CN110847224A

CN110847224A - Filling slope gravity retaining wall reinforcing structure and construction method thereof

Info

Publication number: CN110847224A
Application number: CN201911163322.7A
Authority: CN
Inventors: 胡建伟; 庞成立; 赵旭荣; 李青炜; 江宝庆; 陈学龙; 韩飞
Original assignee: Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
Current assignee: Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-02-28

Abstract

The invention provides a filling slope gravity retaining wall reinforcing structure and a construction method thereof. The reinforced structure comprises an original gravity type retaining wall, a soil filling side slope above the retaining wall, a high-pressure rotary spraying reinforcing body constructed in a foundation of the retaining wall, a lattice anchor rope supporting structure constructed on the retaining wall and a side slope reinforced structure constructed on the soil filling side slope. The invention carries out high-pressure jet grouting reinforcement treatment on the original retaining wall foundation, directly improves the bearing capacity of the retaining wall foundation, changes the passive protection of the original retaining wall into lattice pressure type anchor cable active protection, greatly improves the stability of the original retaining wall such as anti-overturning and anti-sliding, and can effectively control the displacement of the retaining wall; the upper filling side slope adopts the method that geogrids are laid in filling soil, the deformation condition of the soil body is improved and the engineering performance of the soil body is improved by utilizing the interaction between each layer of geogrids and the filling soil, so that the stability of the upper filling side slope is ensured, and the adverse effect of the upper filling soil on the original retaining wall can be effectively reduced.

Description

Filling slope gravity retaining wall reinforcing structure and construction method thereof

Technical Field

The invention relates to the field of slope reinforcement, in particular to a filled slope gravity retaining wall reinforcing structure and a construction method thereof.

Technical Field

The gravity type retaining wall maintains the stability of the retaining wall under the action of the soil pressure behind the wall by the self gravity of the retaining wall. Gravity retaining walls can be constructed of masonry or concrete and are generally made in a simple trapezoidal shape. For natural side slopes or building side slopes of ordinary height, the gravity retaining wall is a widely used protection or treatment mode. When the gravity retaining wall is applied to the support of building side slopes in warehouses, industrial factories or other sites, the requirement on the utilization rate of land in the site is high, the situation that the site is filled with soil and heightened behind the wall due to the change of the planning purpose of the site behind the wall sometimes happens, the filling side slope is formed above the original retaining wall, so that the stress condition of the original retaining wall is changed, and the foundation bearing capacity, the anti-overturning performance, the anti-sliding stability and the like of the original retaining wall cannot meet the current situation; and the bearing capacity requirement of the foundation at the bottom of the retaining wall is correspondingly improved by adopting a measure of heightening the original retaining wall, and the supporting effect has defects, so that an urgent problem is solved on how to reinforce the original retaining wall and how to process the filling side slope on the upper part of the retaining wall so as to ensure the stability of the original retaining wall and the filling side slope.

The prestressed anchor rod (cable) lattice beam frame is widely applied to various side slope supporting or reinforcing engineering in various industries such as traffic, metallurgy, water conservancy and the like as a mature side slope supporting form, the supporting form has the functions of reinforcing shallow rock-soil bodies and deep rock-soil bodies, although the reinforcing method has a certain effect of independently carrying out side slope treatment, the reinforcing method has higher requirement on bearing capacity due to the gravity type retaining wall, particularly fills a side slope on the retaining wall, the bearing capacity of the original retaining wall foundation and the anti-overturning and anti-sliding stability of the retaining wall are changed, and the simple prestressed anchor rod (cable) lattice beam frame cannot achieve the reinforcing effect. And the general prestressed anchor rod (cable) lattice beam frame adopts a tension type anchor rod (cable), the anchor rod (cable) enters the rock-soil body with a certain depth behind the original retaining wall, the cement slurry wrapped by the anchoring section of the anchor rod (cable) and the peripheral rock-soil body form a stable cohesive force, the free section of the anchor rod (cable) is anchored at the node of the lattice beam through pretension and concrete sealing, and forms a whole with the lattice beam frame, the anchoring force of the anchor rod (cable) anchoring section and the peripheral rock-soil body bears the soil pressure behind the retaining wall, and the displacement of the retaining wall is controlled through the pretension and locking of the free section. Because the grout body in the fixed section of the tension type anchor rod (cable) is in a tension state after the anchor rod is loaded in a working state, the tensile strength of the grout body is very low, a tension crack is easy to appear in slurry in the working state, and underground water is easy to permeate into the interior of the anchor rod through the crack, so that the long-term corrosion resistance of the body of the tension type anchor rod (cable) is poor, and the stress is uneven.

Disclosure of Invention

The invention provides a filling side slope gravity retaining wall reinforcing structure and a construction method thereof according to the defects of the prior art, the structure is suitable for the condition that the stability of the original retaining wall and the upper filling side slope is insufficient due to the fact that large-area filling is needed in site planning on the upper part of the original side slope gravity retaining wall reinforcing structure, the foundation bearing capacity of the original retaining wall can be directly improved, the stability of the original retaining wall such as overturning resistance and sliding resistance can be enhanced, the overall stability of the filling side slope can be enhanced, and the adverse effect of upper filling on the original retaining wall can be reduced.

In order to solve the above problems, the present invention provides a fill side slope gravity type retaining wall reinforcing structure, which comprises an original gravity type retaining wall and a fill side slope above the retaining wall, and is characterized in that: the reinforced structure also comprises a high-pressure jet grouting reinforced body constructed in the foundation of the retaining wall, a lattice anchor rope supporting structure constructed on the retaining wall and a side slope reinforced structure constructed in a soil filling side slope, wherein the high-pressure jet grouting reinforced body consists of a plurality of mutually meshed high-pressure jet grouting piles which are respectively guided into holes from the top and the wall toe of the retaining wall by a geological drilling machine and constructed in the foundation of the retaining wall; the lattice anchor cable supporting structure comprises a lattice beam frame paved on the surface of the retaining wall and a pressure type anchor cable arranged at the node of the lattice beam frame, wherein an anchoring section of the pressure type anchor cable is arranged in a rock-soil body on the rear side of the retaining wall, and a free section of the pressure type anchor cable is locked by tensioning and is fixed at the node of the lattice beam frame by adopting a concrete anchor sealing body; the side slope reinforcing structure comprises a geogrid reinforcing structure arranged in the filling side slope, a drainage blind ditch in the slope and ecological soil bags arranged on the slope surface of the filling side slope, wherein the geogrid reinforcing structure is formed by laying multiple layers of geogrids between filling in the filling process of the filling side slope, the laying direction of each layer of geogrid is perpendicular to a retaining wall, the drainage blind ditch in the slope is parallel to the side slope and is horizontally arranged, and the length reaches the position of a dynamic compaction rolling boundary.

The further technical scheme of the invention is as follows: the reinforced structure also comprises a slope top intercepting drain arranged on the top surface of the slope of the filled soil side and a slope bottom draining drain arranged on the slope bottom surface which is flush with the bottom edge of the retaining wall; the geogrid material adopts high-density polyethylene geogrids, the distance between every two adjacent geogrids is equal, and the geogrids are fixed through U-shaped nails; and reserving the width of 2.5-3.5 m from the geogrid to the side slope surface to serve as a reverse-wrapping slope surface of the ecological soil bag, and spraying and planting grass on the slope surface to form a plant protection slope surface.

The invention has the following excellent technical scheme: the high-pressure rotary jet grouting reinforcement body is constructed by adopting a separation hole, and a drill hole left in the retaining wall after the construction is finished is densely filled with cement paste or cement mortar; the width of the high-pressure rotary spraying reinforcement body is not less than the width of the retaining wall foundation plus 300mm multiplied by 2, the length of the high-pressure rotary spraying reinforcement body is equal to the length of the original retaining wall foundation plus 300mm multiplied by 2, and the depth of a reinforcement area is greater than 0.5 time of the width of the retaining wall foundation; the lapping width among the high-pressure jet grouting piles forming the high-pressure jet grouting reinforcement body is not less than 300 mm. The high-pressure jet grouting pile construction should adopt hole isolation construction, the drilling hole should be noticed to avoid a retaining wall drainage hole, and the drilling hole should be filled with cement paste or cement mortar to be compact after the high-pressure jet grouting reinforcement is completed.

The invention has the following excellent technical scheme: the lattice beam frame consists of horizontal lattice beams and longitudinal lattice beams which are tightly attached to the wall surface of the original gravity type retaining wall; the driving angle of the pressure type anchor cable is 10-15 degrees, the anchor cable steel strand in the anchoring section of the pressure type anchor cable is centered and fixed by a centering support, and the free section of the pressure type anchor cable is subjected to anti-corrosion treatment. After the anchor cable enters the original retaining wall, the rock-soil body is separated from the grout body by adopting a full-length non-cohesive prestressed steel strand, the load borne by the anchor cable is directly transmitted to the bearing plate at the bottom of the anchoring section through the steel strand, and the free section of the anchor cable is locked by tensioning and anchored at the node of the lattice beam by adopting C30 concrete. The lattice beam frame and the pressure type anchor cable form a whole, the bearing plate at the bottom of the anchor cable anchoring section is pressed to bear the soil pressure behind the original retaining wall, and the retaining wall is tensioned and locked to control the displacement of the retaining wall through the free section. The construction of the pressure anchor cable must be strictly carried out according to relevant specification and design requirements.

The invention has the following excellent technical scheme: the pressure type anchor rope includes cement grout body, spiral reinforcing frame, centering support, loading board and anchor rope steel strand wires, and the spiral reinforcing frame is installed in the cement grout body of 1 ~ 3m within range more than the loading board, and the pitch of its spiral reinforcing frame is 20 ~ 60mm, and the spiral reinforcing frame comprises many outer spiral muscle of indulging the muscle with the winding many, and the bottom of spiral reinforcing frame is fixed on the loading board to after forming cement grout body through once slip casting pipe and secondary slip casting pipe to the downthehole slip casting formation cement grout body of anchor rope, its cement grout body wraps up the spiral reinforcing frame completely.

The invention provides a construction method of a filling side slope gravity retaining wall reinforcing structure, which aims at the gravity retaining wall constructed by constructing the original retaining wall by rubble concrete or masonry and is characterized in that the method is suitable for the condition of filling a large area on the upper part of the original side slope gravity retaining wall, and the construction method comprises the following specific steps:

(1) adopting a high-pressure jet grouting pile to reinforce the foundation of the original retaining wall:

a. the technical staff sets out the plane position of high-pressure jet grouting pile according to the design drawing scene to and the depth of construction of high-pressure jet grouting pile, and its high-pressure jet grouting pile's design requirement is: the width of the high-pressure jet grouting reinforcement body is not less than the width of the retaining wall foundation plus 300mm multiplied by 2, the length of the high-pressure jet grouting reinforcement body is equal to the length of the original retaining wall foundation plus 300mm multiplied by 2, the depth of a reinforcement area is greater than 0.5 time of the width of the retaining wall foundation, and the lap joint width of two adjacent high-pressure jet grouting piles is not less than 300 mm;

b. the drilling machine is accurately positioned according to the design drawing, the machine is stably positioned, the vertical shaft, the rotary table and the hole site are aligned, the high-pressure equipment and the pipeline system meet the design and safety requirements, the pipeline is prevented from being blocked, and the sealing is good; drilling the drill rod right against the hole site to the designed depth, inserting the grouting pipe to the designed depth, lifting according to the requirements of the rotary spraying process, performing jet grouting while lifting, performing jet grouting from bottom to top, and enabling the overlap length of the grouting pipe lifted in sections to be not less than 0.1 m; the construction interval time of two adjacent piles can ensure that the pile body constructed firstly has certain stability and is not as high as that of the next pile constructed when the pile body is loosened and damaged, and hole separation construction is adopted in the construction;

c. after grouting, quickly pulling out the grouting pipe, and timely filling cement slurry with a water-cement ratio of 1.0-1.5 for a pit at the top of the pile;

(2) at original retaining wall construction lattice pressure type anchor rope, it is specifically from last to the segmentation construction of layering down, and the work progress is as follows:

a. determining the plane position of the anchor cable hole site according to a design drawing, and carrying out measurement paying-off, wherein the hole site error is not more than +/-50 mm;

b. erecting a construction platform, drilling an anchor hole by using a drilling machine, wherein the driving angle of the anchor hole is 10-15 degrees, the azimuth allowable error is +/-2.0 degrees, the inclination angle allowable error is +/-1.0 degrees, and the drilling depth exceeds the length of a designed anchor cable by 0.5-0.6 m; the installation of the drilling machine is required to be horizontal and stable, the drilling machine is required to be checked at any time in the drilling process, the requirements of the hole diameter and the hole depth of a drilled hole are not less than the design values, and the drilled hole depth is required to exceed the designed anchor cable length by about 0.5m in order to ensure the hole depth of the anchor cable;

c. preparing an anchor cable body, specifically comprising an anchor cable bearing plate, a spiral reinforcing frame with the diameter being 5-10mm smaller than that of the anchor cable bearing plate, an anchor cable steel strand with the surface coated with an anticorrosive protective paint and a centering support, wherein the centering support is arranged at an interval of 1-2 m; the spiral reinforcing frame of the anchor cable comprises spiral ribs, a plurality of longitudinal ribs and a plurality of circular reinforcing ribs, wherein the circular reinforcing ribs are welded on the inner sides of the longitudinal ribs to form a cylindrical reinforcing frame, the spiral ribs are spirally wound on the outer side of the cylindrical reinforcing frame, the spiral ribs are made of smooth round steel ribs with the diameter of 6-8mm, the longitudinal ribs are made of steel bars with the diameter of 10-14 mm, and the circular reinforcing ribs are made of smooth round steel ribs with the diameter of more than 10 mm; when the anchor cable is manufactured, rust removal is firstly carried out, the surface of the anchor cable steel strand is coated with anticorrosive protective paint, and the blanking length of the anchor cable steel strand is the sum of the designed length of the anchor cable, the height of an anchor head, the length of a jack, the thicknesses of a tool anchor and a working anchor and the stretching operation allowance; placing the anchor cable body containing the spiral reinforcing frame in the drill hole in the step b, forming grouting body through twice grouting, wherein the pressure of the first grouting is more than or equal to 0.5MPa, and the pressure of the second grouting is more than or equal to 2.0 MPa; the rod body is checked in detail before the anchor cable is installed, damaged protective layers, accessories and the like are repaired, and the force is uniformly applied in the pushing process so as to prevent the anchor cable accessories and the protective layers from being damaged in the pushing process;

d. constructing the lattice beam frame according to the following sequence: line measurement positioning → template installation → steel bar installation, anchor cable head installation → concrete pouring in the beam groove → form removal → maintenance;

e. after the strength of the concrete of the lattice beam frame reaches 80% of the designed strength grade, the grouting strength of the anchoring section of the anchor cable is more than 20MPa and reaches 80% of the designed strength grade, tensioning and locking the anchor cable, wherein the locking point is a node of the lattice beam frame, and after the anchor cable is tensioned and locked, the anchor cable is sealed and protected by concrete;

(3) after the retaining wall is reinforced in the step (2), filling a soil slope on the upper part of the original retaining wall, and synchronously reinforcing the soil slope:

a. according to design drawings and the situation of on-site soil texture, a foundation base is levelly filled, detailed measurement and positioning are carried out before excavation, an excavation line is marked, and the positioning and line-releasing position of the reverse ecological soil bag construction must be accurate and error-free; the method comprises the following steps of firstly, laying filler and geogrids on a foundation, wherein the geogrids and the filler are laid at intervals, the filler is compacted and leveled before the geogrids are laid each time, the geogrids cannot be overlapped, curled or bent, and cannot be in direct contact with hard corner filler, U-shaped nails are used for driving the filler into the filler layer to fix the geogrids, and the width larger than 3m is reserved when the geogrids are laid to serve as an ecological bag reverse-wrapping slope; in the construction position of the blind ditch in the slope in the process of laying the filler and the geogrid, reserving a width of 2m at the blind ditch of a construction drawing when laying the geogrid, fixing the joint of the blind ditch and the geogrid, building the side wall of the blind ditch by adopting dry masonry block stones with the building thickness of 200mm, laying a circle by adopting a layer of geotextile in the blind ditch, filling the blind ditch with broken stones, wherein the grain diameter is 20-40 mm, the broken stones are uniform in size, and the pores are clear so as to ensure smooth flowing water;

b. filling planting soil into the ecological bags and sealing, wherein the capacity of each bag is 2/3 of the bag volume, compacting, sealing and locking by using a serging machine, stacking and piling the ecological soil bags along the outer sides of the geogrids, and folding the tie bars back to form a stressed whole body by the geogrids and the ecological soil bags;

c. after the geogrids and the ecological soil bags are installed, soil is paved above the geogrids on the uppermost layer, and vibration type road rolling is adopted.

The invention has the following excellent technical scheme: in the step (1), when the jet grouting pile is constructed, a drilling machine is required to be placed and kept horizontal, a drill rod is kept vertical, and the inclination of the drill rod is not more than 1%; when lifting rotary injection grouting is carried out, rotating and injecting are carried out at the bottom of the pile for 1min, then rotating, lifting and injecting are carried out simultaneously, and during injection, a grouting pipe is gradually lifted after preset injection pressure and preset grouting amount are reached; the preset injection pressure of the high-pressure cement slurry is set to be more than 30MPa, the lifting speed is 0.1m/min, and the injection slurry adopts cement slurry with the water-cement ratio of 1.0-1.5.

The invention has the following excellent technical scheme: after the drilling in the step (2) is finished, pulling out the drill rod and the drilling tool one by one, adopting a polyethylene pipe to recheck the hole depth, cleaning rock powder and soil scraps in the hole, pulling out the polyethylene pipe when the hole depth is not less than the designed length of the anchor cable, and plugging the hole opening with fabric or cement bag paper for standby; rechecking the drilled hole before the anchor cable body is installed, timely cleaning collapsed holes and falling blocks, and checking the anchor cable; in the process of installing the anchor cable body, the pushing force of the anchor cable body is uniform, grouting is conducted upwards from the bottom of a hole, pure cement slurry is adopted as a grouting material, 42.5-grade ordinary portland cement is adopted as cement, the water cement ratio of the slurry is 0.45-0.5, and an expanding agent and an early strength agent are added into the slurry to ensure that the 28-day strength of the anchor cable body is not lower than 1 MPa.

The invention has the following excellent technical scheme: when the frame lattice beam is poured in the step (2), ensuring that the position of the axis of the anchor cable corresponds to the position of a frame node, arranging expansion joints at intervals of 20m on the frame lattice beam, wherein the width of each joint is 50mm, and filling the joints with asphalt reinforcement; and after the anchor cable is tensioned and locked, C30 concrete is used for sealing and protecting, and the thickness of the concrete protection is not less than 10 cm.

The invention has the following excellent technical scheme: in the step (3), the combination part of the filled slope and the undisturbed slope body is excavated into a step shape to increase interface friction, all tree roots, turf and humus soil in the paving range of the geogrid are excavated before construction, and detailed measurement and positioning are carried out before substrate excavation and an excavation line is marked; the backfill of the filling side slope does not contain tree roots, turf and other sundries, so that sharp objects or hard objects existing on the local part of the base are prevented from damaging the geogrid, each layer of the backfill is paved and leveled and then is rolled in time, the compaction process is carried out firstly by light and then by heavy, the operation is carried out firstly from the middle part of the geogrid and is gradually rolled to the tail part of the geogrid, and the backfill close to the slope surface within 15m is pressed by light by a small-sized machine after the slope surface; the specification, the length and the vertical spacing of the geogrids are determined according to relevant specification requirements and design calculation, the folding length of each layer of geogrid is not less than 1.5m (the top is not less than 2.5m and the width of a reverse soil bag is not included), the compaction degree of backfill fillers is detected before the next layer of geogrid is paved, the compaction degree is required to meet the design requirements for paving the next layer of geogrid, and meanwhile, the soil bags which are deformed or damaged in the backfilling and rolling process are timely processed.

The anchor cable disclosed by the invention adopts a specially-made spiral rib structure, and according to a Mander model calculation method, aiming at the grouting body of the pressure type anchor cable, on the premise that the cement is reduced by one grade level, the compressive strength of the cement grouting body can be improved by at least one grade, so that the aims of ensuring that the grouting body meets the design requirement within the range of 1-3 m above a bearing plate, preventing the grouting body from being crushed, improving the reliability of the grouting body, reducing the grade of the designed cement and reducing the construction cost are fulfilled.

The invention has the beneficial effects that:

(1) the original gravity type retaining wall supporting structure is reserved, high-pressure rotary spraying reinforcement treatment is carried out on the retaining wall foundation, and the bearing capacity of the retaining wall foundation is directly improved;

(2) the invention changes the passive protection of the original gravity retaining wall into the active protection of the lattice pressure type anchor cable, improves the stability of the original retaining wall and can effectively control the displacement of the retaining wall; the upper filling side slope adopts the method that geogrids are laid in filling soil, the deformation condition of the soil body is improved and the engineering performance of the soil body is improved by utilizing the interaction between each layer of geogrids and the filling soil, and the geogrids and the soil body in a side slope stabilizing area generate friction resistance to balance the thrust of a sliding area, so that the stability of the filling side slope is ensured;

(3) when the pressure type anchor cable works, the grout body of the fixed section is pressed, is not easy to crack, has good corrosion resistance, has uniform axial force and bonding stress on the anchoring length, and cannot generate gradual bonding and debonding phenomena, so that the stratum strength can be called to the maximum extent.

(4) According to the pressure type anchor cable, the principle that the spiral reinforcing frame restrains cement slurry is utilized, the phenomenon that the grout body near the pressure type anchor cable bearing plate is easily crushed can be effectively solved, meanwhile, the compressive strength of the grout body within the range of 1-3 m above the pressure type anchor cable bearing plate can be obviously improved, the reliability is improved, on the premise that the design requirement is met, the used cement mark number is reduced, and the engineering cost is saved.

(5) The invention effectively solves the problems that the stability of the original retaining wall and the filled side slope is insufficient due to large-area filling on the upper part of the retaining wall and the heightening and supporting effect of the original retaining wall has defects by utilizing the original retaining wall supporting structure, does not need to dismantle the original retaining wall, avoids the risk of side slope instability caused by dismantling engineering, saves the reinforcing cost and the construction period, is ecological and environment-friendly, and is worthy of popularization and application for the side slope reinforcing engineering.

The invention ensures the stability of the original retaining wall and the filling side slope by adopting high-pressure jet grouting reinforcement treatment on the foundation of the original gravity retaining wall at the lower part, integral reinforcement of the lattice anchors and reinforced soil reinforcement on the filling side slope at the upper part, thereby improving the foundation bearing capacity of the original retaining wall, enhancing the stability of the original retaining wall such as anti-overturning, anti-sliding and the like, enhancing the integral stability of the filling side slope and effectively reducing the adverse effect of the filling soil at the upper part on the original retaining wall. The problem of gravity type barricade upper portion large tracts of land fill lead to original barricade and fill slope stability not enough and increase original barricade and have the effect of strutting defect is solved effectively.

Drawings

FIG. 1 is a schematic cross-sectional view of the original retaining wall of the present invention;

FIG. 2 is a schematic cross-sectional view of a reinforcing structure of the present invention;

FIG. 3 is a schematic front view of a reinforcing structure of the present invention;

FIG. 4 is a schematic view of the high pressure jet grouting reinforcement retaining wall foundation of the present invention;

FIG. 5 is a schematic view of a lattice anchor cable construction of the present invention;

FIG. 6 is an enlarged view of portion B of FIG. 5 in accordance with the present invention;

FIG. 7 is a cross-sectional view of a cable centering bracket according to the present invention;

FIG. 8 is a schematic view of the construction of the cable bolt helical reinforcement of the present invention;

FIG. 9 is a flow chart of a construction process for treating a retaining wall foundation by high-pressure jet grouting reinforcement in an embodiment;

FIG. 10 is a flow chart of a construction process of a lattice beam of a prestressed anchor cable in an embodiment;

FIG. 11 is a flow chart of a reinforced earth construction process of an upper fill side slope in the embodiment.

In the figure: 1-retaining wall, 1-retaining wall foundation, 2-high pressure jet grouting reinforcement, 2-1-high pressure jet grouting guide hole, 2-high pressure jet grouting pile, 3-pressure type anchor cable, 3-1-anchor cable grouting body, 3-2-spiral reinforcement frame, 3-centering isolation support, 3-4-bearing plate, 3-5-clamping piece, 3-6-secondary grouting pipe, 3-7-anchor cable steel strand, 3-8-primary grouting pipe, 4-lattice beam frame, 4-1 horizontal lattice beam, 4-2-longitudinal lattice beam, 5-rear rock-soil body, 6-original slope line, 7-drainage blind ditch, 8-geogrid reinforcement structure, 9-ecological soil bag, 10-U-shaped nail, 11-plant slope protection surface, 12-slope top intercepting ditch, 13-slope bottom drainage ditch, 14-filling soil, 15-slope top surface, 16-slope bottom surface, 17-concrete anchor sealing body, 17-1-anchor, 17-2-steel backing plate, 17-3-PVC sleeve, 17-4-anchor sealing concrete, and 18-step-shaped dynamic compaction rolling boundary.

Detailed Description

The invention is further illustrated with reference to the following figures and examples. The invention is further illustrated by the following figures and examples. Fig. 2 to 7 are drawings of the embodiment, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating the embodiment of the present invention. The following claims presented in the drawings are specific to embodiments of the invention and are not intended to limit the scope of the claimed invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "inside", "outside", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships that the products of the present invention are conventionally placed in use, or the orientations or positional relationships that are conventionally understood by those skilled in the art, and are used for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

The gravity type retaining wall reinforcing structure for the fill side slope provided by the embodiment of the invention comprises an original gravity type retaining wall 1 and a fill side slope 14 arranged above the retaining wall 1, wherein the retaining wall 1 is made of rubble concrete or masonry, and the reinforcing structure further comprises a slope top intercepting ditch 12, a slope bottom drainage ditch 13, a high-pressure jet grouting reinforcing body 2 constructed in a retaining wall foundation 1-1, a lattice anchor rope supporting structure constructed on the retaining wall 1 and a side slope reinforcing structure constructed on the fill side slope 14. As shown in fig. 2 to 4, the high-pressure jet grouting reinforcement body 2 is composed of a plurality of mutually engaged high-pressure jet grouting piles 2-2 which are respectively guided from the top and the toe of the retaining wall 1 to the inner side of the foundation 1-1 of the retaining wall by a geological drilling rig; the high-pressure rotary spraying reinforcing body 2 is constructed by adopting a separation hole, and a high-pressure rotary spraying leading hole 2-1 left on the retaining wall 1 after the construction is finished is densely filled with cement paste or cement mortar; the width of the high-pressure rotary spraying reinforcement body 2 is not less than 1-1 width of the retaining wall foundation +300mm multiplied by 2, the length is equal to the length of the original retaining wall foundation 1-1 +300mm multiplied by 2, and the depth of the reinforcement area is more than 0.5 time of the width of the retaining wall foundation 1-1; the lapping width among the high-pressure jet grouting piles forming the high-pressure jet grouting reinforced body 2 is not less than 300 mm.

In the embodiment of the slope gravity type retaining wall reinforcing structure with fill, as shown in fig. 2 to 3, the lattice anchor cable supporting structure includes a lattice beam frame 4 laid on the surface of the retaining wall 1 and pressure type anchor cables 3 arranged at the nodes of the lattice beam frame 4, the anchoring sections of the pressure type anchor cables 3 are arranged in the rock-soil mass 5 at the rear side of the retaining wall 1, and the free sections are locked by tension and fixed at the nodes of the lattice beam frame 4 by using concrete anchor sealing bodies 17. The lattice beam frame 4 consists of horizontal lattice beams 4-1 and longitudinal lattice beams 4-2 which are tightly attached to the wall surface of the original gravity type retaining wall 1. The driving angle of the pressure type anchor cable 3 is 10-15 degrees, as shown in figure 5, the pressure type anchor cable 3 comprises a cement grouting body 3-1, a spiral reinforcing frame 3-2, a centering bracket 3-3, a bearing plate 3-4 and anchor cable steel strands 3-7, the spiral reinforcing frame 3-2 is arranged in the cement grouting body 3-1 within the range of 1-3 m above the bearing plate 3-4, the bottom of the spiral reinforcing frame is fixed on the bearing plate 3-4, the anchor cable steel strands 3-7 in the anchoring section of the pressure type anchor cable 3 are centered and fixed by the centering bracket 3-3, the free section of the pressure type anchor cable 3 is subjected to anticorrosion treatment, after grouting is carried out in the anchor cable hole through the primary grouting pipe 3-8 and the secondary grouting pipe 3-6 to form cement grouting body 3-1, the spiral reinforcing frame 3-2 is completely wrapped by the cement grouting body 3-1; as shown in fig. 6, the spiral reinforcing frame 3-2 is composed of a plurality of longitudinal ribs and spiral ribs wound outside the longitudinal ribs, the thread pitch is 20-60 mm, and the spiral reinforcing frame 3-2 is composed of a plurality of longitudinal ribs and spiral ribs wound outside the longitudinal ribs. According to the method for calculating the spiral rib structure in the embodiment of the invention, aiming at the grouting body 3-1 of the pressure type anchor rope, on the premise that the cement is reduced by one label grade, the compressive strength of the grouting body 3-1 can be improved by at least one cement label, and the grouting body 3-1 meets the design requirement within the range of 1-3 m above a bearing plate 3-4, is not crushed, improves the reliability of the grouting body 3-1, reduces the design cement label and reduces the engineering cost.

In the embodiment of the reinforced structure of the gravity retaining wall for fill side slopes, as shown in fig. 2 to 3, the reinforced structure for fill side slopes comprises geogrid reinforced structures 8 arranged in fill side slopes 14, drainage blind ditches 7 in the slopes and ecological soil bags 9 arranged on slope surfaces of the fill side slopes 14, the geogrid reinforced structures 8 are formed by multiple layers of geogrids laid between fills in the filling process of the fill side slopes 14, the geogrid reinforced structures 8 are made of high-density polyethylene geogrids, the distance between two adjacent layers of geogrids is equal, the geogrids are fixed through U-shaped nails, the width of 2.5-3.5 m from the geogrids to the slope surfaces is reserved as reverse-wrapping slope surfaces of the ecological soil bags, and plants are sown on the slope surfaces to form plant protection surface; the specification, length and vertical spacing of the geogrids are determined according to relevant specification requirements and design calculation, and the laying direction of each layer of geogrid is perpendicular to the retaining wall 1. The drainage blind ditches 7 in the slope are parallel to the slope of the slope and are horizontally arranged, the drainage blind ditches 7 are parallel to the slope and tend to be horizontally arranged, and the length of the drainage blind ditches reaches the step-shaped dynamic compaction and rolling boundary 18. The side wall of the drainage blind ditch 7 is built by dry building blocks, the thickness of the drainage blind ditch is 200mm, a layer of geotextile is paved in the drainage blind ditch for one circle, broken stones are filled in the drainage blind ditch 7, the particle size is 20-40 mm, the size of the broken stones is uniform, and pores are clear so as to ensure smooth flowing water.

The concrete construction process of the reinforced structure is further explained by combining the concrete examples, the concrete implementation of the embodiment is carried out for reinforcing a certain filled side slope retaining wall, and the engineering overview is as follows: the site is positioned in a cement plant in Puer city, the original section of building side slope is about 120m long and about 6.5m high, a gravity retaining wall is built as a support, the retaining wall is made of rubble concrete and a concrete foundation is built; as shown in figure 1, a 3m wide platform is left on the wall upper field, a gentle slope (the slope ratio is about 1:5) is placed backwards, the soil of the slope body is plastic-soft plastic powdery clay, and the slope is in a stable state.

Due to the fact that facilities in a plant area are modified and the site planning purpose is changed, earth needs to be backfilled on the upper portion of the original retaining wall of the section of side slope, the backfilling height is about 5m, and the backfilling width is about 20 m. Therefore, a filling side slope is formed above the original retaining wall, so that the stress condition of the original retaining wall is changed, and the foundation bearing capacity, the anti-overturning performance, the anti-sliding stability and the like of the original retaining wall cannot meet the current situation; and the foundation bearing capacity of the original retaining wall is not satisfied by adopting a measure of heightening the original retaining wall, so that an urgent engineering problem is formed on how to reinforce the original retaining wall and how to treat the filling side slope on the upper part of the retaining wall so as to ensure the stability of the original retaining wall and the filling side slope.

The designer comprehensively considers factors such as supporting effect, economy, time limit for a project progress and ecological environmental protection, decides to adopt and carries out high pressure jet grouting reinforcement to the original barricade of lower part and handle the barricade foundation, the whole reinforcement of lattice anchor and the stability of upper portion fill side slope adoption reinforced earth reinforcement assurance original barricade and upper portion fill side slope, and its specific work progress is as follows:

(1) firstly, carrying out high-pressure jet grouting reinforcement treatment on a retaining wall foundation, adopting an XP-30B type triple-pipe jet grouting pile machine for operation, leading holes of an XY-150 geological drilling machine, wherein the diameter of a high-pressure jet grouting pile is 800mm, the pile spacing is 500mm, the construction process is shown in figure 9, and the specific construction steps are as follows:

a. a technician sets out the plane position of the high-pressure jet grouting pile 2-2 on site according to a design drawing;

b. positioning a drilling machine: the drill rig is accurately positioned, the drill rig is required to be placed and kept horizontal, the drill rod is required to be kept vertical, and the inclination of the drill rod is not more than 1%. The machine is stable in position, the vertical shaft, the rotary table and the hole site are aligned, the high-pressure equipment and the pipeline system meet the design and safety requirements, the pipeline is prevented from being blocked, and the sealing is good;

c. after drilling to the designed depth, lifting while spraying and grouting, according to the requirements of rotary spraying (the solidified body is cylindrical), spraying and grouting from bottom to top, wherein the overlap length of the grouting pipe lifted in sections is not less than 0.1 m; in the drilling construction process, after the water jet test, the drill can be started, the water jet pressure is gradually increased, the friction resistance is reduced, and the nozzle is prevented from being blocked; the construction interval time of two adjacent piles can ensure that the pile body constructed firstly has certain stability and is not as high as that of the next pile constructed when the pile body is loosened and damaged, and hole separation construction is adopted in the construction; the injection grouting is carried out by paying attention to the starting sequence of equipment, firstly rotating and injecting for 1min at the bottom of the pile, and then rotating, lifting and injecting simultaneously; when spraying, the grouting pipe is gradually lifted after the preset spraying pressure and spraying amount are reached, the pressure of the high-pressure cement slurry is set to be more than 30MPa, the lifting speed is 0.1m/min, and the water-cement ratio is 1.0;

d. after grouting, the grouting pipe is pulled out quickly, and the pit at the top of the pile is timely filled with cement paste with the water cement ratio of 1.0.

(2) Aiming at an original retaining wall 1 at the lower part, a lattice beam frame 4 and a special pressure type anchor cable 3 are arranged to form an integral lattice anchor cable supporting structure, the hole diameter of a drilled anchor cable is 150mm, the inclination angle of the drilled hole is 10 degrees, the total length of the anchor cable is 15m, an anchoring section is 9m, a YMS-4S15.2 steel strand is adopted, the designed anchoring force Fd is 240kN, the locking value Fl is 180kN, and the transverse and vertical distances are 2.5 m; the retaining wall 1 is provided with 3 rows in the height direction, the size of each truss of reinforced concrete lattice beams is 2.5 multiplied by 2.5m, the size of the cross section of the lattice beam is 400 multiplied by 400mm, the construction process flow is shown in figure 10, and the concrete construction steps are as follows:

b. a construction platform is erected, a proper drilling machine and a drilling mode are selected, the position of the drilling machine is strictly adjusted after the drilling machine is in place, the drilling direction and the inclination angle of the anchor cable meet the design requirements, the azimuth allowable error is +/-2.0 degrees, the inclination angle allowable error is +/-1.0 degrees, the installation requirement of the drilling machine is horizontal and stable, the drilling process is checked at any time, the requirements of the hole diameter and the hole depth of the drilled hole are not less than the design values, and the drilling depth is required to exceed the designed anchor cable length by about 0.5m in order to ensure the hole depth of the anchor;

c. after drilling, pulling out the drill rod and the drilling tool one by one, cleaning the impacter for later use, rechecking the hole depth by using a polyethylene pipe, blowing the hole by using high-pressure wind, pulling out the polyethylene pipe when dust in the hole is completely blown and the hole depth is not less than the designed length of the anchor cable, and plugging the hole opening by using fabric or cement bag paper for later use;

d. preparing an anchor cable spiral reinforcing frame 3-2, wherein the reinforcing frame comprises spiral ribs, a plurality of longitudinal ribs and a plurality of circular reinforcing ribs, the circular reinforcing ribs are welded on the inner layers of the longitudinal ribs to form a cylindrical reinforcing frame, and the spiral ribs are spirally wound on the outer side of the cylindrical reinforcing frame; the spiral ribs are made of smooth round ribs with the diameter of 6-8mm, the longitudinal ribs are made of steel bars with the diameter of 10-14 mm, the round reinforcing ribs are made of smooth round ribs with the diameter larger than 10mm, the spiral diameter of the spiral reinforcing frame 3-2 is determined according to the anchor cable bearing plate 3-4, the spiral diameter is 5-10mm smaller than the diameter of the bearing plate 3-4, and then the diameter of the round reinforcing ribs is determined according to design drawings; when the anchor cable rod body is manufactured, rust removal is firstly carried out, anticorrosion protective paint is coated on the surfaces of 3-7 anchor cable steel strands, in order to enable the 3-7 steel strands to be centered in an anchor hole, a pair of centering supports 3-3 are arranged at intervals of 1.5m, and the blanking length of the anchor cable steel strands is the sum of the designed length of the anchor cable, the height of an anchor head, the length of a jack, the thicknesses of a tool anchor and a working anchor and the stretching operation allowance;

e. the method comprises the following steps of (1) reexamining a drilled hole before the anchor cable body is installed, cleaning when hole collapse and block falling are found, carrying out detailed examination on the anchor cable body, repairing damaged protective layers, accessories and the like, placing the prepared anchor cable body with the spiral reinforcing frame 3-2 into the drilled hole, and uniformly applying force in the pushing process so as to prevent the anchor cable accessories and the protective layers from being damaged in the pushing process;

f. the anchor cable grouting is preferably carried out by adopting a secondary grouting process, the primary grouting pressure is more than or equal to 0.5MPa, the secondary grouting pressure is more than or equal to 2.0MPa, and the grouting must be carried out from the bottom of the hole upwards; the grouting material is pure cement slurry, the cement is 42.5-grade ordinary portland cement, the water cement ratio of the slurry is 0.45-0.5, in order to accelerate the construction progress and ensure the grouting quality, a certain amount of expanding agent and early strength agent are added into the slurry, and the strength of the slurry in 28 days is not lower than 1 MPa;

g. the construction sequence of the reinforced concrete lattice beam frame 4 is as follows: line measurement positioning → template installation → steel bar installation, anchor cable head installation → concrete pouring in the beam groove → form removal → maintenance; when the frame lattice beam 4 is poured, reliable measures are taken to ensure that the position of the axis of the anchor cable corresponds to the position of a frame node, the lattice beam is provided with expansion joints every 20m, the width of each joint is 50mm, and the joints are filled with asphalt reinforcement;

h. after the strength of the lattice beam concrete reaches 80% of the designed strength grade, the grouting strength of the anchor cable anchoring section is more than 20MPa and reaches 80% of the designed strength grade, tensioning and locking the anchor cable can be carried out; and after the anchor cable is tensioned and locked, C30 concrete is used for sealing and protecting, and the thickness of the concrete protection is not less than 10 cm.

(3) Reinforced earth is adopted for reinforcing the upper filling side slope of the original retaining wall 1, the type of the geogrid is EM4, and the unit mass is 350g/m²Thickness of not less than 14mm, longitudinal directionThe tensile strength is more than or equal to 2 kN/m. The length of the geogrid in the direction of the vertical slope surface of the side slope is 15m, the vertical distance is 0.5m, the construction process is shown in figure 11, and the specific construction steps are as follows:

a. original ground cleaning and foundation tamping: according to a design drawing and the condition of on-site soil texture, leveling and filling a foundation, excavating an original side slope, backfilling filler, and excavating a joint part of the filler and an original slope body into a step shape as shown in figure 2 so as to increase interface friction; in order to prevent sharp objects or hard objects existing on the local part of the substrate from damaging the geogrid, all tree roots, turf and humus soil in the paving range of the geogrid are dug out before construction, detailed measurement and positioning are carried out before the substrate is dug out, digging lines are marked out, and the construction positioning and paying-off positions of the reverse-wrapped ecological soil bags 9 must be accurate and error-free;

b. laying a geogrid reinforcing structure 8: the geogrid is laid on the compacted and leveled filler, and cannot be overlapped, curled or bent, or directly contacted with the hard corner filler; in order to avoid disturbance to the geogrid during the spreading and rolling of the filler, U-shaped nails 10 are adopted to drive the filler layer for geogrid fixation, and the width of more than 3m is reserved as a reverse slope of an ecological bag 9 when each layer of geogrid is laid; the specification, length and vertical spacing of the geogrid are determined according to relevant specification requirements and design calculation, and the folding length is not less than 1.5m (the top is not less than 2.5m, and the width of the soil turning bag 9 is not included);

c. filling and installing an ecological soil bag 9: planting soil is filled into the ecological bags and sealed, the volume of each bag is 2/3 of the volume of the bag, the ecological bags are compacted and then sealed and locked by an edge locking machine; stacking and building the ecological soil bags 9 along the outer sides of the geogrids, folding the tie bars back, and fixing the tie bars by using special plastic sewing rods to enable each layer of geogrids and the ecological soil bags 9 to form a stressed whole;

d. spreading and compacting the filler: the filler must not contain tree roots, turf and other impurities. Each layer of filler is rolled in time after being paved flatly, soil is paved on the geogrid according to the specified thickness, and the lower layer of filler is leveled and compact during paving and cannot be in direct contact with the hard sharp-edged granules; generally, a vibration type road roller is adopted, rolling is carried out firstly by light and then by heavy, the operation is generally carried out from the middle part of the geogrid, the geogrid is gradually rolled to the tail part of the geogrid, the filling material within a range of 15m close to the slope surface is pressed by light by a small machine after the slope surface, disturbance to the slope surface is avoided, the geogrid at the topmost layer is long enough and is buried under the filling soil, and the filling soil can provide enough constraint force to be permanently anchored;

e. checking the compaction degree of the backfill soil and the ecological bags: before the next geogrid paving, the backfill filler needs to be subjected to compactness detection, the compactness meets the design requirement, the slope of the ecological soil bag 9 is checked, and the soil bag deformed or damaged in the backfill rolling process is timely processed.

f. And (3) drainage engineering: when the geogrid 8 is constructed and laid, reserving the width of 2m at the position of the drainage blind ditch 7 for construction of the drainage blind ditch 7 according to a design drawing of the drainage blind ditch 7, and fixing the joint of the drainage blind ditch 7 and the geogrid; the side wall of the drainage blind ditch 7 is built by dry building blocks with the thickness of 200mm, a layer of geotextile is paved for a circle in the drainage blind ditch 7, and broken stones are filled in the drainage blind ditch 7, wherein the particle size is 20-40 mm. The broken stones should be uniform in size and the pores should be clear so as to ensure smooth running water.

The original gravity type retaining wall supporting structure is reserved, high-pressure rotary spraying reinforcement treatment is carried out on the retaining wall foundation, the bearing capacity of the retaining wall foundation is improved, passive protection of the original retaining wall is changed into lattice prestressed anchor cable active protection, the stability of the original retaining wall such as overturning resistance and slippage resistance is greatly improved, and the displacement of the retaining wall can be effectively controlled; the upper filling side slope adopts the geogrids laid in filling soil, the deformation condition of the soil body is improved and the engineering performance of the soil body is improved by utilizing the interaction between each layer of geogrids and the filling soil, and the geogrids and the soil body in the side slope stabilizing area generate friction resistance to balance the thrust of the sliding area, so that the stability of the upper filling side slope is ensured, and the adverse effect of the upper filling soil on the original retaining wall can be effectively reduced. The structure and the construction method of the invention have better supporting effect, and long-term monitoring shows that the displacement or deformation values of the original retaining wall and the upper filling side slope are within the allowable range of design and specification.

The invention effectively solves the problems that the stability of the original retaining wall and the filling side slope is insufficient due to large-area filling of the upper part of the gravity retaining wall and the supporting effect defect exists when the original retaining wall is heightened, the original retaining wall does not need to be dismantled, the risk of side slope instability caused by dismantling engineering is avoided, the reinforcing cost and the construction period are saved, the ecological environment is protected, and the method is worthy of popularization and application for the slope retaining wall reinforcing engineering of the type of filling.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only for the purpose of illustrating the structural relationship and principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a fill side slope gravity retaining wall reinforced structure, includes the side slope (14) of filling soil of original gravity retaining wall (1) and retaining wall (1) top, its characterized in that: the reinforced structure also comprises a high-pressure jet grouting reinforced body (2) constructed in the retaining wall foundation (1-1), a lattice anchor rope supporting structure constructed on the retaining wall (1) and a slope reinforced structure constructed on a filling slope (14), wherein the high-pressure jet grouting reinforced body (2) consists of a plurality of mutually-meshed high-pressure jet grouting piles (2-2) which are respectively guided from the top and the wall toe of the retaining wall (1) to the retaining wall foundation (1-1) by a geological drilling machine; the latticed anchor cable supporting structure comprises a latticed beam frame (4) paved on the surface of the retaining wall (1) and pressure type anchor cables (3) arranged at nodes of the latticed beam frame (4), wherein anchoring sections of the pressure type anchor cables (3) are arranged in rock-soil bodies (5) on the rear side of the retaining wall (1), and free sections of the pressure type anchor cables are locked by tensioning and fixed at the nodes of the latticed beam frame (4) by adopting concrete sealing anchor bodies (17); the side slope reinforcing structure comprises a geogrid reinforcing structure (8) arranged in a filling side slope (14), a drainage blind ditch (7) in the slope and ecological soil bags (9) arranged on the slope of the filling side slope (14), wherein the geogrid reinforcing structure (8) is formed by laying multiple layers of geogrids between filling soil in the filling process of the filling side slope (14), the laying direction of each layer of geogrid is perpendicular to the retaining wall (1), and the drainage blind ditch (7) in the slope is parallel to the slope and is horizontally arranged.

2. The fill slope gravity retaining wall reinforcing structure of claim 1, wherein: the reinforced structure also comprises a slope top intercepting ditch (12) arranged on the top surface (15) of the filled side slope and a slope bottom drainage ditch (13) arranged on the bottom surface (16) of the side slope which is flush with the bottom edge of the retaining wall (1); the geogrid reinforcing structure (8) adopts high-density polyethylene geogrids, the distance between every two adjacent geogrids is equal, and the geogrids are fixed through U-shaped nails (10); and reserving the width of 2.5-3.5 m from the slope surface of each layer of geogrid to serve as a reverse-covered slope surface of the ecological soil bag (9), and spraying and planting grass on the slope surface to form a plant protection surface (11).

3. A fill slope gravity retaining wall reinforcing structure according to claim 1 or 2, wherein: the high-pressure rotary-spraying reinforcing body (2) is constructed by adopting a separation hole, and a high-pressure rotary-spraying guide hole (2-1) left on the retaining wall (1) after the construction is finished is densely filled with cement paste or cement mortar; the width of the high-pressure rotary spraying reinforcement body (2) is not less than the width of the retaining wall foundation (1-1) plus 300mm multiplied by 2, the length is the length of the original retaining wall foundation (1-1) plus 300mm multiplied by 2, and the depth of a reinforcement area is more than 0.5 time of the width of the retaining wall foundation (1-1); the lapping width among the high-pressure rotary spraying piles (2-2) forming the high-pressure rotary spraying reinforcing body (2) is not less than 300 mm.

4. A fill slope gravity retaining wall reinforcing structure according to claim 1 or 2, wherein: the latticed beam frame (4) consists of a horizontal latticed beam (4-1) and a longitudinal latticed beam (4-2) which are tightly attached to the wall surface of the original gravity type retaining wall (1); the driving angle of the pressure type anchor cable (3) is 10-15 degrees, the anchor cable steel strand wires (3-7) in the anchoring section of the pressure type anchor cable (3) are centered and fixed by the centering supports (3-3), and the free section of the pressure type anchor cable (3) is subjected to anti-corrosion treatment.

5. A fill slope gravity retaining wall reinforcing structure according to claim 1 or 2, wherein: the pressure type anchor cable (3) comprises a cement grouting body (3-1), a spiral reinforcing frame (3-2), a centering support (3-3), a bearing plate (3-4) and anchor cable steel strands (3-7), wherein the spiral reinforcing frame (3-2) is arranged in the cement grouting body (3-1) within the range of 1-3 m above the bearing plate (3-4), the thread pitch of the spiral reinforcing frame (3-2) is 20-60 mm, the spiral reinforcing frame (3-2) consists of a plurality of longitudinal ribs and spiral ribs wound outside the plurality of longitudinal ribs, the bottom of the spiral reinforcing frame (3-2) is fixed on the bearing plate (3-4), and after the cement grouting body (3-1) is formed by grouting into an anchor cable hole through a primary grouting pipe (3-8) and a secondary grouting pipe (3-6), the spiral reinforcing frame (3-2) is completely wrapped by the cement grouting body (3-1).

6. A construction method of a filling slope gravity type retaining wall reinforcing structure aims at the gravity type retaining wall formed by constructing rubble concrete or masonry on the original retaining wall, and is characterized in that the method is suitable for the condition of large-area filling on the upper portion of the original slope gravity type retaining wall, and the concrete construction steps are as follows:

a. the technical personnel can determine the construction depth of the high-pressure jet grouting pile according to the plane position of the high-pressure jet grouting pile which is set out on the site of the design drawing, and the design requirement of the high-pressure jet grouting pile is as follows: the width of the high-pressure jet grouting reinforcement body is not less than the width of the retaining wall foundation plus 300mm multiplied by 2, the length of the high-pressure jet grouting reinforcement body is equal to the length of the original retaining wall foundation plus 300mm multiplied by 2, the depth of a reinforcement area is greater than 0.5 time of the width of the retaining wall foundation, and the lap joint width of two adjacent high-pressure jet grouting piles is not less than 300 mm;

b. accurately positioning a drilling machine according to a design drawing, drilling a drill rod to the designed depth just opposite to a hole site, inserting a grouting pipe to the designed depth, lifting while performing jet grouting according to the requirements of a rotary jet process, wherein the overlap length of the sectional lifting of the grouting pipe is not less than 0.1m, and adopting hole separation construction in construction;

b. erecting a construction platform, drilling an anchor hole by using a drilling machine, wherein the driving angle of the anchor hole is 10-15 degrees, the azimuth allowable error is +/-2.0 degrees, the inclination angle allowable error is +/-1.0 degrees, and the drilling depth exceeds the length of a designed anchor cable by 0.5-0.6 m;

c. preparing an anchor cable body, specifically comprising an anchor cable bearing plate, a spiral reinforcing frame with the diameter being 5-10mm smaller than that of the anchor cable bearing plate, an anchor cable steel strand with the surface coated with an anticorrosive protective paint and a centering support, wherein the centering support is arranged at an interval of 1-2 m; placing the anchor cable body containing the spiral reinforcing frame in the drill hole in the step b, forming grouting body through twice grouting, wherein the pressure of the first grouting is more than or equal to 0.5MPa, and the pressure of the second grouting is more than or equal to 2.0 MPa;

a. according to design drawings and on-site soil conditions, leveling and filling a foundation, paving filler and geogrids on the foundation, paving the geogrids and the filler at intervals, compacting and leveling the filler before paving the geogrids each time, driving U-shaped nails into the filler layer to fix the geogrids, and reserving the width larger than 3m as an ecological bag reverse-wrapping slope surface when paving the geogrids; reserving the construction position of the blind ditch in the slope in the process of laying the filler and the geogrid, building the blind ditch in the slope by using dry building blocks and stones, and filling broken stones with the particle size of 20-40 mm in the blind ditch;

7. The method of claim 6, wherein the step of constructing the slope gravity retaining wall reinforcement structure comprises the following steps: in the step (1), when the jet grouting pile is constructed, a drilling machine is required to be placed and kept horizontal, a drill rod is kept vertical, and the inclination of the drill rod is not more than 1%; when lifting rotary injection grouting is carried out, rotating and injecting are carried out at the bottom of the pile for 1min, then rotating, lifting and injecting are carried out simultaneously, and during injection, a grouting pipe is gradually lifted after preset injection pressure and preset grouting amount are reached; the preset injection pressure of the high-pressure cement slurry is set to be more than 30MPa, the lifting speed is 0.1m/min, and the injection slurry adopts cement slurry with the water-cement ratio of 1.0-1.5.

8. The method of claim 6, wherein the step of constructing the slope gravity retaining wall reinforcement structure comprises the following steps: after the drilling in the step (2) is finished, pulling out the drill rods and the drilling tools one by one, rechecking the hole depth by adopting a polyethylene pipe, cleaning rock powder and soil scraps in the hole, pulling out the polyethylene pipe when the hole depth is not less than the designed length of the anchor cable, and plugging the hole opening with fabric or cement bag paper for standby; rechecking the drilled hole before the anchor cable body is installed, timely cleaning collapsed holes and falling blocks, and checking the anchor cable; in the process of installing the anchor cable body, the pushing force of the anchor cable body is uniform, grouting is conducted upwards from the bottom of a hole, pure cement slurry is adopted as a grouting material, 42.5-grade ordinary portland cement is adopted as cement, the water cement ratio of the slurry is 0.45-0.5, and an expanding agent and an early strength agent are added into the slurry to ensure that the strength of the anchor cable body is not lower than 1MPa in 28 days.

9. The method of claim 6, wherein the step of constructing the slope gravity retaining wall reinforcement structure comprises the following steps: when the frame lattice beam is poured in the step (2), ensuring that the position of the axis of the anchor cable corresponds to the position of a frame node, arranging expansion joints at intervals of 20m on the lattice beam, wherein the width of each joint is 50mm, and filling the joints with asphalt reinforcement; and after the anchor cable is tensioned and locked, C30 concrete is used for sealing and protecting, and the thickness of the concrete protection is not less than 10 cm.

10. The method of claim 6, wherein the step of constructing the slope gravity retaining wall reinforcement structure comprises the following steps: excavating the combination part of the filled slope and the undisturbed slope body into a step shape in the step (3), excavating all tree roots, turf and humus soil in the paving range of the geogrid before construction, and performing detailed measurement and positioning and marking an excavation line before substrate excavation; the backfill materials of the filled side slope do not contain tree roots, turf and other impurities, each layer of the backfill materials should be rolled in time after being paved and leveled, the rolling is carried out firstly lightly and then heavily in the compaction process, the operation is carried out from the middle part of the geogrid and is gradually rolled to the tail part of the geogrid, and the backfill materials within a range of 15m close to the slope surface are pressed lightly by a small-sized machine after the slope surface; the folding length of each layer of geogrid is not less than 1.5m, the compaction degree of backfill fillers is detected before the next geogrid is paved, and meanwhile soil bags deformed or damaged in the backfill rolling process are timely processed.