CN107254872A - Pile for prestressed pipe stake bottom floating sealing device and its control method - Google Patents

Abstract

The invention discloses a prestressed pipe pile bottom floating solidification device and a control method thereof. In the vast soft clay foundations along the eastern coast, prestressed pipe piles tend to float up after the piling work is completed. The invention provides a solid sealing device, which is constructed by combining spud cans with prestressed pipe piles. After the elevation of the pile foundation is stable, use the inherent dimensions of the pile body and the spud can, and use the measuring rope to measure the disengagement length of the pile body and the spud can, so as to evaluate the degree of floating of the pile body. Then use the holes on the spud cans to pour cement mortar to seal the gaps caused by the floating of the pile body, which greatly improves the safety of the pile foundation under the premise of ensuring low cost.

Description

Prestressed pipe pile bottom floating solidification device and its control method

technical field

The invention belongs to the field of pile foundation construction, and in particular relates to a prestressed pipe pile bottom floating and solidifying device and a control method thereof.

Background technique

With the acceleration of urban development, the scale of municipal infrastructure, bridges, public and civil buildings is increasing, especially in the southeast coastal areas of my country, where the soft clay layer is deep and the requirements for the bearing capacity of the foundation are rising.

Prestressed pipe piles have been used more and more widely in recent years, which depends on several advantages: 1) the use of high-strength steel bars and concrete is conducive to saving materials and energy consumption; Small loss; 3) Low cost, convenient transportation, convenient construction, etc. However, the shear and bending resistance of prestressed pipe piles is poor. During the construction process, it is easily affected by the soil squeezing effect, and the floating of the pile body is an important performance.

Because the pile driving speed is too fast, the soil body is uplifted, and the elevation of the pile foundation that has been driven will be affected. Usually the pile top elevation will increase by more than 30cm, and even the pile will break.

However, when the pile body floats, there is a large gap between the bottom of the pile body and the soil at the pile tip, and the bearing capacity of the pile tip cannot be exerted, and the bearing capacity of the pile foundation is overestimated. When subjected to a large upper load, excessive settlement will occur, which poses a great safety hazard.

The current treatment methods for the floating of prestressed pipe piles mostly adopt methods such as re-drilling and re-pressure. For example, in papers such as "PHC Pipe Pile Floating Phenomenon and Treatment and Prevention", "Detection and Treatment of Pipe Pile Floating Caused by Soil Squeeze Effect", the floating control of prestressed pipe piles is carried out by means of static pressure method and hammering method. In addition, there are control methods such as changing the piling sequence and controlling the progress of piling. However, these methods are difficult to guarantee the construction quality, and the cost is high, and it takes more time, so it is difficult to be widely promoted in projects.

Against this background, the present invention provides a better solution to the floating problem of prestressed pipe piles based on the principles of low cost and less time-consuming.

Contents of the invention

During the construction of prestressed pipe piles, due to the existence of the soil squeezing effect, phenomena such as floating are prone to occur, which will bring great safety hazards to the upper structure. The traditional solution is mainly re-pressing, which is costly, time-consuming and difficult to control the quality. The present invention aims at the bottom gap caused by floating, adopts the method of grouting to eliminate the gap, can measure the floating amount more accurately, and overcomes the floating problem of pile foundation with less cost, less time-consuming, better effect and less consumables , which has important engineering significance.

The concrete technical scheme that the present invention adopts is as follows:

The prestressed tubular pile bottom floating solidification device includes a spud can and the pile body of the prestressed tubular pile. The pile body is hollow, and the spud can is divided into an embedded part and a pile tip part connected to each other. The embedded part is assembled and fixed on the pile In the bottom of the inner cavity of the pile body, the pile tip is conical and the cone top surface is circumferentially arranged with reserved steel bars matching the bottom of the pile body, which is used to connect the bottom of the pile body. The maximum diameter of the pile tip is the same as the outer diameter of the pipe pile. Consistent; the embedded part is reserved with axial and radial channels, the axial channel vertically penetrates the embedded part, and the radial channel connects the axial channel and the outer surface of the embedded part, and is used to send the pile body and the spud can Pour cement mortar into the potential breakaway gap. In the present invention, the potential disengagement gap refers to the gap formed between the pile body and the cone top surface of the pile tip during the floating process, but the gap does not exist permanently, and it is during the process of driving the pile body into the foundation and The pile body does not exist before it floats up.

Preferably, the depth of the embedded part entering the inner cavity of the pile body is not less than 50 cm, so as to ensure reliable contact between the two and facilitate smooth grouting.

Preferably, the reserved steel bars are connected to the bottom surface of the pile body by welding, bolts or other connection methods.

Preferably, the cross-section of the embedded part is consistent with the cross-section of the inner cavity of the pile body, so as to ensure that the grout will not overflow from the gap between the two.

Preferably, the channel is formed by embedding a metal pipe or a plastic pipe in the embedding part.

Preferably, the radial channel is arranged at or near the bottom surface where the embedded part and the pile tip part are connected, so that it can grout any floating gap and avoid grouting dead angle.

Preferably, there are multiple radial channels uniformly distributed on the bottom cross-section of the embedded part to make the grouting more uniform.

Another object of the present invention is to provide a method for controlling the floating of the bottom of the prestressed pipe pile based on the above floating sealing device, the steps are as follows:

Step 1: According to the diameter and length of the pile body of the designed prestressed pipe pile, pour the corresponding spud can, and reserve a hole on the spud can during pouring, and assemble and fix the embedded part of the spud can into the inner cavity of the pile body, and the depth It should be greater than 50cm to maintain the assembly reliability between the embedded part and the pile body;

Step 2: Tightly connect the pile body and the reserved reinforcement on the spud can, and then measure the distance L1 from the top of the pile body to the top _of the embedded part;

Step 3: Drive the prestressed pipe pile into the design position to the design elevation;

Step 4: After the piling is completed, use the measuring rope to measure the distance L ₂ from the top of the pile body to the top of the embedded part again. After the distance value L ₂ is stable, compare it with L ₁ to obtain the separation distance between the pile body and the spud can ΔL=L ₂ -L ₁ ; when ΔL exceeds the set threshold, lower the conveying pipe to the top of the embedding part, and inject grout into the separation gap between the pile body and the spud can through the reserved hole to eliminate the pile Bottom-up effect.

Preferably, during the grouting process, the grouting speed and the grouting amount need to be controlled to avoid segregation.

Preferably, the actual grouting amount is not less than the gap volume formed by the separation between the pile body and the spud can, and generally needs to be multiplied by a safety factor greater than 1.

Compared with the prior art, the present invention has the beneficial effects as follows:

1. This method provides a new solution for eliminating the gaps caused by the floating of prestressed pipe piles during the construction process. Compared with traditional methods, it has lower cost, less time-consuming, less consumable materials, and better results.

2. This method can accurately measure the height of the gap between the bottom of the pile and the soil layer caused by the floating of the pile foundation, avoiding the error caused by the expansion and contraction of the pile foundation and the rebound of the soil layer;

3. This method can evaluate the height of the floating void and decide whether to eliminate the void by grouting;

4. This method can calculate the theoretically required grouting amount through parameters such as the floating amount and the hole size of the spud can, which saves more building materials.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and implementation steps.

Fig. 1 is the sectional view of complete prestressed pipe pile among the present invention;

Fig. 2 is a schematic diagram of the floating situation of prestressed pipe piles in the present invention;

Fig. 3 is a sectional view of the spud can in the present invention;

Fig. 4 is a top view of the spud shoe in the present invention;

In the figure: pile body 1, spud shoe 2, gap 3, embedded part 4, pile tip part 5, tunnel 6, reserved steel bar 7.

detailed description

The present invention will be further elaborated and illustrated below in conjunction with the accompanying drawings and examples. The technical features of the various implementations in the present invention can be combined accordingly on the premise that there is no conflict with each other.

The complete prestressed pipe pile bottom floating solidification device is shown in Figure 1. The device includes a spud can and a pile body of a prestressed pipe pile. In the present invention, the pile body 1 can be a round pile or a square pile, which is not limited here. The pile body has a hollow inner cavity. As shown in FIG. 3 , the spud can is divided into an embedded part 4 and a pile tip part 5 which are connected to each other, and the embedded part 4 is assembled and fixed in the bottom of the inner cavity of the pile body 1 . The embedded part of the spud can 2 should have a sufficient height to ensure the grouting effect, and it should generally be significantly larger than the common spud can, generally not less than 50cm. In this embodiment, the diameter of the embedded part 4 is consistent with the inner diameter of the pile body 1, which is 400mm; the length of the pile body 1 is 10m, the height of the embedded part 4 is 700mm, the pile tip part is conical, and the maximum diameter is consistent with the outer diameter of the pile body 1 , is 600mm. As shown in Figure 4, the cone top surface of the pile tip part 5 is circumferentially arranged with reserved steel bars 6 matching the bottom surface of the pile body, which can be connected to the bottom of the pile body by welding or bolts and other connection methods. Concrete can also be supplemented to increase strength after pouring. As shown in Figure 2, during the floating process of the prestressed pipe pile, the bottom of the pile body 1 will break away from the spud can 2, and separate from the cone top surface of the pile tip part 5, forming a floating gap 3. The embedded part is pre-embedded with metal pipes or plastic pipes during pouring to form reserved axial and radial channels 6, and the diameter of the pipes should be considered for smooth grouting. The axial channel runs through the entire embedded part vertically along the axis of the embedded part 4, and the radial channel communicates with the outer surface of the axial channel and the embedded part. The cross-section of the embedded part 4 is consistent with the cross-section of the inner cavity of the pile body 1. After the two are assembled, the embedded part 4 can block the inner cavity of the pile body 1, so that the grout enters the tunnel 6 under pressure. The outlet of the radial channel is set at the bottom surface where the embedded part 4 and the pile tip part 5 are connected or slightly higher than the bottom surface, so that cement mortar can be poured into the potential separation gap between the pile body 1 and the spud can 2 through the channel 6, and because The grout outlet is located at the bottom of the potential detachment gap, as long as there is a gap, the floating gap can be eliminated by grouting 3 .

In order to maintain the uniformity of grouting, a plurality of radial channels can be provided, which are evenly distributed on the bottom cross-section of the embedded part at the same included angle.

Based on the above-mentioned floating and sealing device, a method for controlling the floating of the bottom of the prestressed pipe pile can be realized, and the steps are as follows:

Step 1: According to the diameter (600mm) and length (10m) of the pile body 1 of the designed prestressed pipe pile, pour the corresponding pile shoe 2. In order to facilitate the subsequent pouring of cement mortar, certain holes need to be left on the pile shoe 2 during pouring 6; Then, assemble and fix the embedded part of the spud can into the inner cavity of the pile body, the depth should be greater than 50cm (actually 700m), and the diameter should be consistent with the inner diameter of the pipe pile (400mm) to ensure reliable contact;

Step 2: Tightly connect the pile body 1 and the reserved steel bar 7 on the spud can 2, and measure the distance L ₁ from the top of the pile to the top of the spud can (L ₁ =LL ₀ =9.3m) with a measuring rope;

Step 3: Drive the prestressed pipe pile body 1 into the design position according to the standard construction method to the design elevation;

Step 4: After the piling is completed, measure the distance from the top of the pile body to the top of the embedded part again, and record it as L ₂ after the distance value stabilizes. In this example, assuming that the gap at the bottom of the pile is ΔL=30mm due to the floating of the pile body 1, the theoretically measured L ₂ =9.6m is compared with L ₁ to obtain the disengagement distance between the pile body 1 and the spud can 2 ΔL=L ₂ -L ₁ , evaluate the degree of floating of the pile body 1, and judge that it is necessary to perform grouting to seal the void 3 generated by the floating. If the separation distance ΔL between the pile body and the spud can exceeds the set threshold, it needs to be grouted; otherwise, no grouting is required. Thresholds can be determined by specification or by experiment. In this embodiment, ΔL is too large and grouting is required, so the next step is performed.

Step 5: Estimating the amount of grouting according to the floating amount, the theoretical grouting amount required in this embodiment is calculated as: V=π*(0.3 ² −0.2 ² )*0.03=4.7L. Cement mortar is poured through the reserved channel 6 on the spud can. In order to ensure sufficient grouting, the actual grouting volume in this embodiment can be 3×V=14.1L. At the top of boot 2, pay attention to the grouting speed and grouting volume to avoid segregation and other situations.

After grouting and consolidation, the disengagement gap 3 between the pile body 1 and the spud can 2 is filled with cement mortar, which can fully exert the bearing capacity of the pile tip and improve the safety of the superstructure.

Aiming at the voids caused by the soil squeezing effect in the construction of prefabricated pipe piles, the present invention provides a new idea. Compared with the traditional re-drilling and re-pressing method, the operation is simple and safe, the efficiency is higher, the cost is lower, and the time-consuming and consumable materials are less. Wide applicability and great market prospect.

The above-described example is only a preferred solution of the present invention, but it is not intended to limit the present invention, and all technical solutions obtained by means of equivalent replacement or equivalent transformation all fall within the protection scope of the present invention .

Claims (10)

1. a kind of pile for prestressed pipe stake bottom floating sealing device, it is characterised in that the pile body including shoe and pile for prestressed pipe, institute The pile body stated is hollow, and shoe is divided into embedded part and the pile top part of interconnection, and embedded part is fixed on the interior of pile body In the portion of bottom of chamber, and the reserved steel bar that pile top part matches in coniform and vertex of a cone face ring to laying with pile body bottom surface, for even Pile extension body bottom, the maximum gauge of pile top part is consistent with pile tube external diameter；The embedded part is reserved with hole axially and radially Road, the vertically communicated embedded part of axial channel, radial direction duct connection shaft to duct and the outer surface of the embedded part, for Cement injection mortar in the potential disengaging gap of pile body and shoe.

2. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described embedded part enters The depth for entering pile body inner chamber is not less than 50cm.

3. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described reserved steel bar leads to Cross welding or bolt is connected with pile body bottom surface.

4. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described embedded part is horizontal Section is consistent with the cross section of pile body inner chamber.

5. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described duct is by metal Pipe or plastic tube are embedded in embedded part in advance and formed.

6. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described radial direction duct is set It is placed in bottom surface or bottom surface vicinity that embedded part is connected with pile top part.

7. pile for prestressed pipe stake bottom floating sealing device as claimed in claim 1, it is characterised in that described radial direction duct has It is a plurality of, uniformly with the bottom cross section of embedded part.

8. a kind of pile for prestressed pipe stake bottom floating control method based on floating sealing device described in claim 1, its feature exists In step is as follows：

Step 1：According to the pile body diameter and length of design pile for prestressed pipe, corresponding shoe is poured, and when pouring in shoe Upper reserving hole channel, the embedded part assembling of shoe is fixed in pile body inner chamber, and depth should be greater than 50cm, keep embedded part Assembly reliability between pile body；

Step 2：It is close to connect pile body and the reserved steel bar in shoe, then measure at the top of pile body to described embedded part top Apart from L₁；

Step 3：Pile for prestressed pipe is squeezed into design attitude to designed elevation；

Step 4：After the completion of piling, measured again using lining rope at the top of pile body at the top of described embedded part apart from L₂, treat away from From value L₂After stable, with L₁It is compared, obtains pile body and the disengaging distance, delta L=L of shoe₂-L₁；When Δ L exceedes given threshold When, delivery pipe is transferred to described embedded part, and by reserved duct into the disengaging gap of pile body and shoe Slip casting, to eliminate the influence that a bottom is floated.

9. the pile for prestressed pipe stake bottom floating control method of floating sealing device as claimed in claim 1, it is characterised in that During slip casting, injection speed and grouting amount need to be controlled, it is to avoid isolation situation occurs.

10. the pile for prestressed pipe stake bottom floating control method of floating sealing device as claimed in claim 1, it is characterised in that Actual grouting amount is not less than the interstitial volume of the disengaging part formation of pile body and shoe.