CN112482409B

CN112482409B - Combined supporting device and construction method thereof

Info

Publication number: CN112482409B
Application number: CN202011404220.2A
Authority: CN
Inventors: 梅岭; 董鑫; 王雷; 张颖; 姚凯
Original assignee: Jiangsu University of Science and Technology
Current assignee: Kunshan Jinhui Urban Construction Foundation
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2022-09-23
Anticipated expiration: 2040-12-04
Also published as: CN112482409A

Abstract

The invention discloses a combined supporting device which comprises an anchor rod, an expanding head and a slope surface layer, wherein the anchor rod is connected with the expanding head, the anchor rod is made of more than two kinds of cement mortar with different strength grades in consideration of the instability of contact surfaces of different soil layers, the slope surface layer comprises modified silt and a reinforcing mesh, the reinforcing mesh is laid on a slope surface of a side slope, and the side slope is connected with the slope surface of the side slope through the modified silt so as to prevent the side slope from weathering erosion and rainfall erosion from the outside to the inside. The invention also discloses a construction method of the combined supporting device. The anchor rod is provided with the enlarged head at the end part, the rod body and the steel strand are arranged in the anchor rod, and the anchor rod is integrated after cement mortar grouting, so that a larger anchoring force can be provided for the anchor rod, and meanwhile, the steel strand improves the strength of the enlarged head and is not easy to break; the anchor rod adopts the mode of slip casting more than biliquid, and the cement mortar of high strength grade is located different soil layer contact surface positions moreover, is of value to bearing the external force that forms because of the soil layer changes, and the anchor rod does not receive the damage simultaneously.

Description

Combined supporting device and construction method thereof

Technical Field

The invention relates to the field of support, in particular to a combined support device and a construction method thereof.

Background

China has broad width of members, complicated and changeable topography and landform, numerous mountains, wide distribution of formed natural slopes, rapid development of national economy and construction, and a large amount of artificial slopes formed by excavation of foundation pits, so the supporting problem of various slope projects is very prominent.

The anchoring is one of common methods in the slope management, only the action of an anchoring section of an anchor rod is considered for the anchoring condition of the slope, the anchoring section is in a stable soil layer, the danger of a certain range of contact surfaces of different soil layers is ignored, and protective measures are not adopted in a targeted manner. In addition, when protective measures are taken on the slope, the slope is generally sprayed with cement or concrete by hanging a net, and a large amount of materials such as cement are also used.

Chinese patent application No. 201811416973.8 discloses a high strength biliquid slip casting stock, pours into the interior pole into the biliquid of high strength simultaneously through the three-way pipe with the biliquid of high strength, and the misce bene is down followed through a grout outlet injection tunnel country rock under the effect of inner rod front end spacer. But the problems are that: the grouting mode does not consider the dangerousness and protection requirements of different soil layer contact surfaces, and only changes the grouting mode and the grout type. The Chinese patent with the application number of 201010250823.1 discloses a portal frame type anchor pipe soil nail spraying net supporting process and modified reinforced cement paste used by the process, wherein vertical large-diameter anchor pipe soil nails are added on the basis of the existing conventional soil nail spraying net supporting technology, and the cement paste is sprayed by adopting a new formula of modified curing admixture. However, the modified reinforced cement slurry has a wide variety of components, and particularly, the mixing ratio of the compound admixture is complicated.

Generally speaking, the existing supporting method does not consider the instability of contact surfaces of different soil layers, and although the improvement method has effect, the method is complicated and the procedure is complex.

Disclosure of Invention

The invention aims to: in order to overcome the defects in the prior art, the invention aims to provide a safe and reliable combined supporting device with strong stability, and the invention also aims to provide a construction method of the combined supporting device, which is simple to operate, good in improvement effect and capable of saving materials.

The technical scheme is as follows: the invention relates to a combined supporting device which comprises an anchor rod, an enlarged head and a slope surface layer, wherein the anchor rod is connected with the enlarged head, the anchor rod is made of more than two kinds of cement mortars with different strength grades in consideration of the instability of contact surfaces of different soil layers, the slope surface layer comprises modified silt soil and reinforcing steel mesh sheets, the reinforcing steel mesh sheets are laid on the slope surface of a side slope, and the modified silt soil is connected with the slope surface of the side slope, so that the side slope is prevented from weathering erosion and rainfall erosion from the outside to the inside.

The enlarged head is ellipsoid, spherical or conical, can provide bigger withdrawal resistance for the stock, and the anchor effect is superior to ordinary stock.

The stock includes body of rod one, body of rod two and the body of rod three that links to each other in order, and the cement mortar intensity of body of rod two is greater than the cement mortar intensity of body of rod one and body of rod three, only need exceed at least one rank can. And because the contact surfaces of different soil layers are easy to be unstable, the rod body II with the highest cement mortar strength corresponds to the soil layer interface. Under the action of high-strength cement mortar, the shear strength and the compressive strength of the anchor rod are improved, the shear force transmitted by roadway confining pressure can be effectively borne, and landslide danger caused by factors such as soil layer change is reduced.

The anchor rod is internally provided with a connecting rod. One end of the anchor rod is provided with an anchor disc, and the other end of the anchor rod is connected with the anchor backing plate and the anchor device. And a stiffening plate is arranged between the anchor backing plates. The anchor disc is connected with the steel strand through an extrusion anchor. The connecting rod and the steel strand play a synergistic role in jointly bearing the tension on the anchor rod.

In order to effectively utilize huge river channel dredging soil and reduce the using amount of cement, the modified silt soil comprises 0.1-0.5 part of polyvinyl alcohol fiber, 5-7 parts of cement and 98-100 parts of silt soil. The dosage of the cement is also reduced from the conventional 12-20 parts to 5-7 parts. The modified silt soil has higher strength, and the external doping material is selected from polyvinyl alcohol (PVA) fiber which is stable, non-toxic, low in price, and the first in productivity and yield all around the world. Through experimental research, when the silt soil is improved, the effect is best when the length of the polyvinyl alcohol fiber is 5-7 mm, preferably 6mm, and the improved silt soil has higher strength.

The construction method of the combined supporting device comprises the following steps:

drilling an anchor hole, wherein the end part of the anchor hole is drilled with a variable diameter, and the diameter of the anchor hole is larger than that of an anchor rod;

welding an anchor disc on the connecting rod, and placing the steel strands into the drilled hole together after the steel strands are installed through the extrusion anchorage device;

step three, drilling and grouting, namely, using more than two cement mortars with different strength grades to manufacture an anchor rod, namely, using the cement mortars with common strength grades to perform grouting from the bottom, changing to use the cement mortars with high strength grades to continue grouting after reaching a certain length range of contact surfaces of different soil layers, and replacing the cement mortars with common strength again until the drilled hole is fully filled after the grouting in the length range is finished;

step four, installing an anchor backing plate, a stiffening plate and an anchorage device at one end of the anchor rod exposed out of the slope surface of the side slope;

and fifthly, hanging a reinforcing mesh on the slope surface of the side slope, spraying modified silt soil, and finishing support.

The working principle is as follows: the anchor rod grouting adopts cement mortar with various strength grades, and the high-strength cement mortar is used for grouting anchor rod sections penetrating through different soil layer contact surfaces within a certain length range, has higher strength, and can particularly bear pressure, shearing force and the like formed due to soil layer change. When the slope is subjected to net hanging and slurry spraying treatment, the silt soil which is poor in mechanical property and is usually discarded and accumulated is utilized as resources, but the silt soil which is modified by the admixture is high in strength, and the cement consumption is saved.

Has the advantages that: compared with the prior art, the invention has the following remarkable characteristics:

1. the end part of the anchor rod is provided with the expanding head, the anchor rod is internally provided with the rod body and the steel strand, and the whole body is formed after cement mortar grouting, so that a larger anchoring force can be provided for the anchor rod, and meanwhile, due to the existence of the steel strand, the strength of the expanding head is improved and the expanding head is not easy to break;

2. the anchor rod adopts a mode of grouting more than two fluids, and cement mortar with high strength grade is positioned at the contact surface positions of different soil layers, so that the anchor rod is beneficial to bearing external force formed by soil layer change and is not damaged;

3. when the net is hung and the slurry is sprayed, silt soil modified by polyvinyl alcohol fiber and cement is used for the slurry on the slope, so that the silt soil which is increased year by year and has low utilization rate is utilized, the cement consumption can be saved, and the PVA has high yield and good environmental protection;

4. the modified dredged soil has greatly improved strength and permeability, and the strength is higher than that of the common guniting material.

Drawings

FIG. 1 is a schematic structural view of the present invention;

fig. 2 is a cross-sectional view of a rock bolt 1 of the present invention;

fig. 3 is a schematic structural view of the sloping surface layer 3 of the present invention.

Detailed Description

The directions shown in the drawings of the specification are up, down, left and right.

Referring to fig. 1, the combined supporting device comprises a multi-fluid grouting anchor rod 1 with an enlarged head 2 and a slope surface layer 3 made of modified materials. The inclination angle of the formed hole of the anchor rod 1 is recommended to be 15-25 degrees, and the thickness of the slope surface layer 3 hanging net guniting is not less than 5 cm. The top surface of the side slope is a slope top, the bottom surface of the side slope is a slope foot, and the side slope is sequentially provided with a first soil layer 12 and a second soil layer 13 from top to bottom. The rod body part with the highest strength of the anchor rod 1 spans the interface of the soil layers, namely the contact surface of the first soil layer 12 and the second soil layer 13. The surface of the side slope 4 is sprayed with a slope surface layer 3 for reinforcement.

As shown in fig. 2, a connecting rod 5 is arranged at the center of the inside of the anchor rod 1, two parallel anchor discs 6 are welded at one end of the connecting rod 5 close to the enlarged head 2, and the anchor discs 6 are fixedly connected with steel strands 11 through an extrusion anchor 10. The enlarged head 2 may be ellipsoidal, spherical or conical. The anchor disc 6, the extrusion anchor 10 and the steel strand 11 are all arranged in the enlarged head 2. The other end of the connecting rod 5 extends out of the slope surface layer 3 and is fixed on the slope surface 4 of the side slope through an anchor backing plate 7, a stiffening plate 9 and an anchorage device 8. The stiffening plate 9 is welded between two adjacent anchor backing plates 7. The anchor rod 1 is composed of a first rod body 101, a second rod body 102 and a third rod body 103 which are connected in sequence. The second rod body 102 spans the interface of the first soil layer 12 and the second soil layer 13 and is made of strength-grade cement mortar. The first rod body 101 and the third rod body 103 are made of cement mortar with common strength grade, and the cement mortar of the second rod body 102 is higher than the first rod body 101 and the third rod body 103 by at least one grade.

As shown in fig. 3, the slope surface layer 3 includes modified silt 301 and a reinforcing mesh 302, reinforcing bars of the reinforcing mesh 302 are arranged as bidirectional reinforcing bars, and the modified silt 301 is made of silt modified by polyvinyl alcohol (PVA) fiber combined with cement. Experimental research shows that when 98-100 parts of silt soil are used, 0.1-0.5 part of PVA with the fiber length of 5-7 mm and 5-7 parts of cement are added, so that the improved silt soil has high strength. The preferable weight portions are 100 portions of silt soil, 0.1 portion of PVA and 6 portions of cement. The length of PVA is preferably 6 mm.

The construction method of the supporting device comprises the following steps:

drilling an anchor hole, drilling a variable-diameter hole at the end part of the anchor hole, wherein the diameter of the variable-diameter hole is larger than or equal to the diameters of a first rod body 101, a second rod body 102 and a third rod body 103, and forming an ellipsoidal, spherical or conical expanded head 2;

welding the anchor disc 6 on the connecting rod 5, and placing the steel strands 11 into the drilled holes together after the steel strands are installed through the extrusion anchorage device 10;

step three, drilling and grouting, namely, using more than two cement mortars with different strength grades to manufacture the anchor rod 1, namely, using common strength grade cement mortars to perform grouting from the bottom, manufacturing a rod body I101 after reaching a certain length range of contact surfaces of different soil layers, using high strength grade cement mortars to perform continuous grouting until the grouting in the length range is completed, manufacturing a rod body II 102, and replacing the common strength cement mortars to perform grouting again until the drilled hole is fully filled, thereby manufacturing a rod body III 103;

fourthly, installing an anchor backing plate 7, a stiffening plate 9 and an anchor 8 at one end of the connecting rod 5 exposed out of the slope surface 4;

and fifthly, hanging a reinforcing mesh 302 on the slope surface 4 of the side slope, spraying modified silt 301, and completing supporting.

Claims

1. The utility model provides a combination supporting device which characterized in that: the anchor rod (1) is connected with the enlarged footing (2), the anchor rod (1) is made of cement mortar with more than two different strength grades, the slope surface layer (3) comprises modified silt soil (301) and a reinforcing steel bar net piece (302), and the reinforcing steel bar net piece (302) is laid on the slope surface (4) and is connected with the slope surface (4) through the modified silt soil (301);

the anchor rod (1) comprises a first rod body (101), a second rod body (102) and a third rod body (103) which are sequentially connected, and the cement mortar strength of the second rod body (102) is greater than that of the first rod body (101) and the third rod body (103);

the modified silt soil (301) comprises 0.1 part of polyvinyl alcohol fiber, 6 parts of cement and 100 parts of silt soil, wherein the length of the polyvinyl alcohol fiber is 6 mm;

a connecting rod (5) is arranged in the anchor rod (1); one end of the anchor rod (1) is provided with an anchor disc (6), and the other end of the anchor rod is connected with an anchor backing plate (7) and an anchor device (8); stiffening plates (9) are arranged between the anchor backing plates (7); the anchor disc (6) is connected with the steel strand (11) through an extrusion anchor (10);

the hole forming inclination angle of the anchor rod (1) is 15-25 degrees, and the thickness of the slope surface layer (3) in net hanging and guniting is not less than 5 cm.

2. A combined supporting device according to claim 1, characterised in that: the enlarged head (2) is in an ellipsoid shape, a spherical shape or a conical shape.

3. A construction method of a combined supporting device according to claim 1 or 2, characterized by comprising the steps of:

drilling an anchor hole, wherein the end part of the anchor hole is drilled with a variable diameter hole, and the diameter of the hole is larger than that of the anchor rod (1);

secondly, connecting the anchor disc (6) to the connecting rod (5), and placing the steel strand (11) into the drilled hole together after the installation of the extrusion anchor (10);

step three, drilling and grouting, namely manufacturing the anchor rod (1) by using more than two cement mortars with different strength grades until the drilled hole is fully filled;

fourthly, an anchor backing plate (7), a stiffening plate (9) and an anchor (8) are arranged at one end of the anchor rod (1) exposed out of the slope surface (4);

and fifthly, hanging a reinforcing mesh (302) on the slope surface (4) of the side slope, and spraying modified silt soil (301) to complete supporting.