Foam concrete slope crest reconstruction and extension structure in landslide field area and construction method

Abstract

The invention provides a foam concrete slope crest reconstruction and extension structure in a landslide field area and a construction method thereof. The slope crest reconstruction and extension structure comprises a slope surface protection structure constructed after grading sloping of a slope surface of an original slope, a row of anti-slide piles constructed on a grading sloping slope surface platform of the original slope, a row of beam top stand columns fixed above pile top connecting beams of the anti-slide piles, and a row of anchoring piles constructed in the original slope and close to a building. An inter-stand-column breast board is arranged between every two adjacent beam top stand columns, foam concrete structures are filled between the inter-stand-column breast boards and the graded sloping net hanging concrete spraying structures, and a plurality of sets of horizontal opposite-pulling anchor cables are connected between the beam top stand columns and the anchor pile top connecting beams. The overall stability of the reconstruction and extension site landslide is greatly improved, and slope crest displacement is effectively controlled; the surface subsidence of the slope top behind the anchoring pile is effectively controlled within a design and standard range; meanwhile, the foam concrete structure is used for filling the roadbed, so that filling pressure can be relieved, and compactness and strength are guaranteed.

Description

Technical Field

[0001] The invention relates to the field of landslide disaster prevention and control and reconstruction and expansion of industrial and civil construction sites near the top of landslides, and in particular to a foam concrete slope top reconstruction and expansion structure and method for landslide sites capable of improving disaster prevention benefits. Technical Background

[0002] With the rapid development of society, urban municipal construction, industrial plants and storage sites have increasingly higher space utilization rates and are often built on sloping or mountainous terrain, thus forming artificial high and steep slopes. Due to the backwardness of the overall planning or insufficient assessment of the slope top load and slope stability and safety, especially the pursuit of convenient construction and low cost, some high and steep slopes are only designed and constructed with simple slope support, such as graded slope spraying concrete or graded slope spraying concrete + short anchor rods. As time goes by, the slope top load increases, rainfall and other reasons cause the slope to shift and collapse or even develop into a deep landslide. The increase in surface settlement at the top of the slope can easily cause the foundation settlement and deformation of the structures near the top of the slope, especially the shallow foundation, leaving a huge safety hazard for the construction and operation of the site.

[0003] At the same time, with the changes in the later planning, such as the upgrading and renovation of municipal public buildings and industrial park equipment, the original slope top road cannot meet the rapidly increasing demand for long trucks. At the same time, the fire passage is widened and related pipe network facilities are added. It is necessary to improve the traffic carrying capacity of the slope top road, so as to renovate and expand the slope top. How to renovate and expand the slope top on the steep slope, how to support the slope or potential landslide after the renovation and expansion and ensure long-term stability and safety, and improve the disaster prevention benefits have become urgent problems to be solved. The traditional solution is often to use anti-slide piles + columns + multiple rows of long anchor cables + retaining plates or double rows of piles + thick pile top foundation + columns + retaining plates + multiple rows of long anchor cables, and then backfill the roadbed and renovate and expand the slope top road facilities. The traditional solution is expensive, takes a long time to build, requires a large amount of excavation and filling, and increases the load on the top of the slope, exacerbating slope instability. It is difficult for the anchor cables to ensure the depth of the anchor section below the potential deep sliding zone, and the setting of deep and long anchor cables is also prone to conflict with the foundations of buildings near the top of the slope, which is greatly detrimental to the safety and stability of new high and steep slopes and potential landslides, and poses a great threat to the normal operation of the factory area on the top of the slope, especially the displacement-sensitive, important structures and equipment. Summary of the invention

[0004] In view of the shortcomings and defects of the prior art, the present invention provides a foam concrete slope top reconstruction and expansion structure and a construction method for improving the disaster prevention benefits of landslide sites. The present invention can improve the overall stability of the landslide in the reconstruction and expansion site, effectively control the displacement of the slope top, and reduce the later settlement and deformation of the slope top.

[0005] In order to achieve the above technical purpose, the present invention provides a foam concrete slope top reconstruction and expansion structure in a landslide area, including an original slope and a building located on the top of the original slope, and an expansion road and ancillary structures are constructed on the slope surface adjacent to the building. The slope top reconstruction and expansion structure includes a slope protection structure constructed after the slope surface of the original slope is graded and sloped, a row of anti-sliding piles constructed on the slope surface platform of the original slope, a row of beam top columns fixed above the anti-sliding pile top connecting beam, and a row of anchor piles constructed in the original slope and adjacent to the building, wherein the beam top columns are The height extends to the top of the slope, and the beam top column and the anchor pile are parallel to each other. An inter-column retaining plate is provided between two adjacent beam top columns. A foam concrete structure is built between the inter-column retaining plate and the graded slope hanging mesh sprayed concrete structure. The foam concrete structure is backfilled to the height of the original slope top. The expanded road extends horizontally to the top surface of the foam concrete structure. The top of the anchor pile is located in the original slope, and two adjacent anchor piles are connected as a whole by an anchor pile top connecting beam, and a plurality of groups of horizontal tension anchor cables are connected between the beam top column and the anchor pile top connecting beam.

[0006] The preferred technical solution of the present invention is as follows: the horizontal distance between the construction position of the anti-slip piles and the buildings is greater than the overall width of the construction and expansion road and ancillary structures; the anti-slip piles are constructed using separated holes, the anti-slip piles are located as a whole in the original slope, the pile bottoms are embedded in the stable and solid strata below the deep sliding zone, the top connecting beam of the anti-slip piles is located on the original slope surface grading platform, and a crown beam is arranged on the top of the beam top column.

[0007] The preferred technical solution of the present invention is as follows: the distance between the anchor pile and the building is 2.0 to 5.0 m, the top of the anchor pile is located at a depth of 1.5 to 2.5 m in the slope, and the bottom of the anchor pile is embedded in a stable and solid stratum below the deep sliding zone; the column piles and the anchor piles are arranged in parallel and the number and spacing correspond one to one, the tension anchor cables are arranged horizontally, and the setting position of each tension anchor cable corresponds to the anchor pile and the column, and the two ends are respectively fixed to the anchor pile top connecting beam and the corresponding column, and are fixed by the sealing anchor structure after prestressing.

[0008] The preferred technical solution of the present invention is as follows: the slope protection structure includes a slope protection layer formed by spraying concrete after hanging a steel mesh on the stepped slope with graded slope, and steel anchor rods driven into the slope from the slope surface, and a drainage structure is constructed at the bottom of the original slope.

[0009] A more preferred technical solution of the present invention is that the anti-slide piles, columns, retaining plates and anchor piles are all cast-in-place reinforced concrete structures.

[0010] The preferred technical solution of the present invention is as follows: the foam concrete structure is cast in layers, with multiple layers of steel mesh laid flat inside, the spacing between two adjacent layers of steel mesh is 0.5 to 1 m, and both ends of each layer of steel mesh are fixedly connected to the slope protection structure and retaining plate of the original slope by drilling and planting reinforcement.

[0011] The present invention also provides a construction method for the above-mentioned landslide area foam concrete slope top reconstruction and expansion structure, and the specific construction steps are as follows:

[0012] Step S1: measuring and locating the positions of anti-slip piles and anchor piles; the positions of anti-slip piles are determined according to the overall width of the expanded road and auxiliary structures, and the distance between the anchor piles and the buildings is 2.0 to 5.0 m;

[0013] Step S2: At the anti-slide pile construction setting position, reinforced concrete anti-slide piles are constructed by using holes to ensure the length and verticality of the pile body and perform integrity testing; the anti-slide pile is located in the original slope as a whole, and the pile bottom is embedded in the stable and solid stratum below the deep sliding zone;

[0014] Step S3: At the same time, a foundation trench with a depth of 1.5 to 2.5 m is excavated at the set position of the slope top, and reinforced concrete anchor piles are constructed on the bottom surface of the foundation trench in parallel with the anti-sliding piles and in the same number as the anti-sliding piles to ensure the length and verticality of the pile body and perform integrity testing; the bottom of the anchor pile is embedded in the stable and solid stratum below the deep sliding zone;

[0015] Step S4: construct the anchor pile top connecting beam, reserve anchor holes in the beam, drill horizontal holes in the slope direction, install anchors and initially lock them, backfill the anchor pile foundation groove, and restore the temporary road to traffic;

[0016] Step S5: construct the top connecting beam of the anti-sliding pile at the same time, set up scaffolding formwork upward to construct reinforced concrete columns and retaining plates, and column top crown beams, and reserve holes for the columns and retaining plates through which horizontal anchors pass;

[0017] Step S6: Laying steel mesh in layers and filling foam concrete in layers to the reserved anchor elevation position, with the distance between two adjacent layers of steel mesh being 0.5 to 1 m;

[0018] Step S7: tensioning the tension anchors in sequence according to the design requirements and prestressing force, locking them, and sealing the anchors with concrete pouring;

[0019] Step S8: Continue to lay the steel mesh and pour the foam concrete to the bottom surface of the designed expansion road according to step S6;

[0020] Step S9: construct, renovate and widen the expanded road, complete the construction of the slope top guardrail and auxiliary structures, repair the intercepting drainage ditch at the bottom of the slope, and complete the construction of the entire slope top expansion structure.

[0021] A preferred technical solution of the present invention: In step S1, the distance between the anchor pile and the building is determined according to the following method: according to the mechanism of the anchor pile acting as an isolation pile to control surface settlement, the classic Peck method is modified and improved through a large number of engineering case data on surface settlement (Xia Mingyao, Zeng Jinlun. Manual of Design and Construction of Underground Engineering [M]. China Architecture & Building Press. 1999 (253-255).), assuming that the slope before the anchor pile is completely excavated, the depth of the deep sliding zone at the location of the anchor pile is the excavation depth of the slope at this location, and the maximum surface settlement value σ behind the anchor pile is calculated according to the following formula:

[0022] σ=10×K1×a×H(mm);

[0023] Where: K1—correction coefficient; wall-type enclosure wall K1=0.3; column-type enclosure wall K1=0.7; plate-type enclosure wall K1=1.0;

[0024] H—depth of the deep sliding zone where the anchor pile is located;

[0025] a—Ratio of ground surface settlement to excavation depth, expressed in %, which can be directly obtained by referring to the "Relationship Diagram between Ground Surface Settlement and Excavation Depth" in the underground engineering design and construction manual;

[0026] According to the above ground settlement formula, the settlement of the ground surface after the anchor piles are anchored at different positions within the range of 2.0 to 5.0 m from the building is calculated, and when the maximum settlement value σ is less than 2.5 cm, the position of the anchor pile is determined as the final design position of the anchor pile.

[0027] According to the modified Peck method ground settlement formula, the size and distribution trend of ground settlement behind the isolation piles can be quickly calculated in theory. By combining anchors with anti-sliding column piles to form a "gantry stiffness amplification effect", further reasonable corrections can be made on the basis of the above settlement values ​​to effectively ensure that the surface settlement of the slope top is controlled within the design and specification range, thereby further reducing the maximum settlement of important buildings near the top of the slope and reducing uneven settlement.

[0028] A preferred technical solution of the present invention is that the arrangement of the anchor piles and the anchor pile top connecting beams is adjusted according to the architectural sideline contour of the building, and can be arranged in sections into long strips or broken lines.

[0029] The preferred technical solution of the present invention is to formulate a monitoring plan before engineering construction, conduct monitoring during the entire construction process and operation, and provide timely and dynamic feedback on the landslide control effect.

[0030] Beneficial effects of the present invention:

[0031] (1) The present invention utilizes the strong rigidity support of deep embedding of column piles and anchor piles and the active effect of prestressed anchors between the column and anchor piles, which greatly improves the overall stability of the landslide at the reconstruction and expansion site and effectively controls the displacement of the slope top.

[0032] (2) The slope top renovation and expansion of the present invention adopts layered backfilling of foam concrete materials, which has the advantages of light weight, high strength, and high filling density compared with traditional earth and stone backfilling. It can reduce the overall soil pressure of the landslide, and steel mesh is laid between layers and connected and fixed to the supporting structures on both sides, which increases the deformation resistance of the concrete filling material and effectively reduces the later settlement and deformation of the slope top.

[0033] (3) The present invention uses anchor piles that are set close to the outside of the slope top structure, which has greater rigidity. The layout of the anchor piles and their connecting beams can be flexibly adjusted according to the contour of the building edge of the adjacent structure. They can be arranged in sections into long strips or broken lines, thereby isolating the landslide body to be controlled and the displacement-sensitive structure into two areas to the greatest extent.

[0034] (4) The present invention uses anchor piles as isolation piles to control the ground settlement of the slope top. According to the modified Peck method ground settlement formula, the ground settlement size and distribution trend behind the isolation piles can be theoretically and quickly calculated. The "gantry stiffness amplification effect" is formed by combining the anchors with the anti-sliding column piles. Further reasonable corrections are made on the basis of the above settlement values ​​to effectively ensure that the surface settlement of the slope top is controlled within the design and specification range, thereby further reducing the maximum settlement of important buildings near the slope top and reducing uneven settlement.

[0035] (5) Compared with the traditional column pile (double row pile) + multiple rows of deep and long anchor cable scheme, the present invention reduces the amount of earthwork excavation and filling, greatly saves construction cost and construction period, and avoids the problem of conventional pile-anchor scheme that the anchor cable cannot ensure the depth of the bearing layer due to the deep sliding surface, thereby affecting the pull-out resistance of the anchor cable or the deep and long anchor cable is easy to conflict with the foundation of the nearby building on the top of the slope. The support structure of the present invention is reasonable and the construction is convenient, which enhances the overall safety and stability of the landslide and improves the overall disaster prevention benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a cross-sectional view of the foam concrete slope top reconstruction and expansion structure in the slope field area of ​​the present invention;

[0037] Figure 2 It is a cross-sectional view of the original structure of the top of the landslide area before the reconstruction and expansion of the present invention;

[0038] Figure 3 It is an elevation view of the landslide site foam concrete slope top reconstruction and expansion structure of the present invention;

[0039] Figure 4 It is a top view of the slope top reconstruction and expansion structure in which the outer edge lines of the buildings adjacent to the slope top are regular in the present invention;

[0040] Figure 5 It is a top view of the slope top reconstruction and expansion structure in which the outer edge line of the building adjacent to the slope top is irregular in the present invention;

[0041] Figure 6 It is a large-scale drawing of the foam concrete backfill structure in the present invention;

[0042] Figure 7 It is the action mechanism and simplified model diagram of the anchor pile in the present invention;

[0043] Figure 8 This is the corresponding relationship diagram between surface settlement and excavation depth using the modified Peck method.

[0044] In the figure: 1—building, 1-1—building foundation, 2—original road on top of slope, 3—slope protection structure, 3-1—reinforced anchor rod, 4—expanded road, 5—anti-sliding piles, 5-1—anti-sliding pile top connecting beam, 6—anchor piles, 6-1—anchor pile top connecting beam, 7—tension anchor cable, 8—beam top column, 8-1—crown beam, 9—retaining board, 10—sealing anchor structure, 11—foam concrete structure, 12—reinforced mesh, 13—deep sliding belt, 14—intercepting and drainage structure, 15—slope top guardrail, 16—accessory structure, 17—stratum line. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Figures 1 to 6 The drawings are all of embodiments, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating the embodiments of the present invention. The technical solutions shown in the following drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0047] The embodiment of the present invention provides a foam concrete slope top reconstruction and expansion structure in a landslide area, such as Figure 1 , Figures 3 to 6As shown, it includes an original slope and a building 1 located on the top of the original slope, an auxiliary structure 16 and an original road 2 on the top of the slope are arranged on one side of the building 1 adjacent to the original slope surface, and an expanded road 4 is constructed on the slope surface adjacent to the building 1, the top expansion structure includes a slope protection structure 3 constructed after the slope surface of the original slope is graded and leveled, a row of anti-sliding piles 5 constructed on the original slope leveling and leveling slope surface platform, a row of beam top columns 8 fixed above the anti-sliding pile top connecting beam 5-1 and a row of anchor piles 6 constructed in the original slope and adjacent to the building 1: the slope protection structure 3 includes a slope protection layer formed by spraying concrete after hanging a steel mesh on the stepped slope surface of the graded and leveled slope, and a steel anchor rod 3-1 driven into the slope from the slope surface, and a drainage structure 14 is constructed at the bottom of the original slope. The height of the beam top column 8 extends to the top of the slope, and the beam top column 8 is parallel to the anchor pile 6. A retaining plate 9 is provided between two adjacent beam top columns 8. A foam concrete structure 11 is built between the retaining plate 9 and the graded slope hanging mesh spraying concrete structure 3. The foam concrete structure 11 is backfilled to the height of the original slope top. The expanded road 4 extends horizontally to the top of the foam concrete structure 11. A slope top guardrail 15 is provided at the edge of the expanded road 4. The horizontal distance between the construction position of the anti-sliding pile 5 and the building 1 is greater than the overall width of the construction expansion road 4 and the auxiliary structure 16; the anti-sliding pile 5 adopts a spaced hole construction, and the anti-sliding pile 5 is located in the original slope as a whole, and its pile bottom is embedded in the stable and solid stratum below the deep sliding zone 13. The anti-sliding pile top connecting beam 5-1 is located on the graded platform of the original slope surface, and a crown beam 8-1 is provided on the pile top of the beam top column 8.

[0048] The embodiment provides a foam concrete slope top reconstruction and expansion structure in a landslide area, such as Figure 1 , Figure 4 and Figure 5 As shown, the top of the anchor pile 6 is located in the original slope, and two adjacent anchor piles 6 are connected as a whole through the anchor pile top connecting beam 6-1, and multiple groups of horizontal tension anchor cables 7 are connected between the top column 8 and the anchor pile top connecting beam 6-1. The distance between the anchor pile 6 and the building 1 is 2.0-5.0m, the top of the anchor pile 6 is located at a depth of 1.5-2.5m in the slope, and the bottom of the anchor pile 6 is embedded in the stable and solid stratum below the deep sliding belt 13; the column pile 8 and the anchor pile 6 are arranged in parallel and the number and spacing correspond one to one, the tension anchor cable 7 is arranged horizontally, and the setting position of each tension anchor cable 7 corresponds to the anchor pile 6 and the column 8, and the two ends are respectively fixed to the anchor pile top connecting beam 6-1 and the corresponding column 8, and fixed by the sealing anchor structure 10 after applying prestress.

[0049] The embodiment provides a foam concrete slope top reconstruction and expansion structure in a landslide area, such as Figure 1 and Figure 6As shown, the anti-slide piles 5, columns 8, retaining plates 9 and anchor piles 6 are all cast-in-place reinforced concrete structures. The foam concrete structure 11 is cast in layers, and multiple layers of steel mesh 12 are laid flat inside. The spacing between two adjacent layers of steel mesh 12 is 0.5 to 1 m, and both ends of each layer of steel mesh 12 are fixedly connected to the slope protection structure 3 and retaining plate 9 of the original slope by drilling and planting reinforcement.

[0050] The invention has a wide scope of application. It is not only suitable for widening the top of a conventional newly built site with a high steep slope, but also suitable for the landslide protection, reinforcement and control of the top expansion project of a high steep slope with existing support measures; it is not only suitable for the landslide reinforcement near municipal public buildings, but also suitable for the landslide reinforcement near industrial plants and storage sites, and is especially suitable for the small and medium-sized landslide protection, control and reinforcement of industrial plants and equipment with very strict displacement control requirements on the top of the slope, which effectively improves the disaster prevention benefits and is economical and environmentally friendly.

[0051] The embodiment takes the slope top as an example, which is adjacent to an important industrial plant. The specific construction method of the foam concrete slope top reconstruction and expansion structure is as follows:

[0052] Step S1: Measure and locate the positions of the anti-slide pile 5 and the anchor pile 6; the position of the anti-slide pile 5 is determined according to the overall width of the expanded road 4 and the auxiliary structure 16, and the distance between the anchor pile 6 and the building 1 is 2.0-5.0 m. The optimal distance is verified within the above range according to the following calculation: According to the mechanism of the anchor pile playing the role of isolation pile in controlling the surface settlement, the classic Peck method is modified and improved. Assuming that the slope before the anchor pile is fully excavated, the deep sliding zone depth at the location of the anchor pile is the excavation depth of the slope at this location, and the surface settlement σ behind the anchor pile is calculated according to the following formula:

[0053] σ=10×K1×a×H(mm);

[0054] Where: K1—correction coefficient; wall-type enclosure wall K1=0.3; column-type enclosure wall K1=0.7; plate-type enclosure wall K1=1.0;

[0055] H—depth of the deep sliding zone where the anchor pile is located;

[0056] a—Ratio of ground surface settlement to excavation depth, expressed in %, which can be directly obtained by referring to the "Relationship Diagram between Ground Surface Settlement and Excavation Depth" in the underground engineering design and construction manual;

[0057] According to the above ground settlement formula, the settlement of the ground surface after anchoring piles at different positions within the range of 2.0 to 5.0 m from the anchor pile to the building is calculated. The distance between the anchor pile and the building is 2.5 m. The calculation is based on the ordinary stratum. The depth H of the deep sliding zone where the anchor pile is located is approximately 6 m above the anchor pile sliding zone. The distance from the building to be protected to the anchor pile / excavation depth = 2.5 m / 6 m ≈ 0.41, corresponding to Figure 8 The general formation curve a is approximately 0.55, and the correction coefficient K1 is considered as a column-type retaining wall, K1 = 0.7; therefore, the theoretical calculation value of the maximum surface settlement after anchoring the pile is:

[0058] σ=10×K1×a×H(mm)

[0059] σ=10×0.7×0.55×6(mm)

[0060] σ=23.1(mm)

[0061] When the distance between the anchor pile and the building is 2.5m, the theoretical settlement value σ=23.1(mm), which is less than 2.5cm, so the settlement requirement is met, and it can be determined that the distance between the anchor pile and the building is 2.5m;

[0062] The surface settlement mainly occurs in the case of cantilever excavation support on high and steep slopes. However, in this engineering example, the anchor piles and the anti-sliding column piles are formed as a whole by pulling anchors, and the "gantry stiffness amplification effect" needs to be considered. The soil between the gantry frames has not been excavated and has also played a certain passive resistance role relative to the anchor piles. Based on the above settlement value, reasonable corrections are made, and K1 is further adjusted to 0.35 by a factor of 0.5. According to the above formula, the maximum surface settlement σ after further correction is 11.5 (mm), which effectively illustrates that the application of anchor piles is relatively not using isolation piles or only using simple anchor beams (in both cases, H is taken as the length above the sliding zone of the front row of column piles, about 18m, and the theoretical value of the settlement behind the piles is greatly increased, and the overall safety risk of the landslide is greatly increased), ensuring that the ground settlement at the top of the slope is controlled within the design and specification range, and greatly enhancing the control of displacement and settlement of important buildings near the top of the slope.

[0063] The arrangement of the anchor piles 6 and the anchor pile top connecting beams 6 - 1 is adjusted according to the building edge contour of the building 1 , and can be arranged in sections into long strips or broken lines.

[0064] Step S2: At the anti-slide pile construction setting position, reinforced concrete anti-slide piles 5 are constructed by using holes to ensure the length and verticality of the pile body and perform integrity testing; the anti-slide pile 5 is located in the original slope as a whole, and its pile bottom is embedded in the stable and solid stratum below the deep sliding zone 13;

[0065] Step S3: At the same time, a 2m deep foundation trench is excavated at a set position on the top of the slope, and reinforced concrete anchor piles 6 are constructed on the bottom surface of the foundation trench in parallel with the anti-sliding piles 5 and in a corresponding number to ensure the length and verticality of the pile body and perform integrity testing; the bottom of the anchor pile 6 is embedded in a stable and solid stratum below the deep sliding zone 13;

[0066] Step S4: construct the anchor pile top connecting beam 6-1, reserve the anchor 7 hole in the beam, drill horizontally in the direction of the slope, install the anchor 7 and lock it preliminarily, backfill the anchor pile 6 foundation trench, and restore the temporary road to traffic;

[0067] Step S5: construct the top connecting beam 5-1 of the anti-sliding pile at the same time, set up scaffolding formwork upward to construct reinforced concrete columns 8 and retaining plates 9, and column top crown beams 8-1, and reserve holes for the columns 8 and retaining plates 9 through which the horizontal anchors 7 pass;

[0068] Step S6: Laying steel mesh sheets 12 in layers and filling foam concrete 11 in layers to the reserved anchor 7 elevation position, with the distance between two adjacent layers of steel mesh sheets 12 being 0.5 to 1 m;

[0069] Step S7: tensioning the tension anchors 7 in sequence according to the design requirements and prestressing force, locking them, and sealing the anchors with concrete pouring;

[0070] Step S8: Continue to lay the steel mesh 12 and pour the foam concrete 11 to the bottom surface of the designed expansion road 4 according to step S6;

[0071] Step S9: construct, renovate and widen the expanded road 4, complete the construction of the slope top guardrail 15 and the auxiliary structure 16, repair the intercepting drainage ditch at the bottom of the slope, and complete the construction of the entire slope top expansion structure.

[0072] Preferably, the present invention formulates a monitoring plan before engineering construction, conducts monitoring during the entire construction process and operation, and provides timely and dynamic feedback on the landslide control effect.

[0073] The present invention aims at the reconstruction and expansion of the original slope top site, the deformation of the original slope and the potential landslide risk after the reconstruction and expansion, the original slope support structure can no longer meet the deep stability requirements of the landslide on the site after the reconstruction and expansion, and the construction near the slope top is very sensitive to displacement. It avoids the problem that the conventional pile-anchor solution cannot ensure the depth of the bearing layer due to the deep sliding surface, thereby affecting the pull-out force of the anchor cable, or the deep and long anchor cable is easy to conflict with the foundation of the construction near the slope top. It also avoids the defects of the double-row anti-sliding pile solution that lacks a working surface and is expensive. The strong rigidity of the column piles and anchor piles is used to support the The active prestressed action of anchoring between the guardrail and the column-anchor pile greatly improves the overall stability of the landslide at the renovation and expansion site, and effectively controls the displacement of the top of the slope; at the same time, the anchor pile is set near the top of the slope structure, and the anchor pile is used as an isolation pile to control the ground settlement of the top of the slope. The "gantry stiffness amplification effect" is formed by the anchor and anti-sliding column piles, which can isolate the landslide body and displacement-sensitive structures to the maximum extent, and effectively control the ground settlement of the top of the slope behind the anchor pile within the design and specification range; at the same time, the use of foam concrete structure to fill the roadbed can reduce the fill pressure and ensure the density and strength. Overall, this structure and method reduces earth excavation and land occupation, ensures the overall stability of the slope of the renovation and expansion site and the safety of the top of the slope structure, and has a wide range of applications, especially for the protection and control of small and medium-sized landslides with displacement-sensitive industrial plants on the top of the slope, effectively improving the disaster prevention benefits, and is economical and environmentally friendly.

[0074] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the structural relationship and principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A foam concrete slope top reconstruction and expansion structure in a landslide area, comprising an original slope and a building (1) located on the original slope top, an expansion road (4) and an auxiliary structure (16) are constructed on the slope surface adjacent to the building (1), characterized in that: The slope top reconstruction and expansion structure comprises a slope protection structure (3) constructed after the slope surface of the original slope is graded and leveled, a row of anti-sliding piles (5) constructed on the slope surface platform of the original slope, a row of beam top columns (8) fixed above the anti-sliding pile top connecting beam (5-1), and a row of anchor piles (6) constructed in the original slope and adjacent to the building (1), wherein the height of the beam top columns (8) extends to the top of the slope, and the beam top columns (8) and the anchor piles (6) are parallel to each other, and an inter-column retaining plate (9) is provided between two adjacent beam top columns (8). A foam concrete structure (11) is built between the retaining plate (9) between the columns and the graded slope hanging mesh sprayed concrete structure (3), the foam concrete structure (11) is backfilled to the height of the original slope top, and the expanded road (4) extends horizontally to the top surface of the foam concrete structure (11); the top of the anchor pile (6) is located in the original slope, and two adjacent anchor piles (6) are connected as a whole through the anchor pile top connecting beam (6-1), and multiple groups of horizontal tension anchor cables (7) are connected between the beam top column (8) and the anchor pile top connecting beam (6-1).

2. A landslide area foam concrete slope top reconstruction and expansion structure according to claim 1, characterized in that: The horizontal distance between the construction position of the anti-slip pile (5) and the building (1) is greater than the overall width of the construction and expansion road (4) and the auxiliary structure (16); the anti-slip pile (5) is constructed by using a spaced hole, the anti-slip pile (5) is located in the original slope as a whole, and its pile bottom is embedded in the stable and solid stratum below the deep sliding zone (13); the anti-slip pile top connecting beam (5-1) is located on the original slope surface grading platform, and a crown beam (8-1) is arranged on the top of the beam top column (8).

3. A landslide area foam concrete slope top reconstruction and expansion structure according to claim 1 or 2, characterized in that: The distance between the anchor pile (6) and the building (1) is 2.0 to 5.0 m, the top of the anchor pile (6) is located at a depth of 1.5 to 2.5 m in the slope, and the bottom of the anchor pile (6) is embedded in a stable and solid stratum below the deep sliding zone (13); the column piles (8) and the anchor piles (6) are arranged in parallel, and the number and spacing correspond to each other; the tension anchor cables (7) are arranged horizontally, and the arrangement position of each tension anchor cable (7) corresponds to the anchor pile (6) and the column (8), and the two ends are respectively fixed to the anchor pile top connecting beam (6-1) and the corresponding column (8), and are fixed by the sealing anchor structure (10) after applying prestress.

4. A landslide area foam concrete slope top reconstruction and expansion structure according to claim 1 or 2, characterized in that: The slope protection structure (3) comprises a slope protection layer formed by spraying concrete after hanging a steel mesh on a stepped slope and steel anchor rods (3-1) driven into the slope from the slope surface, and a drainage structure (14) is constructed at the bottom of the original slope.

5. A landslide area foam concrete slope top reconstruction and expansion structure according to claim 1 or 2, characterized in that: The anti-sliding piles (5), columns (8), retaining plates (9) and anchor piles (6) are all cast-in-place reinforced concrete structures.

6. A landslide area foam concrete slope top reconstruction and expansion structure according to claim 1 or 2, characterized in that: The foam concrete structure (11) is cast in layers, and multiple layers of steel mesh (12) are laid flat inside the structure. The spacing between two adjacent layers of steel mesh (12) is 0.5 to 1 m. Both ends of each layer of steel mesh (12) are fixedly connected to the slope protection structure (3) and the retaining plate (9) of the original slope by drilling and planting reinforcement.

7. A construction method for the landslide site foam concrete slope top reconstruction and expansion structure according to any one of claims 1 to 6, wherein the specific construction steps are as follows: Step S1: measuring and locating the positions of anti-slip piles and anchor piles; the positions of anti-slip piles are determined according to the overall width of the expanded road and auxiliary structures, and the distance between the anchor piles and the buildings is 2.0 to 5.0 m; Step S2: At the anti-slide pile construction setting position, reinforced concrete anti-slide piles are constructed by using holes to ensure the length and verticality of the pile body and perform integrity testing; the anti-slide pile is located in the original slope as a whole, and the pile bottom is embedded in the stable and solid stratum below the deep sliding zone; Step S3: At the same time, a foundation trench with a depth of 1.5 to 2.5 m is excavated at the set position of the slope top, and reinforced concrete anchor piles are constructed on the bottom surface of the foundation trench in parallel with the anti-sliding piles and in the same number as the anti-sliding piles to ensure the length and verticality of the pile body and perform integrity testing; the bottom of the anchor pile is embedded in the stable and solid stratum below the deep sliding zone; Step S4: construct the anchor pile top connecting beam, reserve anchor holes in the beam, drill horizontal holes in the slope direction, install anchors and initially lock them, backfill the anchor pile foundation groove, and restore the temporary road to traffic; Step S5: construct the top connecting beam of the anti-sliding pile at the same time, set up scaffolding formwork upward to construct reinforced concrete columns and retaining plates, and column top crown beams, and reserve holes for the columns and retaining plates through which horizontal anchors pass; Step S6: Laying steel mesh in layers and filling foam concrete in layers to the reserved anchor elevation position, with the distance between two adjacent layers of steel mesh being 0.5 to 1 m; Step S7: tensioning the tension anchors in sequence according to the design requirements and prestressing force, locking them, and sealing the anchors with concrete pouring; Step S8: Continue to lay the steel mesh and pour the foam concrete to the bottom surface of the designed expansion road according to step S6; Step S9: construct, renovate and widen the expanded road, complete the construction of the slope top guardrail and auxiliary structures, repair the intercepting drainage ditch at the bottom of the slope, and complete the construction of the entire slope top expansion structure.

8. The construction method of a landslide area foam concrete slope top reconstruction and expansion structure according to claim 1, characterized in that: In step S1, the distance between the anchor pile and the building is determined according to the following method: according to the mechanism of the anchor pile playing the role of isolation pile in controlling the surface settlement, the classic Peck method is modified and improved. Assuming that the slope before the anchor pile is completely excavated, the depth of the deep sliding zone at the location of the anchor pile is the excavation depth of the slope at this location, and the maximum surface settlement value σ behind the anchor pile is calculated according to the following formula: σ=10×K1×a×H(mm); Where: K1—correction coefficient; wall-type enclosure wall K1=0.3; column-type enclosure wall K1=0.7; plate-type enclosure wall K1=1.0; H—depth of the deep sliding zone where the anchor pile is located; a—Ratio of ground surface settlement to excavation depth, expressed in %, which can be directly obtained by referring to the "Relationship Diagram between Ground Surface Settlement and Excavation Depth" in the underground engineering design and construction manual; According to the above ground settlement formula, the settlement of the ground surface after the anchor piles are anchored at different positions within the range of 2.0 to 5.0 m from the building is calculated, and when the maximum settlement value σ is less than 2.5 cm, the position of the anchor pile is determined as the final design position of the anchor pile.

9. The construction method of a landslide area foam concrete slope top reconstruction and expansion structure according to claim 7, characterized in that: The arrangement of the anchor piles (6) and the anchor pile top connecting beams (6-1) is adjusted according to the building edge contour of the building (1), and can be arranged in sections into a long strip or a broken line shape.

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