.

The hole-forming method of the above-mentioned construction method of the present invention is suitable for construction in strata where the hole wall can keep self-supporting after hole-forming or after simple measures are taken. Most cohesive soils in nature can generally maintain self-supporting holes in circular holes with small diameters in the shallow part; for sandy soils and gravel soils, a hard shell of a certain thickness is formed around the holes after being compacted into holes. layer, the hole wall can generally maintain self-support; if the hole wall is still difficult to maintain self-support, it can be used to backfill the formed hole with cohesive soil and then squeeze the hole according to the current compaction method to form a certain thickness on the hole wall. Cohesive soil hard shell retaining wall. When forming piles in the sand layer where groundwater is very rich or other hole walls can not keep self-supporting after the hole is formed, the double-pipe internal impact construction method that has pile pipe retaining walls as reported in Publication No. CN 1912255A can be adopted. Or after the closed end of the combined ramming tube is removed, the ramming tube is sunk to the design depth as a retaining wall.

In the process of using the rammer to ram the bottom of the rammed tube above, in order to avoid the disadvantages caused by the rammer directly ramming the closed bottom end, and to reduce the ramming stress and noise in the pipe end components, it is possible to After pre-loading some solid fillers including coarse sand and gravel in the ramming tube, ramming with the inner rammer.

After the required pile holes are formed in the above manner, the carrier construction and the dense pile body concrete can be carried out in the pile holes according to the methods currently used and/or reported. For example, the method provided in the specific examples can be used to drop corresponding solid fillers into said pile holes, and replace the soil fetcher or pointed ram at the lower end of the ramming tube with a flat-bottomed ram for tamping. Hit until the required penetration is reached to form an enlarged head carrier, and then continue to press on the pile material with a flat-bottomed rammer for tamping to make the pile compact.

During the concrete construction of the pile body, the flat-bottomed tamp head can be used to directly press on the concrete for tamping, so as to make the concrete of the pile body dense and increase the filling volume, so the pile body has good quality, high strength, large pile side friction resistance, and single pile bearing capacity Lego.

It can be understood that, compared with the existing reported composite carrier rammed and expanded pile construction method, the superiority of the above-mentioned construction method of the present invention is obvious. First of all, in the current composite carrier rammed and expanded pile method construction, because the rammer directly rams the soil layer, especially for the wet and sticky soil layer, the soil adheres to the surface of the rammer, which not only increases the resistance when pulling the hammer, The tamping energy when the hammer is dropped is also weakened, and the soil in the pipe is seriously splashed outwards during the hammering, which makes the working environment condition worse, and is also unfavorable for environmental protection requirements. The rammer in the construction method of the present invention rams in a ramming tube closed at the bottom. The rammer does not directly contact the soil layer and will not be stained with soil. Therefore, for a certain drop height, the ramming energy remains unchanged. The force does not increase, and the bottom soil of the pipe will not splash out of the pipe and affect the environment. In addition, the construction method of composite carrier rammed and expanded piles is not suitable for construction in underwater gravel layers due to the serious water hammer effect during ramming, which greatly weakens the ramming force and makes it difficult to form holes, and the water in the pipe splashes outwards seriously. . In this construction method, the rammer does not directly ram the water, so there is no water hammer effect, and holes can still be formed underwater, and the water in the holes will not splash out. Secondly, the current composite carrier rammed and expanded pile method can only be carried out by alternating ramming and pressing pipes. The construction method is single, and the applicable soil layer has limitations. When encountering hard soil layers, the immersed pipe speed is slow or even difficult to form holes. For this reason, it is often necessary to use a long auger or a mechanical Luoyang shovel to preform the hole. The construction method of the present invention can change the corresponding hole-forming method at any time according to the situation of the geological soil layer, so the hole-forming ability is strong, the applicable soil layer is wide, the construction speed is fast, and the soil quality in the soil extractor can be adjusted after the hole is formed to the designed depth. Check to confirm whether the bearing layer has reached the design requirements. In addition, the current composite carrier rammed and expanded pile construction method belongs to the pile-forming method by squeezing the soil, which often causes quality problems such as broken piles, necking and hanging feet due to the soil-squeezing effect. In order to reduce or eliminate the influence of its squeezing effect, it is also necessary to adopt the above-mentioned method of pre-forming holes. Moreover, when it is used as a pile foundation, the distance between the piles is required to be relatively large due to the soil squeezing effect, so that the cap is relatively large and uneconomical. When the construction method of the present invention is constructed in the soil layer with serious soil squeezing effect, the soil-taking method can be used to form holes, thereby effectively reducing or eliminating the influence of the soil squeezing effect, and the pile spacing can be smaller than that of the current composite carrier rammed and expanded piles. more economical. On the other hand, in the concrete construction of the pile body, the current composite carrier tamping pile construction method is to pour fluid concrete in the pile pipe, and insert and vibrate with a vibrating rod to form a pile. In the construction method of the present invention, relatively dry concrete can be used, and the flat-bottomed tamp head can be used to tamp on the concrete. Not only the pile body concrete is relatively dense, of good quality, and high in strength, but also the contact surfaces of the pile body concrete and the soil layer around the pile are interlaced, and the It can be rammed into candied haws piles to increase pile side resistance and improve the bearing capacity of single piles. Therefore, the construction method of the present invention is suitable for a wide range of soil layers, low noise, strong hole-forming ability, fast construction speed, good pile body quality, high single pile bearing capacity and can absorb part of solid construction waste, and is especially suitable for composite foundations. The construction of plain concrete rigid piles (CFG piles) and gravel piles can also be used for the construction of reinforced concrete piles.

The above content of the present invention will be further described in detail below in conjunction with the specific implementation manners of the examples shown in the accompanying drawings. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples. Without departing from the above-mentioned technical idea of the present invention, various replacements or changes made according to common technical knowledge and customary means in this field shall be included in the scope of the present invention.

Description of drawings

Fig. 1 is the schematic flow sheet of construction method of the present invention in the stratum that has hard soil layer construction plain concrete carrier pile.

Fig. 2 is a schematic flow diagram of the construction method of the present invention for constructing a reinforced concrete carrier pile in a stratum without a hard soil layer.

Detailed ways

Example 1

When constructing a carrier pile in a stratum with a hard soil layer, the internal ramming pipe 2 (integral structure, or The combined structure formed by connecting each other through the connecting structure) and the hole-forming structure system including the internal rammer 1. After the bottom of the internal ramming tube 2 is pre-loaded with solid fillers including coarse sand and gravel, the closed bottom end of the internal ramming tube 2 is rammed with the internal rammer 1, and the earth taker 3 is rammed into the soil , and then lift the earth taker 3 out of the ground, remove the internal soil and put it back into the original pile hole to continue tamping, repeat this operation until the inner tamping pipe 2 sinks into the soil layer to the design depth, and then carry out the carrier in the formed pile hole. Construction and compaction of pile body concrete. The specific operation process is shown in steps (a) to (h) in Figure 1:

(a) move the machine into place;

(b) Ramming the earth taker into the soil layer;

(c) When it is difficult to tamp into the hard layer, lift the earth taker out of the ground and remove the internal soil;

(d) Continuing to ram the earth-taker until it reaches the design depth;

(e) Lift the soil extractor and change it into a flat-bottomed tamp head 4, and drop into a solid filling material in the pile hole;

(f) put down the internal ramming tube 2 to ram the filling material expanding head 6 of the carrier and measure the three-strike penetration;

(g) drop into the pile body concrete in sections and continue to compact with the flat-bottom tamp head 4;

(h) After the concrete construction of the pile body reaches the required elevation, the construction of a pile is completed.

Example 2

When constructing carrier piles in strata without hard soil layers, the inner ramming pipe 2 (integral form, Or a combined form formed by connecting with each other through a connecting structure) and a hole-forming structure system including the internal rammer 1. After the bottom of the inner ramming tube 2 is pre-loaded with solid fillers including coarse sand and gravel, the closed bottom end of the inner ramming tube 2 is rammed with the inner rammer 1, and the pointed rammer 4 is kept Ram to the design depth. Then carry out carrier construction and compact pile body concrete in the formed pile hole. The specific operation process is shown in steps (a) to (h) in Figure 2:

(a) Move the machine into place, and connect the lower part of the internal ramming tube 2 to the pointed ram head 5;

(b) Ramping the pointed tamp head 5 into the formation;

(c) tamping the pointed tamp head 5 to the design depth;

(d) Put the pointed tamp head 5 out of the ground and replace it with a flat-bottomed tamp 4, and drop solid filler into the pile hole;

(e) put down the ramming tube and ram the filler expanding head 6 to form the carrier and measure the three-strike penetration;

(f) put into the reinforcement cage after putting forward the flat-bottomed tamp head 4;

(g) drop the pile body concrete material into the hole and press the flat-bottom tamp head 4 on the concrete surface for tamping;

(h) After the concrete construction of the pile body reaches the required elevation, the construction of a pile is completed.

Claims (5)

1. The construction method of the carrier pile. After the hole is drilled to the design depth by single-tube internal tamping at the pile position, solid filler is filled in the formed pile hole and tamped to form an enlarged head carrier and dense pile body concrete. Its characteristics It adopts a pore-forming structure system consisting of a ramming tube with a closed bottom end and an internal ramming hammer connected to the bottom end through a connecting structure. The tamping force rams the pore-forming structural units step by step or directly into the soil until the ramming tube sinks into the soil layer to the designed depth, and then carries out carrier construction and compacts the pile body concrete in the formed pile holes. The pore-forming structural units These are soil fetchers, pointed rams, or flat-bottomed rams. 2. The construction method of the carrier pile as claimed in claim 1, characterized in that said hole-forming structural unit is an earth taker and a flat rammer head, and the ramming force of the closed bottom end of the ramming pipe is earlier passed through the internal rammer. Ram the earth taker into the soil, then lift the earth taker out of the pile and remove the soil inside, then put it back into the original pile hole and continue tamping, repeat this operation until the earth taker sinks into the soil layer to the designed depth, and then Put solid filling material into the pile hole, and replace the soil fetcher at the lower end of the ramming tube with a flat-bottomed ram to ram until the required penetration is reached to form an enlarged head carrier, and then continue to use the flat-bottomed ram to press on the pile material. Ramping compacts the pile body. 3. The construction method of the carrier pile as claimed in claim 1, characterized in that said hole-forming structural unit is a pointed ram head and a flat ram head, which is first passed through the internal rammer at the closed bottom end of the ramming tube. The impact force makes the pointed ram sink into the soil layer to the designed depth, then put solid filler into the formed pile hole, tamp with the flat-bottomed ram to reach the required penetration, and form an enlarged head carrier, and then continue to use the flat-bottomed ram The ram head is pressed on the pile material for tamping to compact the pile body. 4. The construction method of carrier piles according to any one of claims 1 to 3, characterized in that said rammed pipes with closed bottoms are combined rammed pipes which are connected to each other by at least two pipe sections. 5. The construction method of the carrier pile as claimed in any one of claims 1 to 3, characterized in that the bottom of the closed rammer tube is pre-loaded with solid fillers including coarse sand and gravel , and then use the inner rammer to ram inside the ramming tube.

Images