A soil high slope cable anchor support system and construction method for the roof of a cave

Abstract

The present invention discloses a cable anchor support system and construction method for a soil high slope at the top of a tunnel. This solution can not only improve the stability of the soil slope but also protect the structural safety, thereby expanding the application scope of the cable anchor support system in the high soil slope at the top of the tunnel. The structure of the support system includes prestressed cable anchors, reinforced concrete grid beams, and reinforced concrete anchor piers. The grid beams include cross beams and longitudinal beams arranged at equal intervals. The anchor piers are arranged at the cross nodes of the cross beams and longitudinal beams at intervals. One end of the prestressed cable anchor is fixed to the anchor pier, and the other end of the prestressed cable anchor is inserted into the bedrock of the soil high slope. The construction method steps include performing groove excavation treatment on the excavation surface of the soil high slope, excavating longitudinal grooves arranged at equal intervals, excavating transverse grooves arranged at equal intervals, performing prestressed cable anchor construction at the intersection nodes of the cross beams and longitudinal beams, and arranging reinforced concrete anchor piers at the grid beam nodes provided with prestressed cable anchors.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy and hydropower, and particularly relates to a special layout and construction method of a prestressed anchor cable support system for a framed beam on a high soil slope at the top of a tunnel, and is particularly applicable to water conservancy and hydropower projects with high and steep soil slopes at the top of the tunnel. Background Art

[0002] During the construction of water conservancy and hydropower projects and slopes, there are often situations where the overburden layer and the completely and strongly weathered layer at the top of the tunnel are relatively thick and unevenly distributed. There are usually two forms of support adopted. One is to slow down the excavation slope ratio and add a framed beam for support. The advantage of this support form is that the structure is simple and the construction is convenient, but it occupies a large space, and when there is heavy rain or the load on the slope top road increases, the high and steep slope is prone to creep, resulting in slope instability; the other is to add an anchor cable framed beam support system. This support structure applies prestress to the anchor cables to tightly connect the potential soil mass with the stable rock mass, which not only increases the anti-sliding force of the soil mass but also effectively connects each anchor cable into a whole through the framed beam on the slope surface, forming a reinforcement system from the surface to the inside, so as to achieve the purpose of preventing the overall slope from instability.

[0003] In the anchor cable framed beam system, the anchor cables are usually arranged at the node positions of the framed beams with equal spacing. During the actual construction process, considering that the anchor cable holes cannot penetrate the tunnel, for the anchor cables above the tunnel axis, horizontal angle deflection is required. There will be a situation of cross-collision between the deflected anchor cables and the adjacent anchor cables, which affects the strength of the overall support system and reduces the stability of the high soil slope. In view of the lack of systematic and in-depth research on the protection measures for the framed beam anchor cable system of the high soil slope at the top of the tunnel, it has practical engineering significance to conduct special design on the anchor cable support system for the high slope at the top of the tunnel. Summary of the Invention

[0004] The technical problem solved by the invention is: aiming at the above problems, a kind of anchor cable support system and construction method for a high soil slope at the top of a tunnel are proposed, which can not only improve the stability of the soil slope but also protect the structural safety, thereby expanding the application range of the anchor cable support system in the high soil slope at the top of the tunnel.

[0005] To achieve the above object, the invention adopts the following technical solutions:

[0006] An anchor cable support system for a high soil slope at the top of a tunnel of the invention includes prestressed anchor cables, a framed beam made of reinforced concrete, and an anchor pier made of reinforced concrete. The framed beam includes cross beams and longitudinal beams arranged at equal intervals. The anchor piers are arranged at intervals at the cross nodes of the cross beams and longitudinal beams. One end of the prestressed anchor cable is fixed to the anchor pier, and the other end of the prestressed anchor cable is inserted into the bedrock of the high soil slope.

[0007] Preferably, slope protection vegetation is arranged in the framed beam.

[0008] A construction method for a cable anchor support system for a high soil slope at the top of a cave, the method comprising the following steps:

[0009] Step 1, excavate the soil slope smoothly at a specified slope ratio, and backfill the parts with excessive excavation with concrete;

[0010] Step 2, temporarily support the soil slope by means of drilling drainage holes, system bolts or anchor bars;

[0011] Step 3, perform grooving treatment on the excavation surface of the high soil slope, excavate longitudinal grooves arranged at equal intervals, pour reinforced concrete in the longitudinal grooves, and reserve holes for the construction of prestressed cable anchors to complete the pouring construction of the longitudinal beams;

[0012] Step 4, excavate transverse grooves arranged at equal intervals, pour reinforced concrete in the transverse grooves, insert a row of cross beams directly above the top of the cave, and reserve holes for the construction of prestressed cable anchors between the cross beams and the longitudinal beams;

[0013] Step 5, perform construction of prestressed cable anchors at the intersection nodes of the cross beams and the longitudinal beams, and space one intersection node of the cross beam and the longitudinal beam between adjacent prestressed cable anchors, ensure that the anchoring end of the prestressed cable anchor penetrates into the bedrock to a certain depth, and reserve a certain length of steel strand at the hole opening for subsequent tensioning. The prestressed cable anchors located above the top of the cave are deflected horizontally, and the deflection angle is controlled within 45°, ensuring that the hole slope error is not greater than 2%;

[0014] Step 6, arrange reinforced concrete anchor piers at the grid beam nodes provided with prestressed cable anchors, and determine the size of the anchor pier head according to the bearing capacity and the stress area.

[0015] Preferably, in step 4, a row of cross beams is inserted between adjacent cross beams above the top of the cave, and prestressed cable anchors are constructed at the cross beam nodes to ensure that there will be no cross collision between adjacent cable anchors.

[0016] Preferably, in step 5, the prestressed cable anchors located above the top of the cave are deflected at an angle to ensure that the cable anchors will not penetrate through the cave chamber.

[0017] Therefore, the present invention has the following beneficial effects: (1) Large-tonnage prestressed cable anchors are anchored in the stable rock mass in the slope body, and by applying prestress, the deep deformation and failure of the slope soil body are resisted. (2) The reinforced concrete frame attached to the slope surface plays a role in hoop reinforcement on the surface rock and soil of the slope body, restricting the deformation and failure of the surface rock and soil. (3) After the vegetation on the slope surface is restored, the loss of water and soil on the slope surface can be prevented. (4) After the cable anchors of the soil slope at the top of the cave are arranged in a staggered manner, it is ensured that there will be no cross collision between the cable anchors, improving the safety and stability of the overall cable anchor support system. The structure is simple and the construction is convenient. Description of the Drawings

[0018] Figure 1 Front view of the cable lattice beam system above the tunnel roof for a cable - anchor support system of a tunnel - roof soil high - slope in the present invention.

[0019] Figure 2 Sectional view of the cable - anchor support system along the tunnel axis direction for a cable - anchor support system of a tunnel - roof soil high - slope in the present invention.

[0020] Figure 3 Three - dimensional side view of a prestressed cable in the present invention.

[0021] Annotations in the figure: 1. Prestressed cable; 2. Anchor rod; 3. Lattice beam; 301. Cross beam; 302. Longitudinal beam; 4. Slope protection vegetation; 5. Drainage hole; 6. Anchor pier. Detailed implementation manners

[0022] The following further describes the present invention in conjunction with the accompanying drawings and detailed implementation manners.

[0023] As Figure 1 、 Figure 2 、 Figure 3 shown, a cable - anchor support system for a tunnel - roof soil high - slope in the present invention includes a prestressed cable 1, a lattice beam 3 made of reinforced concrete, and an anchor pier 6 made of reinforced concrete. The lattice beam 3 includes cross beams 301 and longitudinal beams 302 arranged at equal intervals. The anchor piers are arranged at the cross - nodes of the cross beams and longitudinal beams. One end of the prestressed cable is fixed to the anchor pier, and the other end of the prestressed cable is inserted into the bedrock of the soil high - slope. Slope protection vegetation 4 is arranged within the lattice beam.

[0024] The present invention also provides a construction method for a cable - anchor support system of a tunnel - roof soil high - slope. The method includes the following steps:

[0025] Step 1: Excavate the soil slope smoothly at a specified slope ratio, and backfill the concrete at the parts with excessive over - excavation.

[0026] Step 2: Temporarily support the soil slope by drilling drainage holes 5, installing systematic anchor rods 2 or anchor - reinforced piles.

[0027] Step 3: Conduct grooving treatment on the excavation surface of the soil high - slope, excavate longitudinal grooves arranged at equal intervals, pour reinforced concrete in the longitudinal grooves, and reserve holes for the construction of prestressed cables to complete the pouring construction of the longitudinal beams.

[0028] Step 4: Excavate transverse grooves arranged at equal intervals, pour reinforced concrete in the transverse grooves, insert a row of cross beams directly above the tunnel roof, and reserve holes for the construction of prestressed cables at the positions between the cross beams and longitudinal beams.

[0029] Preferably, in step 4, a row of cross beams is inserted between adjacent cross beams above the top of the hole, and prestressed anchor cables are constructed at the cross beam nodes to ensure that there will be no cross collisions between adjacent anchor cables.

[0030] Step 5: Construct prestressed anchor cables at the intersection nodes of the cross beams and longitudinal beams, and there is a space of one intersection node of the cross beams and longitudinal beams between adjacent prestressed anchor cables. Ensure that the anchoring end of the prestressed anchor cable is driven into the bedrock to a certain depth, and a certain length of steel strand is reserved at the hole opening for subsequent tensioning. The prestressed anchor cables located above the top of the hole are deflected horizontally, and the deflection angle is controlled within 45°, ensuring that the hole slope error is not greater than 2%.

[0031] Preferably, in step 5, the prestressed anchor cables located above the top of the hole are deflected at an angle to ensure that the anchor cables will not penetrate the chamber.

[0032] Step 6: Arrange reinforced concrete anchor piers at the lattice beam nodes provided with prestressed anchor cables, and the size of the anchor pier head is determined according to the bearing capacity and the stress area.

[0033] The roof high soil slope support system designed in this application effectively solves the problem that the overburden layer and the completely and strongly weathered layer of the roof high slope are thick and unevenly distributed and cannot be effectively supported by arranging the anchor cable holes staggered within the range of the roof concrete lattice beam. By connecting the anchor cables and anchor rods fixed on the ground surface to the lattice beam, the contact area between the unfavorable structural plane and the support system is effectively increased, and the stability of the supported part is improved. At the same time, in order to avoid cross collisions with other anchor cables, the anchor cables at the supported part are deflected by a certain angle along both sides of the axis, which has high reliability and practicability.

Claims

1. Construction method of anchor cable support system for soil high slope at tunnel top Characterized in that The method includes the following steps: Step 1: Excavate the soil slope smoothly with a specified slope ratio, and backfill the concrete at the parts with excessive over-excavation; Step 2: Adopt the method of drilling drainage holes, system anchor bolts or anchor bars to carry out temporary support for the soil slope; Step 3: Carry out groove excavation treatment on the excavation surface of the soil high slope, excavate longitudinal grooves arranged at equal intervals, pour reinforced concrete in the longitudinal grooves, and reserve holes for the construction of prestressed anchor cables to complete the pouring construction of the longitudinal beams; Step 4: Excavate transverse grooves arranged at equal intervals, pour reinforced concrete in the transverse grooves, insert a row of cross beams directly above the tunnel top, and reserve holes for the construction of prestressed anchor cables at the positions between the cross beams and the longitudinal beams; Step 5: Carry out prestressed anchor cable construction at the intersection nodes of the cross beams and the longitudinal beams, and leave a node of the intersection of a cross beam and a longitudinal beam between adjacent prestressed anchor cables. Ensure that the anchorage end of the prestressed anchor cable penetrates into the bedrock to a certain depth, and reserve a certain length of steel strand at the hole mouth for subsequent tensioning. The prestressed anchor cables located above the tunnel top are deflected horizontally, and the deflection angle is controlled within 45°, ensuring that the hole slope error is not greater than 2%; Step 6: Arrange reinforced concrete anchor piers at the frame beam nodes where prestressed anchor cables are provided, and the size of the anchor pier head is determined according to the bearing capacity and the stress area.

2. The construction method of the anchor cable support system for the soil high slope at the tunnel top according to claim 1 Characterized in that In the step 4, a row of cross beams is inserted between adjacent cross beams above the tunnel top, and prestressed anchor cables are constructed at the cross beam nodes to ensure that there will be no cross collision between adjacent anchor cables.

3. The construction method of the anchor cable support system for the soil high slope at the tunnel top according to claim 1 Characterized in that In the step 5, the prestressed anchor cables located above the tunnel top are deflected at an angle to ensure that the anchor cables will not penetrate through the tunnel chamber.

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