Graded retaining and reinforcing system for changing deep filling slope into terraced field and construction method

Abstract

The invention provides a graded retaining and reinforcing system for changing a terraced field from a deep filling slope and a construction method. The graded retaining and reinforcing system is used for supporting multi-stage terraces formed on the surface of an original-state slope through improvement of piling and filling deep and thick filling soil, and comprises multi-stage steel rail pile retaining wall supporting structures which are arranged on the outer edges of all stages of terraces and used for supporting the terraces. The multi-stage steel rail pile retaining wall supporting structure comprises a plurality of A-type steel rail pile retaining walls located on the slope surface and B-type steel rail pile retaining walls located at the slope bottom, the A-type steel rail pile retaining walls are arranged between adjacent terraces, and the B-type steel rail pile retaining walls are arranged on the outer edge of the lowest terrace. The overall stability of the deep filling slope-to-terrace field with the slope crest adjacent to the industrial factory building and the road is greatly improved, and the displacement of the slope crest is effectively controlled; the equal-height grading micro pile retaining wall structure is used for conducting grading retaining on the deep filling slope, and the stress of the supporting structure is more scientific and reasonable.

Description

Technical Field

[0001] The present invention relates to the fields of deep fill slope management engineering and farmland ecological planning, protection and efficiency enhancement, and in particular to a graded retaining and reinforcement system and a construction method for converting deep fill slopes into terraces. Technical Background

[0002] With rapid social development, land utilization rates are increasing at industrial construction sites for industries such as metallurgy and building materials. This is particularly true in southwest my country, where flat land is scarce. Construction is often carried out on sloping or mountainous terrain, resulting in deep fill slopes. Due to overall planning and historical reasons, existing slopes need to be transformed into terraces to maintain the size of basic farmland. The top of the slope is adjacent to industrial construction land, while the bottom is adjacent to other land uses such as ditches, ponds, and woodlands. Slope-to-terracing is generally suitable for existing slopes with a comprehensive slope range of 10 to 18°. The slopes are directly converted into terraces, with multiple levels, each with a height difference of less than 1.5 meters. To control the height difference, the width of each terrace is kept small, and the height difference between terraces is transitioned by setting ridges and steep slopes. However, when the overall height difference between the top and bottom of a slope is large, the overall slope gradient of the converted slope reaches 20-25°, and the original slope is deep filled and the top of the slope is adjacent to a heavily loaded road, the risks of soil erosion and overall instability are high due to factors such as poor geological and hydrological conditions and loads, human activities, and possible heavy rainfall. Therefore, improper terrace planning and support can lead to a high risk of soil erosion and overall instability. Therefore, how to plan the conversion of such deep fill 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 issues worthy of research and urgent solutions.

[0003] Traditional solutions mainly include: (1) graded retaining wall solutions. However, due to the deep fill, pure gravity retaining walls are very wide and thick, occupying a large area, and the foundation is still in the fill, resulting in insufficient anti-overturning and anti-slip measures; (2) the use of anti-slip piles or pile anchor solutions. This solution is expensive and time-consuming. In addition, anchor holes in deep fill are prone to collapse, making it difficult to ensure the anchor bearing layer. Due to insufficient pull-out bearing capacity, there is a risk of overturning of support piles. Traditional support solutions to avoid shallow sliding and overall sliding of slopes are often expensive and time-consuming. The amount of excavation and filling is large, the disturbance of the original soil greatly aggravates the instability of the slope, and the quality of the anchor cables is difficult to ensure. This poses a great threat to soil and water conservation in the conversion of deep fill slopes into terraces, farmers' production operations, and the normal operation of slope-top roads and factories. Summary of the Invention

[0004] In response to the shortcomings and defects of the existing technology, the present invention provides a graded support and reinforcement system and construction method for converting deep fill slopes into terraces. The reinforcement system utilizes the advantages of flexible pile arrangement of micro-rail piles, little disturbance to rock and soil, and high combined stiffness to ensure the permanent stability and safe operation of terraces and important surrounding structures, prevent soil erosion, and maximize the overcoming of the shortcomings of traditional terraces such as excessive grading, poor regularity, and complete reliance on manual farming, thereby maintaining farmland ecology and improving production quality. Compared with traditional solutions, it is economical, practical, and convenient.

[0005] In order to achieve the above technical objectives, the present invention provides a hierarchical support and reinforcement system for converting deep fill slopes into terraces, which is used to support multiple terraces formed by filling deep fill on the original slope surface. The reinforcement system includes a multi-level rail pile retaining wall support structure arranged at the outer edge of each terrace to support it. The multi-level rail pile retaining wall support structure includes multiple A-type rail pile retaining walls located on the slope surface and B-type rail pile retaining walls located 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 walls are arranged at the outer edge of the lowest terrace.

[0006] The A-type rail pile retaining wall and the B-type rail pile retaining wall located at the bottom of the slope both include a retaining wall body and a plurality of rail piles embedded in the retaining wall body. The plurality of rail piles are arranged along the retaining wall body, and the pile tops are connected as a whole by a pile top crown beam. The upper part of the rail piles and the pile top crown beam are both located in the retaining wall body, and 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 an upper shallow drainage hole and a bottom deep water diversion hole.

[0007] The width and height of the retaining wall of the B-type rail pile retaining wall are both greater than those of the A-type rail pile retaining wall. The rail pile layout density of the B-type rail pile retaining wall is greater than that of the A-type rail pile retaining wall. The depth of each rail pile of the B-type rail pile retaining wall 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 B-type rail pile retaining wall.

[0008] The better technical solution of the present invention is as follows: a retaining wall drainage ditch is provided on the outside of the bottom of the retaining wall of the A-type rail pile retaining wall and the B-type rail pile retaining wall, and the water outlets of the upper shallow drainage holes and the bottom deep water diversion holes are both located above the retaining wall drainage ditch, and the retaining wall drainage ditch is used to collect water discharged from the shallow drainage holes and the bottom deep water diversion holes; the retaining wall body is a mortar-made stone retaining wall or a concrete wall.

[0009] The preferred technical solution of the present invention is as follows: guardrails and wall-top roads are provided on the top of the retaining walls of the A-type rail pile retaining wall and the B-type rail pile retaining wall; longitudinal farming roads are arranged inside each level of terraces at intervals of 100 to 200 meters, and up and down gentle slope roads are built at the intersections of the longitudinal farming roads and the retaining walls of each level, so that the wall-top roads are smoothly connected with the longitudinal farming roads inside the terraces.

[0010] The better technical solution of the present invention is as follows: the rail piles of the A-type rail pile retaining wall and the B-type rail pile retaining wall are arranged at equal vertical intervals, the upper part of the rail piles is entirely arranged inside the retaining wall body, and the bottom of the rail piles 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 pile top crown beam of the A-type rail pile retaining wall and the B-type rail pile retaining wall are equal to the length and width of the corresponding retaining wall body, the thickness of the pile top crown beam is 0.8 to 1.2 meters, and the crown beam top elevation is 0.8 to 1.2 meters below the wall top elevation.

[0012] The present invention also provides a construction method for a graded retaining reinforcement system for converting a deep fill slope into a terraced field. The specific construction steps are as follows:

[0013] S1. Plan and design the graded heights of backfilled soil terraces. Calculate the total elevation difference based on the planned top and bottom elevations. Divide the total elevation difference by the total width of the farmland to determine the comprehensive slope ratio, which is then converted into the comprehensive slope. When the comprehensive slope is between 20 and 25 degrees, the terraces are divided into platforms with a height difference of 3 to 6 meters per level. Each level should be at least 10 meters wide, with a large height difference at the bottom, for a total of N levels of terraces.

[0014] S2. Based on the width of each terrace of backfill soil and the graded height difference, combined with the original slope stratum after modification, the stratum characteristics and physical and mechanical parameters of the original soil and backfill soil, the slope top and slope load, and the hydrogeological conditions, and using survey drilling or inclinometer monitoring data to determine the depth and location of the shallow and deep sliding zones, use existing software to calculate the slope landslide thrust T1 of the overall deep sliding surface of the slope and the slope landslide thrust T2 of each shallow sliding surface, and then calculate the slope landslide thrust T1 of the overall deep sliding surface below the 1st to N-1th terraces in turn. n , T1 n =T1 n-1 -T2, where n is any level of terrace;

[0015] S3. Calculate the landslide thrust borne by the rail piles in each terraced track pile retaining wall. Assuming that the A-type track pile retaining wall is mainly used to support and control shallow sliding, and the B-type track pile retaining wall is mainly used to support and control deep sliding, the landslide thrust borne by the middle rail piles of each A-type track pile retaining wall is obtained as T A = T2, the landslide thrust T borne by the middle rail pile of the B-type rail pile retaining wallB Equal to the landslide thrust of the entire deep sliding surface below the N-1th terrace;

[0016] S4. Calculate the landslide thrust T that a single rail pile in each level of the A-type rail pile retaining wall needs to bear based on the setting parameters of each level of the A-type rail pile retaining wall and the landslide thrust borne by the middle rail pile in each level of the A-type rail pile retaining wall. A ':T A '=T A *d / m;

[0017] According to the setting parameters of each level of B-type rail pile retaining wall and the landslide thrust borne by the middle rail pile of the B-type rail pile retaining wall, the landslide thrust T that a single rail pile in each level of B-type rail pile retaining wall needs to bear is calculated. B ':T B '=T B *d / m;

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

[0019] S5. The landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to bear, calculated in S4. A ' and T B 'Select rail piles; 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 rail pile retaining wall and type B rail pile retaining wall A 、k B , k A =P / T A ', k B =P / T B '; The safety factor k of each type of rail pile when used in type A rail pile retaining wall and type B rail pile retaining wall is calculated A 、k B Compare with the safety factor k that meets the design requirements;

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

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

[0022] S6. After selecting the rail pile model, the rail pile retaining wall is constructed. The specific process is as follows:

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

[0024] S602. Construct the bottom layer of B-type steel rail pile retaining wall, drainage ditch, upper shallow drainage holes, and bottom deep water diversion holes 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 A-type rail pile retaining walls at all levels;

[0026] S604. After the overall backfill and the construction of rail pile retaining walls at all levels are completed, the industrial site on the top of the slope will be backfilled, and the road factory buildings and their ancillary structures will be built. The bottom of the slope will be leveled, and at the same time, the road guardrails on the top of the wall and the terraced farming road system will be constructed.

[0027] Further technical solutions of the present invention:

[0028] The calculation formula of the anti-sliding force P of different types of rail piles in step S5 is as follows:

[0029]

[0030] Where P is the anti-sliding force of the rail pile, [σ] is the allowable tensile stress of the rail, W is the bending modulus of the rail section, and d is the maximum size of the rail section. B is the bottom width of the rail, h is the rail height, and [σ] is taken as 615.4MPa.

[0031] A preferred technical solution of the present invention: In step S4, the retaining wall width of the A-type rail pile retaining wall is 1.8 to 2.5 meters, the spacing d between adjacent rail piles in the A-type rail pile retaining wall is 1.0 to 2.5 meters, and the number of rail pile rows is 1 to 2; the retaining wall width of the B-type rail pile retaining wall is 2.5 to 5 meters, no less than 1 / 3 of the height of the B-type retaining wall is buried in the original slope soil layer, and the spacing d between adjacent rail piles in the B-type rail pile retaining wall is 1.0 to 2. The A-type and B-type rail pile retaining walls are made of mortar masonry or concrete, with rail types of 38kg / m to 50kg / m. The bottom 0.5m to 0.8m of the rail pile holes are poured with concrete, and the rest are poured with cement mortar. A reinforced concrete cap beam with a thickness of 1m to 1.2m is set on the top of the pile. The shallow drainage holes of the retaining walls of each level are arranged in multiple rows at a horizontal and vertical interval of 2m, and the deep water diversion holes at the bottom are arranged in a row at an interval of 10 to 15m.

[0032] The preferred technical solution of the present invention: the construction surface cleaning in S601 is specifically to clear the original slope, remove obstacles, and remove and appropriately replace soft soil layers such as silt, garbage debris, etc.; during the construction process 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 upper backfill and support structure construction shall not be carried out before the concrete strength of the lower retaining wall and the crown beam of the rail pile reaches the design requirements; after the construction of S604 is completed, the terraced roads and retaining walls at all levels will form a drainage system, and reservoirs at all levels will be built to provide water for farmland irrigation.

[0033] The preferred technical solution of the present invention is to monitor the entire construction process, monitor the displacement and force of the slope road factory buildings, terraces and retaining walls during the construction and operation periods, and the monitoring period shall be no less than 2 years, until the monitoring data tends to be stable and meets the specifications and design requirements.

[0034] The rail piles of the present invention can utilize waste rails, the quality of the rails meets national standards, and heavy rails are used.

[0035] Beneficial effects of the present invention:

[0036] (1) The terrace planning and support system of the present invention are scientific and reasonable. A-type and B-type rail pile support systems are respectively set on the slope surface and the slope bottom to provide tiered support for the potential shallow slippage of each level of ridges and the overall potential deep slippage, so that the force distribution of the support system is more balanced and reasonable, thereby ensuring the support effect.

[0037] (2) The present invention utilizes the advantages of micro rail piles, such as flexible pile position arrangement, small disturbance to rock and soil, and large combined stiffness. Based on the test results of the stress state of rail anti-slip piles, the available anti-slip 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 model and specifications of the finished rail piles that meet the design requirements are selected in a targeted manner. Combined with the commonly used rubble concrete retaining wall scheme, shallow drainage holes and deep water diversion holes are arranged in stages to discharge the groundwater in the slope in time, which can ensure the permanent stability and safe operation of the terrace and its surrounding important structures and prevent soil erosion.

[0038] (3) The present invention aims to address the factors of non-traditional terraces, such as large comprehensive slope angles, deep fill, large undulating original slope terrain, poor stratum properties, and unfavorable surrounding environmental loads. The present invention minimizes the number of levels and increases the width of each level of terraces. In combination with a graded steel rail pile retaining wall graded support system, an overall farming road system and a drainage and irrigation system are set up to maximize the overcoming of the shortcomings of traditional terraces, such as excessive levels, poor regularity, and complete reliance on manual farming, thereby maintaining farmland ecology and improving production quality.

[0039] (4) Compared with traditional solutions such as graded retaining walls, anti-slip piles or pile-anchor support solutions, the present invention adopts vertical retaining walls and uses the top of the wall to build agricultural roads to reduce the area occupied by cultivated fields, reduce the amount of earthwork excavation and filling and the serious disturbance to the original soil, and can use scrap 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, which enhances the safety and stability of the terraces and improves the overall social, economic and ecological environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 1 is a longitudinal cross-sectional schematic diagram of the A-type rail pile retaining wall of the present invention;

[0042] Figure 3 1 is a schematic transverse cross-sectional view of the A-type rail pile retaining wall of the present invention;

[0043] Figure 4 1 is a longitudinal cross-sectional schematic diagram of the B-type rail pile retaining wall of the present invention;

[0044] Figure 5 2 is a schematic transverse cross-sectional view of a B-type rail pile retaining wall according to the present invention;

[0045] Figure 6 This is a schematic diagram of the connection of terraced farming roads at various levels of the present invention;

[0046] Figure 7 Schematic diagram of the cross section of the rail pile in the present invention;

[0047] Figure 8 It is a schematic diagram of the potential sliding mode of the graded retaining slope of the rail pile retaining wall of the present invention.

[0048] In the figure: 1-1—top land redline, 1-2—bottom land redline, 2—terraces, 3—A-type rail pile retaining wall, 3-1—retaining wall, 3-2—rail pile, 3-20—rail, 3-21—rail pile drilling hole, 3-22—cement slurry; 3-3—pile top cap beam, 3-4—upper shallow drainage hole, 3-5—bottom deep drainage hole, 3-6

[0049] —Retaining wall drainage ditch, 3-7—Guardrail, 3-8—Wall top road, 4—Original slope surface, 5—B-type 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 retaining structure, 11—Longitudinal agricultural road, 12—Potential shallow slip surface, 13—Potential deep slip surface, α-Comprehensive slope angle. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 8 The accompanying drawings are simplified versions of the embodiments and are only used to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the accompanying drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0051] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0052] In the first embodiment, a graded retaining reinforcement system for converting a deep fill slope into a terraced field is provided. Figures 1 to 8 As shown, it is used to support the multi-level terraces 2 formed by filling thick fill on the original slope surface 4. The slope belongs to the agricultural land within the red line, the top of the slope is adjacent to the red line of the newly built industrial land and its site, and the bottom of the slope is other types of land; the reinforcement system includes a multi-level rail pile retaining wall support structure arranged on the outer edge of each terrace 2 to support it, and the multi-level rail pile retaining wall support structure includes a plurality of A-type rail pile retaining walls 3 located on the slope surface and a B-type rail pile retaining wall 5 located at the bottom of the slope. The A-type rail pile retaining wall 3 is arranged between adjacent terraces, and the B-type rail pile retaining wall 5 is arranged at the outer edge of the lowest terrace 2; the width and height of the retaining wall of the B-type rail pile retaining wall 5 are both larger than the retaining wall of the A-type rail pile retaining wall 3, the rail pile layout density of the B-type rail pile retaining wall 5 is greater than the rail pile layout density of the A-type rail pile retaining wall 3, and the depth of each rail pile of the B-type rail pile retaining wall 5 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 B-type rail pile retaining wall 5.

[0053] In the first embodiment, Figures 1 to 7As shown, the A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5 located at the bottom of the slope both include a retaining wall body 3-1 and a plurality of rail piles 3-2 embedded in the retaining wall body 3-1. The plurality of rail piles 3-2 are arranged along the retaining wall body 3-1, and the pile tops are connected as a whole through the pile top crown beam 3-3. The upper parts of the rail piles 3-2 and the pile top crown beam 3-3 are both located in the retaining wall body 3-1, and the lower part of each rail pile 3-2 is inserted into the stable soil layer below the original slope. There are upper shallow drainage holes 3-4 and bottom deep water diversion holes 3-5; a retaining wall drainage ditch 3-6 is provided on the outside of the bottom of the retaining wall 3-1 of the A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5, and the water outlets of the upper shallow drainage holes 3-4 and the bottom deep water diversion holes 3-5 are both located above the retaining wall drainage ditch 3-6, and the retaining wall drainage ditch 3-6 is used to collect water discharged from the upper shallow drainage holes 3-4 and the bottom deep water diversion holes 3-5; the retaining wall 3-1 is a mortared stone retaining wall or a concrete wall.

[0054] The retaining wall 3-1 of the A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5 is equipped with a guardrail 3-7 and a top road 3-8. Inside each level of terrace 2, longitudinal farming roads 11 are arranged at intervals of 100 to 200 meters. Up and down gently sloping roads are constructed at the intersections of the longitudinal farming roads 11 and the retaining wall 3-1 at each level, ensuring a smooth connection between the top road 3-8 and the longitudinal farming roads 11 inside the terrace. The rail piles 3-2 of the A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5 are arranged at equal vertical intervals. The upper portions of the rail piles 3-2 are integrally disposed within the retaining wall 3-1, and the bottoms of the rail piles 3-2 are embedded in the stabilized soil layer, forming a micro-pile retaining wall structure with the retaining wall 3-1. The length and width of the pile top crown beam 3-3 of the A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5 are equal to the length and width of the corresponding retaining wall 3-1. The thickness of the pile top crown beam 3-3 is 0.8 to 1.2 meters, and the top elevation of the crown beam is 0.8 to 1.2 meters below the wall top elevation.

[0055] The graded retaining and reinforcement system for converting deep fill slopes into terraces in Example 1 is a multi-level rail pile retaining wall support and reinforcement system designed and constructed for deep fill conversion on an existing slope. The slope is agricultural land within the redline, with the top adjacent to the newly constructed industrial land redline and its site, and the bottom of the slope is land for other purposes. Longitudinal agricultural roads are installed at regular intervals within each terrace, and gently sloping roads are constructed at the intersections of these longitudinal roads and the retaining walls, ensuring a smooth connection between the roads along the top of the slope and the roads within the terraces. The A-type rail pile retaining wall 3 and the B-type rail pile retaining wall 5 in the embodiment are both made of C30 rubble concrete. The rail piles are integrally arranged inside the rubble concrete retaining wall, with no less than two rows of vertical grouting rail piles. Vertical steel pipe piles are evenly spaced and arranged in a plum blossom pattern. The pile diameter is 30 cm, the rail type is 38 kg / m to 50 kg / m, and the spacing is generally 1.0 to 2.5 m. C30 concrete is poured 0.5 m from the bottom of the pile hole, and M30 cement mortar is poured in the remaining 0.5 m. The bottom of the rail pile is embedded in the stable soil layer, forming a high-rigidity "micro-pile retaining wall structure." A reinforced concrete cap beam is integrally set on the top of the rail pile. The length and width of the cap beam are equal to the length and width of the retaining wall. The thickness of the cap beam is about 1 m, and the elevation of the top of the cap beam is about 1 m below the elevation of the wall top. The size and specifications of the intercepting drainage ditch, shallow drainage hole, and deep water diversion hole are designed and determined according to the slope catchment area and the maximum rainfall in the rainy season. The shallow drainage holes of each level of retaining wall are arranged in multiple rows at a horizontal and vertical interval of 2m, and the deep water diversion holes at the bottom are arranged in a row at an interval of 10 to 15m.

[0056] The construction process of the present invention is further described below with reference to specific use cases. In Example 2, a newly built industrial park on the top of a slope is used as an example, and the original slope needs to be converted into terraces with deep fill. The specific construction method of the steel rail pile retaining wall graded support (reinforcement) system for converting the deep fill slope into terraces is described. The specific design and construction steps are as follows:

[0057] S1. Planning and designing the graded heights of backfill terraces. Calculate the total elevation difference based on the planned top and bottom elevations. Divide the total terrace elevation difference by the total width of the farmland to determine the comprehensive slope ratio and convert it into a comprehensive slope. Specifically, based on the planned top and bottom elevations, the total elevation difference H = 21m, and the total width of the farmland is W = 50m. This converts to a comprehensive terrace slope α = 22°. The comprehensive terrace slope α can be directly calculated: the overall terrace slope ratio = tanα = H / W, where α = arctan(H / W). Given a calculated slope within the range of 20-25°, it is necessary to consider designing as a non-traditional terrace. The terraces are divided into platforms with a uniform elevation difference of approximately 5m per level, each 12m wide (including the retaining wall width), and a slightly larger elevation difference of 6m at the bottom. A total of four terrace levels are determined. The width and elevation difference of the lowest terrace are 14m and 6m, respectively, while the width and elevation difference of the upper three terrace levels are 12m and 5m, respectively.

[0058] S2. Based on the width of each terrace and the vertical support height difference confirmed in step S1, combined with the original topography, the characteristics of the original soil and backfill soil layers, the physical and mechanical parameters, the load conditions on the top and slope surface, the hydrogeological conditions, and the survey drilling or inclinometric monitoring data, the depth and location of the shallow and deep sliding zones are determined. The above parameters are input into the slope correction software or other professional software. The software automatically searches for the most unfavorable sliding surface based on the limit equilibrium principle. The overall deep sliding surface and the shallow sliding surfaces of each level are calculated in stages according to the overall slope and local slope. The slope landslide thrust T1 of the overall deep sliding surface of the slope and the slope landslide thrust T2 of each shallow sliding surface are calculated. The calculation results in this case are T1 = 1050 kN / m and T2 = 230 kN / m. According to the formula T1 n =T1 n-1 -T2 calculates the landslide thrust of the entire deep sliding surface below the 1st to 3rd terraces in sequence. The specific calculation is as follows (from top to bottom):

[0059] The first terrace: along its shallow sliding surface, the landslide thrust is T21 = T2 = 230 kN / m; along the entire deep sliding surface below this terrace, the terrace slope landslide thrust is T11 = T1-T21 = 820 kN / m.

[0060] The second terrace: along its shallow sliding surface, the landslide thrust is T22 = T2 = 230 kN / m; along the entire deep sliding surface below this terrace, the terrace slope landslide thrust is T12 = T11-T22 = 590 kN / 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 terrace slope along the overall deep sliding surface below this level of terrace is T13=T12-T23=360kN / m.

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

[0063] S4. In Example 2, the rail piles in the A-type rail pile retaining wall are arranged in two rows, and the spacing d between the rail piles in the same row is 2.5m. The rail piles in the B-type rail pile retaining wall are arranged in three rows, and the spacing d between the rail piles in the same row is 2m. The pile lengths of the A-type rail pile retaining wall and the B-type rail pile retaining wall are both 15m, and the row spacing is 1m. Considering the differences in potential landslide thrust at each level, they are arranged in a plum blossom shape. Based on the rail pile spacing d, the number of rail pile rows m, and the landslide thrust borne by the rail piles in each level of the A-type rail pile retaining wall, the landslide thrust T that a single rail pile in each level of the A-type rail pile retaining wall needs to bear is calculated. A ':

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

[0065] According to the rail pile spacing d, the number of rail pile rows m and the landslide thrust borne by the middle rail pile of each level of B-type rail pile retaining wall, the landslide thrust T that a single rail pile in each level of B-type rail pile retaining wall needs to bear is calculated. B ':T B '=T B *d / m=360*2 / 3=240kN;

[0066] S5. The landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to bear, calculated in S4. A ' and T B 'Selection of rail piles;

[0067] First, the anti-slip force P of different types of rail piles was calculated. These rail piles are anti-slip piles embedded in the sliding mass and are subjected to bending above and below the potential sliding surface, generating resistance. Based on the test results of the anti-slip pile stress state, the corresponding calculation formula was used to estimate the rail anti-slip force. The test results of the anti-slip pile stress state show that the rail bends near the sliding surface and exerts pressure on the soil. The maximum bending moment is above and below the potential sliding surface, with the positive and negative bending moments separated by 0.5 to 0.75 m. Based on this, the calculation formula for the anti-slip force of rail piles is given as:

[0068]

[0069] The test results of 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, the revised calculation formula for the anti-slip force of rail piles is established:

[0070]

[0071] Where P1 and P2 are anti-slip forces, [σ] is the allowable tensile stress of the rail, W is the bending modulus of the rail section, L is the distance of positive and negative bending moments near the sliding surface, and d is the maximum size of the rail section. B is the bottom width of the rail, h is the rail height, L is 0.625m, and [σ] is 615.4MPa.

[0072] The rail pile model selection range is 38KG / m, 43KG / m, and 50KG / m. The anti-slip forces of various types of rails calculated according to the above two formulas are shown in Table 1:

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

[0074]

[0075] For safety reasons, the calculation result of P2 is used as the anti-sliding force P of the selected rail pile in the embodiment; let P = P2, and calculate the safety factor k of each type of rail pile when used in type A rail pile retaining wall and type B rail pile retaining wall. A 、k B , k A =P / T A ', k B =P / T B '; The safety factor k of each type of rail pile when used in type A rail pile retaining wall and type B rail pile retaining wall is calculated A 、k B Compare with the safety factor k that meets the design requirements;

[0076] When k A ≧k, then this type of rail pile meets the design requirements of type A rail pile retaining wall;

[0077] When k B ≧k, then this type of rail pile meets the design requirements of type B rail pile retaining wall.

[0078] In the second implementation, the minimum value of 38KG / m is uniformly taken according to the most economical solution during the trial calculation. According to the above table "Calculation results of anti-slip force of rail anti-slip piles", a single rail pile can provide a resistance P2 of about 330.5kN. According to the requirement that the safety factor of the first-level slope is not less than 1.35, when rail piles with a specification of 38KG / m are selected, for a single A-type 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 B-type rail pile: resistance / sliding thrust = P2 / TB = 330.5 / 240 = 1.37 > 1.35, which meets the design requirements. Therefore, it can be judged that the rail piles with a specification of 38KG / m can be used for type A rail pile retaining wall, but are not suitable for type B rail pile retaining wall. In order to improve safety, a higher-level model of rail piles can be selected, that is, the specification of 43KG / m. After calculation, it meets the design requirements. In order to unify the construction, the project selected rail piles with a specification of 43KG / m for construction.

[0079] S6. After selecting the rail pile model, the rail pile retaining wall is constructed. The specific process is as follows:

[0080] S601. Measure and lay out the lines, marking the plane position and elevation of each terrace retaining wall. Clean the construction surface, clear the original slope, remove obstacles, and remove and replace soft soil layers such as silt and debris as appropriate.

[0081] S602. Construct the bottom layer of B-type steel rail pile retaining wall, drainage ditch, upper shallow drainage holes, and bottom deep water diversion holes according to the design drawings and requirements;

[0082] S603. Backfill and compact soil from bottom to top according to the design drawings and requirements, and construct all levels of A-type rail pile retaining walls. During construction, ensure the safety and stability of the temporary excavation and support for the retaining walls, and control the quality of the foundation and backfill behind the walls. Do not proceed with upper-level backfill and support structure construction until the concrete strength of the lower retaining walls and rail pile crown beams reaches the design requirements.

[0083] S604. After the overall backfill and rail pile retaining wall construction at all levels are completed, the industrial site on the top of the slope will be backfilled, and the road, factory building, and ancillary structures will be constructed. The bottom of the slope will be leveled, and the top wall road guardrails and terraced farming road system will be constructed simultaneously.

[0084] S605. After the construction is completed, terraced roads and retaining walls at all levels will form a drainage system, and reservoirs at all levels will be built to provide water for farmland irrigation.

[0085] S7. Monitoring should be carried out throughout the construction process. The displacement and stress of the slope road workshop, terraces and retaining walls should be monitored during the construction and operation period. The monitoring period should be no less than 2 years until the monitoring data stabilizes and meets the specifications and design requirements.

[0086] The rail piles of the embodiment are made of a large amount of recycled scrap rails, the quality of the rails is in line with national standards, and heavy rails are used.

[0087] The terrace planning graded height and support system of the present invention are scientific and reasonable, and the potential shallow slippage and overall potential deep slippage of the ridges at each level are supported in stages, so that the force distribution of the support system is more balanced and reasonable, and the support effect is guaranteed. The present invention utilizes the advantages of flexible arrangement of micro-rail piles, small disturbance to the rock and soil, and large combined stiffness, and is combined with the commonly used rubble concrete retaining wall scheme. The graded arrangement of shallow drainage holes and deep water diversion holes can timely discharge groundwater from the slope, which can ensure the permanent stability and safe operation of the terraces and their surrounding important structures, and prevent soil erosion. Compared with traditional terraces, the present invention has fewer grades and larger terrace widths at each level. It is equipped with an overall farming road system and drainage and irrigation system, which maximizes the overcoming of the shortcomings of traditional terraces with too many grades, poor regularity, and complete reliance on manual farming, thereby maintaining farmland ecology and improving production quality. Compared with traditional solutions such as graded retaining walls, anti-slip piles or pile-anchor support solutions, the present invention reduces the occupied area of ​​arable land and the amount of earthwork excavation and filling, avoids serious disturbance of the original soil, and can utilize scrap rails, which is conducive to resource recycling, saving overall construction costs and construction time, and is green and environmentally friendly.

[0088] The hierarchical retaining and reinforcement system for converting deep fill slopes into terraces in the present invention has a wide range of applications. It is suitable for deep fill of original slopes due to the construction of industrial plants. Since the soil properties of the original slope are poor and the quality of the fill on the slope is difficult to control, the planned fill slope is planned for agricultural land, and the comprehensive slope ratio is within the range of about 20 to 25 degrees. In order to achieve large-scale mechanized planting, each terrace should not be divided into too small blocks, thereby forming multiple terraces with relatively large graded height differences. It is easy to form multiple levels after the deep fill slope is converted into terraces. If the potential sliding surface and the deep sliding surface along the fill interface are not properly supported, the slope will be at risk of shallow sliding or even overall landslide. In particular, the increase in load on the slope top or the infiltration of heavy rainfall will lead to a sharp increase in risk. In order to ensure the permanent stability and safe operation of the terraces and important structures around them, prevent soil erosion, and maximize the overcoming of the shortcomings of traditional terraces with too many levels, poor regularity, and complete reliance on manual farming, maintain farmland ecology and improve production quality, an economical, practical, and convenient support or reinforcement system and construction method are proposed.

[0089] The above shows and describes 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 above embodiments and descriptions are merely illustrative of the structural relationships and principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A hierarchical retaining and reinforcement system for converting a deep fill slope into a terraced field, used for supporting a multi-level terraced field (2) formed by stacking deep fill on an original slope surface (4), characterized by: The reinforcement system comprises a multi-stage steel rail pile retaining wall support structure arranged at the outer edge of each terrace (2) to support it, the multi-stage steel rail pile retaining wall support structure comprising a plurality of A-type steel rail pile retaining walls (3) located on the slope surface and a B-type steel rail pile retaining wall (5) located at the bottom of the slope, the A-type steel rail pile retaining walls (3) being arranged between adjacent terraces, and the B-type steel rail pile retaining walls (5) being arranged at the outer edge of the lowest terrace (2); The A-type rail pile retaining wall (3) and the B-type rail pile retaining wall (5) located at the bottom of the slope both comprise a retaining wall body (3-1) and a plurality of rail piles (3-2) embedded in the retaining wall body (3-1); the plurality of rail piles (3-2) are arranged along the retaining wall body (3-1); the pile tops are connected as a whole by a pile top crown beam (3-3); the upper parts of the rail piles (3-2) and the pile top crown 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 an upper shallow drainage hole (3-4) and a bottom deep water diversion hole (3-5); The width and height of the retaining wall of the B-type rail pile retaining wall (5) are both greater than those of the retaining wall of the A-type rail pile retaining wall (3); the rail pile arrangement density of the B-type rail pile retaining wall (5) is greater than the rail pile (3-2) arrangement density of the A-type rail pile retaining wall (3); and the depth of each rail pile of the B-type rail pile retaining wall (5) 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 B-type rail pile retaining wall (5).

2. The hierarchical retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1 is characterized by: A retaining wall drainage ditch (3-6) is provided on the outer side of the bottom of the retaining wall body (3-1) of the A-type rail pile retaining wall (3) and the B-type rail pile retaining wall (5); the water outlets of the upper shallow drainage holes (3-4) and the bottom deep water diversion holes (3-5) are both located above the retaining wall drainage ditch (3-6); the retaining wall drainage ditch (3-6) is used to collect water discharged from the upper shallow drainage holes (3-4) and the bottom deep water diversion holes (3-5); and the retaining wall body (3-1) is a mortar-laid stone retaining wall or a concrete wall.

3. A hierarchical retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1 or 2, characterized in that: The retaining wall bodies (3-1) of the A-type steel rail pile retaining wall (3) and the B-type steel rail pile retaining wall (5) are provided with guardrails (3-7) and wall top roads (3-8); longitudinal farming roads (11) are provided inside each level of terraces (2) at intervals of 100 to 200 m, and gently sloping roads are built at the intersections of the longitudinal farming roads (11) and the retaining wall bodies (3-1) at each level, so that the wall top roads (3-8) are smoothly connected to the longitudinal farming roads (11) inside the terraces.

4. A hierarchical retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1 or 2, characterized in that: The rail piles (3-2) of the A-type rail pile retaining wall (3) and the B-type rail pile retaining wall (5) are both arranged at equal vertical intervals; the upper portions of the rail piles (3-2) are integrally arranged inside the retaining wall body (3-1); the bottoms of the rail piles (3-2) are embedded in the stable soil layer, forming a micro-pile retaining wall structure with the retaining wall body (3-1).

5. The hierarchical retaining and reinforcement system for converting deep fill slopes into terraces according to claim 1 or 2, characterized in that: The length and width of the pile top crown beam (3-3) of the A-type rail pile retaining wall (3) and the B-type rail pile retaining wall (5) are equal to the length and width of the corresponding retaining wall body (3-1), the thickness of the pile top crown beam (3-3) is 0.8 to 1.2 m, and the top elevation of the crown beam is 0.8 to 1.2 m below the wall top elevation.

6. A construction method for a graded retaining and reinforcement system for converting a deep fill slope into terraced fields according to any one of claims 1 to 5, characterized in that: The specific construction steps are as follows: S1. Plan and design the graded heights of backfilled soil terraces. Calculate the total elevation difference based on the planned top and bottom elevations. Divide the total elevation difference by the total width of the farmland to determine the comprehensive slope ratio, which is then converted into the comprehensive slope. When the comprehensive slope is between 20 and 25 degrees, the terraces are divided into platforms with a height difference of 3 to 6 meters per level. Each level should be at least 10 meters wide, with a large height difference at the bottom, for a total of N levels of terraces. S2. Based on the width of each terrace of backfill soil and the graded height difference, combined with the original slope stratum after modification, the stratum characteristics and physical and mechanical parameters of the original soil and backfill soil, the slope top and slope load, and the hydrogeological conditions, and using survey drilling or inclinometer monitoring data to determine the depth and location of the shallow and deep sliding zones, use existing software to calculate the slope landslide thrust T1 of the overall deep sliding surface of the slope and the slope landslide thrust T2 of each shallow sliding surface, and then calculate the slope landslide thrust T1 of the overall deep sliding surface below the 1st to N-1th terraces in turn. n , T1 n =T1 n-1 -T2, where n is any level of terrace; S3. Calculate the landslide thrust borne by the rail piles in each terraced track pile retaining wall. Assuming that the A-type track pile retaining wall is mainly used to support and control shallow sliding, and the B-type track pile retaining wall is mainly used to support and control deep sliding, the landslide thrust borne by the rail piles in each A-type track pile retaining wall is obtained as T. A = T2, the landslide thrust T borne by the middle rail pile of the B-type rail pile retaining wall B Equal to the landslide thrust of the entire deep sliding surface below the N-1th terrace; S4. Calculate the landslide thrust T that a single rail pile in each level of the A-type rail pile retaining wall needs to bear based on the parameter settings of each level of the A-type rail pile retaining wall and the landslide thrust borne by the rail piles in each level of the A-type rail pile retaining wall. A ':T A '=T A *d / m; According to the setting parameters of each level of B-type rail pile retaining wall and the landslide thrust borne by the middle rail pile of the B-type rail pile retaining wall, the landslide thrust T that a single rail pile in each level of B-type rail pile retaining wall needs to bear is calculated. B ':T B ′=T B *d / m; In the above two formulas, d is the distance between rail piles in the rail pile retaining wall; m is the number of rail pile rows in the rail pile retaining wall; S5. The landslide thrust T that a single rail pile in the Type A and Type B rail pile retaining walls needs to bear, calculated in S4. A ' and T B 'Select rail piles; 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 rail pile retaining wall and type B rail pile retaining wall A 、k B , k A =P / T A ', k B =P / T B '; The safety factor k of each type of rail pile when used in type A rail pile retaining wall and type B rail pile retaining wall is calculated A 、k B Compare with the safety factor k that meets the design requirements; When k A ≧k, then this type of rail pile meets the design requirements of type A rail pile retaining wall; When k B ≧k, then this type of rail pile meets the design requirements of type B rail pile retaining wall; S6. After selecting the rail pile model, the rail pile retaining wall is constructed. The specific process is as follows: S601. Measure and lay out the lines, mark the plane position and elevation of each terrace retaining wall, and clean the construction surface; S602. Construct the bottom layer of B-type steel rail pile retaining wall, drainage ditch, upper shallow drainage holes, and bottom deep water diversion holes 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 A-type rail pile retaining walls at all levels; S604. After the overall backfill and the construction of rail pile retaining walls at all levels are completed, the industrial site on the top of the slope will be backfilled, and the road factory buildings and their ancillary structures will be built. The bottom of the slope will be leveled, and at the same time, the road guardrails on the top of the wall and the terraced farming road system will be constructed.

7. The construction method of a graded retaining and reinforcement system for converting a deep fill slope into terraced fields according to claim 6 is characterized by: The calculation formula of the anti-sliding force P of different types of rail piles in step S5 is as follows: Where P is the anti-sliding force of the rail pile, [σ] is the allowable tensile stress of the rail, W is the bending modulus of the rail section, and d is the maximum size of the rail section. B is the bottom width of the rail, h is the rail height, and [σ] is taken as 615.4MPa.

8. The construction method of a graded retaining and reinforcement system for converting a deep fill slope into terraced fields according to claim 6 is characterized by: In the step S4, the retaining wall width of the A-type rail pile retaining wall is 1.8 to 2.5 m, the spacing d between adjacent rail piles in the A-type rail pile retaining wall is 1.0 to 2.5 m, and the number of rail pile rows is 1 to 2; the retaining wall width of the B-type rail pile retaining wall is 2.5 to 5 m, and not less than 1 / 3 of the height of the B-type retaining wall is buried in the original slope soil layer, the spacing d between adjacent rail piles in the B-type rail pile retaining wall is 1.0 to 2.5 m, and the number of rail piles is 1 to 2. The number of rows is 3 to 4; the A-type rail pile retaining wall and the B-type rail pile retaining wall adopt mortar masonry or concrete wall, the rail model is 38KG / m to 50KG / m, the bottom 0.5m to 0.8m of the rail pile hole is poured with concrete, and the rest is poured with cement mortar; a 1m to 1.2m thick reinforced concrete cap beam is set on the top of the pile; the shallow drainage holes of each level of retaining wall are arranged in multiple rows at a horizontal and vertical interval of 2m, and the deep water diversion holes at the bottom are arranged in a row at an interval of 10 to 15m.

9. The construction method of a graded retaining and reinforcement system for converting a deep fill slope into terraced fields according to claim 6, characterized in that: The construction surface cleaning in S601 is specifically to clear the original slope, remove obstacles, and remove and appropriately replace soft soil layers such as silt, garbage debris, etc.; during the construction process 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 upper backfill and support structure construction shall not be carried out before the concrete strength of the lower retaining wall and the crown beam of the rail pile reaches the design requirements; after the construction of S604 is completed, the terraced roads and retaining walls at all levels will form a drainage system, and reservoirs at all levels will be built to provide water for farmland irrigation.

10. The construction method of a graded retaining and reinforcement system for converting a deep fill slope into terraced fields according to claim 6, characterized in that: The entire construction process will be monitored, and the displacement and force of the slope road factory buildings, terraces and retaining walls will be monitored during the construction and operation period. The monitoring period will be no less than 2 years, until the monitoring data becomes stable and meets the specifications and design requirements.

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