CN108316297A - A kind of tubular type soil nailing and its construction method - Google Patents

Abstract

The invention relates to a tubular soil nail and a construction method thereof. Tubular soil nails include flower steel pipes and anchoring structures, one end of the flower steel pipe is a tapered drill bit, the other end is an open end, the open end is provided with threads, the surface of the flower steel pipe body is provided with a grout hole, and the outer wall of the flower steel pipe is welded There are spiral steel ribs, and the spiral steel ribs are close to the tapered drill bit; during pressure grouting, one end of the grouting sleeve is connected to the open end of the flower pipe, and the other end is softly connected to the grouting; after the pressure grouting is completed, the grouting The slurry casing is removed, and the anchor structure is installed at the open end of the flower pipe. The steel pipe of the present invention is directly drilled into the soil body, avoiding problems such as hole collapse, buried drill and necking when drilling and grouting are performed in soft soil areas. Mechanical rotary drilling is used to drill into the soil, reducing the difficulty of steel pipes entering the soil and the loss of steel pipes in the process of entering the soil, and speeding up the construction progress; the spiral steel ribs make the soil around the flower pipes loose, and the grout formed during pressure grouting Composite reinforcement with soil has a larger diameter, which improves the pullout resistance of soil nails.

Description

A tubular soil nail and its construction method

technical field

The invention belongs to the field of geotechnical engineering, and in particular relates to a tubular soil nail and a construction method thereof.

Background technique

Soil nails are widely used in rock and soil anchoring projects such as foundation pits and slopes. Traditional soil nails generally use reinforced soil nails and steel pipe type soil nails. The construction process of reinforced soil nails requires mechanical drilling in advance. It is located in the center of the hole, so that the steel bar can fully play its role. After the soil nail is inserted, the mortar is injected to make the soil nail and the soil embedded. This form of soil nailing, in some areas with soft soil, such as backfill soil, soft muddy soil, liquefiable sand, etc., this form of soil nailing is usually difficult to form a stable borehole. During the drilling process, problems such as hole collapse, buried drilling and necking are prone to occur. Existing steel pipe type soil nails (CN 206646502 U) and new-type driven soil nails (CN 204849758 U) both adopt a mechanical driving method, which is easy to cause damage to the steel pipe driving part during the driving and tamping process. The soil around the middle steel pipe is compressed, which makes it difficult for the mortar to penetrate into the soil, and it is difficult to ensure the formation of a uniform slurry-soil composite. Moreover, the diameter of the formed composite reinforcement of slurry and soil is small, and the quality of the soil nail cannot be guaranteed, resulting in soil nail resistance. Lower pullout force.

Contents of the invention

The invention provides a tubular soil nail formed by high-pressure grouting of steel pipes and a construction method thereof. The use of a new type of spiral steel rib pattern steel pipe is convenient for mechanically screwing the steel pipe into the soil, reducing the difficulty of entering the soil and the loss of the steel pipe in the process of entering the soil, and avoiding the damage of the end of the steel pipe when driving the steel pipe in the traditional way; at the same time, the spiral steel rib During the drilling process, the soil around the steel pipe can be loosened. During the pressure grouting process, the diameter of the composite reinforcement formed by the surrounding slurry of the flower pipe and the soil is relatively large, which improves the pullout resistance of the soil nail.

Technical scheme of the present invention is as follows:

A tubular soil nail, comprising a flower-shaped steel pipe, an anchoring structure and a grouting casing, the anchoring structure includes a fixing nut and a steel backing plate; one end of the flower-shaped steel pipe is a tapered end, the other end is an open end, and the opening The end of the steel pipe is provided with threads, and the surface of the steel pipe body is provided with a grout hole. The outer wall of the steel pipe body is welded with a spiral steel rib, and the spiral steel rib is close to the tapered drill bit; Fill the grout; after taking out the grouting hose, connect one end of the grouting sleeve to the open end of the flower pipe, and connect the other end to the grouting hose for pressure grouting; after the pressure grouting is completed, remove the grouting sleeve Next, a steel backing plate and a fixing nut are installed at the open end of the flower steel pipe, and the fixing nut is matched with the thread at the open end of the flower steel pipe.

Preferably, the pulp outlet holes are arranged in a quincunx or spiral arrangement. Avoid a large reduction in strength at the same section of the flower pipe.

Preferably, the diameter of the pulp hole is 5-10mm, and the spacing is 0.2-0.5m.

One end of the grouting casing is connected and fixed with the open end of the flower steel pipe by a screw, and the other end (small-diameter end) is connected and fixed with the grouting tube by a steel wire.

The flower steel pipe is anchored to the sprayed concrete surface, and the steel backing plate is used as a force transmission member under the anchor, the size is 0.3×0.3m, the thickness is 10-15mm, and a round hole with the same diameter as the steel pipe is left in the center.

Preferably, the height of the spiral steel ribs is 30-50 mm, the rib width is 3-5 mm, and the spacing is 100 mm. The arrangement length is about 0.5-1.0 m, and the arrangement length of the threads at the open end is 50-100 mm.

The flower-shaped steel pipes are arranged in a quincunx-shaped arrangement on the concrete surface layer, and the horizontal spacing and vertical spacing are 0.8-1.5m.

The present invention also provides a construction method of tubular soil nails, comprising the following steps:

1) Shotcrete surface layer: Determine and reserve the hole position of the flowered steel pipe on the wall of the foundation pit, bonza steel mesh, and shotcrete to form the shotcrete surface layer;

2) Construction of flower pipes: When the strength of the concrete surface layer reaches the specified strength, the flower pipes are mechanically drilled into the soil;

3) Sealing: Seal the hole around the open end of the flower pipe to avoid the mortar spraying out from around the open end during the pressure grouting process;

4) Pressure grouting: first use a small-diameter grouting hose to go deep into the bottom of the flower steel pipe, gradually fill the flower steel pipe with slurry from the inside to the outside, and take out the grouting hose; connect one end of the grouting sleeve to the opening of the flower steel pipe One end is connected, and the other end is connected to the grouting hose for pressure grouting, the grouting pressure is 1-2MPa, and the pressure is stabilized for 5 minutes;

5) Install the anchoring structure: After the grouting is completed, remove the grouting sleeve, install a steel backing plate at the open end of the flower steel pipe, and use mechanical equipment to tighten the fixing nut to the thread at the open end of the flower steel pipe to provide micro-prestress, and the flower The steel pipe and the concrete surface are connected as a whole, so that the pressure of the concrete surface is transmitted to the steel pipe and soil nails, and they are jointly stressed.

The outstanding beneficial effects of the present invention are:

(1) The present invention has strong reliability, adopts steel pipe type soil nails, and the steel pipe is rotated to drill into the soil, which avoids construction problems such as hole collapse, buried drill and necking when construction is carried out in soft soil areas;

(2) The end of the steel pipe in the soil adopts a spiral steel rib structure, which reduces the difficulty of the steel pipe in the soil and the loss of the steel pipe in the process of entering the soil, and can speed up the construction progress; at the same time, the end anchorage force is improved in the formed soil nail structure, Prevent the mortar body from separating from the steel pipe;

(3) Soil nails have high pull-out resistance. During the drilling process of the steel pipe, the spiral steel rib makes the soil around the steel pipe loose. During the pressure grouting, the composite reinforcement of the slurry and the soil formed has a larger diameter, which improves the pullout resistance of the soil nail;

(4) The deformation of the support structure is small. The matching use of steel pipe port threads, fixing nuts and steel backing plates can provide micro-prestress for soil nails to reduce the deformation of the support structure;

(5) The columnar concretions of cement slurry formed around the soil nail by pressure grouting can improve the shear strength of the soil nail, prevent the soil from sliding, and then improve the stability of the foundation pit.

(6) It has strong practicability and can be widely used in soft soil areas such as backfill, soft muddy soil, and liquefiable sandy soil.

Description of drawings

Fig. 1 is the schematic diagram of spent steel pipe and grouting sleeve of the present invention;

Fig. 2 is the schematic plan view of the overall structure after the tubular soil nail support of the present invention is completed;

Labels and symbols

1-flower steel pipe; 2-grouting sleeve; 3-sprayed concrete surface; 4-fixed nut; 5-steel backing plate; 6-spiral steel rib; 7-tapered end; .

Detailed ways

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

Example 1

As shown in Figures 1 and 2, a tubular soil nail includes a flowered steel pipe 1, an anchoring structure and a grouting sleeve 2, the anchoring structure includes a fixing nut 4 and a steel backing plate 5; the flowered steel pipe 1 One end is a tapered end 7, the other end is an open end, and the open end is provided with a screw thread. The surface of the pipe body of the flower steel pipe 1 is provided with a slurry outlet hole 8, which is used for the slurry in the pipe to penetrate into the soil layer under high pressure. The body of the flower steel pipe 1 A spiral steel rib 6 is welded on the outer wall, and the spiral steel rib 6 is adjacent to the tapered end 7; the inside of the flower pipe 1 is first filled with slurry through the grouting hose; after the grouting hose comes out, the grouting sleeve 2 One end is connected to the open end of the flower pipe 1, and the other end is connected to the grouting hose for pressure grouting (the grout penetrates into the soil from the holes on the pipe body); after the pressure grouting is completed, remove the grouting sleeve 2 1. A steel backing plate 5 and a fixed nut 4 are installed at the open end of the spent steel pipe 1, and the fixed nut 4 is matched with the threads at the open end of the spent steel tube 1. The pulp outlet holes 8 are arranged in plum blossom or spiral. The diameter of the slurry outlet 8 is 5-10mm, and the spacing is 0.2-0.5m. The flower steel pipe 1 is anchored to the sprayed concrete surface 3, and the steel backing plate 5 is used as a force transmission member under the anchor, the size is 0.3×0.3m, the thickness is 10-15mm, and a circular hole with the same diameter as the steel pipe is left in the center. The height of the spiral steel ribs 6 is 30-50mm, the width of the ribs is 3-5mm, the spacing is 100mm, and the length of the arrangement is about 0.5-1.0m;

Flower steel pipe 1 can be used The common circular steel pipe with a thickness of 3mm is processed and manufactured, and the flowered steel pipe 1, the supporting fixing nut 4 and the steel backing plate 5 are uniformly processed and manufactured by the factory.

The flower-shaped steel pipes 1 are arranged in a quincunx-shaped arrangement on the support surface layer, and the horizontal spacing and vertical spacing are 0.8-1.5m. The allowable deviation of hole distance is not more than 50mm.

The construction method of tubular soil nailing comprises the following steps:

1. Shotcrete surface layer: determine and reserve hole positions for the flowered steel pipe 1 on the foundation pit wall, bonza steel mesh, and shotcrete to form the shotcrete surface layer 3;

2. Construction of the flower steel pipe 1: When the strength of the concrete surface layer 3 reaches the specified strength, the flower steel pipe 1 is mechanically drilled into the soil; At the bottom of the hole, dilute the residue at the bottom of the hole and lift out the mud to ensure the quality of grouting; the length of the washing hole should be consistent with the length of the steel pipe; the sewage from the washing hole should be drained in time to prevent the slope from collapsing due to the soaking of sewage.

3. Hole sealing: Seal the hole around the opening end of the flower pipe 1 to avoid the mortar spraying out from around the opening end during the pressure grouting process;

4. Pressure grouting: first use the grouting hose to go deep into the bottom of the flower steel pipe, gradually fill the flower steel pipe with slurry from the inside to the outside, and take out the grouting hose; connect one end of the grouting sleeve (10) to the flower steel pipe ( 6) The open end is connected, and the other end is connected to the grouting hose for pressure grouting. The grouting pressure is 1-2MPa, and the pressure is stabilized for 5 minutes;

5. Install the anchoring structure: After the grouting is completed, remove the grouting sleeve 2, install the steel backing plate 5 at the opening end of the flower pipe, and tighten the fixing nut 4 to the thread at the opening end of the flower pipe.

6. After the completed soil nails reach 70% of the design strength, that is, 6 to 7 days after the construction of soil nails, the soil can be excavated to the depth of the next soil nail level, and the construction of the next soil nail can be carried out.

Claims (7)

1. A tubular soil nail is characterized in that: it comprises a flowered steel pipe (1), an anchoring structure and a grouting casing (2), and the anchoring structure comprises a fixed nut (4) and a steel backing plate (5); One end of the flower steel pipe (1) is a tapered end (7), the other end is an open end, and the open end is provided with threads, the surface of the flower steel pipe (1) is provided with a slurry hole (8), and the flower steel pipe (1) ) the outer wall of the pipe body is welded with a spiral steel rib (6), and the spiral steel rib (6) is adjacent to the tapered end (7), and the inside of the flower steel pipe (1) is first filled with slurry through the grouting hose; Then one end of the grouting sleeve (2) is connected to the open end of the flower pipe (1), and the other end is connected to the grouting hose for pressure grouting; after the pressure grouting is completed, the grouting sleeve (2) is removed, A steel backing plate (5) and a fixed nut (4) are installed at the open end of the flower steel pipe (1), and the screw thread at the open end of the flower steel pipe (1) is matched with the fixed nut (4). 2. A tubular soil nail according to claim 1, characterized in that, the grout holes (8) are arranged in a plum blossom or a spiral arrangement. 3. A tubular soil nail as claimed in claim 2, characterized in that the diameter of the grout outlet hole (8) is 5-10mm, and the distance is 0.2-0.5m. 4. A tubular soil nail as claimed in claim 1, characterized in that one end of the grouting sleeve (2) is connected and fixed with the open end of the flower pipe (1) by a screw, and the other end is connected with the grouting hose by a steel wire. The connection is fixed. 5. A kind of tubular soil nail as claimed in claim 1, characterized in that, the flower steel pipe (1) is anchored to the sprayed concrete surface (3), and the steel backing plate (5) is used as an anchor to transmit force The component has a size of 0.3×0.3m, a thickness of 10-15mm, and a round hole with the same diameter as the steel pipe in the center. 6. A tubular soil nail as claimed in claim 1, characterized in that the spiral steel rib (6) has a height of 30-50 mm, a rib width of 3-5 mm, a spacing of 100 mm, and an arrangement length of about 0.5-5 mm. 1.0m; the thread arrangement length of the open end is 50-100mm. 7. The construction method of tubular soil nailing as claimed in claim 1, is characterized in that, comprises the following steps: 1) Shotcrete surface layer: determine and reserve the hole position of the flowered steel pipe (1) on the wall of the foundation pit, bonza steel mesh, and shotcrete to form the shotcrete surface layer (3); 2) Construction of the flower-shaped steel pipe (1): when the strength of the concrete surface layer (3) reaches the specified strength, the flower-shaped steel pipe (1) is mechanically rotated into the soil; 3) Sealing: Seal the holes around the open end of the flower pipe (1) to avoid the mortar spraying out from around the open end during the pressure grouting process; 4) Pressure grouting: first use the grouting hose to go deep into the bottom of the flower steel pipe, gradually fill the flower steel pipe with slurry from the inside to the outside, and take out the grouting hose; connect one end of the grouting sleeve (10) to the flower steel pipe ( 6) The open end is connected, and the other end is connected to the grouting hose for pressure grouting. The grouting pressure is 1-2MPa, and the pressure is stabilized for 5 minutes; 5) Install the anchoring structure: After the grouting is completed, remove the grouting sleeve (2), install the steel backing plate (5) at the open end of the flower steel pipe, and tighten the fixing nut (4) to the open end of the flower steel pipe with mechanical equipment. thread.