Comprehensive prevention and control construction method for high slope of border mountain

Abstract

The invention provides a comprehensive prevention and control construction method for a high slope of a limb mountain, and belongs to the technical field of slope supporting, a pressure dispersion type anchor cable is adopted to replace a common tension type anchor rod, the pressure dispersion type anchor cable is provided with bearing bodies at different depths of a steel strand, the steel strand is divided into different anchoring units, stress is balanced, and the pressure dispersion type anchor cable is used for replacing the common tension type anchor rod; when a complicated soil layer of a high slope of a mountain near the edge is reinforced, larger anchoring force can be provided.

Description

Technical Field

[0001] The invention belongs to the technical field of slope support, and specifically discloses a comprehensive prevention and control construction method for high slopes adjacent to a mountain. Background Art

[0002] With the rapid advancement of urbanization and the vigorous development of infrastructure construction, there are more and more ultra-high and ultra-steep slope support projects in densely populated urban areas. As a permanent structure, the slope retaining structure should coexist harmoniously with humanity and nature, and the slope retaining structure must have the same service life as the adjacent main structure. Therefore, it is necessary to select a permanent slope retaining structure according to local conditions. The anchor cable lattice beam retaining wall has weak destructiveness to the original slope water and soil, and can be built along the terrain. It has greater economic advantages than pile-sheet walls and anti-slip piles, and greening can be done between the lattice beams to integrate with the environment.

[0003] However, the common tension anchor rods currently used cannot fully utilize the friction resistance of the soil layer due to the low bearing capacity of a single anchor, which requires increasing the drilling depth and the length of the anchor rod body. This brings great difficulty to the construction of permanent slope support projects under the conditions of high slopes and complex soil layers of the adjacent mountains, and the reliability and durability of the anchor rods are difficult to guarantee. Summary of the invention

[0004] The present invention provides a comprehensive prevention and control construction method for high slopes adjacent to mountains. A pressure-dispersed anchor cable is used to replace ordinary tension-type anchor rods. The pressure-dispersed anchor cable sets bearing bodies at different depths of steel strands, and divides the steel strands into different anchoring units to balance the force. When reinforcing complex soil layers on the high slopes adjacent to mountains, a greater anchoring force can be provided.

[0005] The above-mentioned comprehensive prevention and control construction method for high side slopes of adjacent mountains comprises the following steps:

[0006] S1, anchor hole drilling

[0007] According to the designed pile number, a ruler is used to measure, and the line is laid out in combination with leveling. The anchor hole position is accurately located with iron rods and paint marks. The drilling rig is accurately positioned in strict accordance with the designed hole position, inclination and azimuth, and the drilling rig is fixed firmly with fasteners, and the angle is controlled with an angle measuring tool;

[0008] S2, anchor cable production and installation

[0009] The following steps are involved:

[0010] t1, anchor bar cutting

[0011] The anchor bar body is made of unbonded steel strands with PE sleeves. The cutting length is cut according to the designed length of the anchor cable + the length of the embedded end + the length of the tensioning section. The anchor bar body is cut mechanically.

[0012] t2, P-type anchor installation

[0013] Cut off the PE sleeve at the anchor end of the anchor body according to the designed length, clean it and install the P-type anchor, and use the extruder to squeeze the P-type anchor to connect and fix it with the anchor body;

[0014] t3, carrier assembly

[0015] Insert the anchor bar into the anti-corrosion treated bearing plate, fix the bearing plate to the P-type anchor with bolts and limit plates, and fix the pressure-bearing spiral bar at the front end of the bearing plate;

[0016] t4, guide cap installation

[0017] The guide cap is directly welded to the bearing plate at the front end of the anchor bar body. After welding, the guide cap and all bearing bodies are painted with anti-rust paint for anti-corrosion treatment;

[0018] t5, cable ring installation

[0019] Tie the stringing rings on the anchor bar body according to the designed intervals, and install the stringing rings at the opening of the anchor hole for positioning;

[0020] t6, grouting pipe installation

[0021] Pass the grouting pipe through the central axis of the wire ring and the bearing plate and tie it up to fix it. The front end of the grouting pipe enters the guide cap and the rear end is sealed with tape to prevent blockage.

[0022] t7, acceptance of pressure dispersion anchor cables;

[0023] t8, transport qualified pressure dispersion anchor cables to corresponding holes for installation;

[0024] S3, anchor hole grouting

[0025] The grouting material is cement paste, and the grouting is done by the bottom hole return grouting method;

[0026] S4, lattice beam formwork casting

[0027] Measure and lay out, repair and clean the uneven surface layer, then dig the lattice beam foundation groove, lay the mortar leveling layer on the slope of the lattice beam foundation groove, and then make and install the lattice beam reinforcement. According to the design requirements, fix the lattice beam reinforcement on the steel pipe and anchor pad pressure plate, and pour concrete;

[0028] S5, anchor cable tensioning and locking

[0029] The anchor body of the pressure-dispersed anchor cable is divided into a free section and an anchor section. The anchor section is divided into multiple anchor units of different lengths through multiple groups of bearing bodies. Tensioning is carried out according to the different anchor lengths of each anchor unit, first the long unit and then the short unit. The differential load of each anchor unit is first calculated, the difference is supplemented by the units, and then the overall synchronous graded tensioning is carried out.

[0030] S6, Anchor Pier Installation

[0031] Install the hole pad, steel casing, steel mesh, and steel bars of the anchor hole, pour concrete, and install the anchor pad and anchor head of the pressure-dispersing anchor cable.

[0032] In step S1, the inclination error of the drilling rig guide rail does not exceed ±1°, and the azimuth error does not exceed ±2°; during the construction process, regularly check the fastening status of the fasteners; select the corresponding anchor hole drilling rig for drilling according to the stratum, drill at a low speed and push at low pressure, and when the hole is 50 cm, check the hole direction again and adjust the drilling rig in time; the hole diameter and hole depth are required to be no less than the design value, and the overdrilling is not less than 20 cm. After reaching the design depth, drill steadily for 3 to 5 minutes.

[0033] In step S1, if a hole collapse is encountered during the drilling process, the drilling is stopped immediately, and grouting is used to consolidate the wall, with a grouting pressure of 0.1 to 0.2 MPa. Drilling is resumed after 24 hours, or a pipe-following drilling process is used.

[0034] In step S1, after the anchor hole is drilled, high-pressure air with a wind pressure of 0.2 to 0.4 Ma is used to remove all rock powder, soil powder and water in the hole. After the hole is cleaned, the hole mouth is temporarily blocked.

[0035] In step S2, the anchor bar body adopts Φ15.2mm 1860 grade steel strand, which complies with the provisions of the current national standard "Prestressed Concrete Steel Strand". The steel strand is a finished coil. After being transported to the site, 80% of the material is subjected to nondestructive testing and pre-tensioning inspection, among which the diameter inspection of the steel strand is based on 10% reel sampling, the performance inspection of the steel strand is based on 5% reel sampling, and the performance inspection of the steel strand is sampled from no less than 3 reels, and a test piece is cut from each reel for tensile testing.

[0036] In step S2, the pressure distribution type anchor cable includes three anchoring units, each anchoring unit includes two anchor bars, and the connection strength between a single anchor bar and the bearing plate is greater than 200 kN.

[0037] In step t8, before the anchor cable is installed in the hole, the anchor hole is re-checked, the collapsed hole and fallen blocks are cleaned, the water in the hole is blown out with high-pressure air, and the pressure is 80% of the grouting pressure. The anchor cable is checked, the anchor cable number and the anchor hole number are checked, the damaged accessories are repaired or replaced, the anchor cable is manually lifted to the hole position, and the anchor cable is sent into the anchor hole. It is pushed straight and smoothly without pausing in the middle to avoid loosening or jamming.

[0038] In step S3, the water-cement ratio of the cement paste is 0.45-0.50, the slurry strength is not less than 40MPa, and it is used as soon as it is mixed. The cement used is PO42.5R ordinary Portland cement; the grouting pipe is inserted to 300mm from the bottom of the hole, and the grouting pressure is 2.0MPa until fresh slurry overflows from the hole mouth. If the slurry surface at the hole mouth is found to fall back, the bottom of the hole is pressurized and replenished 2-3 times within 30mins to ensure that the slurry in the hole is full.

[0039] In step S4, the cross-sectional dimensions of the lattice beam, the length of the cross beam segments and the length of the vertical beam are determined according to the construction drawings. Expansion joints are set on the cross beams, one every 15 to 25 m. The expansion joints are 20 mm wide and are filled with asphalt linen.

[0040] In step S5, a step-by-step loading method is adopted, and the loading forces are 0.3, 0.5, 0.7, 0.9, and 1.1 times of the design load of the pressure-dispersed anchor cable, respectively. The first four load levels have a residence time of 5 minutes, and the last load level has a residence time of 10 minutes.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention adopts a pressure-dispersed anchor cable. Since the anchor body adopts an unbonded steel strand covered with a PE sleeve, it is isolated from the slurry. The steel strand can deform freely (elongate or shorten) within the elastic range. When the landslide body is displaced, it has a greater ability to adapt to deformation and good seismic performance. It can provide greater anchoring force when reinforcing complex soil layers on high slopes of adjacent mountains. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a schematic diagram of the structure of the pressure dispersion anchor cable (with guide cap installed);

[0045] Figure 2 for Figure 1 A cross-sectional view of the third anchoring unit;

[0046] Figure 3 for Figure 1 A cross-sectional view of the second anchoring unit;

[0047] Figure 4 for Figure 1 A cross-sectional view of the first anchoring unit;

[0048] Figure 5 for Figure 1 A schematic diagram of the structure of the middle guide cap part;

[0049] Figure 6 It is a structural diagram of a pressure-dispersed anchor cable (without installing a guide cap);

[0050] Figure 7 Schematic diagram of the free extension length of each anchoring unit.

[0051] In the figure: 1-anchor body; 2-bearing body; 2.1-P-type anchor; 2.2-bearing plate; 3-wire ring; 4-guide cap; 5-anchor pad; 6-anchor head; 7-grouting pipe;

[0052] 100. Anchor hole. DETAILED DESCRIPTION

[0053] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] This embodiment provides a comprehensive prevention and control construction method for high side slopes of adjacent mountains, using a pressure-dispersed anchor cable instead of an ordinary tension anchor rod, the pressure-dispersed anchor cable includes an anchor bar body 1, a bearing body 2, a wire ring 3, a guide cap 4, an anchor pad 5 and an anchor head 6, and the bearing body 2 includes a P-type anchor 2.1, a bearing plate 2.2 and a pressure-bearing spiral bar. The anchor bar body 1 uses an unbonded steel strand with a self-contained PE protective sleeve, which is separated from the anchoring section grouting body. Anchor bars 1 of different lengths are connected through the bearing body 2, and the anchoring section is divided into a plurality of anchoring units of different lengths. When the anchor cable is tensioned, the tension is directly transmitted to the bearing body 2, and the bearing body 2 produces a pushing and compacting effect on the grouting body of the entire anchoring section.

[0055] Since the entire length of the grouting stone body of the anchoring section of the pressure-dispersed anchor cable is under pressure, multiple bearing plates 2.2 are arranged on the anchor cable, which can alleviate the stress concentration phenomenon of the anchoring section, and has the advantages of being able to give full play to the bonding force of the soil to the anchor cable grouting body and not easy to crack. The steel strand used is an unbonded steel strand, which has a certain anti-corrosion function, reduces the process of anti-corrosion painting on the steel strand, saves manpower and material resources, and protects the environment. This construction method is particularly suitable for situations where the single anchor bearing capacity is high or needs to be used in a strong corrosive stratum.

[0056] 1. The entire construction method includes the following steps

[0057] S0, Construction Preparation

[0058] Before the formal construction of the anchor cable, a construction organization design should be completed to clarify the construction method, construction technology, process flow, personnel organization and related construction equipment, purchase and testing of anchor cable materials, testing of slurry raw materials and mix ratios, calibration of tensioning equipment and related machinery, and application for a single project commencement report.

[0059] After the application for the commencement report of a single project, the focus of the comprehensive construction preparation of the anchor cable is to conduct a destructive tensile test of the cable according to the anchoring stratum and anchoring tonnage. Generally, three test holes are grouped together, and the specific location of the test holes should be determined on site by the construction, supervision and design representatives, so that the stratum of the anchoring section of the test hole should be able to represent the actual situation of the anchoring stratum of the engineering hole. After the construction of the basic test anchor hole is completed, the tension test can be carried out after the anchoring slurry reaches 28 days of age and the anchor pier concrete strength reaches 80%. During the test, detailed data such as loads at all levels and displacement of the anchor head 6 should be recorded, and the test report should be submitted to the design unit in time before the construction of the engineering anchor cable to determine whether the design parameters meet the stability and safety requirements of the anchoring project, and then determine whether the length of the anchoring section needs to be corrected.

[0060] Before anchor cable construction, remove slag and dangerous rocks from the working surface and set up a working platform. Four rows of scaffolding are used for prestressed anchor cable construction. The scaffolding dimensions are: 1.8m step distance of vertical poles, 1.5m horizontal distance and vertical distance of vertical poles, and steel pipe model Φ48. The thickness of the wooden board used to build the pipe rack platform shall not be less than 45mm. The pipe rack must be stable to ensure the rigidity of the pipe rack. Measures such as diagonal bracing, connecting wall (wall) parts, scissor bracing and increasing the density of columns in the main load-bearing parts shall be adopted to meet the load-bearing requirements; safety signs, safety nets and safety ropes shall be set up in the platform operation area and passages. A 5t manual hoist is installed on the platform pipe rack for lifting drilling equipment on the upper and lower platforms. The load-bearing vertical poles and horizontal poles shall be denser, and a special person shall be assigned to direct the lifting. The operators shall wear safety helmets and safety ropes, and no one shall be under the lifting platform. After the scaffolding is erected, it must be accepted before it can be used.

[0061] S1, anchor hole drilling

[0062] According to the designed pile number, a ruler is used to measure, and the line is laid out in combination with leveling measurement. The anchor hole position is accurately located with iron rods and paint marks. The drilling rig is accurately positioned in strict accordance with the designed hole position, inclination and azimuth, and the drilling rig is clamped with a clamp fastener to fix the drilling rig firmly. The angle is controlled by an angle measuring tool. The inclination error of the drilling rig guide rail does not exceed ±1°, and the azimuth error does not exceed ±2°. During the construction process, the fastening state of the clamp fasteners is checked regularly. The anchor cable hole should be selected according to the stratum. The hole is drilled at a low speed and pushed at low pressure. When the hole is about 50cm, the hole direction must be checked again and the drilling rig must be adjusted in time. In addition, water flushing and flushing of the hole wall are strictly prohibited during the drilling process. At the same time, the drilling speed is strictly controlled to prevent the hole from being deflected, twisted or changed in diameter. The borehole diameter and hole depth requirements shall not be less than the design value, and the overdrilling shall not be less than 20cm. After the drilling reaches the design depth, the drilling cannot be stopped immediately. It is required to drill steadily for 3 to 5 minutes to prevent the bottom of the hole from being pinched out and the anchor hole should be cleaned in time. Fill in the drilling inspection record sheet in time during the drilling process, and make on-site records of the formation changes, drilling status (drilling pressure, drilling speed), groundwater and some special situations of each hole during the drilling process. If a hole collapses during the drilling process, stop drilling immediately, notify the supervision engineer, and use grouting to consolidate the wall (grouting pressure 0.1-0.2MPa), and then resume drilling after 24 hours, or use the pipe drilling process.

[0063] After the anchor hole is drilled, use high-pressure air (wind pressure 0.2 ~ 0.4Ma) to remove all rock (soil) powder and water from the hole. After the hole is clean, the hole mouth should be temporarily blocked to prevent rock chips and debris from falling into the hole. The anchor body 1 can be installed only after passing the on-site supervision inspection.

[0064] S2, anchor cable production and installation

[0065] t1, anchor bar cutting

[0066] The anchor cable reinforcement body adopts Φ15.2mm 1860 grade steel strand, which must comply with the current national standard "Prestressed Concrete Steel Strand" (GB / T5224-2003). The steel strand is a coil product. After being transported to the site, 80% of the material should be inspected for flaws and pre-tensioning. The steel strand diameter inspection is based on 10% coil sampling, and the steel strand performance inspection is based on 5% coil sampling (no less than 3 coils). One specimen is cut from each coil for tensile testing, and the test results should meet the design requirements.

[0067] Before cutting the anchor bar 1, a production platform 50 cm above the ground and a simple sun and rain shelter that is suitable for the designed length of the anchor bar should be built. The cutting length of the anchor bar 1 is cut according to the designed length of the anchor cable + 80 mm embedded end + 1.2 m tensioning section. The anchor cable must be cut by mechanical cutting of the anchor bar 1. Electric welding and gas cutting of the anchor bar 1 are prohibited.

[0068] t2, P-type anchor installation

[0069] Cut off 8 to 10 cm of the PE sleeve end of the anchoring end of the anchor body 1, clean it and install the P-type anchor 2.1 (including the extrusion spring and the extrusion sleeve), place it in the center hole of the GYJA special extruder and start extrusion after aligning and centering with the extrusion head. The extrusion force is 330 to 400 kN. After extrusion, the outer end of the anchor body 1 should be exposed 2 to 5 cm. The length of the P-type anchor 2.1 should be 72.5 to 74 mm, and the diameter should be 30.35 to 30.55 mm. When the P-type anchor 2.1 is just squeezed out of the center hole, stop the oil supply and return the oil immediately. The extrusion work of one P-type anchor 2.1 is completed. When extruding the P-type anchor 2.1, the extrusion quality should be strictly controlled. The extrusion must be dense and without empty heads. If empty heads appear, they should be cut off and re-extruded. The P-type anchor 2.1 can only be put into braiding after passing the inspection.

[0070] t3, carrier assembly

[0071] The anchor bar body 1 is inserted into the anti-corrosion treated bearing plate 2.2, and the bearing plate 2.2 is fixed to the P-type anchor 2.1 with bolts and limit plates, and the pressure-bearing spiral bar is fixed at the front end of the bearing plate 2.2. In this embodiment, the pressure-dispersed anchor cable is composed of three anchoring units, each of which is composed of two anchor bar bodies 1 anchored in the bearing body 2. The anchor bar bodies 1 are symmetrically anchored to the steel bearing plate through the P-type anchor 2.1, and 3% of the samples are sampled for testing, and the connection strength of each bar is required to be greater than 200kN.

[0072] t4, guide cap installation

[0073] The guide cap 4 is directly welded to the bearing plate 2.2 at the front end of the anchor body 1. After welding, the guide cap 4 and all the bearing bodies 2 are painted with anti-rust paint for anti-corrosion treatment. The gap between the bearing plate 2.2 and the guide cap 4 needs to be filled with anti-corrosion grease to prevent the P-type anchor 2.1 from corrosion.

[0074] t5, cable ring installation

[0075] The stringing rings 3 are tied on the anchor bar body 1 at intervals of 1.0m to 1.5m, and the stringing rings 3 are installed at the openings of the anchor holes for positioning.

[0076] t6, grouting pipe installation

[0077] The grouting pipe 7 is passed through the center axis of the wire ring 3 and the bearing plate 2.2 and tied and fixed. The front end of the grouting pipe 7 enters the guide cap 4 by 15 cm, and the rear end is sealed with adhesive tape to prevent clogging.

[0078] t7, Acceptance of pressure dispersion anchor cables

[0079] The finished anchor bar 1 has no crossover or overlap, and can only be used after passing the acceptance. After the anchor bar 1 is bundled, its length should be carefully checked, and whether the PE plastic sleeve of the anchor bar 1 is worn by the steel plate when installing the bearing body 2. If it is worn, it can be tightened with transparent tape. The anchor bar 1 and other cable body accessories are arranged and tied into bundles according to the requirements of the construction drawings. The distance between the bearing plate 2.2 and the wire ring 3 is 2m. The anchor bar 1 uses zinc-free iron wire curtain.

[0080] Qualified anchor cables should be registered and labeled with anchor cable number and length to prevent installation in the wrong hole. The exposed ends of anchor bars 1 at different positions of carriers 2 should be marked to ensure that each group of carriers 2 corresponding to each anchor bar 1 can be clearly distinguished during pre-tightening to avoid compensation errors. For example, the anchor heads 6 in different groups can be marked and distinguished at the exposed ends of the anchor cables with yellow, black and red colored tapes. The anchor bars 1 are tied with zinc-free iron wire.

[0081] t8, transport qualified pressure dispersion anchor cables to the corresponding holes for installation

[0082] Transport qualified pressure-dispersed anchor cables to the corresponding hole positions. During installation, they are manually lifted upwards to the cable-laying area through a steel pipe ladder. When the height difference is large, a crane is used for cooperation. During horizontal transportation, the distance between each support point shall not be less than 2m; and the turning radius should not be too small. During vertical transportation, it shall be advanced horizontally according to the designed inclination angle and azimuth. It is strictly prohibited to shake, twist and string to prevent the bundle from being scattered and blocked in the middle. After the installation is completed, the anchor bars shall not be knocked or heavy objects shall not be hung at will. The installation of the anchor bar body 1 must be carried out under the condition of on-site supervision.

[0083] Before installing the anchor cable in the hole, re-check the anchor hole, clean up the collapsed hole and the fallen blocks, blow out the water in the hole with high-pressure air, the pressure is 80% of the grouting pressure, and check the anchor cable, mainly check the patency of the grouting pipe 7, check the anchor cable number and the anchor hole number, and repair or replace the damaged accessories. Manually lift the anchor cable to the hole position, send the anchor cable into the anchor hole, and push it straight and smoothly without pausing in the middle to avoid loosening or blocking. The exposed length of the anchor cable must meet the requirements of the tensioning construction operation. After the anchor cable is installed in place, wrap the exposed part of the anchor cable in time.

[0084] S3, anchor hole grouting

[0085] The grouting material is cement paste, with a water-cement ratio of 0.45-0.50, a slurry strength of not less than 40MPa, and it is used as soon as it is mixed. The cement is PO42.5R ordinary Portland cement. The grouting pipe 7 is inserted to 300mm from the bottom of the hole, and the bottom grouting method is used for grouting. The general grouting pressure is 2.0MPa until fresh slurry overflows from the hole. If the slurry surface at the hole mouth is found to fall back, the bottom of the hole should be pressurized and filled 2-3 times within 30 minutes to ensure that the slurry in the hole is full.

[0086] After the drilling is completed, anchor grouting must be carried out within 24 hours. In broken strata, anchor grouting should be carried out immediately after the drilling is completed. During grouting, grouting should be carried out according to the grouting equipment and grouting pressure required by the design. Grouting should be returned from the bottom of the hole. At the same time, it is strictly forbidden to pull out the grouting pipe 7. When the grouting surface at the hole mouth falls back, grouting should be replenished in time through the grouting pipe 7. After the anchor hole grouting is completed, the length of the anchor bar 1 of the prestressed anchoring project must be tested.

[0087] S4, lattice beam formwork casting

[0088] The lattice beam is made of C30 concrete. First, measure and lay out, repair and clean the uneven surface layer, and then excavate the lattice beam foundation groove. The depth of the lattice beam foundation groove is not less than 200mm. After the slope is repaired and the lattice beam foundation groove is excavated, a 2cm mortar leveling layer is first laid on the slope of the lattice beam foundation groove, and then the lattice beam reinforcement is made and installed. The steel bars around the anchor hole are dense and must be vibrated carefully to ensure the pouring quality. The steel bar binding and formwork are carried out according to the design requirements. It is strictly forbidden to cut corners. The size of the reinforced concrete formwork meets the requirements of the specification, and the formwork should be stable and accurately positioned.

[0089] According to the construction drawings, the cross-sectional dimensions of the lattice beam, the length of the horizontal beam segment and the length of the vertical beam are determined. The horizontal beam is provided with expansion joints, one every 15 to 25 meters, with a width of 20 mm, and filled with asphalt linen. Before pouring concrete, a 130 mm diameter steel pipe and an anchor pad pressure plate must be pre-embedded and fixed on the lattice beam reinforcement according to the design requirements. The axis of the anchor is consistent with the direction of the anchor hole and is neatly placed. Then, the concrete is poured and vibrated on site together. Especially when the reinforcement of the anchor and the anchor bracket is dense, the vibration is careful to ensure the construction quality.

[0090] The anchor bracket is the most important concentrated force-bearing part. The inclination angle of the anchor bracket should be made strictly according to the design requirements. The anchor bracket must be made of a steel mold and the corrugated pipe is accurately installed to isolate the anchor bar body 1 and the concrete. The spiral reinforcement and anchor pad 5 ensure that the anchor bar body 1 is perpendicular to the surface of the anchor bracket.

[0091] The concrete is required to be commercial concrete. The same reaction structure should be poured continuously and the concrete should be vibrated to be fully dense. In particular, the anchor bracket must be cast as a whole with the beam body, and concrete slurry is prohibited from entering the corrugated pipe and anchor pad 5. When the reinforced concrete reaction structure reaches the age, the anchor cable pull-out bearing capacity test must be required.

[0092] S5, anchor cable tensioning and locking

[0093] Before the anchor cable is tensioned, the following work should be completed: sampling inspection of steel strand material; acceptance of each process stage; anchor clamps with certificates and sampling inspections; tensioning equipment has been calibrated and calibration documents have been issued; grouting and cushion concrete strengths meet design requirements. During tensioning, the pressure-bearing surface of the anchor inclined support seat should be flat and in a straight line with the anchor bar and jack axis, and tensioning and locking can be performed according to the design procedure. After tensioning and locking, the reserved section of the anchor bar shall not be cut, and the quality inspection of the anchor cable tensioning must be required.

[0094] The pressure-dispersed anchor cable is divided into a free section and an anchoring section. The anchoring section is divided into multiple anchoring units of different lengths through multiple groups of bearing bodies 2, and the length of each anchoring unit is 6 to 8 meters. When prestressing tendons, ordinary prestressed anchor cable tensioning adopts the method of synchronous graded tensioning of all steel strands, while the pressure-dispersed anchor cable is tensioned in a certain order according to the different anchoring lengths of each anchoring unit. It is necessary to first calculate the differential load of each unit, make up for the difference in the units, and then perform overall synchronous graded tensioning.

[0095] Calculation of bearing capacity of each anchor unit:

[0096] T=Td / n (1)

[0097] Where: Td——design composite anchor bearing capacity;

[0098] n is the number of anchoring units in each composite anchor.

[0099] Calculation of the elongation of each anchor unit:

[0100] δ i =T×L i / (E s ×A s ) (2)

[0101] Where: Li is the free extension length of the ith anchor unit;

[0102] T——bearing capacity of each anchor unit;

[0103] Es——elastic modulus of prestressed tendons;

[0104] As is the cross-sectional area of ​​the prestressed tendon.

[0105] The displacement difference between the anchor units can be obtained as follows:

[0106] Δ 1-2 =δ1-δ2, Δ 2-3 =δ2-δ3 (3)

[0107] When the anchor cable is tensioned, the different elongation values ​​of each unit caused by the different free section lengths are first compensated.

[0108] Compensation tension 1 unit: T1 = Δ 1-2 ×E s ×A s / L1

[0109] Compensation tension (1+2) unit: T2 = Δ 2-3 ×E s ×A s / L2+T1+Δ 2-3 ×E s ×A s / L1

[0110] After completing the compensatory tensioning of each unit anchor, the (1+2+3) units are tensioned at the same time, using a step-by-step loading method. The loading forces are 0.3, 0.5, 0.7, 0.9, and 1.1 times the design load, respectively. The first four levels of load stay for 5 minutes, and the last level of load stays for 10 minutes.

[0111] Cutting and sealing the anchor can only be carried out after the anchor cable tensioning quality inspection is qualified. When cutting the anchor bar 1, more than 10cm should be reserved behind the anchor to prevent slipping. Finally, the anchor head 6 is sealed with concrete of the same grade or higher grade as the reaction structure according to the design requirements.

[0112] S6, Anchor Pier Installation

[0113] The anchoring construction is strictly carried out in accordance with the requirements of the construction drawings. The specifications and binding spacing of the steel bars should meet the design requirements, and the concrete strength should not be lower than C35 (28d age). Before pouring concrete, the slope surface should be washed clean first, and then the hole pad, steel casing and steel mesh should be installed. The concrete is mainly pumped into the warehouse, partially loaded with a bucket truck, transported to the construction platform by a hoist, transferred into the mold with a small bucket, and vibrated with a vibrator. The installation of the anchor pad should ensure that the axis of the other channels is vertical, the casing is aligned with the axis of the channel, and the gap between the casing and the channel is sealed. After the concrete pouring is completed, water it in time for maintenance.

[0114] 2. Quality Assurance Measures

[0115] 2.1 The construction shall be organized strictly according to the design drawings and the current construction acceptance specifications, and the specific operations shall be carried out strictly according to the approved construction plan.

[0116] 2.2 Carry out self-inspection, mutual inspection and other inspection work carefully, and conduct acceptance inspection of hidden projects in a timely manner. The next step of the construction shall not be carried out without acceptance.

[0117] 2.3 Before tensioning construction, the drawings and construction status should be carefully reviewed. Tensioning can only be carried out after the compressive strength of the concrete test blocks cured under the same conditions on site reaches the design allowable tensioning strength.

[0118] 2.4 Construction shall be strictly carried out according to the requirements of the drawings. Any problems found shall be reported to the relevant units in a timely manner, and construction shall continue after verification by the relevant departments.

[0119] 2.5 Tensioning can only be carried out when the concrete strength of the grouting body and the anchor inclined support base reaches more than 80% of the design strength.

[0120] 2.6 The anchor should be installed closely and aligned with the anchor plate and jack. The axis of the jack should be in a straight line with the anchor hole and the axis of the staggered cable. The anchor head must not be bent or deflected to ensure uniform and coaxial load. If necessary, use steel gaskets to adjust.

[0121] 2.7 Before tensioning, necessary inspection should be carried out on the appearance of the tensioned beam to confirm that the quality of concrete pouring is qualified.

[0122] 2.8 If any abnormal cracks are found, the relevant units should be notified in time to find out the cause and adjust the tensioning plan if necessary. Tensioning can only be carried out after approval.

[0123] 2.9 The pressure-bearing surface of the anchor support base should be flat and perpendicular to the axis of the anchor cable.

[0124] 3. Safety measures

[0125] 3.1 Strictly implement the safety operating procedures during construction. Prior briefing should be conducted before construction. Safety education should be provided to tensioning operators before construction in each area.

[0126] 3.2 Anchors and clamps should be properly kept by designated personnel to avoid rust, stain, mechanical damage or loss. During construction, the anchors should be treated with anti-rust treatment after the final tensioning is completed.

[0127] 3.3 Before tensioning, carefully check the safety of the tensioning platform and set up a safety baffle of appropriate height on the tensioning platform to prevent accidents during tensioning from causing harm to personal safety.

[0128] 3.4 Construction operators must be equipped with safety protection equipment and wear safety helmets when entering the construction site. Operators must wear safety belts when working at heights.

[0129] 3.5 From the application of prestress to the sealing after anchoring, operators are not allowed to move in front of the anchor unless effective shielding measures are taken.

[0130] 3.6 During the tensioning process, when measuring the elongation value or removing the tool anchor, the operator should stand on the side of the jack and non-prestressed construction personnel should be prohibited from entering the tensioning area.

[0131] 3.7 From the beginning of tensioning to the completion of grouting, it is forbidden to hit the tools, steel strands and the tensioning equipment. If the tensioning equipment makes abnormal sound during tensioning, it should be stopped immediately for inspection and maintenance.

[0132] 3.8 The safety valve on the hydraulic pump should be adjusted to a state where it can automatically open under the maximum working oil pressure. The oil pressure gauge must be installed tightly and fully buckled. The high-pressure oil pipe used between the oil pump and the jack, as well as the joints of the oil circuit, must be complete and tight, and the oil circuit must be unobstructed. No oil leakage should be maintained at the maximum working oil pressure for more than 5 minutes. If there is any damage, it should be repaired and replaced in time.

[0133] 3.9 In special circumstances, when replacing the clamp, a jack should be installed. When taking other measures to relax the prestressed tendons, safety protection work at the construction site should be done carefully.

[0134] 3.10 Grouting workers must stand on both sides of the jig when operating. It is strictly forbidden to face the jig or step on the high-pressure oil pipe.

[0135] 3.11 Before using the tensioning equipment, the high-pressure oil pump and jack should be tested for no-load operation. They can be officially used only if there are no abnormal conditions. The high-pressure oil pipe should be subjected to a pressure resistance test before use. Those that fail the test cannot be used.

[0136] 3.12 Electrical equipment shall be managed by a dedicated person, the switch box shall meet the technical requirements, the power cord shall be tested before use, no illegal operation shall be performed, the main power supply shall be cut off after the operation is completed, and all electrical equipment shall be covered. Strictly abide by the electricity use system at the construction site.

[0137] 3.13 When cutting steel strands, care should be taken to prevent the grinding wheel from breaking and injuring people. Operators should wear protective glasses.

[0138] 3.14 During the construction process, prevent tools or machinery from falling from height and injuring people.

[0139] IV. Environmental Protection Measures

[0140] 4.1 The construction area must have full-time environmental protection management personnel and clearly define job responsibilities.

[0141] 4.2 Carry out environmental protection publicity and education activities in various forms, continuously improve employees' environmental awareness and legal concepts and conduct assessments, hold regular analysis meetings based on the on-site environmental protection work management situation, and formulate specific measures.

[0142] 4.3 Fine-grained bulk materials that are easy to fly, such as cement, should be stored in closed warehouses. Effective measures must be taken during transportation to prevent spillage and open-air storage is prohibited.

[0143] 4.4 Wastewater generated during on-site operations is prohibited from being discharged anywhere. It must be introduced into sedimentation tanks for quantitative sedimentation before being discharged into municipal pipelines.

[0144] 4.5 A dedicated oil and paint depot shall be set up on site. No other items shall be placed in the oil depot, and the floor and walls of the depot shall be specially treated to prevent leakage. A dedicated person shall be responsible for storage, use and custody to prevent oil from escaping, bubbling or dripping and polluting water sources.

[0145] V. Benefit Analysis

[0146] 5.1 Economic Benefits

[0147] The pressure-dispersed anchor cable used in this construction method uses unbonded steel strands, which are coated with a mixture of dehydrated butter and paraffin wax and extruded with PE materials. No anti-corrosion measures are required for the entire length of the steel strand. After the pressure-dispersed anchor cable is in place in the anchor cable hole, the entire hole can be grouted at one time, which reduces manpower and material resources. Due to its balanced force and good corrosion resistance, the anchor cable has little loss and damage, which increases its durability and reduces maintenance costs.

[0148] 5.2 Social Benefits

[0149] The pressure-type dispersed anchor cable anchoring section grouting stone body used in this construction method is under pressure for the entire length, and the anchor cable is arranged with multiple bearing plates 2.2, which can alleviate the stress concentration degree of the inner anchor section and reduce its stress peak value. It has the advantages of being able to give full play to the bonding force of the soil to the anchor cable grouting body and not easy to crack. Under the same geological conditions, it provides greater anchoring force than ordinary tension-type anchor cables, which is conducive to the stability of high and steep slope projects. The steel strand used is an unbonded steel strand, which has good anti-corrosion function, reduces the process of anti-corrosion painting on the steel strand, saves manpower and material resources, and protects the environment.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive prevention and control construction method for high side slopes of adjacent mountains, characterized in that: The following steps are involved: S1, anchor hole drilling According to the designed pile number, a ruler is used to measure, and the line is laid out in combination with leveling. The anchor hole position is accurately located with iron rods and paint marks. The drilling rig is accurately positioned in strict accordance with the designed hole position, inclination and azimuth, and the drilling rig is fixed firmly with fasteners, and the angle is controlled with an angle measuring tool; S2, anchor cable production and installation The following steps are involved: t1, anchor bar cutting The anchor bar body is made of unbonded steel strands with PE sleeves. The cutting length is cut according to the designed length of the anchor cable + the length of the embedded end + the length of the tensioning section. The anchor bar body is cut mechanically. t2, P-type anchor installation Cut off the PE sleeve at the anchor end of the anchor body according to the designed length, clean it and install the P-type anchor, and use the extruder to squeeze the P-type anchor to connect and fix it with the anchor body; t3, carrier assembly Insert the anchor bar into the anti-corrosion treated bearing plate, fix the bearing plate to the P-type anchor with bolts and limit plates, and fix the pressure-bearing spiral bar at the front end of the bearing plate; t4, guide cap installation The guide cap is directly welded to the bearing plate at the front end of the anchor bar body. After welding, the guide cap and all bearing bodies are painted with anti-rust paint for anti-corrosion treatment; t5, cable ring installation Tie the stringing rings on the anchor bar body according to the designed intervals, and install the stringing rings at the opening of the anchor hole for positioning; t6, grouting pipe installation Pass the grouting pipe through the central axis of the wire ring and the bearing plate and tie it up to fix it. The front end of the grouting pipe enters the guide cap and the rear end is sealed with tape to prevent blockage. t7, acceptance of pressure dispersion anchor cables; t8, transport qualified pressure dispersion anchor cables to corresponding holes for installation; S3, anchor hole grouting The grouting material is cement paste, and the grouting is done by the bottom hole return grouting method; S4, lattice beam formwork casting Measure and lay out, repair and clean the uneven surface layer, then dig the lattice beam foundation groove, lay the mortar leveling layer on the slope of the lattice beam foundation groove, and then make and install the lattice beam reinforcement. According to the design requirements, fix the lattice beam reinforcement on the steel pipe and anchor pad pressure plate, and pour concrete; S5, anchor cable tensioning and locking The anchor body of the pressure-dispersed anchor cable is divided into a free section and an anchor section. The anchor section is divided into multiple anchor units of different lengths through multiple groups of bearing bodies. Tensioning is carried out according to the different anchor lengths of each anchor unit, first the long unit and then the short unit. The differential load of each anchor unit is first calculated, the difference is supplemented by the units, and then the overall synchronous graded tensioning is carried out. S6, Anchor Pier Installation Install the hole pad, steel casing, steel mesh, and steel bars of the anchor hole, pour concrete, and install the anchor pad and anchor head of the pressure-dispersing anchor cable.

2. The method for comprehensive prevention and control of high slopes adjacent to the mountain according to claim 1 is characterized in that: In step S1, the drilling rig guide rail inclination error does not exceed ±1°, and the azimuth error does not exceed ±2°; During the construction process, regularly check the fastening status of the fasteners; Select the appropriate anchor hole drilling rig for drilling according to the stratum, drill at a low speed and push at low pressure, and when the hole is 50cm, check the hole direction again and adjust the drilling rig in time; The borehole diameter and depth must not be less than the designed value, and the overdrilling must be no less than 20 cm. After reaching the designed depth, the drilling must be steady for 3 to 5 minutes.

3. The method for comprehensive prevention and control of high slopes on adjacent mountains according to claim 2 is characterized in that: In step S1, if a hole collapse is encountered during the drilling process, the drilling is stopped immediately, and grouting is used to consolidate the wall, with a grouting pressure of 0.1 to 0.2 MPa. Drilling is resumed after 24 hours, or a pipe-following drilling process is used.

4. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 3 is characterized in that: In step S1, after the anchor hole is drilled, high-pressure air with a wind pressure of 0.2 to 0.4 Ma is used to remove all rock powder, soil powder and water in the hole. After the hole is cleaned, the hole mouth is temporarily blocked.

5. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step S2, the anchor bar body adopts Φ15.2mm 1860 grade steel strand, which complies with the provisions of the current national standard "Prestressed Concrete Steel Strand". The steel strand is a finished coil. After being transported to the site, 80% of the material is subjected to nondestructive testing and pre-tensioning inspection, among which the diameter inspection of the steel strand is based on 10% reel sampling, the performance inspection of the steel strand is based on 5% reel sampling, and the performance inspection of the steel strand is sampled from no less than 3 reels, and a test piece is cut from each reel for tensile testing.

6. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step S2, the pressure distribution type anchor cable includes three anchoring units, each anchoring unit includes two anchor bars, and the connection strength between a single anchor bar and the bearing plate is greater than 200 kN.

7. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step t8, before the anchor cable is installed in the hole, the anchor hole is re-checked, the collapsed hole and fallen blocks are cleaned, the water in the hole is blown out with high-pressure air, and the pressure is 80% of the grouting pressure. The anchor cable is checked, the anchor cable number and the anchor hole number are checked, the damaged accessories are repaired or replaced, the anchor cable is manually lifted to the hole position, and the anchor cable is sent into the anchor hole. It is pushed straight and smoothly without pausing in the middle to avoid loosening or jamming.

8. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step S3, the water-cement ratio of the cement paste is 0.45-0.50, the paste strength is not less than 40 MPa, and it is used immediately after mixing. The cement used is PO42.5R ordinary Portland cement; The grouting pipe is inserted to 300mm from the bottom of the hole, and the grouting pressure is 2.0MPa, until fresh slurry overflows from the hole mouth. If the slurry surface at the hole mouth is found to fall back, grouting is injected at the bottom of the hole 2 to 3 times within 30 minutes to ensure that the hole is full of slurry.

9. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step S4, the cross-sectional dimensions of the lattice beam, the length of the cross beam segments and the length of the vertical beam are determined according to the construction drawings. Expansion joints are set on the cross beams, one every 15 to 25 m. The expansion joints are 20 mm wide and are filled with asphalt linen.

10. The comprehensive prevention and control construction method for high side slopes of adjacent mountains according to claim 1 is characterized in that: In step S5, a step-by-step loading method is adopted, and the loading forces are 0.3, 0.5, 0.7, 0.9, and 1.1 times of the design load of the pressure-dispersed anchor cable, respectively. The first four load levels have a residence time of 5 minutes, and the last load level has a residence time of 10 minutes.

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