Red clay high and steep slope collapse reinforcing structure and construction method thereof

Abstract

The invention provides a red clay high and steep slope collapse reinforcing structure and a construction method thereof. The pile-anchor supporting structure is constructed at the position, close to the edge line of the outer side of the building, of the top of the original side slope, the reinforced soil supporting structure is constructed on the original side slope lattice anchor supporting system and located on the outer side of the pile-anchor supporting structure, and the 1-2 layers of grouting reinforcing bodies are constructed below the foundation of the building at the top of the slope. The pile-anchor supporting structure comprises supporting row piles entering a rock supporting layer and a plurality of pre-stressed anchor cables. The reinforced soil supporting structure comprises a reinforced soil layer structure which is formed by conducting layer-by-layer compaction and backfilling after an original slump slope body is excavated out, and the grouting reinforcement body is a reinforcing structure formed by foam concrete grouting. According to the method, the stability of the red clay high and steep slope is improved, the scouring and erosion resistance of the slope surface is effectively improved, displacement of a slope top road and a building is controlled, an original slope supporting system is fully utilized, and disturbance to undisturbed soil and damage to an existing supporting structure are reduced as much as possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of red clay high and steep slope collapse treatment engineering and reinforcement of structures near the top of the slope, in particular to a red clay high and steep slope collapse reinforcement structure and a construction method thereof. BACKGROUND

[0002] With the rapid development of society, the space utilization rate of urban municipal construction, industrial plant or warehouse site is getting higher and higher, and these sites are often built on sloping or mountainous terrain, thus forming artificial high and steep slopes. The characteristics of red clay seriously affect the safety of these high and steep slope engineering projects. Red clay often has developed fissures, and the surface fissures are mostly vertical openings in the form of cracks, which gradually close into a network downward. Red clay has two special properties: first, the thickness varies greatly, and because of the development of many network fissures, the integrity of the soil structure is destroyed, which promotes the movement of groundwater in the soil layer, reduces the strength of the soil, and thus the structure and strength of red clay are greatly uneven in the horizontal and vertical directions; second, it usually has strong swelling and shrinking properties, thus causing different degrees of swelling and shrinking disasters. The surface layer of red clay often contains organic matter, and the lower part gradually transitions to bedrock, and the contact surface between the two often becomes a weak structural surface; especially in low-lying areas, groundwater often accumulates, making the red clay in a soft plastic and plastic state, reducing the strength and increasing the compressibility, which is not only unfavorable for the foundation, but also often causes sliding along the contact surface if it is on a slope, in addition, the red clay in karst areas often has soil holes and fissures, which not only affect the bearing capacity of the foundation, but also are prone to collapse.

[0003] Therefore, when various engineering constructions are carried out on red clay sites, due to various reasons such as insufficient investment by the construction party, over-ambitious design, insufficient layout of survey holes, or improper construction, the site stratum conditions often change greatly or rainfall causes the original high and steep red clay slope support system to be insufficient in strength, and after treatment, the upper part continuously collapses and deforms, the upper support structure fails, which seriously affects the overall stability of the slope and the safety of the roads and houses near the top of the slope, and if direct backfilling and reinforcement or improper reinforcement measures are taken, and with the passage of time, the increase of slope top load, rainfall and other reasons, the risk continues to increase, and even the overall stability of the slope, the destruction of the road on the top of the slope, and the collapse of the house are caused. The traditional solutions mainly include the following two ways:

[0004] (1) Communicate with the road and house ownership party to change the road design route and demolish the house, in which case, due to the involvement of many departments and procedures, the impact on municipal planning investment is too great, and the overall coordination period is very long;

[0005] (2) Use traditional reinforcement schemes, such as Figure 3As shown, the anti-sliding pile + column + multiple rows of long anchor cable + soil retaining plate combined support system is arranged outside the planned road on the slope top, and then the roadbed is backfilled, and the slope top road facilities are constructed; the traditional reinforcement scheme is expensive and has a long construction period, the overall support system bears a large soil pressure and bending moment, the support structure strength and rigidity requirements are high, large-diameter piles and columns need to be arranged, a wide construction platform needs to be arranged at the bottom of the slope damage affected area, the undisturbed soil and the original support structure greatly aggravate the slope instability, and deep and long anchor cables need to be arranged, otherwise it is difficult to enter the stable rock layer, in addition, the original collapsed loose red clay body has not been completely removed and treated, the soil holes and cracks are developed and unevenly distributed, the soil body has poor properties, is very sensitive to underground water, and is very unfavorable to the support structure, thereby greatly threatening the overall stability of the slope and the normal operation of the slope top road and buildings.

[0006] In order to ensure the permanent stability of the high and steep red clay slope during the construction process and the operation stage and the safety of the adjacent buildings, an economic, practical and convenient rigid-flexible combined reinforcement system and construction method are urgently needed. SUMMARY

[0007] The present application can improve the stability of the high and steep red clay slope, effectively improve the slope surface anti-scouring and erosion capacity, and effectively control the displacement of the slope top adjacent road and buildings within the design and specification range.

[0008] In order to solve the above technical problems, the present application provides a red clay high and steep slope collapse reinforcement structure for reinforcing the red clay high and steep slope with roads and buildings on the slope top, the reinforcement structure comprises a lattice anchor support structure system designed and constructed in the original slope, the reinforcement structure further comprises a pile-anchor support structure constructed on the edge line outside the adjacent building on the original slope top, a reinforced soil support structure constructed on the original slope lattice anchor support structure and outside the pile-anchor support structure, and 1-2 layers of grouting reinforcement bodies constructed below the building foundation on the slope top; the pile-anchor support structure comprises a support row pile and multiple rows of pre-stressed anchor cables arranged at intervals on the support row pile, the adjacent two pile bodies of the support row pile are hung with a net and sprayed with concrete, and the support row pile and the pre-stressed anchor cable both enter the rock bearing layer; the reinforced soil support structure comprises a reinforced soil layer structure formed by excavating the original collapsed slope body and then compacting and backfilling layer by layer, and a slope top road is constructed on the top of the reinforced soil support structure; the grouting reinforcement body is a reinforcement structure formed by foamed concrete grouting.

[0009] The further technical scheme of the present application is: the lattice anchor supporting structure system of the original design and construction of the slope includes a reinforced concrete frame beam formed by supporting and pouring on the original slope excavation slope surface and a steel anchor rod or a steel strand anchor cable punched into the slope from the intersection of the reinforced concrete frame beam; the steel anchor rod or the steel strand anchor cable has a horizontal and vertical spacing of 2.0-3.5 m and a punching angle of 20°-25°; the lower part of the original slope is bounded by the red line of the slope bottom road, and the upper part is bounded by the planned guardrail; the drainage structure is arranged on the top and the bottom of the slope, and the drainage structure on the top is arranged on the top of the reinforced soil supporting structure.

[0010] The preferable technical scheme of the present application is: the supporting row pile is a supporting structure connected by a plurality of pile bodies through a waist beam and a crown beam, the pile body of the supporting row pile is drilled and constructed from a position 1-2 m away from the edge line of the building outside the original landslide slope top before the original landslide slope body is excavated, the crown beam and the waist beam of the supporting row pile and the prestressed anchor cable are constructed from top to bottom after the original landslide slope body is excavated and before the reinforced soil supporting structure is constructed, the prestressed anchor cable is arranged at the position of the waist beam, and each prestressed anchor cable is punched into the slope body between the pile bodies and enters the rock bearing layer.

[0011] The preferable technical scheme of the present application is: the reinforced soil supporting structure includes a backfill soil layer and a plurality of geogrids arranged in the backfill soil layer, a drainage layer is constructed on the vertical surface close to the pile anchor supporting structure and the bottom surface close to the lattice anchor supporting structure system, the slope surface of the reinforced soil supporting structure forms an ecological slope surface by backfilling a planting soil layer and planting plants, a seepage prevention layer is arranged on the top of the reinforced soil supporting structure, and the slope top road is constructed above the seepage prevention layer.

[0012] The preferable technical scheme of the present application is: the grouting reinforcement body is punched into the soil layer below the slope top building foundation from the pile bodies of the supporting row pile during the excavation construction process of the soil body in front of the pile according to the designed height after the construction of the supporting row pile and the crown beam of the supporting row pile is completed, and the grouting reinforcement body is formed by injecting foam concrete through the grouting flower pipe, the grouting reinforcement body covers the crack, soil hole or cave area in the slope body, and the horizontal extension range of the grouting reinforcement body covers the slope top building foundation; the compressive strength of the foam concrete after curing is greater than or equal to 1 MPa.

[0013] The preferable technical scheme of the present application is: the original slope top close to the building is a common residential house or an industrial building, the foundation type is a shallow foundation, and the distance between the building and the original slope top edge line is within 1 times the total height of the slope; the foundation of the building is entirely or more than 1 / 2 of the part in the range of the potential most unfavorable sliding surface of the slope.

[0014] In order to achieve the above technical purpose, the application also provides a construction method of the red clay high and steep slope collapse reinforcing structure, characterized in that the construction method is used for reinforcing the red clay high and steep slope with roads and buildings on the slope top, the distance between the building on the slope top and the original slope top edge line is within the total height of the original slope, the slope body of the original slope appears collapse deformation, the reinforcing structure is used for reinforcing the collapsed slope body of the original slope, and the specific construction steps are as follows:

[0015] S1. confirming the original slope range affected by the collapse through geological survey, confirming the actual position of the potential most unfavorable sliding surface, the actual situation of the stratum in the slope collapse and influence range, and the distribution of the karst cave, soil cave or fissure in the slope, and reflecting the slope collapse influence range, the potential most unfavorable sliding surface, the survey actual stratum situation in the original slope design scheme graph;

[0016] S2. determining the design graph of the reinforcing structure according to the design scheme profile and elevation graph after the step S1, determining the layout positions of the pile anchor support structure, the reinforced soil support structure and the grouting reinforcement body on the design graph, the support row piles of the pile anchor support structure are located at the positions 1-2 m away from the outer edge line of the building, the prestressed anchor cables of the pile anchor support structure are arranged in 2-3 layers, are punched into the slope body from the waist beam part of the support row piles, and the support row piles and the prestressed anchor cables are inserted into the rock bearing stratum, the layout range of the reinforced soil support structure covers the collapse deformation area of the original slope, and the reinforced soil support structure is located outside the pile anchor support structure, the grouting reinforcement body is arranged in 1-2 layers and is located in the range of the shallow soil cave, fissure or karst cave below the building foundation on the slope top, the length of the grouting flower pipe of the grouting reinforcement body is not less than the horizontal depth of the potential most unfavorable sliding surface + 5 m, and the compressive strength of the foam concrete after curing is greater than or equal to 1 MPa;

[0017] S3. constructing the pile anchor support structure according to the design graph of the reinforcing structure, constructing the pile body of the support row piles from the slope top of the original slope, after the pile body is cured to the design strength, excavating the soil body in front of the piles from top to bottom layer by layer, and the excavation range covers the collapse deformation area of the original slope; in the excavation process, the crown beam, the prestressed anchor cable and the waist beam of the support row piles are constructed in sequence, and the soil body between the adjacent pile bodies of the support row piles is supported by net spraying concrete, until the design bottom elevation is reached; after the construction of the support row piles is completed and before the spraying concrete between the piles is closed, a row of horizontal grouting flower pipes are punched from the pile bodies at the positions of the shallow soil cave, fissure or karst cave range in the excavation surface according to the design position and length, and the premixed foam concrete is injected into the grouting flower pipes to form the grouting reinforcement body;

[0018] S4. After the pile-anchor supporting structure construction maintenance is completed, continue to construct the reinforced soil supporting structure on the outside: flatten the foundation in the excavation area, and roll the flattened foundation to ensure that the compaction degree and bearing capacity meet the design and specification requirements; construct a bottom drainage layer on the bottom surface of the excavation area, lay the bottom geogrid according to the actual position of the construction line, and then start the layered backfilling, rolling of the soil layer to the bottom elevation of the next layer, and then lay the geogrid, and repeat the backfilling to the slope top height; and during the backfilling, set the longitudinal drainage layer between the reinforced soil supporting structure and the pile-anchor supporting structure;

[0019] S5. After the backfilling of the reinforced soil supporting structure is completed, construct a seepage prevention layer on the top surface of the reinforced soil supporting structure, and construct a slope top intercepting and drainage ditch on the top surface of the seepage prevention layer, wherein the seepage prevention layer is a waterproof clay layer;

[0020] S6. After the entire slope reinforcement is completed, restore the slope greening, and construct the slope top road and the auxiliary structure.

[0021] The preferred technical scheme of the present application: In the S1 step, the range of the original slope affected by the landslide is confirmed to include the landslide height, depth, and affected slope length, and the floating soil is cleaned to reduce the slope, and the slope surface is temporarily covered during the rainy season to prevent rainwater infiltration from causing the slope to collapse; the actual situation of the landslide and affected range of the slope site is confirmed, including confirming the stratum type, stratum thickness, soil-rock interface, and underground water condition, confirming the size, position, and depth of the karst cave and soil cave, and especially the development condition of the shallow soil cave inside the most unfavorable sliding surface and near the building foundation.

[0022] The further technical scheme of the present application: In the S4 step, the arrangement of the reinforcing material of the reinforced soil supporting structure should meet the following provisions:

[0023] When the height of the reinforced soil supporting structure is less than or equal to 3.0 m, the length of the reinforcing material should be no less than 4.0 m; when the height of the reinforced soil supporting structure is greater than 3 m and less than or equal to 6.0 m, the length of the reinforcing material should be no less than 5.0 m; when the height of the reinforced soil supporting structure is greater than 6.0 m, the minimum length of the reinforcing material should be no less than 0.8 times the wall height and no less than 5 m;

[0024] When checking the internal stability of the reinforced soil supporting structure, the tensile strength and anti-pulling stability of the reinforced soil retaining wall are checked according to the relevant provisions of the Railway Subgrade Retaining Structure Design Specification TB 10025; according to the failure model, the potential failure surface of the reinforced soil supporting structure is at an angle of to the horizontal plane, and the relationship between the potential failure surface depth and the wall height is approximately ; wherein φ is the internal friction angle of the fill, and s is the potential failure surface depth, and h is the wall height.

[0025] The preferred technical scheme of the present application: the specifications of the pile body and the prestressed anchor cable of the pile-anchor support structure in the S2 step are determined by using the existing geotechnical design theory and Li Zheng software analysis and calculation; the position and the number of layers of the grouting reinforcement body are determined according to the position and size of the shallow soil hole confirmed by the survey, generally 1-2 layers are set, the grouting flower pipe passes through the soil hole position, the vertical depth of the grouting reinforcement is controlled within the range of 5m below the building foundation, the length of the grouting flower pipe is not less than the horizontal depth of the soil hole plus 3m, and the compressive strength of the foam concrete after curing is greater than or equal to 1MPa; the slope greening in the S6 step adopts the ecological slope surface planting bag greening of the reinforced soil support structure.

[0026] The beneficial effects of the present application are:

[0027] (1) The present application maximizes the use of the original design construction slope support structure system, adopts the pile-anchor support structure to ensure the safety of the adjacent building under the excavation working condition and strictly limits the displacement settlement, the reinforced soil support structure bears the soil pressure and road load within a limited width after the construction of the pile-anchor support structure system, ensures the overall stability of the filled slope and the safe operation of the slope top road, fully utilizes the strength of the stratum, combines rigidity and flexibility, and reasonably bears the stress, thereby fully ensuring the stability and safety of the slope, the slope top road and the building during the construction stage and the operation stage.

[0028] (2) The newly-built pile-anchor support structure is arranged adjacent to the shallow foundation building to be protected, which is beneficial to control the displacement settlement of the building, the newly-built flexible reinforced soil structure simultaneously serves as the passive reinforcement area of the newly-built rigid support structure, the permanent support safety of the rigid support structure is greatly increased, and the late settlement deformation of the slope top is effectively reduced.

[0029] (3) The present application uses the structural design to quickly determine the length of the reinforcement, saves the reinforcement while ensuring the internal stability of the reinforced soil retaining wall, and sets the horizontal and vertical gravel drainage layers and the clay waterproof layer on the slope top, which effectively isolates and quickly discharges the underground water in the slope body, avoids the adverse effects of rainwater infiltration on the slope, and further reduces the safety risk of the slope.

[0030] (4) The present application uses the unique advantages of strong fluidity, light weight and high strength of the foam concrete to solve the problem that the traditional grouting material (cement slurry or ordinary concrete) has poor horizontal fluidity and is difficult to completely fill the soil hole fissure, fully reinforces and strengthens the shallow soil hole fissure near the building foundation and the sliding zone, avoids the further development of the soil hole fissure and the collapse and subsidence caused by the later rainwater infiltration, and prevents the uneven settlement of the adjacent building foundation;

[0031] (5) Compared with the traditional column pile (double-row pile) + multi-row long anchor cable scheme, the application reduces the serious disturbance to the original soil body and the original supporting structure, greatly saves the cost and construction period, avoids the problem that the upper anchor cable is difficult to enter the bearing layer or the bearing layer is not enough, and the original collapsed loose red clay body is treated by "replacement", the supporting structure system of the application is reasonable, convenient to construct, enhances the overall slope safety and stability, and improves the overall red clay high and steep slope collapse reinforcement engineering benefit.

[0032] The application greatly improves the stability of the red clay high and steep slope, effectively improves the slope surface erosion prevention and control ability, controls the displacement of the road and residential buildings adjacent to the slope top, and combines rigidity and flexibility by using the newly-built rigid support and the reinforced soil flexible support adjacent to the building structure, fully utilizes the original slope supporting system, and reduces the disturbance to the original soil and the damage to the existing support structure as much as possible. Compared with the traditional reinforcement scheme, in addition to reducing the engineering cost, shortening the construction period and reducing carbon emissions, the comprehensive benefit of the red clay high and steep slope collapse reinforcement treatment is greatly improved. The application is suitable for the case that the strength of the original high and steep red clay slope supporting system is insufficient due to the large change of the site stratum or rainfall, the shallow soil hole and fissure develop, the upper part continuously collapses and deforms after treatment, the upper supporting structure fails, and the overall stability of the slope and the safety of the road and houses adjacent to the slope top are seriously affected. In order to ensure the permanent stability of the high and steep red clay slope during the construction process and the operation stage and the safety of the adjacent building structure, an economic, practical and convenient rigid-flexible combined reinforcement system and construction method is provided. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a profile view of the original supporting structure and the collapse process of the red clay high and steep slope in the embodiment of the application;

[0034] Figure 2 is a profile view of the red clay high and steep slope collapse reinforcement structure in the embodiment of the application;

[0035] Figure 3 is a profile view of the traditional reinforcement scheme of the red clay high and steep slope collapse in the embodiment of the application;

[0036] Figure 4 is a potential fracture surface schematic diagram of the reinforced soil retaining wall of the application;

[0037] Figure 5 is a shallow soil hole grouting reinforcement schematic diagram in the embodiment of the application;

[0038] Figure 6 is a large sample structure diagram of the grouting flower pipe structure in the embodiment of the application.

[0039] In the figure: 1 - building, 2 - slope top line, 3 - lattice anchor support structure system, 3-1 - steel anchor rod or steel strand anchor cable, 3-2 - reinforced concrete frame beam, 4 - potential most unfavorable sliding surface, 5 - rock bearing stratum, 6 - original landslide slope body, 7 - slope bottom line, 8 - support row pile, 9 - prestressed anchor cable, 10 - reinforced soil support structure, 10-1 - geogrid, 10-2 - drainage layer, 10-3 - impermeable layer, 11 - slope top road, 12 - slope bottom road red line, 13 - intercepting and draining ditch, 14 - drainage hole, 15 - safety guardrail, 16 - grouting reinforcement body, 17 - grouting flower pipe, 18 - soil cave or karst cave. DETAILED DESCRIPTION

[0040] The application will be further described below in conjunction with the drawings and examples. The application will be further described below in conjunction with the drawings and examples. The drawings Figures 1 to 6 are the drawings of the examples, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating the examples of the application. The technical solutions shown in the drawings below are specific solutions of the examples of the application, and are not intended to limit the scope of the claimed application. Based on the examples in the application, all other examples obtained by those of ordinary skill in the art without creative labor fall within the scope of the application.

[0041] The red clay high and steep slope landslide reinforcement structure provided in the example is used for reinforcing a red clay high and steep slope with a road and a building 1 on the slope top, and the reinforcement structure comprises a lattice anchor support structure system 3 originally designed and constructed for the slope, as Figure 1 shown, the lattice anchor support structure system 3 originally designed and constructed for the slope comprises reinforced concrete frame beams 3-2 formed by supporting and pouring on the slope surface of the original slope 2 after the slope surface is excavated, and steel anchor rods or steel strand anchor cables 3-1 punched into the slope from the intersection of the reinforced concrete frame beams 3-2, the steel anchor rods are ordinary anchor rods or prestressed anchor rods, and the steel strand anchor cables are ordinary anchor cables or prestressed anchor cables; the steel anchor rods or steel strand anchor cables 3-1 have a horizontal and vertical spacing of 2.0-3.5 m and a punching angle of 20°-25°; the lower part of the original slope 2 is bounded by the slope bottom road red line 12, and the upper part is bounded by the planned guardrail 15; no drainage hole 14 is arranged on the slope surface, and intercepting and draining structures 13 are arranged on the slope top and the slope bottom; the slope top of the original slope 2 is adjacent to the ordinary house or industrial building 1, the foundation type is a shallow foundation, and the building 1 is within one times the total height of the slope from the slope top boundary line of the original slope 2; the foundation of the building 1 is entirely or more than half of the foundation within the range of the potential most unfavorable sliding surface 4 of the slope; the slope body of the original slope is deformed by landslide, and the reinforcement structure is used for reinforcing the original landslide slope body 6 area.

[0042] As Figure 2As shown, the reinforcement structure in the embodiment includes a pile anchor support structure constructed on the original slope top near the outer edge line of the building 1, a reinforced soil support structure 10 constructed on the original slope lattice anchor support system 3 and located outside the pile anchor support structure, and 1-2 layers of grouting reinforcement bodies 16 constructed below the foundation of the building 1 on the slope top. The pile anchor support structure includes a support row pile 8 and multiple rows of prestressed anchor cables 9 arranged at intervals on the support row pile 8, the support row pile 8 is hung with a net and sprayed with concrete between two adjacent pile bodies, and the support row pile 8 and the prestressed anchor cable 9 both enter the rock bearing layer 5, thereby ensuring the safety of the adjacent building under the excavation condition and strictly limiting the displacement settlement. The support row pile 8 is a support structure connected by multiple pile bodies through waist beams and crown beams, the pile body of the support row pile 8 is drilled and constructed from a position 1-2 m away from the outer edge line of the building 1 on the original landslide slope top before the original landslide slope body 6 is excavated, the crown beam and the waist beam of the support row pile 8, and the prestressed anchor cable 9 are constructed from top to bottom after the original landslide slope body is excavated and before the reinforced soil support structure 10 is constructed; the prestressed anchor cable 9 is arranged at the position of the waist beam, and each prestressed anchor cable 9 is punched into the slope body from between the pile bodies and enters the rock bearing layer 5.

[0043] In the embodiment, as shown in FIG. 1, the original landslide slope body 6 is excavated to form a new slope body 2, and the new slope body 2 is reinforced by the reinforcement structure. Figure 2As shown, the reinforced soil retaining structure 10 includes a reinforced soil layer structure formed by layer-by-layer compaction backfilling after the original landslide slope body 6 is excavated, and a slope top road 11 is constructed at the top of the reinforced soil retaining structure 10; the reinforced soil retaining structure 10 includes a backfill soil layer and a plurality of layers of geogrids 10-1 arranged in the backfill soil layer, and a drainage layer 10-2 is constructed near the vertical surface of the pile anchor retaining structure and the bottom surface of the lattice anchor retaining structure system 3, the slope surface of the reinforced soil retaining structure 10 is formed into an ecological slope surface by backfilling a planting soil layer and planting plants, the top of the reinforced soil retaining structure 10 is provided with an anti-seepage layer 10-3, and the slope top road 11 is constructed above the anti-seepage layer 10-3. The grouting reinforced body 16 is a reinforced structure formed by foamed concrete grouting; the slope top interception and drainage structure 13 is arranged at the top of the reinforced soil retaining structure 10. The reinforced soil retaining structure 10 serves as a flexible supporting system, bears the earth pressure and road load within a limited width, and ensures the internal stability of the filled slope and the safe operation of the slope top road. The grouting reinforced body 16 is a reinforced layer formed by horizontally punching a grouting flower pipe 17 into the soil layer below the foundation of the slope top building 1 from between the pile bodies of the supporting row piles 8 during the excavation construction process of the soil body in front of the supporting row piles 8 after the construction of the supporting row piles 8 and the crown beam is completed, and injecting foamed concrete through the grouting flower pipe 17, the grouting reinforced body 16 covers the fissure, soil hole or karst cave area in the slope body, and the horizontal extension range of the grouting reinforced body 16 covers the foundation of the slope top building 1; the compressive strength of the foamed concrete after curing is ≥1MPa. The grouting reinforced body 16 fills and improves the red clay body with developed shallow soil holes and fissures in the slope body.

[0044] The embodiment takes the slope top of a high and steep slope of red clay in an industrial park as an example, which is adjacent to a built shallow foundation house and a planned road, the slope height is 14-18m, according to the geological exploration data, the upper part of the slope is red clay with a thickness of 3-9m, and the lower part is strongly to moderately weathered limestone with developed soil holes and karst caves. As shown in the original slope supporting structure in the embodiment, Figure 1 The original slope design and construction steps are as follows: according to the slope ratio of the original slope design drawing, the normal construction process flow of the slope lattice anchor is carried out: slope earthwork excavation, slope surface finishing-drainage ditch and drainage hole construction-while anchor cable construction-lattice beam construction-prestressed anchor cable tensioning, locking and anchoring-seeding and greening of the slope surface, the overall slope excavation and supporting construction follows the principle of top-down. The design slope ratio is 1:0.5, and the distance from the slope top to the built structure is about 10-12m.

[0045] Due to the large changes in the field formation, the actual thickness of the red clay soil layer exceeds the formation thickness in the geological exploration report, the development degree of shallow soil hole fissure is underestimated, and the original high and steep red clay slope support system is insufficient in strength due to continuous rainfall. After the original scheme is treated, the upper part of the slope appears continuous collapse deformation, which makes the upper support structure fail, seriously affects the overall stability of the slope and the safety of the road and house near the slope top, and the reinforcement design and construction of the original slope support system of the collapsed slope must be considered. The specific reinforcement construction steps are as follows:

[0046] S1. After evaluation, it is confirmed that the slope collapse height is about 5~9m, the maximum depth of collapse is 6~8m, the affected range of the slope is about 3 sections, and the width is 25m, 35m and 50m respectively. After slightly cleaning the floating soil, the slope shape is reduced, and the slope surface is temporarily covered during the rainy season to prevent rainwater infiltration from causing the slope collapse to worsen;

[0047] S2. Supplementary investigation, research and confirmation of the actual location of the potential most unfavorable sliding surface and the actual situation of the slope collapse and the affected range of the formation (including formation type, formation thickness, soil-rock interface, groundwater condition, etc.), confirmation of the development of karst cave and soil cave (size, location, depth, etc.), especially the development of shallow soil cave in the sliding zone and near the foundation of the building, the slope collapse affected range, the potential most unfavorable sliding surface, the actual formation situation of the supplementary investigation are arranged and superimposed in the original design scheme diagram;

[0048] S3. According to the design scheme profile and elevation view after the superimposition of S1 step, determine the design drawing of the reinforcement structure; specifically, according to the profile and elevation view after superimposition, newly design includes the pile anchor support structure arranged below the original slope top adjacent to the building structure, the reinforced soil support structure 10 arranged above the original slope lattice anchor support system 3 and outside the pile anchor support structure, and the grouting reinforcement body 16 constructed below the building 1 foundation on the slope top. The newly added pile anchor support structure is located between the planned road on the slope top and the existing building structure, and is about 1-2 m away from the building structure foundation; according to the mature geotechnical design theory and Lizheng software analysis and calculation, considering the temporary excavation support working condition and the permanent support working condition during operation, the support pile specifications (pile diameter 0.8 m, pile length 12 m, pile center distance 1.2 m), anchor cable specifications (anchor cable hole diameter 150 mm, anchor cable row number 2, anchor cable spacing 2.4 m, anchor cable height 1.5 m and 4.5 m below the pile top respectively, and prestress size 160-200 KN) are determined; the reinforced soil support structure outside the pile anchor support structure is considered according to the earth pressure in the limited width range, and the internal stability is met according to the structural design, and the parameters of the reinforced soil retaining wall (model, reinforcement length, layer spacing, etc.) are determined; the position and layers of the grouting reinforcement body are determined according to the position and size of the shallow soil hole confirmed by the survey, and two layers are set, the grouting flower pipe passes through the soil hole position, the grouting flower pipe length is not less than the horizontal depth of the soil hole + 3 m and not less than the horizontal depth of the sliding zone + 5 m, the grouting flower pipe 17 length from top to bottom is 12 m for the first layer and 6 m for the second layer, and the pre-mixed foam concrete is injected, and the compressive strength of the foam concrete after curing is ≥1 MPa;

[0049] The reinforcement arrangement of the reinforced soil support structure 10 should be determined by structural design according to the relevant industry geosynthetic material regulations, and when designed according to the structure, the following provisions should be met:

[0050] (1) When the reinforced soil support height is less than or equal to 3.0 m, the reinforcement length should be not less than 4.0 m; when the reinforced soil support height is greater than 3 m and less than or equal to 6.0 m, the reinforcement length should not be less than 5.0 m; when the reinforced soil support height is greater than 6.0 m, the minimum length of the reinforcement should not be less than 0.8 times the wall height and should not be less than 5 m.

[0051] (2) The shoulder type reinforced soil retaining wall should appropriately increase the reinforcement length, and the minimum reinforcement length should not be less than 1 times the wall height.

[0052] When checking the internal stability of the reinforced soil support structure, the reinforcement strength and anti-pulling stability checking of the reinforced soil retaining wall can be carried out according to the relevant provisions of the “Railway Subgrade Retaining Structure Design Specification” TB 10025. According to the failure model, the potential failure surface of the reinforced soil retaining wall is , and the relationship between the potential failure surface depth and the wall height is approximately . where s is the potential failure surface depth, h is the wall height, and φ is the internal friction angle of the fill.

[0053] The reinforced soil retaining structure 10 in the embodiment is 7-9 m high, the wall surface slope ratio is 1:0.3, the internal friction angle of the fill is 35°, the single-stage wall height is ≤10 m, and the wall surface is 8-10 m away from the supporting pile 8. According to the above formula, the angle between the potential failure surface of the reinforced soil retaining wall and the horizontal plane is 62.5°, and the maximum depth of the potential failure surface is 4.8 m. According to the structural design, the earth pressure in the limited width range is considered, and the internal stability is met, so that the parameters (reinforcing material model, length, layer spacing, etc.) of the reinforced soil retaining wall are determined. The length of the reinforcing material can be set to 0.8-1.2 times the wall height. The full-length length of the reinforcing material is 8-12 m (considering the lengthening of the base), the spacing of the unidirectional geogrid is 0.8 m, the composite geogrid is interlaid, the spacing of the adjacent unidirectional and composite geogrids is 0.4 m, and the Tensa geogrid and related connecting pieces that have passed the detection are used.

[0054] S4. Construct the pile-anchor supporting structure according to the reinforcement structure design drawing: construct the pile body of the supporting pile row 8 from the top of the original slope, after the pile body is cured to the design strength, excavate the original slope soil in front of the pile layer by layer from top to bottom, and the excavation range covers the sliding deformation area of the original slope; in the excavation process, the crown beam, the prestressed anchor cable 9 and the waist beam of the supporting pile row 8 are sequentially constructed, and the soil between the adjacent pile bodies of the supporting pile row 8 is supported by net spraying construction, until the excavation reaches the design bottom elevation; after the construction of the supporting pile row 8 is completed and the spraying between the piles is closed, after the excavation surface reaches the position of the shallow soil hole, crack or karst cave confirmed by the survey, a row of horizontal grouting flower pipes 17 are punched from the pile body according to the design position and length, and the pre-mixed foamed concrete is injected to form a grouting reinforced body; during the construction process, the anchor cable is tensioned, locked, sealed and poured according to the design requirements, and the excavation and support are carried out simultaneously;

[0055] S5. After the construction and curing of the pile-anchor supporting structure are completed, the reinforced soil supporting structure 10 on the outside is continuously constructed: the foundation in the excavation area is leveled, and the compacted foundation is rolled to ensure that the compactness and bearing capacity meet the design and specification requirements; the bottom drainage layer is constructed on the bottom surface of the excavation area, the bottom geogrid is laid according to the actual position of the construction line, and then the soil layer is backfilled and rolled to the bottom elevation of the next layer, and the geogrid is laid, and the backfilling is repeated in turn to the slope top height; and in the backfilling process, the longitudinal drainage layer is arranged between the reinforced soil supporting structure 10 and the pile-anchor supporting structure;

[0056] S5. After the backfilling of the reinforced soil supporting structure 10 is completed, the anti-seepage layer 10-3 is constructed on the top surface of the reinforced soil supporting structure 10, and the top of the anti-seepage layer 10-3 is constructed with the top of the slope top drainage ditch, and the anti-seepage layer 10-3 is made of waterproof clay layer;

[0057] S6. After the whole slope reinforcement is completed, the slope greening is restored, the slope top road 11 and the auxiliary structure are constructed, and the slope greening adopts the ecological slope surface planting bag greening of the reinforced soil supporting structure.

[0058] The present application can make a monitoring scheme before construction, monitor during the whole construction process and operation period, and dynamically feedback the slope reinforcement effect, especially the displacement and settlement values of the slope top road and building structures in time. The present application greatly improves the stability of the red clay high and steep slope, effectively improves the slope surface erosion resistance, effectively controls the displacement of the building structures such as the road and houses adjacent to the slope top, and simultaneously utilizes the newly-built rigid support and the reinforced soil flexible support adjacent to the building structures, combines rigidity and flexibility, fully utilizes the original slope supporting system, reduces the disturbance to the original soil and the damage to the existing supporting structure as much as possible, the newly-built flexible reinforced soil structure simultaneously serves as the passive reinforcement area of the newly-built rigid support structure, greatly increases the permanent support safety of the rigid support structure, compared with the traditional reinforcement scheme, not only reduces the engineering cost, shortens the construction period and reduces the carbon emission, but also greatly enhances the comprehensive benefits of the red clay high and steep slope collapse reinforcement.

[0059] The present application is suitable for the case that the original high and steep red clay slope supporting system is insufficient in strength due to the large change of the site stratum condition or rainfall, the shallow soil hole and fissure develop, the upper part continuously collapses and deforms after treatment, the upper supporting structure fails, and the overall stability of the slope and the safety of the road and houses adjacent to the slope top are seriously affected. In order to ensure the permanent stability of the high and steep red clay slope during the construction process and operation period and the safety of the adjacent building structures, an economic, practical and convenient rigid-flexible combined reinforcement system and construction method are provided.

[0060] The basic principles and main features of the present application and the advantages of the present application are shown and described. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the structural relationship and principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A red clay high and steep slope collapse reinforcing structure for reinforcing a red clay high and steep slope with a road and a building (1) constructed on the slope top, the reinforcing structure comprising a lattice anchor support structure system (3) constructed according to the original design of the slope, characterized in that: The reinforcing structure further comprises a pile anchor support structure constructed on the outside edge line of the original slope top near the building (1), a reinforced soil support structure (10) constructed on the original slope lattice anchor support system (3) and located outside the pile anchor support structure, and 1-2 layers of grouting reinforced bodies (16) constructed below the foundation of the slope top building (1); the pile anchor support structure comprises support row piles (8) and multiple rows of prestressed anchor cables (9) arranged at intervals on the support row piles (8), the support row piles (8) are hung with nets and sprayed with concrete between the adjacent two pile bodies, and the support row piles (8) and the prestressed anchor cables (9) all enter the rock bearing layer (5); the reinforced soil support structure (10) comprises a reinforced soil layer structure formed by excavating the original landslide slope body (6) and then layer-by-layer compacting and backfilling, and a slope top road (11) is constructed on the top of the reinforced soil support structure (10); the grouting reinforced body (16) is a reinforcing structure formed by foamed concrete grouting.

2. The red clay high and steep slope collapse reinforcing structure according to claim 1, characterized in that: The original design and construction lattice anchor support structure system (3) of the slope comprises a reinforced concrete frame beam (3-2) formed by supporting and pouring on the excavated slope surface of the original slope (2), and a steel anchor rod or steel strand anchor cable (3-1) punched into the slope from the intersection of the reinforced concrete frame beam (3-2); the steel anchor rod or steel strand anchor cable (3-1) has a horizontal and vertical spacing of 2.0-3.5 m and a punching angle of 20°-25°; the original slope (2) is bounded by the slope bottom road red line (12) at the lower part and the planned protective rail (15) at the upper part; a drainage intercepting structure (13) is arranged on the slope top and the slope bottom, and the drainage intercepting structure (13) on the slope top is arranged on the top of the reinforced soil support structure (10).

3. The red clay high and steep slope collapse reinforcing structure according to claim 1 or 2, characterized in that: The support row pile (8) is a support structure formed by connecting multiple pile bodies through waist beams and crown beams, the pile body of the support row pile (8) is constructed by drilling from a position 1-2 m away from the outside edge line of the building (1) on the original slope top before the original landslide slope body (6) is excavated, and the crown beam and the waist beam of the support row pile (8) and the prestressed anchor cable (9) are constructed from top to bottom after the original landslide slope body is excavated and before the reinforced soil support structure (10) is constructed; the prestressed anchor cable (9) is arranged at the position of the waist beam, and each prestressed anchor cable (9) is punched into the slope body from between the pile bodies and enters the rock bearing layer (5).

4. The red clay high and steep slope collapse reinforcing structure according to claim 1 or 2, characterized in that: The reinforced soil support structure (10) comprises a backfill soil layer and multiple layers of geogrids (10-1) arranged in the backfill soil layer, a drainage layer (10-2) is constructed on the vertical surface near the pile anchor support structure and on the bottom surface near the lattice anchor support structure system (3), the slope surface of the reinforced soil support structure (10) forms an ecological slope surface by backfilling a planting soil layer and planting plants, a seepage prevention layer (10-3) is arranged on the top of the reinforced soil support structure (10), and the slope top road (11) is constructed above the seepage prevention layer (10-3).

5. The red clay high and steep slope collapse reinforcing structure according to claim 1 or 2, characterized in that: The grouting reinforcement body (16) is formed by horizontally inserting a grouting flower pipe (17) between the pile bodies of the support row pile (8) to the soil layer below the foundation of the slope top building (1) during the excavation construction of the soil in front of the pile according to the design height after the completion of the support row pile (8) and the crown beam construction of the support row pile, and injecting foam concrete through the grouting flower pipe (17) to form a reinforced layer. The grouting reinforcement body (16) covers the crack, soil hole or cave area in the slope body, and the horizontal extension range of the grouting reinforcement body (16) covers the foundation of the slope top building (1). The compressive strength of the foam concrete after curing is greater than or equal to 1 MPa.

6. The red clay high and steep slope collapse reinforcing structure according to claim 2, characterized in that: The slope top of the original slope (2) is adjacent to the building (1) which is a common residential house or industrial building, and the foundation type is a shallow foundation. The distance between the building (1) and the slope top edge line of the original slope (2) is within 1 times the total height of the slope. The foundation of the building (1) is entirely or more than half of the part in the range of the potential most unfavorable sliding surface (4) of the slope.

7. The construction method of the red clay high and steep slope collapse reinforcing structure according to any one of claims 1 to 6, characterized in that, The construction method is used for reinforcing the red clay high and steep slope on the slope top with roads and buildings (1). The distance between the building (1) on the slope top and the slope top edge line of the original slope is within the total height of the original slope. The slope body of the original slope appears collapse deformation. The reinforcement structure is used for reinforcing the collapsed slope body of the original slope. The specific construction steps are as follows: S1. Confirm the original slope range affected by the collapse through geological survey, and confirm the actual position of the potential most unfavorable sliding surface (4), the actual situation of the stratum affected by the slope collapse and the distribution of the soil hole, crack or cave in the slope. Reflect the slope collapse affected range, the potential most unfavorable sliding surface (4), the survey actual stratum situation in the original slope design scheme drawing. S2. Determine the design drawing of the reinforcement structure according to the design scheme profile drawing and elevation drawing after the step S1. Determine the layout position of the pile anchor support structure, the reinforced soil support structure (10) and the grouting reinforcement body (16) on the design drawing. The support row pile (8) of the pile anchor support structure is located at the position of 1-2 m away from the outside edge line of the building (1). The prestressed anchor cable (9) of the pile anchor support structure is arranged in 2-3 layers and is inserted into the slope body from the waist beam part of the support row pile. The support row pile and the prestressed anchor cable are inserted into the rock bearing stratum (5). The reinforced soil support structure (10) is arranged in the collapsed deformation area of the original slope and is located outside the pile anchor support structure. The grouting reinforcement body (16) is arranged in 1-2 layers and is located in the shallow soil hole, crack or cave range below the foundation of the slope top building (1). The length of the grouting flower pipe of the grouting reinforcement body (16) is not less than the horizontal depth of the potential most unfavorable sliding surface (4) + 5 m. The compressive strength of the foam concrete after curing is greater than or equal to 1 MPa. S3. Construct the pile-anchor support structure according to the reinforcement structure design drawing: pile bodies of the support pile row (8) are constructed from the top of the original slope, and after the pile bodies are cured to the design strength, the original slope soil in front of the piles is excavated layer by layer from top to bottom, and the excavation range covers the sliding deformation area of the original slope; during the excavation process, the crown beam, the prestressed anchor cable (9) and the waist beam of the support pile row (8) are sequentially constructed, and the soil between the adjacent pile bodies of the support pile row (8) is supported by net spraying concrete construction, until the design bottom elevation is excavated; after the construction of the support pile row (8) is completed and before the spraying concrete between the piles is closed, a row of horizontal grouting pipes (17) are punched into the position of the shallow soil cave, crack or karst cave range confirmed by the survey from the design position and length between the pile bodies, and pre-mixed foamed concrete is injected to form a grouting reinforcement body; S4. After the construction and curing of the pile-anchor support structure are completed, the reinforced soil support structure (10) on the outside is continuously constructed: the excavation area is leveled, and the leveled base is rolled to ensure that the compaction degree and bearing capacity meet the design and specification requirements; the bottom drainage layer is constructed on the bottom surface of the excavation area, the bottom geogrid is laid according to the actual position of the construction line, and then the soil layer is backfilled and rolled layer by layer to the bottom elevation of the next layer, and the geogrid is laid, and the backfilling is repeated layer by layer to the slope top height; and during the backfilling, the longitudinal drainage layer is arranged between the reinforced soil support structure (10) and the pile-anchor support structure; S5. After the backfilling of the reinforced soil support structure (10) is completed, the anti-seepage layer (10-3) is constructed on the top surface of the reinforced soil support structure (10), and the top surface of the anti-seepage layer (10-3) is constructed with the top drainage ditch of the slope, and the anti-seepage layer (10-3) is made of waterproof clay layer; S6. After the entire slope reinforcement is completed, the slope greening is restored, and the slope top road (11) and the auxiliary structure are constructed.

8. The construction method of the red clay high and steep slope collapse reinforcing structure according to claim 7, characterized in that: In the S1 step, the original slope range affected by the landslide is confirmed, including the slope sliding height, depth, affected slope length, and the floating soil is cleared to reduce the slope shape, and the slope surface is temporarily covered during the rainy season to prevent rainwater infiltration from causing the slope to slide further; the actual situation of the slope site landslide and affected range stratum is confirmed, including the stratum type, stratum thickness, soil-rock interface (5), underground water condition, the size, position and depth of the karst cave and soil cave, especially the development of the shallow soil cave inside the most unfavorable sliding surface (4) and near the building foundation (1) below.

9. The construction method of a red clay high and steep slope collapse reinforcing structure according to claim 7 or 8, characterized in that, In the S4 step, the reinforcement material arrangement of the reinforced soil support structure (10) should meet the following requirements: When the reinforced soil support structure height is less than or equal to 3.0 m, the reinforcement material length should be not less than 4.0 m; when the reinforced soil support structure height is greater than 3 m and less than or equal to 6.0 m, the reinforcement material length should be not less than 5.0 m; when the reinforced soil support structure height is greater than 6.0 m, the minimum length of the reinforcement material should be not less than 0.8 times the wall height, which should be not less than 5 m; When checking the internal stability of the reinforced soil retaining structure, the tensile strength and anti-pulling stability of the reinforced soil retaining wall are checked according to the relevant provisions of the Railway Subgrade Retaining Structure Design Specification TB 10025; according to the failure model, the Rankine fracture surface is adopted, the angle between the potential fracture surface of the reinforced soil retaining structure and the horizontal plane is , and the relationship between the depth of the potential fracture surface and the wall height is approximately ; is the internal friction angle of the fill, s is the depth of the potential fracture surface, and h is the wall height.

10. The construction method of the red clay high and steep slope collapse reinforcing structure according to claim 7 or 8, characterized in that: The specifications of the pile body and the prestressed anchor cable of the pile-anchor support structure in the S2 step are determined by using the existing geotechnical design theory and the Lizheng software analysis and calculation; the position and the number of layers of the grouting reinforcement body are determined according to the position and size of the shallow soil hole confirmed by the survey, and generally 1-2 layers are arranged, the grouting flower pipe passes through the soil hole position, the vertical depth of the grouting reinforcement is controlled within the range of 5m below the building (1) foundation, the length of the grouting flower pipe is not less than the horizontal depth of the soil hole plus 3m, and the compressive strength of the foam concrete (17) after curing is greater than or equal to 1MPa; the slope greening in the S6 step adopts the ecological slope planting bag greening of the reinforced soil support structure.

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