A method for lowering the water level of a local inclined shaft by anchor cable construction

Abstract

The application relates to the technical field of building foundation construction, in particular to an anchor cable construction method for local inclined shaft water level lowering, which is a local inclined shaft water level lowering method with inclined water level lowering holes arranged on the side of anchor holes. The specific steps of the local inclined shaft water level lowering method are as follows: (1) concrete vertical pile installation; (2) installation of anchor cables and horizontal steel frames in water pressure-free geological layers or geological layers with low water pressure; (3) installation of anchor cables and horizontal steel frames in geological layers with water pressure; and (4) inclined water level lowering hole sealing. Due to the above process steps, the method has the advantages of simple process, water resource saving, cost reduction, energy saving and environmental protection and the like.

Description

Technical Field

[0001] This invention relates to the field of building foundation construction technology, specifically to an anchor cable construction method for local inclined well water level reduction that is simple in process, saves water resources, reduces costs, and is energy-saving and environmentally friendly. Background Technology

[0002] As is well known, in the construction of foundation pits for underground parking lots or basements, the soil around the foundation pit is usually surrounded by vertical concrete piles. Then, inclined anchor cables are installed between adjacent vertical piles, and the adjacent anchor cables are fixed by a horizontal steel frame. The horizontal steel frame is tightly fastened to the vertical piles by the connection between the prestressed steel bars in the anchor cables and the horizontal steel frame, thereby ensuring the stability of the vertical piles.

[0003] During the installation of anchor cables, due to the coastal geology, different geological layers contain different water and sand layers, which requires dewatering. Existing foundation pit dewatering is related to the setting of water-stop curtains. For well point dewatering inside the closed curtain foundation pit, it can only lower the water level inside the pit, and the impact on groundwater outside the foundation pit can be ignored. When anchor cable construction encounters highly permeable layers and the water pressure is high, double-casing construction is usually adopted. Whether grouting is done first or after the anchor cable is installed, the cement grout will all flow out due to the high water pressure, and cement grout anchor body cannot be formed around the anchor cable, thus failing to guarantee the quality of the anchor body.

[0004] The existing problems with external dewatering are as follows: ① A certain number of wells need to be installed. The large number of wells and the large area to be pumped result in a waste of water resources; ② Mud slurry is also required for wall protection, which causes pollution and is not conducive to environmental protection; ③ A large amount of power is required for pumping, which is not economical and energy-saving; ④ It may also cause ground subsidence, affecting surrounding buildings, roads and pipelines. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an anchor cable construction method for local inclined well water level reduction that is simple in process, saves water resources, reduces costs, and is energy-saving and environmentally friendly.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A method for anchor cable construction for localized dewatering in inclined wells, characterized in that the method involves setting inclined dewatering holes on the side of the anchoring hole for localized dewatering in inclined wells.

[0008] The specific steps of the method for localized deflection of water level using inclined wells described in this invention are as follows:

[0009] (a) Installation of concrete vertical piles: Install concrete vertical piles side by side around the perimeter of the foundation pit structure;

[0010] (ii) Installation of anchor cables and transverse steel frames in geological layers with no water pressure or low water pressure: Drill anchor holes at an angle of 25-35 degrees downwards in the geological layers between the vertical piles. There are sleeves in the anchor holes. Reinforcing bars are inserted into the sleeves and grout is injected through the grouting plastic pipe. When the strength of the anchor body reaches 70-100%, the steel strands extending out of the transverse steel beam are made into prestressed steel strands by a tensioning machine and connected to the transverse steel beam. The transverse steel frame is fastened to the concrete vertical piles by prestressed steel bars.

[0011] (III) Installation of anchor cables and transverse steel frames in water-pressurized geological layers: Drill anchor holes at a 23-35 degree angle downwards in the geological layers between the vertical piles. If the water pressure in the anchor holes can be sealed with paste cement grout, proceed directly with the steps in (II). If the water pressure in the anchor holes cannot be sealed with paste cement grout and sand gushing occurs, drill an inclined dewatering hole at a spacing of 0.5-2 meters next to the anchor hole, with the same depth as the anchor hole. Insert a pumping pipe into the inclined dewatering hole. After pumping out the water, the water pressure in the adjacent anchor holes is reduced to a level where no water emerges from the anchor holes. Grouting can then be carried out by inserting the grouting plastic pipe and the reinforcing steel bars into the anchor holes. Grouting is then performed through the grouting plastic pipe. Due to the reduced water pressure, the grout can solidify around the steel strands to form an anchor body. When the anchor body strength reaches 70-100%, the steel strands extending from the transverse steel beam are tensioned to form prestressed steel strands and connected to the transverse steel beam. The transverse steel frame is then secured to the concrete vertical piles using prestressed reinforcing steel bars.

[0012] (iv) Sealing the inclined dewatering well: After completing step (iii), the inclined dewatering well is sealed.

[0013] After the inclined water level hole anchor cable of the present invention is constructed, it is sealed. The treatment method is as follows: first, inject cement grout with a specific gravity of 1.1-1.2, then inject cement grout with a specific gravity of 1.4-1.5, and the grouting pressure reaches 1.5-2MPa.

[0014] In step (iii) of this invention, the sleeve in the anchor hole is continuously grouted during the pulling process. After the sleeve is completely pulled out, the gap between the anchor cable and the curtain is sealed in time to prevent water leakage. Grout is added multiple times from the primary grouting pipe in a timely manner to ensure that the hole is dense.

[0015] In step (iii) of this invention, there are four grouting plastic pipes, consisting of two long pipes and two short pipes. The length of the short pipes is 1 / 3 to 1 / 2 of the length of the long pipes. The long pipes and short pipes extend into the anchoring hole, with the long pipes extending to the bottom of the anchoring hole and the short pipes extending to a depth of 30-50 cm. The rear ends of the long pipes and short pipes extend out of the opening of the anchoring hole by 20 cm. One of the long pipes is for primary grouting and supplementary grouting, and the other long pipe is for secondary grouting. The short pipes are used for grouting after the steel bars have undergone prestressing, ensuring that the grouting seals the anchoring hole.

[0016] Because of the above-mentioned structure, the present invention has the advantages of simple process, water conservation, reduced cost, energy saving and environmental protection. Detailed Implementation

[0017] The present invention will be further described below:

[0018] A method for anchor cable construction for localized inclined well dewatering, characterized by the use of inclined dewatering holes on the side of the anchoring hole for localized inclined well dewatering. The specific steps of the localized inclined well dewatering method are as follows:

[0019] (a) Installation of concrete vertical piles: Install concrete vertical piles side by side around the perimeter of the foundation pit structure;

[0020] (ii) Installation of anchor cables and transverse steel frames in geological layers with no water pressure or low water pressure: Drill anchor holes at an angle of 25-35 degrees downwards in the geological layers between the vertical piles. There are sleeves in the anchor holes. Reinforcing bars are inserted into the sleeves and grout is injected through the grouting plastic pipe. When the strength of the anchor body reaches 70-100%, the steel strands extending out of the transverse steel beam are made into prestressed steel strands by a tensioning machine and connected to the transverse steel beam. The transverse steel frame is fastened to the concrete vertical piles by prestressed steel bars.

[0021] (III) Installation of anchor cables and transverse steel frames in water-pressurized geological layers: Drill anchor holes at a 23-35 degree angle downwards in the geological layers between the vertical piles. If the water pressure in the anchor holes can be sealed with paste cement grout, proceed directly with the steps in (II). If the water pressure in the anchor holes cannot be sealed with paste cement grout and sand gushing occurs, drill an inclined dewatering hole at a spacing of 0.5-2 meters next to the anchor hole, with the same depth as the anchor hole. Insert a pumping pipe into the inclined dewatering hole. After pumping out the water, the water pressure in the adjacent anchor holes is reduced to the point where no water comes out of the anchor holes. Then grouting can be carried out. The grouting plastic pipe and the steel bar are inserted into the anchor hole together. Grouting is carried out through the grouting plastic pipe. Due to the reduction of water pressure, the grout can solidify around the steel strand to form an anchor body. When the anchor body strength reaches 70-100%, the steel strands extending out of the transverse steel beam are made into prestressed steel strands through a tensioning mechanism and connected to the transverse steel beam. The transverse steel frame is fastened to the concrete vertical pile through the prestressed steel bars.

[0022] (iv) Sealing the inclined dewatering well: After completing step (iii), the inclined dewatering well is sealed.

[0023] Furthermore, after the construction of the inclined water level hole anchor cable is completed, a sealing treatment is carried out. The treatment method is as follows: first, inject cement grout with a specific gravity of 1.1-1.2, and then inject cement grout with a specific gravity of 1.4-1.5, with the grouting pressure reaching 1.5-2MPa.

[0024] Furthermore, in step (iii), the sleeve in the anchor hole is continuously grouted during the pulling process. After the sleeve is completely pulled out, the gap between the anchor cable and the curtain is sealed in time to prevent water leakage. Grout is added multiple times from the primary grouting pipe in a timely manner to ensure that the hole is dense.

[0025] Furthermore, in step (iii), there are four grouting plastic pipes: two long pipes and two short pipes. The length of the short pipes is 1 / 3 to 1 / 2 of the length of the long pipes. The long pipes and short pipes extend into the anchoring hole. The long pipes extend into the bottom of the anchoring hole, and the short pipes extend into the anchoring hole to a depth of 30-50 cm. The rear ends of the long pipes and short pipes extend out of the opening of the anchoring hole by 20 cm. One of the long pipes is for primary grouting and supplementary grouting, and the other long pipe is for secondary grouting. The short pipes are used for grouting after the steel bars have undergone prestressing, ensuring that the grouting seals the anchoring hole.

[0026] Because of the above-mentioned structure, the present invention has the advantages of simple process, water conservation, reduced cost, energy saving and environmental protection.

[0027] Example 1:

[0028] A method for anchor cable construction for localized inclined well dewatering, wherein the method involves setting inclined dewatering holes on the side of the anchoring hole. The specific steps of the localized inclined well dewatering method are as follows: (I) Installation of concrete vertical piles: Install concrete vertical piles side by side around the foundation pit structure; (II) Installation of anchor cables and transverse steel frames in geological layers with no water pressure or low water pressure: Drill anchoring holes at a 30-degree angle downwards between the vertical piles. The anchoring holes contain sleeves, and the sleeves are inserted into the sleeves. The reinforcing bars are injected with grout through the grouting plastic pipe. When the anchor body strength reaches 90%, the steel strands extending from the transverse steel beam are made into prestressed steel strands through a tensioning mechanism and connected to the transverse steel beam. The transverse steel frame is fastened to the concrete vertical pile through the prestressed reinforcing bars; (III) Installation of anchor cables and transverse steel frames in geological layers with water pressure: Drill anchor holes at a 30-degree angle downwards in the geological layers between the vertical piles. If the water pressure in the anchor holes can be sealed with paste cement grout, directly use the method in step (II). In cases where the water pressure in the anchor hole cannot be sealed with paste-like cement grout and sand gushing occurs, a slanted dewatering hole is drilled 1 meter away from the anchor hole, with the same depth as the anchor hole. A pumping pipe is inserted into this slanted dewatering hole to pump out water. After pumping, the water pressure in the adjacent anchor hole is reduced to a point where no water emerges from the anchor hole. Grouting can then proceed. The grouting plastic pipe and reinforcing steel are inserted together into the anchor hole, and grouting is performed through the grouting plastic pipe. Due to the reduced water pressure, grouting... After grouting, the grout can solidify around the steel strand to form an anchor body. When the anchor body strength reaches 90%, the steel strand extending from the transverse steel beam is tensioned to form a prestressed steel strand and connected to the transverse steel beam. The transverse steel frame is then fastened to the concrete vertical pile by prestressed steel bars. (IV) Sealing of the inclined dewatering hole: After completing step (III), the inclined dewatering hole is sealed. The inclined dewatering hole is sealed after the anchor cable construction is completed. The treatment method is as follows: First, inject cement grout 1. With a specific gravity of 2, cement grout with a specific gravity of 1.5 is injected, and the grouting pressure reaches 2MPa. In step (III), the sleeve in the anchor hole is continuously replenished with grout during the pulling process. After the sleeve is completely pulled out, the gap between the anchor cable and the curtain is sealed in time to prevent water leakage. Grout is replenished multiple times in time from the primary grouting pipe to ensure that the hole is dense. There are four grouting plastic pipes in step (III), which are divided into two long pipes and two short pipes. The length of the short pipe is 1 / 3 of the length of the long pipe. The long pipe and the short pipe extend into the anchor hole. The long pipe extends into the bottom of the anchor hole, and the short pipe extends into the anchor hole to a depth of 50 cm. The rear ends of the long pipe and the short pipe extend out of the opening of the anchor hole with a length of 20 cm. One of the long pipes is the primary grouting and replenishment grouting pipe, and the other long pipe is the secondary grouting pipe. The short pipe is used for grouting after the steel bar has been prestressed, which ensures that the grouting seals the anchor hole.

[0029] Example 2

[0030] A method for anchor cable construction for localized inclined well dewatering, comprising a method of localized inclined well dewatering with inclined dewatering holes on the side of the anchor hole, and the specific steps of the localized inclined well dewatering method are as follows:

[0031] (a) Installation of concrete vertical piles: Install concrete vertical piles side by side around the perimeter of the foundation pit structure;

[0032] (ii) Installation of anchor cables and transverse steel frames in geological layers with no water pressure or low water pressure: Drill anchor holes at an angle of 25-35 degrees downwards in the geological layers between the vertical piles. There are sleeves in the anchor holes. Reinforcing bars are inserted into the sleeves and grout is injected through the grouting plastic pipe. When the strength of the anchor body reaches 70-100%, the steel strands extending out of the transverse steel beam are made into prestressed steel strands by a tensioning machine and connected to the transverse steel beam. The transverse steel frame is fastened to the concrete vertical piles by prestressed steel bars.

[0033] (III) Installation of anchor cables and transverse steel frames in geological layers with water pressure: Drill anchor holes at a 23-degree angle downwards between the vertical piles. If the water pressure in the anchor holes can be sealed with cement paste, proceed directly with the steps in (II). If the water pressure in the anchor holes cannot be sealed with cement paste and sand gushing occurs, drill an inclined dewatering hole at a distance of 0.5 meters next to the anchor hole, with the same depth as the anchor hole. Insert a pumping pipe into the inclined dewatering hole to pump water. After pumping water to reduce the water pressure in the adjacent anchor holes to the point where no water comes out of the anchor holes, grouting can be carried out. The grouting plastic pipe and the reinforcing steel are inserted into the anchor holes together, and grouting is carried out through the grouting plastic pipe. Due to the reduction of water pressure, the grout can solidify around the steel strand to form an anchor body. When the anchor body strength reaches 70%, the steel strands extending out of the transverse steel beam are made into prestressed steel strands through a tensioning mechanism and connected to the transverse steel beam. The transverse steel frame is then fastened to the concrete vertical pile through the prestressed steel bars.

[0034] (iv) Sealing of the inclined dewatering borehole: After completing step (iii), the inclined dewatering borehole is sealed. The sealing process is performed after the anchor cable construction of the inclined dewatering borehole is completed. The method is as follows: first, inject cement grout with a specific gravity of 1.1, then inject cement grout with a specific gravity of 1.4, with a grouting pressure reaching 1.5 MPa. During the extraction process of the casing in the anchoring hole in step (iii), grout is continuously added. After the casing is completely extracted, the gap between the anchor cable and the curtain is sealed promptly to prevent water leakage. Grout is added multiple times from the primary grouting pipe to ensure the borehole is dense. In step (iii) described above, there are four grouting plastic pipes, consisting of two long pipes and two short pipes. The length of the short pipes is 1 / 3 of the length of the long pipes. The long pipes and short pipes extend into the anchoring hole. The long pipes extend to the bottom of the anchoring hole, and the short pipes extend to a depth of 30 cm. The rear ends of the long pipes and short pipes extend out of the opening of the anchoring hole by 20 cm. One of the long pipes is for primary grouting and supplementary grouting, and the other long pipe is for secondary grouting. The short pipes are used for grouting after the steel bars have undergone prestressing, ensuring that the grouting seals the anchoring hole.

[0035] The numerical range of this patent is the scope of protection of this patent. Results within this range indicate that this patent can achieve a maximum pumping volume of only 1 / 10 of the original overall water level drop, thus saving a significant amount of water resources.

[0036] By adopting the above solution, the overall subsidence of the road surface due to the drop in water level can be avoided. Moreover, there is no need to install manholes, the amount of water pumped is very small, and the amount of water pumped from the current local water level is at most 1 / 10 of the original amount of water pumped when the overall water level drops. This can save a lot of water resources, eliminate the need for mud wall protection, and produce no pollution. Furthermore, only a small-power pump is needed to pump water from the local water level, which is energy-saving and environmentally friendly. It will not cause ground subsidence and will not affect the laying of surrounding buildings, roads, and pipelines.

Claims

1. A method for constructing an anchor cable for locally lowering the water level in an inclined shaft, characterized in that The construction method is a method for locally lowering water level of inclined shaft with slanting water level lowering holes on the side of anchoring holes, and the specific steps of the method are as follows: (1) installation of concrete vertical piles: the concrete vertical piles are installed side by side around the periphery of the foundation pit building; (2) installation of anchor cables and horizontal steel frames in water pressure-free geological layers or geological layers with low water pressure: the anchoring holes are drilled in the geological layers between the vertical piles at an angle of 25-35 degrees downward, the anchoring holes are provided with casings, the reinforcing bars are inserted into the casings and grout is injected through the grouting plastic pipes, when the anchoring body strength reaches 70-100%, the steel strands extending out of the horizontal steel beams are connected with the horizontal steel frames through the tensioning machine to form the steel strands with prestress, and the horizontal steel frames are buckled on the concrete vertical piles through the prestressed reinforcing bars; (3) installation of anchor cables and horizontal steel frames in geological layers with water pressure: the anchoring holes are drilled in the geological layers between the vertical piles at an angle of 23-35 degrees downward, when the water pressure in the anchoring holes can be blocked by the paste-like cement grout, the step in step (2) is directly used, when the water pressure in the anchoring holes cannot be blocked by the paste-like cement grout and sand gushing occurs, a slanting water level lowering hole is drilled at a distance of 0.5-2 meters from the anchoring hole, the drilling depth is the same as that of the anchoring hole, the water suction pipe is inserted into the slanting water level lowering hole to perform water pumping, after the water pumping, the water pressure in the adjacent anchoring hole is reduced to the case that no water is discharged from the anchoring hole, then the grouting plastic pipe and the reinforcing bar are inserted into the anchoring hole, the grouting plastic pipe is used for grouting, due to the reduced water pressure, the grout after grouting can solidify around the steel strands to form the anchoring body, when the anchoring body strength reaches 70-100%, the steel strands extending out of the horizontal steel beams are connected with the horizontal steel frames through the tensioning machine to form the steel strands with prestress, and the horizontal steel frames are buckled on the concrete vertical piles through the prestressed reinforcing bars; In step (3), the grouting plastic pipe is provided with four pipes, which are divided into two long pipes and two short pipes, the length of the short pipe is 1 / 3-1 / 2 of the length of the long pipe, the long pipe and the short pipe are inserted into the anchoring hole, the long pipe is inserted into the bottom of the anchoring hole, the depth of the short pipe inserted into the anchoring hole is 30-50 centimeters, the rear end of the long pipe and the short pipe extends out of the hole of the anchoring hole by 20 centimeters, one of the long pipes is a one-time grouting and supplementary grouting pipe, the other long pipe is a two-time grouting pipe, and the short pipe is used for grouting after the prestressing operation of the reinforcing bar, which ensures that the anchoring hole is closed by grouting, In step (3), the casing in the anchoring hole is continuously supplemented with grout during the pulling-out process, the space between the anchor cable and the curtain is sealed in time after the casing is pulled out to avoid water leakage, the one-time grouting and supplementary grouting pipe is used for one-time grouting and timely supplementary grouting to ensure the compactness of the hole; (4) sealing of the slanting water level lowering hole: after step (3) is completed, the slanting water level lowering hole is sealed, the slanting water level lowering hole is closed after the anchor cable construction is completed, and the treatment method is as follows: first, the cement grout with a specific gravity of 1.1-1.2 is injected, and then the cement grout with a specific gravity of 1.4-1.5 is injected, and the grouting pressure reaches 1.5-2 MPa.