CN110004927A - Construction method of prestressed micro piles - Google Patents

Abstract

The invention discloses a prestressed micro-pile construction method, comprising the following steps: drilling a pile hole on a side slope; inserting a steel pipe pile into the pile hole; bundling an anchor cable on a grouting pipe, and inserting the grouting pipe It is inserted into the bottom of the steel pipe pile; the grouting material is injected into the steel pipe pile through the grouting pipe, and after the grouting material is solidified, the anchor cable is stretched through the fixed platform set on the slope surface to apply Prestressing, which can form the prestressing of the micro pile and the surrounding rock and soil, improve the mechanical performance of the micro pile and the surrounding rock and soil, improve the anti-slip force of the rock and soil in the anti-sliding section, and at the same time can effectively improve the resistance of the micro pile. Compressive and shear strength.

Description

Construction method of prestressed micro piles

technical field

The invention relates to the technical field of slope protection, in particular to a construction method for prestressed micro-pile.

Background technique

Micro piles generally refer to cast-in-place piles with a diameter of less than 400mm and a slenderness ratio of more than 30, which are constructed by drilling, strong reinforcement and pressure grouting. Because of their small aperture, convenient construction, and easy access to equipment, they are increasingly Favored by more people. In recent years, the use of micro piles and grouting technology in slope protection and landslide treatment and roadbed disease treatment has become more and more popular, providing a lot of convenience for slope protection, landslide and roadbed disease emergency treatment.

However, the strength of this kind of small micro-pile is also greatly reduced, and it cannot meet the target strength requirements in the treatment of slopes, landslides and roadbed diseases with complex geological structures and high protection strength requirements, resulting in In the treatment of these slopes, landslides, and roadbed diseases, only large-scale supports and other structures can be used. Therefore, improving the strength of the existing micro piles and the surrounding rock and soil mass to meet the requirements of more slope protection, landslide treatment, and treatment of roadbed diseases is of great significance for improving the convenience of slope protection construction and quickly realizing landslide and roadbed disaster control. very positive meaning.

SUMMARY OF THE INVENTION

Based on this, it is necessary to provide a prestressed micro-pile construction method for the problem that the strength of the traditional micro-pile is low and cannot meet the demand.

A prestressed micro-pile construction method, comprising the following steps:

(1) Drilling pile holes on the slope;

(2) inserting the steel pipe pile into the pile hole;

(3) Bundle the anchor cable on the grouting pipe, and insert the grouting pipe into the bottom of the steel pipe pile;

(4) inject grouting material into the steel pipe pile through the grouting pipe;

(5) After the grouting material is solidified, the anchor cable is stretched through the fixed platform arranged on the slope surface to apply prestress to the anchor cable.

In one embodiment, before the step of inserting the steel pipe pile into the pile hole, it further comprises:

The pile holes are cleaned.

In one embodiment, the anchor cable includes an anchor section and a free section, and the step of bundling the anchor cable on the grouting pipe is as follows:

The anchor cable is bundled on the grouting pipe by a fastener, and an expansion piece is sleeved at the lower end of the grouting pipe, and the expansion piece supports the anchoring section to form a protrusion.

In one of the embodiments, after the step of bundling the anchor cable on the grouting pipe with fasteners, the method further includes:

The centering piece is bundled on the free section, the centering ring is inserted into the steel pipe pile, and the centering piece is located between the free section and the centering ring to support the grouting pipe, so that the grouting pipe is supported. The grouting pipe and the steel pipe pile are coaxial.

In one embodiment, before the anchor cable is bundled on the grouting pipe, it further comprises:

Inject butter into the protective cover, and then set the protective cover on the anchor cable.

In one embodiment, before the anchor cable is bundled on the grouting pipe, it further comprises:

Degreasing and rust removal are performed on the anchoring section of the anchor cable, and anti-corrosion treatment is performed on the free section of the anchor cable.

In one of the embodiments, the fixing platform includes a ground beam and a wedge-shaped spacer set on the ground beam, and the step of tensioning the anchor cable through the fixing platform arranged on the slope is as follows:

The ground beams and the wedge-shaped spacers are poured on the side slope. During the pouring process, the anchors are put into the concrete, and the anchor cables are made to pass through the anchors. The anchor cable is tensioned.

In one embodiment, after the step of tensioning the anchor cable through the anchor plate, the step further includes:

The anchor plate and the anchor cable are sealed with concrete blocks.

In one of the embodiments, the step of drilling a pile hole on the side slope is as follows:

The pile holes are drilled on the side slope by a pneumatic dry drilling construction method.

In one embodiment, the process of injecting grouting material into the steel pipe pile through the grouting pipe is completed by multiple grouting, and the grouting adopts cement mortar with a strength not lower than M30 at 1-2MPa under pressure.

In the above prestressed micro pile construction method, the anchor cable is inserted into the bottom of the steel pipe pile along with the grouting pipe, and the grouting material is injected into the steel pipe pile from bottom to top through the grouting pipe. The lower end of the cable is anchored in the stable formation. The other end of the anchor cable extends out of the steel pipe pile and is connected to the fixed platform set on the slope to apply prestress to the anchor cable, form the prestress of the micro pile and the surrounding rock and soil, and improve the micro pile and the surrounding rock and soil. It can improve the anti-sliding force of rock and soil in the anti-sliding section, and at the same time can effectively improve the compressive and shear strength of micro piles.

Description of drawings

Fig. 1 is the flow chart of the construction method of prestressed micro-pile in one embodiment;

FIG. 2 is a schematic structural diagram of a prestressed micropile in one embodiment;

Fig. 3 is the structural representation of the steel pipe pile in Fig. 2;

Fig. 4 is the sectional view of line A-A in Fig. 2;

FIG. 5 is a cross-sectional view taken along line B-B in FIG. 2 .

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention, so the invention is not limited by the specific implementation disclosed below.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for the purpose of illustration only and do not represent the only embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

Please refer to FIG. 1 , a prestressed micro-pile construction method in an embodiment, in order to realize the pre-stressed micro-pile construction method, the prestressed micro-pile support structure shown in FIG. 2 is adopted. The prestressed micro-pile construction method specifically includes the following steps:

Step S110: Drilling pile holes on the side slope.

Specifically, when drilling a pile hole on a side slope, it should be excavated from the upper part of the side slope. When the upper-level slope is excavated and formed, prestressed micro-pile is constructed first and then slope protection is carried out to avoid long-term exposure of the slope. After the prestressed micro piles of the upper-level slope are completed, the next-level slope is excavated. The diameter and depth of the pile hole should meet the design requirements. When drilling the pile holes on the side slope, use the pneumatic dry drilling construction method to drill the pile holes on the side slope, and water drills cannot be used to avoid soil pollution and collapse of the pile holes. The pile hole should be cleaned to ensure that the hole wall of the pile hole is free of contaminants, so as to ensure that the bonding strength between the grouting material body and the rock mass is maintained. If the stratum is loose and broken, the drilling technique with casing should be adopted to keep the pile hole intact and not collapse.

Step S120: Insert the steel pipe pile 100 into the pile hole

Please refer to FIG. 3 together, the outer diameter of the steel pipe pile 100 is smaller than or equal to the diameter of the pile hole, and the length of the steel pipe pile 100 is adapted to the depth of the pile hole. The side wall of the steel pipe pile 100 is provided with a slurry outlet hole 102, the number of the slurry outlet hole 102 is multiple, and the plurality of slurry outlet holes 102 are arranged at intervals along the axial direction of the steel pipe pile 100. The grouting material injected into the steel pipe pile 100 can flow into between the outer wall of the steel pipe pile 100 and the side wall of the pile hole through the grouting hole 102. After the grouting material solidifies, the steel pipe pile 100 can be connected to the rock mass. .

Step S130: The anchor cable 200 is bundled on the grouting pipe 110, and the grouting pipe 110 is inserted into the bottom of the steel pipe pile 100.

Please also refer to FIG. 4 , when lowering the reinforcement cage, the anchor cable 200 is lowered into the steel pipe pile 100 through the grouting pipe 110 at the same time. In one embodiment, the anchor cable 200 is bundled on the grouting pipe 110 by the fasteners 210. In order to ensure the stability of the anchor cable 200, a plurality of fasteners 210 are equally spaced to bind and fix the anchorage. Specifically, the fastener 210 is an iron wire, and the anchor cable 200 is a steel strand. The steel strand shall be high-strength and low-relaxation steel strand, and the standard strength of the steel strand shall not be less than 1860MPa. An on-site pull-out test must be carried out before the construction of the anchor cable 200. During the construction of the anchor cable 200, the pre-tension is carried out with 1.1 times the design prestress, and finally it is locked according to the design value.

The anchor cable 200 includes an anchoring section 202 and a free section 204 , wherein the anchoring section 202 is tied to the lower end of the grouting pipe 110 , and the free section 204 is tied to the upper end of the grouting pipe 110 . At the same time, before the anchor cable 200 is bundled in the grouting pipe 110, the anchoring section 202 of the anchor cable 200 needs to be degreasing and rust removed, and the free section 204 of the anchor cable 200 is subjected to anti-corrosion treatment. damage. The outer jacket of the anchor cable 200 is provided with a protective cover 230 , and the protective cover 230 can protect the entire anchor cable 200 . Specifically, the protective cover 230 may be a PVC hose, and grease is injected between the protective cover 230 and the steel strand.

Please also refer to FIG. 5 , further, a plurality of expansion pieces 220 are sleeved at the lower end of the grouting pipe 110 at intervals, and the fasteners 210 and the expansion pieces 220 are arranged at intervals along the axial direction of the grouting pipe 110 , and the expansion pieces 220 may be The anchoring section 202 supporting the anchor cable 200 forms a protrusion, and the protrusion can ensure the stable connection between the anchoring section 202 and the stable formation. The expansion piece 220 may be made of a circular thick steel plate or a rubber plate, and the expansion piece 220 is provided with an accommodating groove 222 for accommodating the anchor cable 200 .

In order to ensure that after the grouting pipe 110 is inserted into the steel pipe pile 100, the grouting pipe 110 is coaxial with the steel pipe pile 100, the free section 204 of the anchor cable 200 is bundled with a centering piece 244, and the steel pipe pile 100 is inserted with a centering piece 244. The centering ring, the position of the centering ring corresponds to the free section 204 of the anchor cable 200, and the centering piece 244 is supported between the anchor cable 200 and the centering ring. The centering piece 244 can support the grouting pipe 110 , ensure that the grouting pipe 110 is coaxial with the steel pipe pile 100 , and prevent the grouting pipe 110 and the anchor cable 200 from shaking in the steel pipe pile 100 . Specifically, the centering member 244 is formed by bending a steel sheet, both ends of the centering member 244 are bound on the protective sleeve 230 by iron wires, and the centering ring can be a steel pipe. The grouting pipe 110 is provided with three centering pieces 244 in the circumferential direction, and the included angle between two adjacent centering pieces 244 is 120°, so as to ensure the stable support of the grouting pipe 110.

Please refer to FIG. 2 , the grouting pipe 110 needs to be inserted into the bottom of the steel pipe pile 100 , and there is a certain distance between the grouting pipe 110 and the bottom of the steel pipe pile 100 to ensure that the grouting material can flow out smoothly. The grouting plug 250 needs to be installed at the opening of the steel pipe pile 100, and the grouting plug 250 seals the opening of the steel pipe pile 100 to prevent external debris from falling into the steel pipe pile 100 and affecting the grouting material. The length of the grouting pipe 110 is greater than the length of the steel pipe pile 100, and the grouting pipe 110 extends out of the steel pipe pile 100 through the grouting plug 250 to facilitate the injection of the grouting material.

The grouting plug 250 can be made of non-woven fabric, and the shape is a set of annular belts on the heat shrinkable tube. Before grouting, the grouting plug 250 is filled with a pressure of 0.2-0.4MPa, and the grouting plug 250 is filled after it reaches the strength of 20MPa. High pressure grouting. The grouting plug 250 is provided with an exhaust pipe 252 connecting the inside and the outside of the steel pipe pile 100 , and the gas and impurities in the grouting material can be discharged through the exhaust pipe 252 .

Step S140 : inject grouting material into the steel pipe pile 100 through the grouting pipe 110 .

Please refer to FIG. 2 again. Specifically, the grouting material is high-pressure slurry, which is completed by multiple grouting. The grouting material can be cement mortar, cement slurry, or slurry with other chemical components. In this embodiment, the grouting material is cement slurry, and the grouting is carried out with a cement slurry with a strength not lower than M30 under a pressure of 1-2 MPa. It is recommended that the water-cement ratio be 0.45, the specific ratio and the amount of various additives to be added. Must be determined by field test.

Step S150 : after the grouting material is solidified, the anchor cable 200 is stretched through the fixing platform 300 arranged on the slope surface 10 to apply prestress to the anchor cable 200 .

After the grouting material is solidified, the anchoring section 202 of the anchor cable 200 is fixed to the stable ground. The anchoring end of the anchor cable 200 is formed by using OVM15 anchors 330 to be anchored on the fixed platform 300 on the slope, so as to apply prestress to the anchor cable 200. Specifically, the fixing platform 300 includes a ground beam 310 and a wedge-shaped spacer 320 disposed on the ground beam 310 . The ground beam 310 and the wedge-shaped spacer 320 are formed by casting at the same time, and the ground beam 310 is provided with steel bars to ensure that the ground beam 310 has sufficient strength. The ground beam 310 and the wedge-shaped spacer 320 are provided with a steel sleeve 260 for the grouting pipe 110 and the anchor cable 200 to pass through.

During the pouring process of the ground beam 310 and the wedge-shaped spacer 320 , the anchor 330 is put into the concrete, and the steel sleeve 260 is passed out of the anchor 330 , so that the anchor cable 200 is passed out of the anchor 330 . After the solidified strength of the concrete is greater than 22 MPa, the anchor plate 340 is set on the wedge-shaped spacer 320 , and the anchor cable 200 is fixed on the anchor plate 340 to apply prestress to the anchor cable 200 . After the tension of the anchor cable 200 is completed, the anchor plate 340 and the anchor cable 200 can be sealed by using the concrete block 350 to prevent the anchor plate 340 and the anchor cable 200 from being corroded by rainwater.

In the above prestressed micro-pile construction method, when the reinforcement cage is lowered, the anchor cable 200 is inserted into the bottom of the steel pipe pile 100 along with the grouting pipe 110, and the grouting material is injected into the steel pipe pile 100 from bottom to top through the grouting pipe 110. , after the grouting material is solidified, the anchoring section 202 of the anchor cable 200 can be anchored in the stable formation. The anchoring end of the anchor cable 200 extends out of the steel pipe pile 100 and is connected to the fixing platform 300 arranged on the slope surface 10 to apply prestress to the anchor cable 200 to form a prestress on the micro pile and the surrounding rock and soil, so as to improve the micro-pile and the surrounding rock and soil. The mechanical performance of the pile and the surrounding rock and soil mass can improve the anti-sliding force of the rock and soil mass in the anti-sliding section, and at the same time, it can effectively improve the compressive and shear strength of the micro pile.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (10)

1. a prestressed miniature pile construction method, is characterized in that, comprises the following steps: (1) Drilling pile holes on the slope; (2) inserting the steel pipe pile into the pile hole; (3) Bundle the anchor cable on the grouting pipe, and insert the grouting pipe into the bottom of the steel pipe pile; (4) inject grouting material into the steel pipe pile through the grouting pipe; (5) After the grouting material is solidified, the anchor cable is stretched through the fixed platform arranged on the slope surface to apply prestress to the anchor cable. 2. The prestressed micro-pile construction method according to claim 1, wherein before the step of inserting the steel pipe pile into the pile hole, the method further comprises: The pile holes are cleaned. 3. The prestressed micro-pile construction method according to claim 1, wherein the anchor cable comprises an anchoring section and a free section, and the step of bundling the anchor cable on the grouting pipe is as follows: The anchor cable is bundled on the grouting pipe by a fastener, and an expansion piece is sleeved at the lower end of the grouting pipe, and the expansion piece supports the anchoring section to form a protrusion. 4. The prestressed micro-pile construction method according to claim 3, characterized in that, after the step of bundling the anchor cable on the grouting pipe with fasteners, it further comprises: The centering piece is bundled on the free section, the centering ring is inserted into the steel pipe pile, and the centering piece is located between the free section and the centering ring to support the grouting pipe, so that the grouting pipe is supported. The grouting pipe and the steel pipe pile are coaxial. 5. The prestressed micro-pile construction method according to claim 3, wherein before the anchor cable is bundled on the grouting pipe, the method further comprises: Inject butter into the protective cover, and then set the protective cover on the anchor cable. 6. The prestressed micro-pile construction method according to claim 3, wherein before the anchor cable is bundled on the grouting pipe, the method further comprises: Degreasing and rust removal are performed on the anchoring section of the anchor cable, and anti-corrosion treatment is performed on the free section of the anchor cable. 7 . The prestressed micro-pile construction method according to claim 1 , wherein the fixed platform comprises a ground beam and a wedge-shaped spacer set on the ground beam, and the anchor cable is passed through the The steps for tensioning the fixed table are as follows: The ground beams and the wedge-shaped spacers are poured on the side slope. During the pouring process, the anchors are put into the concrete, and the anchor cables are made to pass through the anchors. The anchor cable is tensioned. 8 . The prestressed micro-pile construction method according to claim 7 , wherein after the step of tensioning the anchor cable through the anchor plate, the method further comprises: 8 . The anchor plate and the anchor cable are sealed with concrete blocks. 9. The prestressed micro-pile construction method according to claim 1, wherein the step of drilling a pile hole on the side slope is as follows: The pile holes are drilled on the side slope by a pneumatic dry drilling construction method. 10. The prestressed micro-pile construction method according to claim 1, characterized in that, in the process of injecting grouting material into the steel pipe pile through the grouting pipe, multiple grouting is used to complete the grouting. Use cement mortar with strength not lower than M30 under the pressure of 1-2MPa.