Grading retaining and reinforcing system and construction method for deep filling slope converted into terrace

Abstract

The application provides a grading retaining and reinforcing system and a construction method for transforming a deep filling slope into a terrace. The grading retaining and reinforcing system is used for supporting a multi-stage terrace formed by piling deep filling on an original slope surface. The reinforcing system comprises a multi-stage rail pile retaining wall support structure arranged at the outer edge of each terrace for supporting the terrace. The multi-stage rail pile retaining wall support structure comprises a plurality of A-type rail pile retaining walls arranged on the slope surface and a B-type rail pile retaining wall arranged at the bottom of the slope. The A-type rail pile retaining walls are arranged between adjacent terraces, and the B-type rail pile retaining wall is arranged at the outer edge of the lowermost terrace. The application greatly improves the overall stability of the deep filling slope adjacent to an industrial plant and a road, effectively controls the displacement of the slope top, and uses the equal-height grading "micro pile retaining wall structure" to support and retain the deep filling slope. The stress of the support structure is more scientific and reasonable.

Description

Technical Field

[0001] This invention relates to the fields of deep fill slope treatment engineering and farmland ecological planning, protection and efficiency enhancement, specifically a graded support and reinforcement system and construction method for converting deep fill slopes into terraced fields. Background Technology

[0002] With rapid social development, industrial construction sites such as metallurgy and building materials are increasingly utilizing land space, especially in southwestern my country where flat land is limited, often requiring construction on slopes or mountainous terrain, resulting in deep fill slopes. Due to overall planning and some historical reasons, original slopes need to be converted into terraces to maintain the scale of basic farmland. The top of the slope is adjacent to industrial construction land, and the bottom is adjacent to other types of land such as ditches, ponds, and woodlands. Slope conversion into terraces is generally suitable for original slopes with a comprehensive slope range of 10-18°, directly converted by excavation and filling in multiple stages, with each stage's elevation difference controlled within 1.5m. To control the elevation difference between stages, the width of each terrace is relatively small, and the elevation difference between terraces is transitioned by setting up field ridges to create steeper slopes. However, when the overall elevation difference between the top and bottom of a slope is large, the comprehensive slope range for converting a slope into terraces reaches 20-25°, and the original slope has deep fill, with the top adjacent to a heavy-load road, the slope is susceptible to damage from adverse geological and hydrological conditions, loads, human activities, and potential heavy rainfall. If the terrace planning and support are inadequate, the risk of soil erosion and overall instability is high. Therefore, how to plan the conversion of such deep-filled slopes into terraces to improve agricultural production efficiency, and what support system to choose to prevent shallow and overall slope slippage and control slope displacement, have become problems worthy of research and urgent solutions.

[0003] Traditional solutions mainly include: (1) graded retaining wall scheme, but due to the deep fill, the pure gravity retaining wall is very thick and occupies a large area, and the foundation is still in the fill, which often results in insufficient resistance to overturning and sliding; (2) using anti-slide piles or pile anchor scheme, which is expensive and has a long cycle, and because the anchor cable drilling in the deep fill is prone to collapse, the anchor bearing layer is difficult to guarantee, and the support piles are prone to overturning due to insufficient pull-out bearing capacity. Traditional support schemes to avoid shallow and overall sliding of slopes are often expensive and have a long construction period. The amount of excavation and filling of earth and stone is large, the disturbance of the original soil greatly aggravates the instability of the slope, and the quality of the anchor cable is difficult to guarantee, which poses a great threat to the soil and water conservation of deep fill slopes converted into terraces, farmers' production operations, and the normal operation of roads and factories on the top of the slope. Summary of the Invention

[0004] This invention addresses the shortcomings and defects of existing technologies by providing a graded support and reinforcement system and construction method for converting deep fill slopes into terraces. This reinforcement system utilizes the advantages of flexible micro-rail pile placement, minimal disturbance to the soil and rock mass, and high combined stiffness to ensure the permanent stability and safe operation of the terraces and surrounding important structures, prevent soil erosion, and maximize the overcoming of the disadvantages of traditional terraces, such as excessive gradation, poor regularity, and complete reliance on manual cultivation. It also maintains the farmland ecology and improves production quality, making it more economical, practical, and convenient than traditional solutions.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a graded support and reinforcement system for converting deep fill slopes into terraces. This system is used to support multi-level terraces formed by filling deep fill slopes on original slopes. The reinforcement system includes a multi-level steel rail pile retaining wall support structure installed on the outer edge of each terrace. The multi-level steel rail pile retaining wall support structure includes multiple A-type steel rail pile retaining walls located on the slope and B-type steel rail pile retaining walls located at the bottom of the slope. The A-type steel rail pile retaining walls are installed between adjacent terraces, and the B-type steel rail pile retaining walls are installed on the outer edge of the lowest terrace.

[0006] Both the Type A rail pile retaining wall and the Type B rail pile retaining wall located at the bottom of the slope include a retaining wall body and multiple rail piles embedded in the retaining wall body. The multiple rail piles are arranged along the retaining wall body, and the top of the piles are connected as one unit by a pile top cap beam. The upper part of the rail piles and the pile top cap beam are located in the retaining wall body. The lower part of each rail pile is inserted into the stable soil layer below the original slope. The retaining wall body is provided with upper shallow drainage holes and bottom deep water inlet holes.

[0007] The width and height of the retaining wall of the type B rail pile retaining wall are both greater than those of the type A rail pile retaining wall. The rail pile density of the type B rail pile retaining wall is greater than that of the type A rail pile retaining wall. Furthermore, the depth to which each rail pile of the type B rail pile retaining wall is inserted into the stable soil layer below the original slope is not less than 1 / 3 of the total length of the rail piles of the type B rail pile retaining wall.

[0008] The preferred technical solution of the present invention is as follows: the retaining wall of the type A rail pile retaining wall and the type B rail pile retaining wall is provided with a retaining wall drainage ditch on the outer side of the wall bottom, and the outlet of the upper shallow drainage hole and the bottom deep water inlet hole are both located above the retaining wall drainage ditch. The retaining wall drainage ditch is used to collect the water discharged from the upper shallow drainage hole and the bottom deep water inlet hole; the retaining wall is a masonry retaining wall or a concrete wall.

[0009] The preferred technical solution of the present invention is as follows: the top of the retaining wall of the type A steel rail pile retaining wall and the top road of the wall are provided with guardrails and the top road; longitudinal farm roads are set at intervals of 100~200m inside each level of terrace, and gentle slope roads are built at the intersection of the longitudinal farm roads and the retaining walls of each level, so that the top road of the wall is smoothly connected to the longitudinal farm roads inside the terrace.

[0010] The preferred technical solution of the present invention is as follows: the rail piles of the type A rail pile retaining wall and the type B rail pile retaining wall are arranged vertically at equal intervals. The upper part of the rail pile is set inside the retaining wall body, and the bottom of the rail pile is embedded in the stable soil layer, forming a micro-pile retaining wall structure with the retaining wall body.

[0011] The preferred technical solution of the present invention is as follows: the length and width of the capping beam at the top of the pile of the type A steel rail pile retaining wall and the type B steel rail pile retaining wall are equal to the length and width of the corresponding retaining wall body, the thickness of the capping beam is 0.8 to 1.2 m, and the top elevation of the capping beam is 0.8 to 1.2 m below the top elevation of the wall.

[0012] This invention also provides a construction method for a graded retaining and reinforcement system for converting deep fill slopes into terraces, with the specific construction steps as follows:

[0013] S1. The design of the terraced fields with graded heights is based on the planned elevation of the top and bottom of the slope. The total elevation difference is calculated, and the total elevation difference of the terraced fields is divided by the total width of the farmland to obtain the comprehensive slope ratio and convert it into the comprehensive slope. When the comprehensive slope is between 20 and 25°, the terraced fields are divided into levels with an elevation difference of 3 to 6 meters per level. The width of each level of terraced fields is not less than 10 meters. The bottom elevation difference is relatively large. The terraced fields are divided into N levels in total.

[0014] S2. Based on the width of each terrace and the elevation difference of each level of backfill soil, combined with the strata of the original slope after modification, the strata characteristics and physical and mechanical parameters of the original soil and backfill soil, the slope top surface load, and the hydrogeological conditions, and by using borehole or inclination monitoring data to determine the development depth and location of shallow and deep slip zones, the landslide thrust T1 of the overall deep slip surface of the slope and the landslide thrust T2 of each level of shallow slip surface are calculated using existing software. The landslide thrust T1 of the overall deep slip surface below the 1st to N-1th terrace levels is calculated sequentially. n T1 n =T1 n-1 -T2, where n is any level of terraced field;

[0015] S3. Calculate the landslide thrust borne by the rail piles in the steel rail pile retaining wall of each terrace. Assume that type A steel rail pile retaining walls primarily support and control shallow landslides, and type B steel rail pile retaining walls primarily support and control deep landslides. Then, obtain the landslide thrust T borne by the rail piles in each type A steel rail pile retaining wall. A =T2, the landslide thrust T borne by the central rail pile of the B-type rail pile retaining wall.B It is equal to the slope landslide thrust of the entire deep sliding surface below the N-1th level terrace;

[0016] S4. Based on the installation parameters of each level of Type A rail pile retaining wall and the landslide thrust borne by the rail piles in each level of Type A rail pile retaining wall, calculate the landslide thrust T that a single rail pile in each level of Type A rail pile retaining wall needs to bear. A ’ T A ’ =T A *d / m;

[0017] Based on the installation parameters of the Type B rail pile retaining wall and the landslide thrust borne by the rail piles in the Type B rail pile retaining wall, calculate the landslide thrust T that a single rail pile in the Type B rail pile retaining wall needs to bear. B ’ T B ’ =T B *d / m;

[0018] In the two formulas above, d represents the spacing between the rail piles in the rail pile retaining wall; m represents the number of rows of rail piles in the rail pile retaining wall.

[0019] S5. Based on the landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to withstand, calculated in S4. A ’ and T B ’ Select the appropriate type of rail pile; calculate the anti-slip force P of different types of rail piles, and calculate the safety factor k of each type of rail pile when used in type A and type B rail pile retaining walls. A、 k B k A =P / T A ’ k B =P / T B ’ The calculated safety factor k for each type of rail pile when used in Type A and Type B rail pile retaining walls. A、 k B Compare with the safety factor k that meets the design requirements;

[0020] When k A If k ≥ k, then the rail pile of this type meets the design requirements for Type A rail pile retaining wall;

[0021] When k B If k ≥ k, then the rail pile of this type meets the design requirements for type B rail pile retaining wall;

[0022] S6. After selecting the appropriate type of rail pile, construction of the rail pile retaining wall will proceed. The specific steps are as follows:

[0023] S601. Measure and set out, mark the plane position and elevation of the positioning line of each terrace retaining wall, and clean the construction surface;

[0024] S602. Construct the bottom layer B-type steel rail pile retaining wall, drainage ditch, upper shallow drainage hole and bottom deep water inlet hole according to the design drawings and requirements;

[0025] S603. Backfill and compact the soil from bottom to top according to the design drawings and requirements, and construct the A-type steel rail pile retaining walls at all levels;

[0026] S604. After the overall backfilling and construction of the retaining walls of various levels of steel rail piles are completed, the backfilling of the industrial site on the top of the slope and the construction of roads, factories and their ancillary structures will be carried out, the bottom of the slope will be leveled, and the construction of the road guardrails on the top of the wall and the terraced farmland road system will be carried out at the same time.

[0027] Further technical solutions of the present invention:

[0028] The calculation formulas for the anti-slip force P of different types of rail piles in step S5 are as follows:

[0029]

[0030] In the formula, P is the anti-slip force of the rail pile. For the allowable tensile stress of the rail, The flexural modulus of the rail section. This is the maximum dimension of the rail cross-section. , For the bottom width of the rail, For track elevation, Take 615.4 MPa.

[0031] The preferred technical solution of the present invention is as follows: In step S4, the width of the retaining wall of the type A rail pile retaining wall is 1.8-2.5m, the spacing d between adjacent rail piles in the type A rail pile retaining wall is 1.0-2.5m, and the number of rail pile rows is 1-2 rows; the width of the retaining wall of the type B rail pile retaining wall is 2.5-5m, and at least 1 / 3 of the height of the type B retaining wall is buried in the original slope soil layer, and the spacing d between adjacent rail piles in the type B rail pile retaining wall is 1.0-2m. The retaining wall is 5m high, with 3 to 4 rows of rail piles. The A-type and B-type rail pile retaining walls are constructed of masonry or concrete, with rails ranging from 38KG / m to 50KG / m. Concrete is poured into the bottom 0.5m to 0.8m of the pile hole, and cement mortar is poured into the rest. A 1m to 1.2m thick reinforced concrete capping beam is installed on the top of the pile. Shallow drainage holes at each level of retaining wall are arranged in multiple rows at 2m intervals, while deep drainage holes at the bottom are arranged in a row at 10 to 15m intervals.

[0032] The preferred technical solution of this invention is as follows: In S601, the surface cleaning specifically involves clearing the original slope, removing obstacles, and removing and appropriately replacing weak soil layers such as silt, debris, etc.; During the construction process in S603, attention should be paid to the safety and stability of the temporary excavation and support of the retaining wall, controlling the quality of the foundation and backfill behind the wall, and the upper-level backfill and support structure construction should not be carried out before the concrete strength of the lower-level retaining wall and the top cap beam of the rail pile reaches the design requirements; After the completion of S604, the terrace roads and retaining wall drainage system at all levels are formed, and water storage ponds at all levels are constructed to provide irrigation water for farmland.

[0033] The preferred technical solution of this invention is to monitor the entire construction process, including the displacement and stress of the slope-top road, factory, terraces, and retaining walls during the construction and operation periods. The monitoring period is no less than 2 years, until the monitoring data tends to stabilize and meet the specifications and design requirements.

[0034] The rail piles in this invention can utilize scrap rails, and the quality of the rails meets national standards, using heavy-duty rails.

[0035] The beneficial effects of this invention are:

[0036] (1) The terrace planning and grading height and the retaining system of the present invention are scientific and reasonable. Type A and Type B steel rail pile retaining systems are set on the slope and the bottom of the slope respectively. The potential shallow slippage and the overall potential deep slippage of each level of the field ridge are supported in stages, so that the force distribution of the retaining system is more balanced and reasonable, and the support effect is guaranteed.

[0037] (2) This invention utilizes the advantages of flexible arrangement of micro rail piles, small disturbance to the soil and rock mass, and large combined stiffness. Based on the test results of the stress state of the rail anti-slide piles, the available anti-slide force of various types of rail piles is derived and calculated. Combined with the calculation results of the potential landslide thrust in different parts of the terrace, the finished rail piles of the appropriate model and specifications that meet the design requirements are selected. Combined with the commonly used rubble concrete retaining wall scheme, shallow drainage holes and deep water diversion holes are set in stages to discharge the groundwater in the slope in a timely manner. This can ensure the permanent stability and safe operation of the terrace and its surrounding important buildings and structures, and prevent soil erosion.

[0038] (3) In view of the factors such as large slope angle, deep fill, large undulation of original slope terrain, poor stratum properties, and unfavorable surrounding environmental load of non-traditional terraces, this invention minimizes the number of tiers and increases the width of each tier of terraces. Combined with a tiered steel rail pile retaining wall tiered support system, an overall agricultural road system and drainage and irrigation system are set up to overcome the shortcomings of traditional terraces, such as too many tiers, poor regularity, and complete reliance on manual cultivation, so as to maintain the farmland ecology and improve the quality of production.

[0039] (4) Compared with traditional solutions such as graded retaining walls, anti-slide piles or pile-anchored retaining schemes, the present invention adopts vertical retaining walls and uses the top of the walls to build farm roads to reduce the area occupied by farmland, reduce the amount of earthwork excavation and filling and the serious disturbance to the original soil, and can use scrap steel rails as support, which can recycle resources, save overall cost and construction time, and is green and environmentally friendly. The support structure system of the present invention is reasonable and easy to construct, enhances the safety and stability of terraced fields, and improves the overall social, economic and ecological benefits. Attached Figure Description

[0040] Figure 1 This is a cross-sectional schematic diagram of the overall effect of the graded support and reinforcement system of the present invention;

[0041] Figure 2 This is a longitudinal cross-sectional schematic diagram of the Type A steel rail pile retaining wall in this invention;

[0042] Figure 3 This is a schematic cross-sectional view of the Type A steel rail pile retaining wall in this invention;

[0043] Figure 4 This is a longitudinal cross-sectional schematic diagram of the B-type steel rail pile retaining wall in this invention;

[0044] Figure 5 This is a schematic cross-sectional view of the B-type steel rail pile retaining wall in this invention;

[0045] Figure 6 This is a schematic diagram of the connection of agricultural roads at various levels in the terraced fields according to the present invention;

[0046] Figure 7 This is a schematic diagram of the cross-section of the rail pile in this invention;

[0047] Figure 8 This is a simplified diagram of the potential slippage mode of the graded support slope of the rail pile retaining wall according to the present invention.

[0048] In the diagram: 1-1—Slope top land boundary line, 1-2—Slope bottom land boundary line, 2—Terraced fields, 3—Type A steel rail pile retaining wall, 3-1—Retaining wall body, 3-2—Steel rail pile, 3-20—Steel rail, 3-21—Steel rail pile borehole, 3-22—Cement grout; 3-3—Pile top cap beam, 3-4—Upper shallow drainage hole, 3-5—Bottom deep water intake hole, 3-6—Retaining wall drainage ditch, 3-7—Guardrail, 3-8—Road on top of the wall, 4—Original slope surface, 5—Type B steel rail pile retaining wall, 6—Slope top industrial park road, 7—Slope bottom, 8—Slope top industrial plant, 9—Slope top intercepting drainage ditch, 10—Slope top enclosure structure, 11—Longitudinal farm road, 12—Potential shallow slip surface, 13—Potential deep slip surface, α—Comprehensive slope angle. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 8 All accompanying drawings are simplified versions of embodiments and are intended only to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the drawings below are specific solutions of embodiments of the present invention and are not intended to limit the scope of the claimed invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Example 1 illustrates a graded retaining and reinforcement system for converting deep fill slopes into terraces, such as... Figures 1 to 8 As shown, this is used to support multi-level terraces 2 formed by deep backfilling on an original slope 4. The slope is agricultural land within the red line, the top of the slope is adjacent to the red line of newly built industrial land and its site, and the bottom of the slope is land of other uses. The reinforcement system includes a multi-level steel rail pile retaining wall support structure deployed on the outer edge of each terrace 2 for its support. The multi-level steel rail pile retaining wall support structure includes multiple A-type steel rail pile retaining walls 3 located on the slope surface and B-type steel rail pile retaining walls 5 located at the bottom of the slope. Type A rail pile retaining wall 3 is set between adjacent terraces, and Type B rail pile retaining wall 5 is set at the outer edge of the lowest terrace 2; the width and height of the retaining wall of Type B rail pile retaining wall 5 are greater than those of Type A rail pile retaining wall 3, the rail pile layout density of Type B rail pile retaining wall 5 is greater than that of Type A rail pile retaining wall 3, and the depth to which each rail pile of Type B rail pile retaining wall 5 is inserted into the stable soil layer below the original slope is not less than 1 / 3 of the total length of the rail piles of Type B rail pile retaining wall 5.

[0052] In Example 1, as Figures 1 to 7As shown, both the type A rail pile retaining wall 3 and the type B rail pile retaining wall 5 located at the bottom of the slope include a retaining wall body 3-1 and multiple rail piles 3-2 embedded in the retaining wall body 3-1. The multiple rail piles 3-2 are arranged along the retaining wall body 3-1, and the pile tops are connected by a pile top capping beam 3-3. The upper parts of the rail piles 3-2 and the pile top capping beam 3-3 are located within the retaining wall body 3-1. The lower part of each rail pile 3-2 is inserted into the stable soil layer below the original slope. The retaining wall body 3-1 is equipped with... The retaining wall 3-1 of the type A rail pile retaining wall 3 and the type B rail pile retaining wall 5 has a retaining wall drainage ditch 3-6 on the outer side of the bottom of the retaining wall body 3-1. The outlets of the upper shallow drainage hole 3-4 and the bottom deep water inlet hole 3-5 are both located above the retaining wall drainage ditch 3-6. The retaining wall drainage ditch 3-6 is used to collect the water discharged from the upper shallow drainage hole 3-4 and the bottom deep water inlet hole 3-5. The retaining wall body 3-1 is a masonry retaining wall or a concrete wall.

[0053] The retaining wall 3-1 of both the Type A and Type B rail pile retaining walls 3-1 is equipped with a guardrail 3-7 and a top road 3-8. Within each level of terrace 2, longitudinal farm roads 11 are arranged at intervals of 100-200m. Gentle slopes are constructed at the intersections of the longitudinal farm roads 11 and the retaining wall 3-1 at each level, ensuring smooth connection between the top road 3-8 and the longitudinal farm roads 11 within the terraces. The rail piles 3-2 of both the Type A and Type B rail pile retaining walls 3-1 are arranged vertically at equal intervals. The upper part of the rail piles 3-2 is entirely embedded inside the retaining wall 3-1, while the bottom of the rail piles 3-2 is embedded in the stable soil layer, forming a micropile retaining wall structure with the retaining wall 3-1. The length and width of the capping beam 3-3 at the top of the A-type steel rail pile retaining wall 3 and the B-type steel rail pile retaining wall 5 are equal to the length and width of the corresponding retaining wall body 3-1. The thickness of the capping beam 3-3 is 0.8 to 1.2 m, and the top elevation of the capping beam is 0.8 to 1.2 m below the top elevation of the wall.

[0054] The graded retaining and reinforcement system for converting deep fill slopes into terraces in Example 1 is a multi-stage steel rail pile retaining wall system designed and constructed for converting deep fill slopes into terraces on existing slopes. The slope is agricultural land within the red line, with the top of the slope adjacent to the red line of newly built industrial land and its site, and the bottom of the slope being land of other uses. Longitudinal farm roads are set at certain intervals within each level of terrace, and gentle slope roads are constructed at the intersections of the longitudinal roads and each level of retaining wall to ensure smooth connection between the roads on the top of the slope and the internal roads of the terraces. In the embodiments, both the Type A rail pile retaining wall 3 and the Type B rail pile retaining wall 5 are constructed of C30 rubble concrete. The rail piles are integrally installed inside the rubble concrete retaining wall, with at least two rows of vertically grouted rail piles arranged in a staggered, equidistant pattern. The pile diameter is 30cm, and the rail type is 38KG / m~50KG / m. The spacing is generally 1.0~2.5m. C30 concrete is poured into the bottom 0.5m of the pile hole, and M30 cement mortar is poured into the remaining hole. The bottom of the rail piles is embedded in the stable soil layer, forming a high-rigidity "micro-pile retaining wall structure". A reinforced concrete capping beam is integrally installed on the top of each rail pile. The length and width of the capping beam are equal to the length and width of the retaining wall, and the thickness of the capping beam is approximately 1m. The top elevation of the capping beam is approximately 1m below the top elevation of the wall. The dimensions and specifications of the intercepting drainage ditch, shallow drainage holes, and deep water inlet holes are designed and determined based on the slope catchment area and the maximum rainfall during the rainy season. The shallow drainage holes of each level of retaining wall are arranged in multiple rows at 2m intervals in both the horizontal and vertical directions, while the deep drainage holes at the bottom are arranged in a row at 10-15m intervals.

[0055] The construction process of this invention will be further explained below with reference to specific application cases. Example 2 takes the construction of a new industrial park on the top of a slope and the need to convert the original slope into terraces with deep soil filling as an example. The specific construction method of the graded support (reinforcement) system of the steel rail pile retaining wall for converting the deep soil filling slope into terraces is as follows:

[0056] S1. The design of the terraced fields with backfill soil is based on the planned elevations of the top and bottom of the slope. The total elevation difference is calculated, and the overall slope ratio is obtained by dividing the total elevation difference by the total width of the farmland. Specifically, the total elevation difference H = 21m is calculated from the planned top and bottom elevations, and the total width of the farmland is W = 50m. The resulting overall slope α = 22° is calculated. The overall slope ratio = tanα = H / W, α = arctan(H / W). Since the calculated slope is within the range of 20-25°, a non-traditional terraced design is considered. The upper terraces are divided into levels with a uniform elevation difference of approximately 5m, each level being 12m wide (including the retaining wall width). The bottom terraces have a slightly larger elevation difference of 6m. A total of four levels of terraces are determined. The lowest level has a width and elevation difference of 14m and 6m respectively, while the upper three levels have widths and elevation differences of 12m and 5m respectively.

[0057] S2. Based on the terrace widths and vertical support height differences confirmed in step S1, combined with the original topography, characteristics of the original soil and backfill soil layers, physical and mechanical parameters, slope top surface load, and hydrogeological conditions, and combined with survey borehole or inclinometer monitoring data, determine the development depth and location of shallow and deep slip zones. Using the Lizheng slope software or other professional software, input the above parameters, and automatically search for the most unfavorable slip surface based on the limit equilibrium principle. Calculate the overall deep slip surface and the shallow slip surfaces at each level for both the overall slope and local slopes. Calculate the slope landslide thrust T1 for the overall deep slip surface and the slope landslide thrust T2 for each level of shallow slip surface. In this case, the calculation results are T1 = 1050 kN / m and T2 = 230 kN / m. According to the formula T1... n =T1 n-1 -T2 calculates the slope landslide thrust of the entire deep sliding surface below the first to third terraces in sequence, as follows (from top to bottom):

[0058] First-level terrace: The landslide thrust along its shallow sliding surface is T21=T2=230kN / m, and the landslide thrust along the entire deep sliding surface below this level of terrace is T11=T1-T21=820kN / m.

[0059] Second-level terraces: The landslide thrust along its shallow sliding surface is T22=T2=230kN / m. Along this level of terraces...

[0060] The landslide thrust of the terraced slope at the lower overall deep sliding surface is T12=T11-T22=590kN / m;

[0061] The third-level terrace: the landslide thrust along its shallow sliding surface is T23=T2=230kN / m, and the landslide thrust along the overall deep sliding surface below this level of terrace is T13=T12-T23=360kN / m.

[0062] S3. Assuming that Type A rail pile retaining walls primarily support and control shallow slippage, and Type B rail pile retaining walls primarily support and control deep slippage, the landslide thrust T borne by the middle rail piles of each type A rail pile retaining wall is obtained. A =T2=230kN / m, the B-type steel rail pile retaining wall is the support for the lowest level terrace (i.e., the fourth level terrace), meaning the landslide thrust T borne by the middle steel rail pile of the B-type steel rail pile retaining wall is... B Equal to the slope landslide thrust of the entire deep sliding surface below the third terrace, yielding T. B =T13=360kN / m.

[0063] S4. In Example 2, the Type A rail pile retaining wall has two rows of rail piles arranged with a spacing d of 2.5m between the rail piles in the same row, while the Type B rail pile retaining wall has three rows of rail piles arranged with a spacing d of 2m between the rail piles in the same row. The pile length of both the Type A and Type B rail pile retaining walls is 15m, and the row spacing is 1m. Considering the differences in potential landslide thrust at each level, they are arranged in a staggered pattern. Based on the rail pile spacing d, the number of rail pile rows (m) in each level of the Type A rail pile retaining wall, and the landslide thrust borne by the central rail pile in each level of the Type A rail pile retaining wall, the landslide thrust T that a single rail pile in each level of the Type A rail pile retaining wall needs to bear is calculated. A ’ :

[0064] T A ’ =T A *d / m=230*2.5 / 2=287.5kN;

[0065] Based on the spacing d of the rail piles in the B-type rail pile retaining wall, the number of rail pile rows m, and the landslide thrust borne by the middle rail pile of the B-type rail pile retaining wall, calculate the landslide thrust T that a single rail pile in the B-type rail pile retaining wall needs to bear. B ’ T B ’ =T B *d / m=360*2 / 3=240kN;

[0066] S5. Based on the landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to withstand, calculated in S4. A ’ and T B ’ Select the appropriate type of rail pile;

[0067] First, the anti-slip force P of different types of rail piles is calculated. These rail piles are anti-slip piles embedded in the sliding body, and they generate resistance under bending above and below the potential sliding surface. Based on the stress state test results of the anti-slip piles, the anti-slip force of the rail is estimated using the corresponding calculation formula. The stress state test results of the anti-slip piles show that the rail is bent near the sliding surface and exerts pressure on the soil. The maximum bending moment is above and below the potential sliding surface, with a positive and negative bending moment difference of 0.5–0.75 m. Based on this, the calculation formula for the anti-slip force of the rail piles is given:

[0068]

[0069] The experimental results from Smyder.vw show that the distance between the maximum positive and negative bending moments is 3 to 4 times the pile diameter; based on this, a modified formula for calculating the anti-slip force of rail piles is established:

[0070]

[0071] In the formula, For anti-slip force, For the allowable tensile stress of the rail, The flexural modulus of the rail section. This represents the distance between the positive and negative bending moments near the sliding surface. This is the maximum dimension of the rail cross-section. , For the bottom width of the rail, For track elevation, Take 0.625m, Take 615.4 MPa.

[0072] The selection range for rail pile models includes three specifications: 38KG / m, 43KG / m, and 50KG / m. The anti-slip forces of various rail models calculated using the above two formulas are shown in Table 1.

[0073] Table 1 Calculation results of anti-slide force of rail anti-slide piles

[0074]

[0075] For safety reasons, the calculation result of P2 is used as the anti-slip force P of the selected rail pile in the embodiment;

[0076] Let P = P2, calculate the safety factor k for each type of rail pile when used in type A rail pile retaining walls and type B rail pile retaining walls. A、 k B k A =P / T A ’ k B =P / T B ’ The calculated safety factor k for each type of rail pile when used in Type A and Type B rail pile retaining walls. A、 k B Compare with the safety factor k that meets the design requirements;

[0077] When k A If k ≥ k, then the rail pile of this type meets the design requirements for Type A rail pile retaining wall;

[0078] When k B If k ≥ k, then the rail pile of this type meets the design requirements for type B rail pile retaining wall.

[0079] In Implementation 2, during the trial calculation, the minimum specification of 38KG / m was uniformly adopted according to the most economical scheme. Based on the "Calculation Results of Anti-slip Force of Rail Piles" table above, a single rail pile can provide approximately 330.5kN of resistance P2. According to the requirement that the safety factor for a first-level slope should not be less than 1.35, when selecting rail piles with a specification of 38KG / m, for a single Type A rail pile: resistance / sliding thrust = P2 / TA = 330.5 / 287.5 = 1.15 < 1.35, which does not meet the design requirements; for a single Type B rail pile: resistance / sliding thrust = P2 / TB = 330.5 / 240 = 1.37 > 1.35, which meets the design requirements. Therefore, it can be determined that the 38KG / m rail piles are suitable for Type A rail pile retaining walls, but not for Type B rail pile retaining walls. To improve safety, a higher-grade rail pile, namely 43KG / m, can be selected. After calculation, it meets the design requirements. For the sake of construction uniformity, the project selected 43KG / m rail piles for construction.

[0080] S6. After selecting the appropriate type of rail pile, construction of the rail pile retaining wall will proceed. The specific steps are as follows:

[0081] S601. Measure and set out, mark the plane position and elevation of the positioning line of each terrace retaining wall, clean the construction surface, clear the original slope, remove obstacles, and remove and appropriately replace soft soil layers such as silt, garbage and debris.

[0082] S602. Construct the bottom layer B-type steel rail pile retaining wall, drainage ditch, upper shallow drainage hole and bottom deep water inlet hole according to the design drawings and requirements;

[0083] S603. Backfill and compact the soil from bottom to top according to the design drawings and requirements, and construct the A-type rail pile retaining walls at all levels. During the construction process, pay attention to the safety and stability of the temporary excavation and support of the retaining wall, control the quality of the foundation and backfill behind the wall, and do not carry out the construction of the upper-level backfill and support structure before the concrete strength of the lower-level retaining wall and the top cap beam of the rail pile reaches the design requirements.

[0084] S604. After the overall backfilling and the construction of the retaining walls of various levels of steel rail piles are completed, the backfilling of the industrial site on the top of the slope and the construction of roads, factories and their ancillary structures are carried out, the leveling of the bottom of the slope is carried out, and the construction of the road guardrails on the top of the wall and the terraced farm road system is carried out at the same time.

[0085] S605. After the construction is completed, the terraced fields at all levels will form a drainage system with retaining walls, and water storage ponds at all levels will be built to provide irrigation water for farmland.

[0086] S7. Monitoring shall be conducted throughout the construction process, including displacement and stress monitoring of the slope-top roads, factories, terraces, and retaining walls during the construction and operation periods. The monitoring period shall be no less than 2 years until the monitoring data tends to stabilize and meets the specifications and design requirements.

[0087] The example rail piles use a large amount of recycled scrap rails, the quality of which meets national standards, and heavy-duty rails are used.

[0088] This invention features a scientifically sound and rationally designed terraced field system with varying heights and support structures. It employs tiered support to address potential shallow and deep slippage at each level of the terrace embankment, resulting in a more balanced and rational stress distribution and ensuring effective support. Utilizing the advantages of flexible placement of micro-rail piles, minimal disturbance to the soil and rock mass, and high combined stiffness, this invention combines these with commonly used rubble concrete retaining wall schemes. The tiered installation of shallow drainage holes and deep water inlets allows for timely drainage of groundwater from the slope, ensuring the permanent stability and safe operation of the terraces and surrounding structures, and preventing soil erosion. Compared to traditional terraced fields, this invention features fewer tiers, wider terraces at each level, and an integrated agricultural road system and drainage / irrigation system. This maximizes the overcoming of the shortcomings of traditional terraced fields, such as excessive tiers, poor regularity, and reliance on manual cultivation, thus maintaining farmland ecology and improving production quality. Compared with traditional solutions such as graded retaining walls, anti-slide piles, or pile-anchored retaining structures, this invention reduces the area occupied by farmland and the amount of earthwork excavation and filling, avoids serious disturbance to the original soil, and can utilize scrap steel rails, which is conducive to resource recycling. Overall, it saves on construction costs and time, and is green and environmentally friendly.

[0089] The graded support and reinforcement system for converting deep fill slopes into terraces in this invention has a wide range of applications. It is suitable for situations where deep fill is needed on existing slopes for industrial plant construction. Due to the poor soil properties of the original slope and the difficulty in controlling the quality of the fill, and given that the fill slope is planned for agricultural use with a slope ratio of approximately 20-25 degrees, it is not advisable to divide each terrace into too small sections for large-scale mechanized planting, resulting in multiple terraces with relatively large differences in elevation. This system addresses the issue of multi-tiered terraces easily formed after converting deep fill slopes into terraces. Potential sliding surfaces and deep sliding surfaces along the interface between the slope and the fill, if not properly supported, pose a risk of shallow slippage or even overall landslides. In particular, increased load on the slope top or infiltration of heavy rainfall can lead to a significant increase in risk. To ensure the permanent stability and safe operation of terraced fields and important surrounding structures, prevent soil erosion, and maximize the overcoming of the shortcomings of traditional terraced fields such as excessive grading, poor regularity, and complete reliance on manual cultivation, while maintaining farmland ecology and improving production quality, an economical, practical, and convenient support or reinforcement system and construction method are proposed.

[0090] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the structural relationships and principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A graded support and reinforcement system for converting deep fill slopes into terraced fields, used for supporting multi-level terraced fields (2) formed by filling deep fill on the original slope surface (4), characterized in that: The reinforcement system includes a multi-level steel rail pile retaining wall support structure that is deployed on the outer edge of each terrace (2) to support it. The multi-level steel rail pile retaining wall support structure includes multiple A-type steel rail pile retaining walls (3) located on the slope and B-type steel rail pile retaining walls (5) located at the bottom of the slope. The A-type steel rail pile retaining walls (3) are set between adjacent terraces, and the B-type steel rail pile retaining walls (5) are set on the outer edge of the lowest terrace (2). The type A rail pile retaining wall (3) and the type B rail pile retaining wall (5) located at the bottom of the slope both include a retaining wall body (3-1) and multiple rail piles (3-2) embedded in the retaining wall body (3-1). The multiple rail piles (3-2) are arranged along the retaining wall body (3-1), and the top of the piles are connected as one unit through the pile top capping beam (3-3). The upper part of the rail piles (3-2) and the pile top capping beam (3-3) are both located in the retaining wall body (3-1). The lower part of each rail pile (3-2) is inserted into the stable soil layer below the original slope. The retaining wall body (3-1) is provided with upper shallow drainage holes (3-4) and bottom deep water inlet holes (3-5). The width and height of the retaining wall of the B-type steel rail pile retaining wall (5) are both greater than those of the retaining wall of the A-type steel rail pile retaining wall (3). The steel rail pile layout density of the B-type steel rail pile retaining wall (5) is greater than that of the A-type steel rail pile retaining wall (3). Furthermore, the depth to which each steel rail pile of the B-type steel rail pile retaining wall (5) is inserted into the stable soil layer below the original slope is not less than 1 / 3 of the total length of the steel rail piles of the B-type steel rail pile retaining wall (5). The retaining wall (3-1) of the type A rail pile retaining wall (3) and the type B rail pile retaining wall (5) are provided with a retaining wall drainage ditch (3-6) on the outer side of the wall bottom. The outlets of the upper shallow drainage hole (3-4) and the bottom deep water inlet hole (3-5) are located above the retaining wall drainage ditch (3-6). The retaining wall drainage ditch (3-6) is used to collect the water discharged from the upper shallow drainage hole (3-4) and the bottom deep water inlet hole (3-5). The retaining wall (3-1) is a masonry wall or a concrete wall. Concrete wall; the top of the retaining wall (3-1) of the type A rail pile retaining wall (3) and the type B rail pile retaining wall (5) is equipped with a guardrail (3-7) and a wall top road (3-8); longitudinal farm roads (11) are set at intervals of 100~200m inside the terraces (2), and gentle slope roads are built at the intersection of the longitudinal farm roads (11) and the retaining wall (3-1) of each level, so that the wall top road (3-8) can be smoothly connected to the longitudinal farm roads (11) inside the terraces.

2. The graded retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1, characterized in that: The rail piles (3-2) of the type A rail pile retaining wall (3) and the type B rail pile retaining wall (5) are arranged vertically at equal intervals. The upper part of the rail piles (3-2) is set inside the retaining wall body (3-1), and the bottom of the rail piles (3-2) is embedded in the stable soil layer. The rail piles and the retaining wall body (3-1) form a micro-pile retaining wall structure.

3. The graded retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1, characterized in that: The length and width of the top cap beam (3-3) of the type A rail pile retaining wall (3) and the type B rail pile retaining wall (5) are equal to the length and width of the corresponding retaining wall body (3-1). The thickness of the top cap beam (3-3) is 0.8 to 1.2 m, and the top elevation of the cap beam is 0.8 to 1.2 m below the top elevation of the wall.

4. A construction method for a graded retaining and reinforcement system for converting deep fill slopes into terraces as described in any one of claims 1 to 3, characterized in that, The specific construction steps are as follows: S1. The design of the terraced fields with backfill soil is based on the planned elevation of the top and bottom of the slope. The total elevation difference is calculated. The total elevation difference of the terraced fields is divided by the total width of the farmland to obtain the comprehensive slope ratio and convert it into the comprehensive slope. When the comprehensive slope is between 20 and 25°, the terraced fields are divided into levels with an elevation difference of 3 to 6 meters. The width of each level of terraced fields is not less than 10 meters. The bottom elevation difference is relatively large. The terraced fields are divided into N levels in total. S2. Based on the width of each terrace and the elevation difference of each level of backfill soil, combined with the strata of the original slope after modification, the strata characteristics and physical and mechanical parameters of the original soil and backfill soil, the slope top surface load, and the hydrogeological conditions, and by using borehole or inclination monitoring data to determine the development depth and location of shallow and deep slip zones, the landslide thrust T1 of the overall deep slip surface of the slope and the landslide thrust T2 of each level of shallow slip surface are calculated using existing software. The landslide thrust T1 of the overall deep slip surface below the 1st to N-1th terrace levels is calculated sequentially. n T1 n =T1 n-1 -T2, where n is any level of terraced field; S3. Calculate the landslide thrust borne by the rail piles in each level of the terraced retaining wall. Assume that type A rail pile retaining walls primarily support and control shallow landslides, and type B rail pile retaining walls primarily support and control deep landslides. Then, obtain the landslide thrust T borne by the rail piles in each level of type A rail pile retaining wall. A =T2, the landslide thrust T borne by the rail piles in the type B rail pile retaining wall. B It is equal to the slope landslide thrust of the entire deep sliding surface below the N-1th level terrace; S4. Based on the installation parameters of each level of Type A rail pile retaining wall and the landslide thrust borne by the rail piles in each level of Type A rail pile retaining wall, calculate the landslide thrust T that a single rail pile in each level of Type A rail pile retaining wall needs to bear. A ’ T A ’ =T A *d / m; Based on the installation parameters of the Type B rail pile retaining wall and the landslide thrust borne by the rail piles in the Type B rail pile retaining wall, calculate the landslide thrust T that a single rail pile in the Type B rail pile retaining wall needs to bear. B ’ T B ’ =T B *d / m; In the two formulas above, d represents the spacing between the rail piles in the rail pile retaining wall; m represents the number of rows of rail piles in the rail pile retaining wall. S5. Based on the landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to withstand, calculated in S4. A ’ and T B ’ Select the appropriate type of rail pile; calculate the anti-slip force P of different types of rail piles, and calculate the safety factor k of each type of rail pile when used in type A and type B rail pile retaining walls. A、 k B k A =P / T A ’ k B =P / T B ’ The calculated safety factor k for each type of rail pile when used in Type A and Type B rail pile retaining walls. A、 k B Compare with the safety factor k that meets the design requirements; When k A If k ≥ k, then the rail pile of this type meets the design requirements of type A rail pile retaining wall; When k B If k ≥ k, then the rail pile of this type meets the design requirements of type B rail pile retaining wall; S6. After selecting the appropriate type of rail pile, construction of the rail pile retaining wall will proceed. The specific steps are as follows: S601. Measure and set out, mark the plane position and elevation of the positioning line of the steel rail pile retaining wall of each terrace, and clean the construction surface; S602. Construct the bottom layer B-type steel rail pile retaining wall, retaining wall drainage ditch, upper shallow drainage hole and bottom deep water inlet hole according to the design drawings and requirements; S603. Backfill and compact the soil from bottom to top according to the design drawings and requirements, and construct the A-type steel rail pile retaining walls at all levels; S604. After the overall backfilling and construction of the retaining walls of various levels of steel rail piles are completed, the industrial site on the top of the slope is backfilled and the roads, factories and their ancillary structures are constructed. The bottom of the slope is leveled, and the construction of the road, guardrail and terraced farm road system on the top of the wall is carried out at the same time.

5. The construction method of a graded retaining and reinforcement system for converting deep fill slopes into terraced fields according to claim 4, characterized in that: The calculation formulas for the anti-slip force P of different types of rail piles in step S5 are as follows: ； In the formula, P is the anti-slip force of the rail pile. For the allowable tensile stress of the rail, The flexural modulus of the rail section. This is the maximum dimension of the rail cross-section. , For the bottom width of the rail, For track elevation, Take 615.4 MPa.

6. The construction method of a graded retaining and reinforcement system for converting deep fill slopes into terraced fields according to claim 4, characterized in that: In step S4, the retaining wall width of the type A rail pile retaining wall is 1.8–2.5 m, the spacing d between adjacent rail piles in the type A rail pile retaining wall is 1.0–2.5 m, and the number of rail pile rows is 1–2; the retaining wall width of the type B rail pile retaining wall is 2.5–5 m, the spacing d between adjacent rail piles in the type B rail pile retaining wall is 1.0–2.5 m, and the number of rail pile rows is 3–4; the type A rail piles The retaining walls and B-type rail pile retaining walls are constructed of masonry or concrete, with rails ranging from 38kg / m to 50kg / m. The bottom 0.5m to 0.8m of the rail pile hole is filled with concrete, and the remainder is filled with cement mortar. A reinforced concrete capping beam of 0.8m to 1.2m thickness is installed on the top of the pile. The shallow drainage holes of each level of rail pile retaining wall are arranged in multiple rows at 2m intervals horizontally and vertically, while the deep drainage holes at the bottom are arranged in a row at 10 to 15m intervals.

7. The construction method of a graded retaining and reinforcement system for converting deep fill slopes into terraced fields according to claim 4, characterized in that: The surface cleaning in S601 specifically involves clearing the original slope, removing obstacles, and removing and appropriately replacing weak soil layers. During the construction of S603, attention should be paid to the safety and stability of the temporary excavation and support of the retaining wall, and the quality of the foundation and backfill behind the wall should be controlled. The construction of the upper-level backfill and support structure should not be carried out before the concrete strength of the lower-level retaining wall and the top cap beam of the rail pile reaches the design requirements. After the completion of the construction of S604, the terrace roads and retaining wall drainage system at all levels will be formed, and water storage ponds at all levels will be built to provide irrigation water for farmland.

8. The construction method of a graded retaining and reinforcement system for converting deep fill slopes into terraced fields according to claim 4, characterized in that: Throughout the construction process, the displacement and stress of the slope-top road, factory, terraces, and retaining walls will be monitored, with a monitoring cycle of no less than 2 years, until the monitoring data stabilizes and meets the specifications and design requirements.

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