High slope construction method

Abstract

The invention provides a high slope construction method. The high slope construction method comprises the following steps: S1, surveying and setting out; s2, excavation of earth and stone; s3, side slope trimming; s4, performing anchor rod engineering; s5, active net hanging; s6, erecting a scaffold; s7, carrying out soil dressing spray-seeding greening construction; before the step S2, monitoring control points are arranged on the high slope; concrete lattice beam construction is carried out while the scaffold is erected in the step S6, the concrete lattice beam construction comprises the following steps of manual foundation trench excavation, lattice beam binding, lattice beam formwork installation and lattice beam concrete pouring which are carried out in sequence, and then the step S7 of soil dressing spray-seeding greening construction is carried out. The high slope protection device has the advantages that the active net is hung before soil dressing spray seeding and greening construction, so that the high slope is protected, loose rock strata and soil are prevented from falling off, and the excavation condition of the slope can be maintained in an auxiliary mode; and the high slope construction efficiency can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of high slope construction, in particular to a high slope construction method. Background Art

[0002] In the field of geotechnical engineering or engineering geology research, the so-called "slope" generally refers to the general term for slope forms such as natural slopes, river bank slopes, tableland edges, landslide accumulation bodies, and artificial slopes (formed by traffic roads, open-pit mining, construction sites and foundation projects, etc.). The slope is mainly composed of the top, surface, foot and a certain range of slopes below. There are many types of slope classifications. For soil slopes with a height greater than 20m and less than 100m or rock slopes with a height greater than 30m and less than 100m, the slope height factor will play an important role and influence on the stability of the slope. The slope stability analysis and protection and reinforcement engineering design should be individually or specially designed and calculated. These slopes are called high slopes. The existing high slope construction has the problems of low efficiency, long construction period, and difficult slope soil support.

[0003] The Chinese patent application publication number is CN 112921989A, and the name published on June 8, 2021 is "High Slope Construction Method". The application includes the following steps: Step S1: Site cleaning: All vegetation, garbage, organic debris, etc. within the scope of the land use and the grass and topsoil within 30 cm of the top of the original ground are cut down and removed; Step S2: Drainage protection: Dig a drainage ditch at the top of the slope; Step S3: Lifting platform erection: Set up a lifting platform to support the excavation equipment on the high slope; Step S4: Slope excavation: Move the excavator to the lifting platform, and the lifting platform moves the excavator to a position close to the top of the slope to excavate the high slope step by step; Step S5: Slope protection: Reinforce the surface of the slope to improve the stability of the slope.

[0004] The shortcomings of the existing technology are that slope excavation is usually carried out in stages from top to bottom, and each stage requires excavation and protection. There is a lack of working processes, which results in a long overall cycle of high slope construction and seriously affects the efficiency of high slope construction. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a high slope construction method, which has a plurality of processes that can work simultaneously and has a good protective effect on the slope earthwork.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A high slope construction method comprises the following steps: S1. Measurement and setting out; S2, earthwork excavation; S3, slope trimming; S4, anchor engineering; S5, active network installation; S6. Scaffolding erection; S7, soil spraying and greening construction; Before step S2, the monitoring control points of the high slope are arranged; in step S6, the concrete lattice beam construction is carried out while the scaffolding is erected. The concrete lattice beam construction includes the following contents in sequence: manual excavation of the foundation trench, lattice beam binding, lattice beam formwork installation and lattice beam concrete pouring, and then step S7 soil spraying and greening construction is carried out.

[0007] The present invention realizes the protection of high slopes by hanging active nets before soil spraying and greening construction, avoiding the falling of loose rock layers and soil, and assisting in maintaining the excavation state of the slopes. The concrete lattice beam construction is completed while the scaffolding is erected, and the concrete lattice beam construction and scaffolding are completed at the same time, and the shape of the slope after excavation is protected, which greatly improves the efficiency of high slope construction.

[0008] Preferably, before performing step S2, a slope top intercepting ditch is first built to intercept water flowing from the hillside to the roadbed.

[0009] As a preferred method, the high slope is divided into several levels of slopes from the first level to the nth level according to the height, and the construction is carried out in different levels of slopes from top to bottom. The multi-level construction method from top to bottom can effectively avoid landslides in the top excavation area and ensure the efficiency and safety of excavation construction.

[0010] Preferably, the high slope is divided into the first to fifth levels according to the height. The following procedures are completed in sequence during the construction of the first level slope: A. arranging monitoring control points, B. repairing the intercepting ditch on the top of the slope, C. performing step S2, and D. performing step S3; the following procedures are completed in sequence during the construction of the second level slope: A. performing the first layer step S2, B. performing step S3, C. performing step S4, D. performing the second layer step S2, E. performing step S3, and repairing the rapids ditch and the drainage ditch, F. performing step S4, and G. performing step S5; the construction of the third level slope, the fourth level slope, and the fifth level slope adopts the same procedures as the second level slope construction on the corresponding slope. The present application constructs the other levels of slopes except the first level in a two-layer operation mode, and each layer of operation includes earthwork excavation, slope repair, anchor rod engineering, and active network hanging, to ensure that the slope will not slide during the construction of each level and each layer, thereby improving the safety of high slope construction.

[0011] As a preferred method, the concrete pouring process of the lattice beam is as follows: before pouring, check the cross-sectional dimensions of the frame, check the number and arrangement of steel bars; the protective layer thickness of the main reinforcement of the frame is not less than 50mm, the net protective layer thickness of the stirrups is not less than 35mm, and the net protective layer thickness of the main reinforcement is not less than 40mm; the steel bars are made into an integral long skeleton; the concrete pouring of the frame is carried out continuously by pouring and vibrating; when there are signs of concrete sliding during the pouring process, quick-setting or early-strength concrete or a cover mold is used to press it down; C30 concrete is used for the pouring of the foundation concrete at the foot of the slope. In order to improve the structural performance of the slope during the pouring of the lattice beam concrete, the lattice beam formed under the requirements of this preferred process has good structural performance, and after the overall forming, it plays a reliable protective and limiting role for the high slope.

[0012] Preferably, step S4 includes the following steps: determining the hole position, positioning the drilling rig, adjusting the angle, drilling, cleaning the hole, installing anchor rods and grouting; when drilling, continue to drill steadily for 1 to 2 minutes after reaching the designed depth; when cleaning the hole, use high-pressure air with a wind pressure between 0.2 and 0.4 MPa to remove rock powder and water from the hole. Steady drilling can prevent the bottom of the hole from pinching out and failing to reach the designed hole diameter, and cleaning the hole can remove sediment, water and rock powder in the hole, so as not to reduce the bonding strength between the cement mortar and the rock and soil of the hole wall.

[0013] As a preferred method, grouting uses M30 cement mortar, with a water-cement ratio of 0.5:1 and a cement-sand ratio of 1:1. The cement used for grouting is 42.5 ordinary Portland cement, and the sand is silt sand. Grouting is first performed from the bottom of the hole. When the cement mortar overflows from the hole mouth, the grouting is stopped. The construction adopts secondary grouting: the primary grouting pressure is not less than 2.0MPa, and the secondary grouting pressure is not less than 4.0MPa. Through the method of secondary grouting, the grouting pressure is increased in the second time to ensure the grouting effect.

[0014] Preferably, step S7 includes the following steps: configuring the guest soil substrate mixture, selecting the thickness of the customer spraying, selecting the plant seeds, spraying the guest soil and maintaining the guest soil. The guest soil is sprayed from top to bottom twice. The first spraying is 5 cm thick. After the guest soil is stable, it is sprayed to the designed thickness. The maintenance management is to cover the guest soil with 30g / m2 non-woven fabric after the sowing construction is completed, and spray water, replant, remove weeds and prevent pests and diseases in a timely and appropriate manner. When the seedlings grow to 5-6cm or 2-3 leaves, the non-woven fabric can be removed to ensure the normal growth of the seedlings. The secondary spraying provides a uniform and reliable guest soil layer to achieve greening and landslide prevention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a process of a high slope construction method disclosed in one embodiment of the present invention; Figure 2 It is a schematic diagram of excavating from top to bottom when the present invention is applied to a high slope divided into five levels. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] The high slope construction method disclosed as one of the embodiments of the present invention comprises the following steps: S1. Measurement and setting out; S2, earthwork excavation; S3, slope trimming; S4, anchor engineering; S5, active network installation; S6. Scaffolding erection; S7, soil spraying and greening construction; like Figure 1 As shown, in order to improve efficiency, other processes are also being carried out while processes S1 and S7 are being carried out. After measuring and laying out in step S1, the monitoring points are arranged and the intercepting ditch on the top of the slope is pre-dug before step S2. Then, according to the results of the measurement and laying out, the reinforcement of the lattice beam is made at the same time. Before the slope is trimmed in step S3, the rapids ditch and the platform drainage ditch are excavated. Before the anchor project in step S4, the steel bars must be brought into the site first, and the steel bars must be inspected and tested. Before the active net is hung in step S5, the active net must be brought into the site and inspected and tested. Before step S7, the planting soil is prepared and mixed, and the three-dimensional net is laid on the slope and fixed with U-shaped nails.

[0018] Before step S2, the monitoring control points of the high slope are arranged; after the lattice beam reinforcement is produced, the concrete lattice beam construction is carried out while the scaffolding is erected in step S6. The concrete lattice beam construction includes the following contents in sequence: manual excavation of the foundation trench, lattice beam binding, lattice beam formwork installation and lattice beam concrete pouring, followed by step S7 soil spraying and greening construction.

[0019] The present invention protects high slopes by hanging active nets before soil spraying and greening construction, avoids the falling of loose rock layers and soil, and can assist in maintaining the excavation of the slope. While the scaffolding is being erected, the construction of concrete lattice beams is completed. The construction of concrete lattice beams and the erection of scaffolding are completed simultaneously in the same time period, and the shape of the slope after excavation is protected, thereby greatly improving the efficiency of high slope construction.

[0020] When performing step S4, while brushing the slope, drilling can be performed first, and the depth of the holes can leave room for appropriate adjustment of the anchor rod; after each anchor hole is drilled, the anchor rod is inserted immediately, and after confirming that the slope is correct, grouting is performed.

[0021] Step S1, measurement and layout, includes measuring the terrain undulation, the proposed site area, rock properties, etc., determining the current state of the slope according to the geological conditions, judging the stability of the rock layer after excavation, and then providing a support plane layout plan.

[0022] Step S3: Slope trimming is performed with a backhoe. If medium-weathered mudstone (above 15Mpa) is encountered, a static crushing agent can be used to break it and trim the slope. After the slope trimming is completed, before the three-dimensional net guest soil is sprayed, the concrete platform drainage ditch is poured to ensure that the site is flat and there is no water accumulation.

[0023] Step S4: In the anchor project, full-length bonded anchors are used, with an inclination angle of 20° and a hole diameter of 100mm. Before use, the steel bars should be straightened, derusted, and degreased, and a centering frame should be set every 2 meters along the axis to ensure the thickness of the steel bar's protective layer. The exposed sections should be treated with hot-dip galvanizing and other anti-corrosion treatments.

[0024] Step S4 includes the following steps performed in sequence: determining the hole position, positioning the drilling rig, adjusting the angle, drilling, cleaning the hole, installing the anchor rod and grouting; When determining the hole position, measure and lay out the anchor holes. According to the design elevation drawing requirements, within the anchor construction range, use instruments to set fixed piles at the starting and ending points, and increase the density in the middle according to conditions, and ensure that they are not damaged during the construction stage. Other hole positions are measured with fixed piles as steel rulers, and the whole section is uniformly laid out. The hole position error shall not exceed ±50mm. Semi-permanent marks are buried at the measured hole positions, and it is strictly forbidden to lay out during construction.

[0025] The specific length of the vertical beam can be determined according to the actual slope height, but the position of the anchor rod must be set out according to the length of the equally divided slope surface, and the spacing can be adjusted appropriately. If the existing brush square slope surface is uneven or there is a special difficult site, the positioning accuracy can be appropriately relaxed or the anchor hole positioning can be adjusted on the premise of ensuring the stability of the slope and the safety of the structure, subject to the approval of the design supervision unit.

[0026] Drilling equipment is selected according to the type of anchoring stratum, anchor hole diameter, anchor depth, and construction site conditions. ZGYX-420S anchor drilling rig is used to drill holes in rock strata; pipe-following drilling technology is used in strata that are prone to hole collapse and drill bit burial, such as broken or soft saturated rock strata.

[0027] Drilling rig in place: Use φ48 mm scaffolding poles to set up a platform, fix the platform to the slope with anchors, and lift the drilling rig onto the platform with a tripod. During the drilling of anchor holes, set up a scaffold that meets the corresponding bearing capacity and stability conditions, measure and place the hole positions according to the slope, accurately install and fix the drilling rig, and strictly and carefully adjust the position of the rig to ensure that the longitudinal and transverse errors of the anchor hole drilling and positioning shall not exceed ±50 mm, the elevation error shall not exceed ±100 mm, the inclination angle and direction of the drilling hole meet the design requirements, the allowable error of the inclination angle is ±1.0°, and the allowable error of the azimuth is ±2.0°. The intersection angle z between the anchor and the horizontal plane shall not exceed 45°, and is designed to be 20°. The drilling rig installation requires horizontality and stability, and should be checked at any time during the drilling process.

[0028] The drilling requires dry drilling, and water drilling is prohibited to ensure that the anchor construction does not deteriorate the engineering geological conditions of the slope rock mass and ensure the bonding performance of the hole wall. The drilling speed is strictly controlled according to the performance of the drilling rig and the anchoring stratum to prevent the distortion and diameter change of the borehole, which may cause difficulties in anchoring or other accidents. During the drilling process, the stratum changes, drilling conditions (drilling pressure, drilling speed), groundwater and some special conditions of each hole should be recorded on site. In case of unfavorable drilling phenomena such as hole collapse and shrinkage, the drilling must be stopped immediately, and the wall grouting treatment (grouting pressure 0.1~0.2MPa) should be carried out in time. After the cement mortar is initially set, the hole should be re-drilled. The borehole diameter and hole depth requirements shall not be less than the design value, the hole mouth deviation shall be ≤±50mm, and the hole depth allowable deviation shall be +200mm. To ensure the anchor hole diameter, the actual drill bit diameter shall not be less than the design hole diameter. To ensure the anchor hole depth, the actual drilling depth shall be greater than the design depth by more than 0.2 m.

[0029] Cleaning of anchor holes: Drilling cannot be stopped immediately after reaching the designed depth. Continue to drill steadily for 1 to 2 minutes to prevent the bottom of the hole from pinching out and failing to reach the designed aperture. When cleaning the hole, use high-pressure air with a wind pressure between 0.2 and 0.4 MPa to remove the rock powder and water in the hole to avoid reducing the bonding strength between the cement mortar and the rock and soil on the hole wall. Except for anchoring relatively hard and intact rock bodies, high-pressure water flushing shall not be used. If pressurized water flows out of the anchor hole, anchor bars and grouting can be installed only after the water pressure and water volume decrease. If necessary, drainage holes can be set at appropriate locations around. If the design requires the treatment of water accumulation inside the anchor hole, grouting and secondary drilling are generally used. Steady drilling of the hole can prevent the bottom of the hole from pinching out and failing to reach the designed aperture. Hole cleaning can remove sediment, water and rock powder in the hole to avoid reducing the bonding strength between the cement mortar and the rock and soil on the hole wall.

[0030] Anchor hole inspection: After the anchor hole is drilled, it must be inspected and qualified by the on-site supervisor before the next process can be carried out. The hole diameter and hole depth inspection generally use the designed hole diameter, drill bit and standard drill rod to inspect the hole under the condition of on-site supervision. During the inspection, the drill bit is required to advance smoothly without impact or shaking. The drill tool inspection length meets the designed anchor hole depth, the drill withdrawal requirement is smooth, and there is no obvious splashing dust and water when blown with high-pressure wind. At the same time, it is required to review the hole position, inclination and orientation of the anchor hole. After all the anchor hole construction sub-items are qualified, the anchor hole drilling inspection can be considered qualified.

[0031] Anchor rod production and installation: The anchor rod body is made of Φ25 threaded steel bars. A set of steel bar positioning brackets is set every 2.0 m along the axis of the anchor rod to ensure that the thickness of the anchor rod's protective layer meets the design requirements. The anti-corrosion measures such as painting and oiling are used to treat the tail end of the anchor rod. The end of the anchor rod should be welded to the frame beam steel bar. If it interferes with the frame steel bar and stirrups, the spacing between the steel bar and stirrups can be partially adjusted. The intersection of the vertical and horizontal main bars must be tied firmly.

[0032] Before installation, make sure that each steel bar is straight, remove rust and oil. Before installing the anchor body, carefully check the anchor hole number again. After confirmation, use high-pressure air to blow the hole, and slowly put the anchor body into the hole manually. Use a steel ruler to measure the length of the anchor exposed outside the hole, calculate the length of the anchor in the hole (the error is controlled within ±50 mm) to ensure the anchoring length.

[0033] After the complete anchor rod is inspected and confirmed by the supervising engineer, it should be stored in a ventilated and dry place in time, and it is strictly forbidden to be exposed to the sun and rain. During the transportation of the anchor rod, the steel bar should be prevented from bending and the positioner from loosening.

[0034] Anchor grouting: Anchor grouting uses M30 cement mortar, with a water-cement ratio of 0.5:1 and a cement-sand ratio of 1:1. The cement used for grouting is 42.5 ordinary Portland cement, and the sand is silt sand. The hole should be cleaned before grouting to drain the water and rock debris in the hole. Grouting should be done from the bottom of the hole first. When the cement mortar overflows from the hole, stop grouting. Secondary grouting is used for construction: the pressure of the first grouting is not less than 2.0MPa, and the pressure of the second grouting is not less than 4.0MPa. The cement mortar should be stirred evenly, and the cement mortar mixed once should be used up before initial setting.

[0035] Atmospheric pressure grouting operation starts from the bottom of the hole. The actual grouting volume is generally greater than the theoretical grouting volume, or the grouting is terminated when the hole is no longer exhausted and the slurry overflows from the hole. If the hole is not filled at one time or settlement occurs after grouting, additional grouting should be performed until it is full. The grouting pressure is 2.0-4.0 MPa, and the grouting volume shall not be less than the calculated volume. The filling coefficient during pressure grouting is 1.1-1.3. The grouting material should be M30 cement mortar with a water-cement ratio of 0.5:1 and a cement-sand ratio of 1:1. The grouting pressure, grouting quantity and grouting time are determined according to the volume of the anchor body and the anchoring formation conditions. After the grouting is completed, the grouting pipe, grouting gun and grouting sleeve should be cleaned, and grouting records should be kept.

[0036] Anchor pull-out test: To ensure that the anchor has reliable anchoring force, it is required to select 5 groups of anchors with 3 anchors in each group for pull-out test under field conditions. The test data must be compared with the original design. If the test results are significantly different from the original design results, the designer should adjust the anchor parameters. The number of tests: 3 anchors per group, a total of five groups. One group is selected for each section, randomly selected. Test load value (ultimate bearing capacity): 157kN.

[0037] Step S5, active net installation, is a pre-process of step S7. The special SNS active net is tightened and fixed on the slope using steel anchor rods with anchor pads, which is suitable for the reinforcement and protection of soil or rock slopes with potential geological disasters such as collapse, collapse, shallow sliding, weathering and spalling, and dangerous rockfall.

[0038] The active net consists of: DO / 08 / 200 flexible active net: made of 1770MPa strength, anti-corrosion grade not less than hot-dip galvanized AB grade, diameter ∅8 steel wire, mesh side length 200mm, standard mesh block specification 5m×3m; S0 / 2.2 / 50 grid mesh: strength is 500MPa, anti-corrosion grade is not lower than hot-dip galvanized AB grade, diameter is Φ3 steel wire, diamond mesh inscribed circle diameter is 65mm, standard mesh block specification is 30 / 20 / 10×3.5m. The overlap width between two adjacent meshes is 100mm, and they are fixed on the slope with U-shaped nails. U-shaped fixing nails are treated with asphalt before use to prevent rust; Anchor rod: Use ∅25HRB400 fully bonded steel anchor rod with exposed section and processed thread, and the exposed end shall be no less than 30cm and hot dip galvanized for anti-corrosion treatment; Anchor plate: diamond-shaped steel plate with hooks at four corners, size not less than 350×170mm, thickness not less than 8mm; its structure can be changed or simplified when necessary; Boundary rope: optional. Consider using it when the terrain boundary is complex or when the boundary sealing effect needs to be improved. ∅12 or ∅16 hot-dip galvanized steel rope, the length of a single rope should not be greater than 40m, and each end of the rope should be equipped with a 2∅16 double-strand steel wire rope anchor rod with a length of 3m; The active net is hung 2m outward from the opening line of the slope, i.e. the boundary, with an anchor spacing of 3.5mx3.5m and a diamond arrangement. The anchor inclination is 20°. When the grille is suspended, the anchor should be nearly perpendicular to the surface of the tensioned grille. The required material area of ​​the grille net = 1.0~1.08×the area to be protected, which is the area of ​​an integer number of grilles. The site can be longitudinally divided as needed. The longitudinal extension between the mesh blocks is sewn with corrugated suture wire processed with the same type of steel wire as the grille weaving. The transverse connection between the mesh blocks is made of ∅8 hot-dip galvanized steel wire rope or the same type of steel wire as the grille weaving, and the length is about 1.2 times the straight length of the suture path. The number of anchor pads is the same as the number of anchor rods, and they are equipped with special nuts.

[0039] Construction sequence and method of active network installation Slope clearing: regularizing terrain boundaries and removing loose soil and loose rocks; Arrange the anchor holes according to the design drawings, and they should be located in natural pits; dig the hole mouth pits at the hole positions where there are no natural pits that can make the grille close to the slope surface; Drilling anchor holes from top to bottom; Then install the anchor and inject grout, clean the anchor head and make its exposed length 10~18cm; When laying and joining the grille, the longitudinal boundaries of the grille should overlap by one to two mesh widths, and no overlap is required in the lateral direction. The suture wire or rope should be passed through the overlapping holes, and the ends should be knotted with the grille wire or fixed with rope clips.

[0040] When installing the boundary rope, the boundary rope is passed through the grid mesh to the steel rope anchor rods at both ends, tensioned and fixed with 4 rope clamps; install the anchor plate and tighten the nuts to apply prestress, so that the grid is tensioned and close to the slope or slightly pressed into the stratum. The prestress of the anchor rod at the suspended part of the grid should not be greater than 30kN; the hook of the anchor plate must be inserted into the grid mesh, the upper boundary and side boundary ropes must be pressed on the outside of the anchor rod, and the lower boundary rope must be pressed on the upper side of the anchor rod; check the tightness of the grid and the slope, and arrange and install auxiliary anchor rods or driven anchors as needed.

[0041] When laying the net, first level the slope according to the designed slope, then sprinkle water to wet it, and then build up 10cm thick soil on the entire slope, and then use the pre-woven galvanized wire mesh to tie it to the anchor bars and the bent ends of the anchor rods. Tie the nets together with wire, and finally spray the nutrient soil containing grass seeds to cover the wire mesh. After spraying, cover it with plastic film or geotextile for maintenance in time, and add sufficient water in time until it germinates and survives.

[0042] Step S6 Scaffolding erection: The scaffolding steel pipe adopts Ф45*3 steel pipe, and the horizontal, longitudinal and vertical spacing of the steel pipe is 1.5m. The first vertical pole of the slope angle is pushed into the bottom of the drainage ditch, and each vertical pole and horizontal pole along the slope surface are driven into the soil or rock layer of the hillside for fixation; three layers of diagonal poles are erected along the slope surface, and the lower part of the frame is used as diagonal braces, and the diagonal braces are supported on the horizontal ground. Anchor rods are laid on the construction operation layer to facilitate the placement of anchor rod construction machinery and construction. After the road cutting excavates the second level of slope, Ф45*3 steel pipe scaffolding is erected along the slope surface, erected in double rows, and a 400cm×40cm×3.5cm springboard is used and fully laid to ensure work safety, platform stability, and operability. The scaffolding has a horizontal span of 3m and a longitudinal step of 2.5m. A steel pipe needs to be added in the middle of the springboard. Before erecting the scaffolding, the position of the anchor rods must be laid out first to prevent conflicts with the scaffolding.

[0043] Step S7 includes the following steps performed in sequence: Prepare the soil-based mixture; the base material mixture is made of greening base material, fiber, and planting soil in a certain proportion; the greening base material is made of organic matter, soil structure improver and other materials, and the standard test is carried out according to the actual characteristics to select the mix ratio; the planting soil is the original surface soil of the project site or the nearby farmland soil, which is crushed through an 8mm sieve, and the water content is ≤20%. The air-dried and sieved planting soil should be waterproofed; the fiber is made of straw, branches, etc. on site, which is crushed into 10-15mm long, and the water content should be waterproofed, and the water content is ≤20%. The mix ratio of the base material mixture in this contract section is selected as greening base material: fiber: planting soil = 1:2:2 (volume ratio).

[0044] Selection of the thickness of the imported soil spraying: The thickness of the imported soil spraying should be about 10 to 12 cm according to the rock conditions of the slope of this contract section, the annual rainfall and the slope gradient of the excavation slope. The thickness of the spraying layer in the rock-fragmented and hard slope sections can be appropriately adjusted according to the actual situation.

[0045] Selection of plant seeds: According to the properties of the soil or rock surface of the construction surface, local climatic conditions, construction season, and in combination with the growth characteristics of various plants, select seeds of herbaceous plants, trees and shrubs with well-developed root systems, and increase the number of similar tree species on local construction surfaces with similar landforms, so that the secondary vegetation will gradually merge with the natural ecological vegetation in the next few years without showing any traces of artificial carving.

[0046] Additive soil spraying and maintenance management: Use a professional additive soil sprayer. After the equipment is in place, adjust the delivery pump pressure and air volume to spray the mixture evenly onto the slope. The additive soil is sprayed from top to bottom in two steps. The first spraying is 5 cm thick. After the additive soil stabilizes, spray it to the designed thickness. The thickness of the spray layer can be appropriately increased in sections with broken rock and hard slopes.

[0047] Maintenance management is to use 30g / m2 Cover the soil with non-woven fabric, spray water, replant, remove weeds and control pests and diseases in a timely and appropriate manner. When the seedlings grow to 5-6cm or 2-3 leaves, the non-woven fabric can be removed to ensure the normal growth of the seedlings. Maintenance management is divided into early and late maintenance. The early maintenance is about 60 days, mainly sprinkler irrigation, keep the soil moist frequently, and the late maintenance depends on natural rainwater. During the maintenance period, pay attention to the prevention and control of pests and diseases.

[0048] The principle of high slope excavation construction is to ensure the safety of construction and surrounding environment and the node construction period. The order and method of earth excavation must be consistent with the design conditions, strictly follow the theory of time and space effect, master the five key points of "layering, segmentation, block, symmetry, and time limit", and follow the principles of "vertical layering, horizontal zoning and segmentation, strictly prohibiting over-excavation, and timely slope protection after the bottom cushion layer of the high slope reaches the design elevation", to ensure rapid construction under the premise of project safety and quality, and reduce the exposure time after soil excavation.

[0049] During excavation, the vertical and horizontal slopes should be sloped with safe slopes according to geological and environmental conditions. The width of the exposed part of each excavation should be controlled within 3-6 meters, and the excavation depth of each layer should be controlled within 2.5-3 meters. It is strictly forbidden to excavate to the bottom at one time under one working condition. The material loading should be 6 meters away from the top edge of the high slope to prevent excessive lateral pressure. When excavating with longitudinal slope, a ditches or water retaining earth embankments should be set outside the top of the slope to prevent surface water from scouring the slope surface and drainage outside the high slope from flowing back into the pit to prevent slope collapse. After excavating the high slope, drainage ditches should be set in time to prevent water accumulation. During construction in the rainy season, the rainy season construction plan should be strictly implemented. When digging mechanically, a 300mm thick soil layer should be retained at the bottom layer and manually excavated and leveled to prevent over-excavation.

[0050] During the construction of concrete lattice beams, the anchor rods of concrete lattice beams are 30cm×30cm C30 reinforced concrete frame beams, and the node positions are anchor rods of Ф25×12000mm@2500*3000, and the anchor rods are grouted with M30 cement mortar. Expansion joints are set every 20m. The lattice beams are embedded in the slope surface 10cm, and the ground is sealed with 2cm thick M10 mortar, and 10cm of grass is sprayed.

[0051] Before construction, the three connections and one leveling work on the construction site must be completed, and the construction auxiliary roads such as access to the working surface have been built; all steel bars and sandstone materials have been tested and sampled; all construction machinery and tools have entered the site and meet the construction production requirements; all operators have entered the site and received technical briefing training; according to the needs of the project and the division of the project, technical personnel, management personnel and other personnel have been in place. After that, measurement and layout are carried out, and the re-measurement of each section after excavation has been completed. The excavated slope body is manually trimmed to meet the requirements of its slope ratio, and then the position of the frame longitudinal beam and cross beam and the starting range of construction are measured and laid out. When excavating the foundation, try to trim the slope as much as possible, flatten the protruding parts, and then accurately dig out the outline of a single beam rib according to the size of the frame vertical beam and cross beam and the thickness of the template. Among them, the lowest level slope platform has a grid slope foot foundation, which can be excavated after measurement and layout and acceptance by the supervisor. Then the steel bar binding is carried out, including the following contents: A. Before the construction and placement of the frame steel bars, first remove the floating slag at the bottom of the frame foundation to ensure the compactness of the foundation, and lay a layer of 1:3 cement mortar cushion at the bottom.

[0052] B. Drive short steel anchors into the slope and prepare mortar pads with the same thickness as the concrete protective layer.

[0053] C. Tie up the steel bars, pad them with mortar pads, keep a certain distance from the slope, and connect them firmly with the short steel bar anchors.

[0054] The template is re-erected, including the following: A. The template is assembled with wooden boards or bridge boards according to the design size. In curved sections, a control point is placed every 5 m for line construction to ensure that the line shape is smooth and meets the construction requirements.

[0055] B. Before erecting the formwork, first check the construction quality of the steel frame and make records, then erect the formwork.

[0056] C. Brush the mold release agent on the surface of the template. The template connection should be flat, tight, with accurate clearance dimensions, and meet design requirements and look beautiful.

[0057] D. Use scaffolding steel rods to support and fix the formwork. The bottom of the formwork should be in close contact with the foundation to prevent slurry leakage and formwork expansion.

[0058] E. Check the quality of the mold and keep original quality inspection records.

[0059] Finally, concrete pouring is carried out, which includes the following contents: Before pouring, check the cross-sectional dimensions of the frame, the number of steel bars and their arrangement; the thickness of the protective layer of the main reinforcement of the frame shall not be less than 50mm, the thickness of the net protective layer of the stirrups shall not be less than 35mm, and the net protective layer of the main reinforcement shall not be less than 40mm; the reinforcement is made into an integral long skeleton, and its production, lap joint and installation shall comply with the design and technical specifications; the pouring of the frame concrete shall be carried out continuously in the manner of pouring and vibrating, and the concrete of each vertical beam shall be poured continuously. If the pouring is interrupted for some reason, the joints shall be handled in the usual way. When there are signs of concrete sliding during the pouring process, quick-setting or early-strength concrete or cover mold pressing shall be used to deal with it. The concrete of each vertical beam shall be poured continuously. If the pouring is interrupted for some reason, the joints shall be handled in the usual way; the construction of the anchor frame is a process of close cooperation between the anchor and concrete frame. The relative position of the anchor rod and the frame is more important than their absolute position, and they must be accurately measured and positioned. When pouring frame concrete, one group of concrete specimens should be made at three locations from bottom to top for testing. C30 concrete should be used for pouring slope foot foundation concrete. During construction, a vibrating rod should be used to vibrate and compact it, and the top surface should be smoothed with a smoothing plaster.

[0060] Before proceeding to step S2, first repair the intercepting ditch on the top of the slope. During excavation, strictly measure and control the excavation of the slope, including positioning and slope rate, and excavate step by step using the step method. After each step is excavated, re-measure in time, repair in time, and construct system anchors and frame lattice beams in time. During the excavation and protection process, the slope should be covered with plastic sheeting at any time to prevent rain erosion. Prepare machines and equipment in advance and fully. Once the protection construction begins, sufficient labor must be organized to fully construct the entire first-level slope surface, and the supply and transportation of materials must keep up closely.

[0061] As one of the embodiments of the present invention, the high slope construction method disclosed is divided into several levels of slopes from the first level to the nth level according to the height, and the slopes of different levels are constructed from top to bottom. Excavation is carried out from the end of the highest elevation point to reduce the exposure time of the high slope soil. The excavation should be kept uniform and balanced so that the stress release during and after the soil excavation is uniform to ensure the safety of the high slope. Scientifically utilize the soil's own potential for controlling displacement, minimize the exposure time of each step of excavation without support, and reduce the displacement and deformation of the high slope. In order to reduce the range of soil disturbance during excavation and minimize the displacement and differential displacement of the soil around the high slope, when approaching the bottom layer of excavation, use a small excavator combined with manual soil repair methods to excavate in blocks and in a balanced manner, strengthen the observation of the surrounding environment, and adjust the excavation progress and working surface in time to ensure that the change values ​​of the high-variability horizontal displacement are within the allowable range.

[0062] For example, Figure 2 As shown in the figure, high slopes are divided into levels one to five according to their height. The following procedures are completed in sequence during the construction of the first level slope: A. Layout of monitoring control points, Repair the drainage ditch on the top of the slope. C. proceed to step S2, D. proceed to step S3; The following steps are completed in sequence during the construction of the second-level slope: A. Perform the first layer step S2, B. proceed to step S3, C. proceed to step S4, D. Perform the second layer step S2, E. Perform step S3 and repair the rapids ditch and drainage ditch. F. proceed to step S4, G. proceed to step S5; The third, fourth and fifth level slopes are constructed on the corresponding slopes using the same procedures as the second level slope. The first level has a height of 3 meters and the second level has a height of 6 meters.

Claims

1. A high slope construction method, characterized in that: The following steps are involved: S1. Measurement and setting out; S2, earthwork excavation; S3, slope trimming; S4, anchor engineering; S5, active network installation; S6. Scaffolding erection; S7, soil spraying and greening construction; Before step S2, the monitoring control points of the high slope are arranged; in step S6, the concrete lattice beam construction is carried out while the scaffolding is erected. The concrete lattice beam construction includes the following contents in sequence: manual excavation of the foundation trench, lattice beam binding, lattice beam formwork installation and lattice beam concrete pouring, and then step S7 soil spraying and greening construction is carried out.

2. A high slope construction method according to claim 1, characterized in that: Before performing step S2, the intercepting ditch on the top of the slope is first repaired.

3. A high slope construction method according to claim 1, characterized in that: The high slope is divided into several levels of slopes from the first level to the nth level according to the height, and the construction is carried out in sequence on the different levels of slopes from top to bottom.

4. A high slope construction method according to claim 3, characterized in that: The high slope is divided into the first to fifth levels according to the height. The following procedures are completed in sequence during the construction of the first level slope: A. arrangement of monitoring control points, B. repairing the intercepting ditch on the top of the slope, C. performing step S2, and D. performing step S3; the following procedures are completed in sequence during the construction of the second level slope: A. performing the first layer step S2, B. performing step S3, C. performing step S4, D. performing the second layer step S2, E. performing step S3, and repairing the rapids ditch and the drainage ditch, F. performing step S4, and G. performing step S5; the construction of the third, fourth and fifth level slopes adopts the same procedures as the second level slope construction on the corresponding slopes.

5. A high slope construction method according to claim 1, characterized in that: The concrete pouring process of the lattice beam is as follows: before pouring, the cross-sectional dimensions of the frame are checked, and the number and arrangement of the steel bars are checked; the protective layer thickness of the main reinforcement of the frame is not less than 50 mm, the net protective layer thickness of the stirrups is not less than 35 mm, and the net protective layer thickness of the main reinforcement is not less than 40 mm; the steel bars are made into an integral long skeleton; the pouring of the frame concrete is carried out continuously in a pouring and vibrating manner; when there is a sign of concrete sliding during the pouring process, quick-setting or early-strength concrete or a cover mold is used to press it down; C30 concrete is used for pouring concrete at the slope foot foundation.

6. A high slope construction method according to claim 1, characterized in that: The step S4 includes the following processes performed in sequence: determining the hole position, positioning the drilling rig, adjusting the angle, drilling, cleaning the hole, installing anchor rods and grouting; when drilling, continuing to drill steadily for 1 to 2 minutes after reaching the designed depth; when cleaning the hole, using high-pressure air with a wind pressure between 0.2 and 0.4 MPa to remove rock powder and water in the hole out of the hole.

7. A high slope construction method according to claim 6, characterized in that: The grouting adopts M30 cement mortar with a water-cement ratio of 0.5:1 and a cement-sand ratio of 1:

1. The cement used for grouting is 42.5 ordinary Portland cement, and the sand is silt sand. When grouting, grouting is first done from the bottom of the hole. When the cement mortar overflows from the hole mouth, the grouting is stopped. The construction adopts secondary grouting: the primary grouting pressure is not less than 2.0MPa, and the secondary grouting pressure is not less than 4.0MPa.

8. A high slope construction method according to claim 1, characterized in that: The step S7 includes the following processes performed in sequence: preparing the guest soil substrate mixture, selecting the thickness of the customer's spraying, selecting plant seeds, spraying the guest soil and maintenance management. The guest soil is sprayed from top to bottom in two times. The first spraying is 5 cm thick. After the guest soil is stable, it is sprayed to the designed thickness. The maintenance management is to cover the guest soil with 30g / m2 non-woven fabric after the sowing construction is completed, and spray water, replant, remove weeds and prevent and control pests and diseases in a timely and appropriate manner. When the seedlings grow to 5-6cm or 2-3 leaves, the non-woven fabric can be removed to ensure the normal growth of the seedlings.

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