A waste concrete sleeper roadbed reinforcing combined structure and design method

Abstract

The application provides a waste concrete sleeper roadbed reinforced combined structure based on waste concrete sleepers, which comprises waste concrete sleepers provided with through holes at two ends, and comprises a plurality of strip structure units laid in parallel, wherein the strip structure unit comprises superposed upper layer structures and lower layer structures, the upper layer structure comprises upper layer structure units connected in a head-to-tail mode, the lower layer structure comprises lower layer structure units connected in a head-to-tail mode, the upper layer structure unit is connected with the lower layer structure unit through a connecting piece one, and the strip structure units are connected through connecting pieces two; and the application also provides a design method of the waste concrete sleeper roadbed, wherein the soil arching effect can be formed when the soil covering thickness is greater than or equal to 1.6 m and the optimal soil covering filler strength is that the internal friction angle is greater than 25 DEG and the cohesion is 8 kPa, and the soil arching effect is beneficial to be formed when the length of the waste concrete sleeper is 2.6 m and the spacing between the sleepers is 1.5 m-2.0 m.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rock foundation, and particularly relates to a waste concrete sleeper roadbed reinforced combined structure and a design method. BACKGROUND

[0002] With the rapid development of the national economy, the construction of highways and high-speed railways has been greatly developed. These projects often encounter soft soil foundations, which have weak bearing capacity and are difficult to meet the basic construction requirements of roadbeds. Moreover, the water content of soft soil foundations directly affects the performance of roadbed fillers, thereby causing settlement problems.

[0003] Currently, methods such as chemical grouting, sand cushion replacement, vertical pile composite foundation, reinforced geogrid reinforcement, or bamboo reinforcement are commonly used, but the following problems exist:

[0004] 1. The use of vertical pile composite foundation or reinforced material construction is costly, increasing the cost of the project;

[0005] 2. The replacement method and reinforcement treatment cannot solve the problem of surface deformation and subsidence caused by the potential erosion of roadbed soil;

[0006] 3. The construction of pile foundation composite foundation is complex and has a long construction period;

[0007] 4. Reinforced soil treatment and vertical pile composite foundation change the flow channel of underground water, and poor underground water flow may cause roadbed slope collapse;

[0008] 5. The use of new building materials for roadbed treatment increases carbon dioxide emissions, which is not conducive to energy saving and emission reduction, and also causes environmental pollution;

[0009] 6. The roadbed treated by the sand cushion and reinforced soil method has poor durability, small roadbed stiffness, and poor overall stability under seismic load, and is easily damaged.

[0010] To solve the above problems, different roadbed treatment methods have appeared in existing construction. For example, a Chinese invention patent with the application date of July 7, 2023, the application number of CN116397476A, and the name of a highway foundation structure reinforced by waste concrete sleepers, which includes an intermediate gravel layer, a reinforcing structure is laid on the upper side of the intermediate gravel layer, the reinforcing structure includes a plurality of waste concrete sleeper groups arranged in sequence along the width direction of the roadbed layer, each waste concrete sleeper group includes a plurality of waste concrete sleepers arranged at intervals along the length direction of the roadbed layer, the length of each waste concrete sleeper extends along the length direction of the roadbed layer, and the adjacent two waste concrete sleeper groups are a first waste concrete sleeper group and a second waste concrete sleeper group, the projection of the corresponding waste concrete sleeper of the first waste concrete sleeper group along the width direction of the roadbed layer spans the front end of the corresponding front side concrete sleeper and the rear end of the rear side concrete sleeper.

[0011] The above existing technology reduces the engineering cost, achieves the purpose of waste utilization and green energy saving, but there is no connecting piece between the waste concrete sleepers, which is easy to move, and the sleepers are arranged in parallel, so the sleepers cannot restrict each other; when the sleepers are filled with stones and compacted, the road surface is subjected to multiple and long-time impacts, and is prone to deformation, cracking and collapse.

[0012] Therefore, how to solve the problem that the existing soft roadbed is prone to surface deformation, cracking and collapse, and improve the durability and stability of the roadbed is a technical problem to be solved. SUMMARY

[0013] In view of the deficiencies in the above background art, the present application provides a waste concrete sleeper roadbed reinforcing combination structure and design method, which solves the problem that the existing soft roadbed is prone to surface cracking, collapse and diseases under the action of underground water erosion, and the durability and stability of the roadbed are poor.

[0014] The technical scheme of the present application is:

[0015] The application discloses a waste concrete sleeper roadbed reinforcing combined structure, which comprises waste concrete sleepers provided with through holes at two ends, a plurality of parallel laid strip structure units, the strip structure unit comprises superposed upper layer structure and lower layer structure, the upper layer structure comprises upper layer structure units connected in head-to-tail mode, the lower layer structure comprises lower layer structure units connected in head-to-tail mode, the upper layer structure unit is connected with the lower layer structure unit through a connecting piece one, and the strip structure units are connected through connecting pieces two. The two-layer waste concrete sleepers are superposed, each waste concrete sleeper has two through holes at left and right ends, the lower layer concrete sleeper and the upper layer concrete sleeper are arranged in staggered superposition mode, the two through holes on one side of the lower layer longitudinal sleeper correspond to the two through holes on the other side of the upper layer longitudinal sleeper in up-down mode, a screw rod is used for connecting the two-layer waste concrete sleepers, nuts are arranged at the upper and lower ends of the screw rod and used for fixing the screw rod, a backing plate provides a counterforce for fixing the nut, the stability of the combined structure is enhanced, a notched transverse waste concrete sleeper is vertically connected between the longitudinal sleepers of the upper layer structure unit, a combined structure is formed, and the notched transverse waste concrete sleeper enhances the connection with the lower layer structure unit and also plays a restraining role on the displacement of the longitudinal sleepers.

[0016] Further, the upper layer structure unit comprises upper layer longitudinal sleepers and upper layer transverse sleepers, and the lower layer structure unit comprises lower layer longitudinal sleepers and lower layer transverse sleepers.

[0017] Further, the upper layer structure unit and the lower layer structure unit are arranged in a staggered mode, the upper layer structure unit is arranged in a staggered mode along a longitudinal direction upwards / downwards, the through hole at the upper end of the lower layer longitudinal sleeper corresponds to the through hole at the lower end of the upper layer longitudinal sleeper, the through hole at the lower end of the lower layer longitudinal sleeper corresponds to the through hole at the upper end of the upper layer longitudinal sleeper, and the lower layer longitudinal sleeper is clamped and matched with the notch arranged on the lower surface of the upper layer transverse sleeper.

[0018] Further, the connecting piece one comprises a screw rod, the screw rod passes through the through hole at one end of the upper layer longitudinal sleeper and the through hole at the other end of the lower layer longitudinal sleeper respectively, the screw rod is stop matched with nuts arranged at two ends of the screw rod, and the backing plate provides a counterforce for fixing the nut, so that the stability of the combined structure is enhanced.

[0019] Further, the connecting piece two comprises s-shaped steel bars, the two ends of the s-shaped steel bars are connected with the strip structure units respectively, and the s-shaped steel bars play a role in reinforcing the integrity of the combined structure and preventing displacement.

[0020] Further, the upper layer longitudinal sleeper and the nut at the upper end of the screw rod, and the lower layer longitudinal sleeper and the nut at the lower end of the screw rod are all provided with backing plates, and the backing plates are provided with holes for the screw rod to pass through.

[0021] A design method based on waste and abandoned concrete sleeper subgrade, comprising the above-mentioned waste concrete sleeper subgrade reinforced composite structure, further comprising the following steps:

[0022] S1: grooves are formed at both ends of the lower surface of the upper transverse sleeper;

[0023] S2: the lower structure unit comprises four lower longitudinal sleepers in H shape and one lower transverse sleeper, and a plurality of lower structure units are laid end to end along the long side of the foundation pit;

[0024] S3: the upper structure unit and the lower structure unit are the same structure, the upper structure unit and the lower structure unit are laid in staggered position, the upper end through hole of the lower longitudinal sleeper is aligned with the lower end through hole of the upper longitudinal sleeper, the lower end through hole of the lower longitudinal sleeper is aligned with the upper end through hole of the upper longitudinal sleeper, the grooves are connected with the middle position of the lower longitudinal sleeper, and a plurality of upper structure units are laid on the lower structure unit end to end along the laid lower structure unit;

[0025] S4: the gasket is placed at the through hole, and the upper structure unit and the lower structure unit are connected by the screw rod and the nut to form a strip-shaped structure unit;

[0026] S5: a plurality of strip-shaped structure units are laid to fill the entire foundation pit, and the adjacent strip-shaped structure units are fixedly connected through the s-shaped steel bars;

[0027] S6: the coarse aggregate is filled in the laid sleeper gap and compacted; the interior of the concrete sleeper composite structure is filled with coarse aggregate, which can bear the load of the upper subgrade, and the coarse aggregate layer forms a channel for the discharge of water in the subgrade soil, which is beneficial to the rapid discharge of water, has good permeability, can quickly discharge underground water, and can prevent the roadbed diseases caused by poor underground water drainage;

[0028] S7: laying geotextile; the geotextile is placed on the interface between the abandoned concrete sleeper composite structure and the upper subgrade covering soil, the geotextile can filter the underground water of the upper soil body, prevent the loss of fine particles of the soil body, maintain the overall structure of the upper subgrade soil body, and increase the uniformity of the load bearing of the concrete sleeper composite structure;

[0029] S8: the subgrade covering soil parameters capable of forming soil arching effect are obtained by calculation model and finite element limit analysis method, and the subgrade covering soil is laid; the overlying soil body is selected from fillers with certain strength and conducive to the formation of soil arching effect, the formation of soil arching can prevent the formation of cavities by underground water erosion and then induce ground deformation and cracking problems, the abandoned concrete sleeper composite structure is placed below the subgrade to improve the strength and stability of the subgrade, or is placed above the pre-buried pipeline and then covered with soil and compacted, so as to prevent the pipeline from being broken and leaking water and causing ground cracking and collapse problems caused by cavities in the foundation.

[0030] Further, the four lower longitudinal sleepers are longitudinal sleeper A, longitudinal sleeper B, longitudinal sleeper C and longitudinal sleeper D, longitudinal sleeper A and longitudinal sleeper B are spaced apart by Xm, longitudinal sleeper C and longitudinal sleeper D are spaced apart by Ym, X and Y are the same distance, longitudinal sleeper A and longitudinal sleeper D are spaced apart by 0.426m, longitudinal sleeper B and longitudinal sleeper C are spaced apart by 0.426m, one lower transverse sleeper is transverse sleeper E, one end of the transverse sleeper E is placed in the middle of longitudinal sleeper A and longitudinal sleeper D, and the other end of the transverse sleeper E is placed in the middle of longitudinal sleeper B and longitudinal sleeper C.

[0031] Further, the surface of the notch is fitted with the surface of the middle position of the lower longitudinal sleeper, and the notch depth is 20mm.

[0032] Further, through the calculation model and the finite element limit analysis method, it is obtained that the soil arching effect can be formed when the soil thickness is greater than or equal to 1.6m, and the optimal soil filling strength is that the internal friction angle is greater than 25° and the cohesive force is 8kPa.

[0033] Further, when the length of the waste concrete sleeper is 2.6m, it is obtained through calculation that X and Y are 1.5m-2.0m, which is beneficial to form the soil arching effect.

[0034] The specific beneficial effects of the present application include:

[0035] 1. Two layers of waste concrete sleepers are stacked, each of the left and right ends of each waste concrete sleeper has two through holes, the lower concrete sleepers and the upper concrete sleepers are arranged in a staggered manner, the two through holes on one side of the lower longitudinal sleeper correspond to the two through holes on the other side of the upper longitudinal sleeper in a vertical manner, a screw rod is used to connect the upper and lower layers of waste concrete sleepers, nuts are arranged at the upper and lower ends of the screw rod to fix the screw rod, a gasket provides a counterforce for fixing the nut, and the firmness of the combined structure is enhanced, a transverse waste concrete sleeper with a notch is vertically connected in the gap between the longitudinal sleepers of the upper structure unit to form a combined structure, the transverse waste concrete sleeper with a notch enhances the connection with the lower structure unit and also restricts the displacement of the longitudinal sleepers;

[0036] 2. The strip-shaped structure units are connected by s-shaped steel bars to enhance the integrity of the combined structure and prevent displacement;

[0037] 3、The concrete sleeper combination structure is filled with coarse aggregate, can bear the load of the upper subgrade, and the coarse aggregate layer forms a channel for the water in the subgrade soil to drain, which is beneficial to the rapid drainage of water, has good permeability, can quickly drain underground water, and can prevent subgrade diseases caused by poor drainage of underground water; the geotextile is placed on the interface between the waste concrete sleeper combination structure and the upper subgrade soil, the geotextile can filter the underground water of the upper soil, prevent the loss of fine particles of the soil, maintain the overall structure of the upper subgrade soil, and increase the uniformity of the load borne by the concrete sleeper combination structure;

[0038] 4、The proper spacing of sleepers, the certain thickness of the soil cover, and the optimal strength of the soil cover filler facilitate the formation of the soil arching effect of the foundation combination structure, the formed soil arching is equivalent to adding a stress arch in the subgrade, the arching effect in the soil layer is different from the arch structure, the arch structure is made of materials in the shape of an arch and plays a role in bearing pressure under the action of load, while the soil arching has its own formation process: under the action of load or gravity, the soil is compressed and deformed, thereby causing uneven settlement and causing the mutual "wedging" effect between soil particles, so that "arch effect" is generated in a certain range of soil layer, due to the existence of the soil arching effect, the active earth pressure behind the enclosure structure is redistributed, in addition to the vertical soil arching effect, the horizontal soil arching effect also exists in the soil, reasonable utilization of the vertical and horizontal soil arching effects can make the stress redistribution of the soil develop in a direction favorable to the project, fully utilize the anti-deformation capacity of the soil, the overlying soil is selected from fillers with certain strength and conducive to the formation of soil arching effect, and the formed soil arch can prevent the formation of cavities caused by underground water seepage and further induce ground deformation and cracking problems;

[0039] 5、The waste concrete sleeper combination structure is placed below the subgrade as a whole, which can improve the strength and stability of the subgrade, or is placed above the pre-embedded pipeline and then covered with soil and compacted, so as to prevent the pipeline from being broken and leaking water, seepage, and further cause ground cracking and collapse problems;

[0040] 6、The concrete sleeper combination structure is a kind of fabricated structure, has fast construction speed and high construction efficiency;

[0041] 7、The waste concrete sleeper is used for waste recycling, which reduces 30%-40% of CO 2 emissions of buildings and reduces solid waste pollution;

[0042] 8、The concrete sleeper combination structure improves the rigidity of the subgrade, makes the subgrade have better anti-seismic performance, prolongs the service life of the road, and improves the durability of the subgrade. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application, the drawings required to be used in the embodiments description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0044] Figure 1 A schematic diagram of the waste concrete sleeper combination structure and the earth covering in the present application;

[0045] Figure 2 A schematic diagram of the waste concrete sleeper combination structure in the present application;

[0046] Figure 3 A sectional view of the waste concrete sleeper combination structure in the present application;

[0047] Figure 4 A side view of the waste concrete sleeper combination structure in the present application Figure 1 ;

[0048] Figure 5 A side view of the waste concrete sleeper combination structure in the present application Figure 2 ;

[0049] Figure 6 A schematic diagram of the connecting piece two;

[0050] Figure 7 An analysis diagram of the influence of the earth covering height on the soil arch of the concrete sleeper combination structure;

[0051] Figure 8 An analysis diagram of the soil arch height changing with the concrete sleeper spacing under different loads;

[0052] Figure 9 An analysis diagram of the influence range of different loads on the overlying soil;

[0053] Figure 10 An analysis diagram of the soil arch height changing with the earth covering height under different sleeper spacings;

[0054] Figure 11 A schematic diagram of the soil arch effect formed on the upper part of the concrete sleeper combination structure;

[0055] Figure 12 An analysis diagram of the soil arch height changing with the filler cohesion under different loads;

[0056] Figure 13 An analysis diagram of the soil arch height changing with the filler internal friction angle under different loads;

[0057] Figure 14 An analysis diagram of the calculation model of the influence of the collapse on the concrete sleeper combination beam;

[0058] Figure 15 A graph showing the influence of load multiplier on the collapse range for the concrete sleeper combined structure.

[0059] BRIEF DESCRIPTION OF DRAWINGS

[0060] 1. upper structure unit; 2. lower structure unit; 3. connecting piece one; 4. connecting piece two;

[0061] 15. screw rod; 16. backing plate; 17. s-shaped steel bar; 18. nut; 19. slot;

[0062] 21. geotextile; 22. coarse aggregate;

[0063] 31. longitudinal sleeper A; 32. longitudinal sleeper B; 33. longitudinal sleeper C; 34. longitudinal sleeper D; 35. transverse sleeper E. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0065] A waste concrete sleeper roadbed reinforced combined structure based on waste concrete sleepers, comprising waste concrete sleepers provided with through holes at two ends, such as Figure 1As shown, it comprises a plurality of parallel laid strip-shaped structural units 10, which comprises superimposed upper layer structure and lower layer structure, the upper layer structure comprises upper layer structure units 1 connected head to tail, the lower layer structure comprises lower layer structure units 2 connected head to tail, the upper layer structure units 1 are connected with the lower layer structure units 2 through connecting piece one 3, and the strip-shaped structural units 10 are connected through connecting piece two 4. The two-layer waste concrete sleeper is superimposed, each end of each waste concrete sleeper has two through holes, the lower layer concrete sleeper is arranged in staggered superposition with the upper layer concrete sleeper, the two through holes on one side of the lower layer longitudinal sleeper correspond to the two through holes on the other side of the upper layer longitudinal sleeper in up-down direction, a screw rod is used to connect the upper and lower two-layer waste concrete sleepers, nuts are arranged at the upper and lower ends of the screw rod to fix the screw rod, a gasket is used to provide a counterforce for fixing the nut, and the firmness of the combined structure is enhanced. A notched transverse waste concrete sleeper is vertically connected between the longitudinal sleepers of the upper layer structure unit, forming a combined structure. The notched transverse waste concrete sleeper enhances the connection with the lower layer structure unit and also plays a restraining role on the displacement of the longitudinal sleepers; the strip-shaped structural units are connected by s-shaped steel bars, which plays a role in enhancing the integrity of the combined structure and preventing displacement. The concrete sleeper combined structure is a kind of fabricated structure, which has a faster construction speed and higher construction efficiency than the cast-in-place structure; the waste and waste concrete sleepers are reused, which reduces the CO 2 emission of buildings by 30%-40%, reduces solid waste pollution, and places the waste concrete sleeper combined structure under the roadbed to improve the strength and stability of the roadbed. The concrete sleeper combined structure can also be placed above the embedded pipeline and then covered with compacted soil to prevent pipeline rupture, water leakage, and ground cracking and collapse caused by ground cavity.

[0066] On the basis of the above embodiment, as a preferred embodiment, the upper layer structure unit 1 comprises an upper layer longitudinal sleeper and an upper layer transverse sleeper, and the lower layer structure unit 2 comprises a lower layer longitudinal sleeper and a lower layer transverse sleeper.

[0067] Preferably, the upper structure unit 1 and the lower structure unit 2 are both in H shape, for example, the lower structure unit 2 comprises four lower longitudinal sleepers and one lower transverse sleeper, the four lower longitudinal sleepers are longitudinal sleeper A31, longitudinal sleeper B32, longitudinal sleeper C33 and longitudinal sleeper D34 respectively, longitudinal sleeper A31 and longitudinal sleeper B32 are spaced apart by Xm, longitudinal sleeper C33 and longitudinal sleeper D34 are spaced apart by Ym, the distance X is the same as the distance Y, longitudinal sleeper A31 and longitudinal sleeper D34 are spaced apart by 0.426m, longitudinal sleeper B32 and longitudinal sleeper C33 are spaced apart by 0.426m, and the lower transverse sleeper is transverse sleeper E35, one end of the transverse sleeper E35 is placed between longitudinal sleeper A31 and longitudinal sleeper D34, and the other end of the transverse sleeper E35 is placed between longitudinal sleeper B32 and longitudinal sleeper C33.

[0068] On the basis of the above-mentioned embodiments, as a preferred embodiment, the upper structure unit 1 and the lower structure unit 2 are arranged in a staggered manner, the upper structure unit 1 is staggered upward / downward along the longitudinal direction, the through hole at the upper end of the lower longitudinal sleeper corresponds to the through hole at the lower end of the upper longitudinal sleeper, the through hole at the lower end of the lower longitudinal sleeper corresponds to the through hole at the upper end of the upper longitudinal sleeper, and the lower longitudinal sleeper is clamped and matched with the notched groove arranged on the lower surface of the upper transverse sleeper.

[0069] On the basis of the above-mentioned embodiments, as a preferred embodiment, as shown in Figure 3 The connecting piece one 3 comprises a screw rod 15, the screw rod 15 passes through the through hole at one end of the upper longitudinal sleeper and the through hole at the other end of the lower longitudinal sleeper respectively, and the screw rod 15 is clamped and matched with the nut 18 arranged at both ends of the screw rod 15.

[0070] Specifically, each end of each waste concrete sleeper has two through holes, the lower concrete sleepers and the upper concrete sleepers are arranged in a staggered manner, the two through holes on one side of the lower concrete sleeper correspond to the two through holes on the other side of the upper concrete sleeper, and each group of through holes is clamped and matched with the screw rod 15 and the nut 18.

[0071] On the basis of the above-mentioned embodiments, as a preferred embodiment, as shown in Figure 3 The upper longitudinal sleeper and the nut 18 at the upper end of the screw rod 15, and the lower longitudinal sleeper and the nut 18 at the lower end of the screw rod 15 are both provided with a backing plate 16, and the backing plate 16 is provided with a hole through which the screw rod 15 passes. The backing plate 16 provides a counterforce for the fixation of the nut 18, thereby enhancing the stability of the combined structure.

[0072] On the basis of the above-mentioned embodiments, as a preferred embodiment, as shown in Figure 6As shown, the connecting piece two includes an s-shaped steel bar 17, two ends of the s-shaped steel bar 17 are connected with the strip-shaped structure unit 10 respectively.

[0073] Specifically, two ends of the adjacent upper layer longitudinal sleeper in the adjacent strip-shaped structure unit 10 are each provided with two through holes, the s-shaped steel bar 17 is provided with two, the two s-shaped steel bars 17 are arranged in X cross, one end of the s-shaped steel bar 17 is connected with the upper layer longitudinal sleeper, the other end of the s-shaped steel bar 17 is connected with the adjacent upper layer longitudinal sleeper, two ends of the s-shaped steel bar 17 are hooked on the screw rod 15, and are clamped between the backing plate 16 and the nut 18.

[0074] The concrete sleeper combined structure is a fabricated structure, has high construction speed and high construction efficiency; the waste concrete sleepers are used, waste is reused, 30%-40% of CO2 emissions of the building are reduced, solid waste pollution is reduced, the roadbed stiffness is improved, the roadbed has better anti-seismic performance, the service life of the road is prolonged, and the durability of the roadbed is improved. 2 The concrete sleeper combined structure is a fabricated structure, has high construction speed and high construction efficiency; the waste concrete sleepers are used, waste is reused, 30%-40% of CO2 emissions of the building are reduced, solid waste pollution is reduced, the roadbed stiffness is improved, the roadbed has better anti-seismic performance, the service life of the road is prolonged, and the durability of the roadbed is improved.

[0075] A design method based on the waste concrete sleeper roadbed, including the above-mentioned waste concrete sleeper roadbed reinforced combined structure, further including the following steps:

[0076] S1: a notch 19 is formed at two ends of the lower surface of the upper layer transverse sleeper; the notch 19 is used for clamping the lower layer longitudinal sleeper, the stability of the reinforced combined structure is strengthened, displacement is prevented, the surface of the notch 19 is attached to the surface of the middle position of the lower layer longitudinal sleeper, and the depth of the notch 19 is 20 mm;

[0077] S2: the lower layer structure unit 2 includes four lower layer longitudinal sleepers in H shape and one lower layer transverse sleeper, a plurality of lower layer structure units 2 are laid in a head-to-tail mode along the long side of the foundation pit; the four lower layer longitudinal sleepers are longitudinal sleeper A31, longitudinal sleeper B32, longitudinal sleeper C33 and longitudinal sleeper D34, longitudinal sleeper A31 and longitudinal sleeper B32 are spaced apart by Xm, longitudinal sleeper C33 and longitudinal sleeper D34 are spaced apart by Ym, the distances X and Y are the same, longitudinal sleeper A31 and longitudinal sleeper D34 are spaced apart by 0.426 m, longitudinal sleeper B32 and longitudinal sleeper C33 are spaced apart by 0.426 m, and the one lower layer transverse sleeper is transverse sleeper E35, one end of the transverse sleeper E35 is placed in the middle of longitudinal sleeper A31 and longitudinal sleeper D34, and the other end of the transverse sleeper E35 is placed in the middle of longitudinal sleeper B32 and longitudinal sleeper C33;

[0078] S3: The upper layer structure unit 1 and the lower layer structure unit 2 are the same structure, and the upper layer structure unit 1 and the lower layer structure unit 2 are laid in staggered superposition, the staggered difference of the two is about half of the length of the H-shaped structure unit, the upper end through hole of the lower longitudinal sleeper is aligned with the lower end through hole of the upper longitudinal sleeper, the through hole at the lower end of the lower longitudinal sleeper is aligned with the through hole at the upper end of the upper longitudinal sleeper, and the two end notches 19 of the upper transverse sleeper are respectively connected with the lower longitudinal sleeper. A plurality of upper layer structure units 1 are laid on the lower layer structure unit 2 in a head-to-tail manner along the laid lower layer structure unit 2;

[0079] S4: The gasket 16 is placed at the through hole, and the upper layer structure unit 1 and the lower layer structure unit 2 are connected by the screw rod 15 and the nut 18 to form a strip-shaped structure unit 10;

[0080] S5: A plurality of strip-shaped structure units 10 are laid to fill the entire foundation pit, and then the adjacent strip-shaped structure units 10 are fixedly connected through the s-shaped steel bar 7. Specifically, a plurality of strip-shaped structure units 10 are laid in parallel, the transverse sleepers in the strip-shaped structure units 10 are seamlessly laid with the transverse sleepers on the left and / or right sides, the end portions of the longitudinal sleepers in the strip-shaped structure units 10 are spaced apart from the end portions of the longitudinal sleepers on the left and / or right sides by 160 mm, and the middle portions of the longitudinal sleepers are spaced apart from the middle portions of the longitudinal sleepers on the left / right sides by 220 mm.

[0081] S6: The coarse aggregate 22 is filled in the laid sleeper gap and compacted; as shown in Figure 4 、 Figure 5 , the inside of the concrete sleeper combined structure is filled with coarse aggregate, which can bear the load of the upper subgrade, and the coarse aggregate layer forms a channel for the discharge of water in the subgrade soil, which is beneficial to the rapid discharge of water and has good permeability, can quickly discharge groundwater, and can prevent subgrade diseases caused by poor groundwater drainage;

[0082] S7: The geotextile 21 is laid on the interface between the waste concrete sleeper combined structure and the upper subgrade covering soil, and the geotextile can filter the groundwater of the upper soil, prevent the loss of fine particles of the soil, maintain the overall structure of the upper subgrade soil, and increase the uniformity of the load bearing of the concrete sleeper combined structure;

[0083] S8: The subgrade covering soil parameters capable of forming a soil arching effect are obtained by a calculation model and a finite element limit analysis method, and the subgrade covering soil is laid. The overlying soil is selected from fillers with certain strength and conducive to the formation of soil arching effect. The formation of soil arching can prevent the formation of cavities by groundwater seepage and then induce ground deformation and cracking problems. The waste concrete sleeper combined structure is placed below the subgrade to improve the strength and stability of the subgrade, or is placed above the pre-buried pipeline and then covered with soil and compacted, so as to prevent the pipeline from being broken and leaking water and causing ground cracking and collapse problems caused by cavities in the foundation.

[0084] On the basis of the above-mentioned embodiments, as a preferred embodiment, as shown in Figure 2 The four lower longitudinal sleepers are longitudinal sleeper A31, longitudinal sleeper B32, longitudinal sleeper C33 and longitudinal sleeper D34, longitudinal sleeper A31 and longitudinal sleeper B32 are spaced apart by Xm, longitudinal sleeper C33 and longitudinal sleeper D34 are spaced apart by Ym, X and Y are the same distance, longitudinal sleeper A31 and longitudinal sleeper D34 are spaced apart by 0.426m, longitudinal sleeper B32 and longitudinal sleeper C33 are spaced apart by 0.426m, one lower transverse sleeper is transverse sleeper E35, one end of transverse sleeper E35 is placed in the middle of longitudinal sleeper A31 and longitudinal sleeper D34, and the other end of transverse sleeper E35 is placed in the middle of longitudinal sleeper B32 and longitudinal sleeper C33.

[0085] On the basis of the above-mentioned embodiments, as a preferred embodiment, the surface of the notch 19 is in contact with the surface of the middle position of the lower longitudinal sleeper, and the depth of the notch 19 is 20mm. The notch 19 is connected with the lower concrete sleeper, which strengthens the stability of the combined structure, restricts each other and prevents displacement.

[0086] On the basis of the above-mentioned embodiments, as a preferred embodiment, through calculation model and finite element limit analysis method, it is concluded that the soil thickness capable of forming soil arching effect is greater than or equal to 1.6m, and the optimal soil filling strength is that the internal friction angle is greater than 25° and the cohesive force is 8kPa.

[0087] Specifically, in the process of calculating the geotechnical engineering by using the finite element limit analysis method, the geometric parameters, shear strength and corresponding elastic modulus in the geotechnical engineering are analyzed systematically, and the corresponding results are calculated according to these parameters. According to the related finite element calculation software, the finite element model is reasonably constructed, and the finite element limit analysis method uses the method of increasing load or reducing geotechnical strength to calculate the limit load and safety factor of the geotechnical engineering.

[0088] On the basis of the above-mentioned embodiments, as a preferred embodiment, when the length of the waste concrete sleeper is 2.6m, it is concluded by calculation that X and Y are 1.5m-2.0m, which is beneficial to form soil arching effect. The spacing between longitudinal sleepers should consider the length of the upper transverse sleeper, generally the length of the sleeper is 2.6m, minus the length of the lap joint part, and the spacing between longitudinal sleepers of 1.8m is preferred to form soil arching effect.

[0089] The core of the design method of the waste concrete sleeper subgrade is:

[0090] 1. Determine the spacing between the waste concrete sleepers in the first direction in each combined structure;

[0091] 2. Determine the thickness of the soil covering the upper part of the combined structure;

[0092] 3. Determine the strength of the covering filler;

[0093] Therefore, the appropriate spacing of the sleepers, the thickness of the covering, and the optimal strength of the covering filler facilitate the formation of a soil arch effect in the foundation composite structure, and the formed soil arch is equivalent to an additional stress arch in the roadbed. The generation of the arch effect in the soil layer is different from that of the arch structure, which is made of materials in the shape of an arch and plays a role in bearing pressure under the action of load. The soil arch has its own formation process: under the action of load or gravity, the soil body is compressed and deformed, thereby causing uneven settlement and causing the mutual “wedging” effect between soil particles, which produces an “arch effect” in a certain range of soil layer. Due to the existence of the soil arch effect, the active earth pressure behind the retaining structure is redistributed, and in addition to the vertical soil arch effect, the horizontal soil arch effect also exists in the soil body. Reasonable use of the vertical and horizontal soil arch effects can make the stress redistribution of the soil body develop in a direction favorable to the project and fully utilize the self-deformation resistance of the soil body.

[0094] Specifically, as Case 1: The ground of a certain park is paved with marble, and every year, local ground cracking and collapse will occur along the upper ground along the water supply pipeline. The ground covering of the park is alluvial silt soil, the cohesion of the alluvial silt soil is 5 kPa, and the internal friction angle is 25°. During the road widening process, in order to prevent the deformation and collapse of the tile pavement, it is proposed to use a waste concrete sleeper composite structure to enhance the foundation.

[0095] First, as shown in Figure 7 , a calculation model of the waste concrete sleeper composite structure and the alluvial silt soil is constructed, and the finite element limit analysis method is used to observe the influence of the covering height on the generation of the soil arch effect of the concrete sleeper composite structure and whether the soil arch can be formed. Under the condition of the optimal covering filler strength, the parameters of the alluvial silt soil are known, the cohesion is 5 kPa, and the internal friction angle is 25°. The influence of the change of the height of the covering and the spacing between the waste concrete sleepers in the first direction of each composite structure on the height of the formed soil arch under different loads is studied, and the results show that:

[0096] 1. With the increase of the spacing between the waste concrete sleepers in the first direction of each composite structure, the height of the soil arch first increases and then decreases;

[0097] 2. As shown in Figure 8 , the spacing between the waste concrete sleepers in the first direction of the composite structure is 4 m to 5 m, and the height of the soil arch is the smallest; the spacing is 1.5 m to 2 m, and the height of the soil arch is the largest;

[0098] 3. Under the condition that the spacing between the waste concrete sleepers in the first direction of the composite structure is the same, as shown in Figure 9As shown, the height of the soil arch generated by applying high-intensity load is greater than the height of the soil arch generated by applying low-intensity load, the greater the load, the greater the influence on the deformation of the upper soil body, and when the load is 100 kN / m 2 , the maximum depth of influence is about 0.65 m;

[0099] 4. In the case where the spacing between the waste concrete sleepers in the first direction of the combined structure is not the same, as shown in Figure 10 , the influence of the soil covering height on the soil arch height is shown, and with the increase of the soil covering height, the soil arch height first decreases and then increases, and when the foundation soil covering height is about 5 m, the soil arch effect is the smallest, and the height of the soil arch is about 0.78 m; when the foundation soil covering height is about 6 m, the soil arch effect is the largest, and the maximum height of the soil arch is about 0.9 m.

[0100] According to the numerical calculation analysis, considering the safety reserve of 2 times the load, the spacing between the waste concrete sleepers in the first direction of each combined structure is between 1.5-2.0 m, and the structural requirement of a sleeper length of about 2.6 m is considered in the design, and the optimal selection is 1.8 m.

[0101] Therefore, through the calculation model and the finite element limit analysis method, it is concluded that the soil covering thickness capable of forming the soil arch effect should be greater than or equal to 1.6 m.

[0102] The specific construction scheme is as follows:

[0103] 1. The spacing between the waste concrete sleeper combined structures is 1.8 m, which is arranged along the pipeline direction and arranged directly above the pipeline;

[0104] 2. The combined structure adopts type IIIa concrete sleeper, which is 2.6 m long, 0.32 m wide at the bottom, 0.14 m wide at the top, 0.26 m high, and the four through holes are all 45 mm in diameter;

[0105] 3. The first direction sleeper A31 and the first direction sleeper D34 are spaced apart by 0.426 m, and the first direction sleeper B32 and the first direction sleeper C33 are spaced apart by 0.426 m;

[0106] 4. The concrete sleepers between the upper and lower layers are fixed by a 0.626 m long Φ39 screw rod and a matching hexagonal nut;

[0107] 5. The steel backing plate for the nut provides a counterforce, which is 450 mm long, 200 mm wide, and 8 mm thick, and two holes with a diameter of 42 mm are provided on the steel backing plate, and the hole centers correspond to the reserved holes of the concrete sleeper;

[0108] 6. Use the grinder to open a 20mm deep notch at both ends of the waste concrete sleeper, the notch is 140mm away from the end of the waste concrete sleeper, the notch is 230mm long and 210mm wide, and the notch is vertically placed in the gap between the upper layer of waste concrete sleepers in the combined structure;

[0109] 7. The waste concrete sleeper combined structure is filled with coarse aggregate, and the filling height is 0.54m;

[0110] 8. A layer of geotextile is placed on the coarse aggregate;

[0111] 9. Backfilling the alluvial silt and layering compaction, and finally carrying out ground hardening treatment.

[0112] Specifically, as case two: a road engineering appears deformation in the embankment after being completed and used for 2 years, and the pavement appears collapse. The specific performance is that several pits with a depth of 0.20m to 0.40m and a maximum area of about 2 square meters appear on the section of the pavement, the total length of the collapsed section is about 1 kilometer, and the width is about 8m, which seriously affects the passing efficiency of the passing vehicles and the safety of the vehicles and people. There are two reasons for the collapse: 1. The pavement appears subsidence, mainly because the water content of the soil in the roadbed is too large, which makes the soil strength poor, and the subsidence occurs under the action of gravity, causing the pavement cracks. 2. The limestone in this area develops locally, and there is a karst phenomenon. After the water in the roadbed flows in the karst cave, the fine particles of the soil are carried away, which aggravates the subsidence and collapse of the pavement.

[0113] First, as shown in Figure 11 , a model of a multi-group combined structure with a roadbed height of 6m and a waste concrete sleeper spacing of 1.8m is established by using finite element limit analysis, and the numerical simulation material of the concrete sleeper is a linear elastic body.

[0114] Main parameters of the model:

[0115] 1. The elastic modulus of the new concrete sleeper is 3.6×104kPa, and the Poisson's ratio is 0.167;

[0116] 2. The elastic modulus of the waste concrete sleeper is 3.06×104kPa, and the Poisson's ratio is 0.21.

[0117] The internal friction angle and the cohesive force of the roadbed soil filling are set to 25° and 5kPa respectively, the influence of the change of a single strength parameter of the soil filling on the soil arch height generated between the concrete sleeper combined structure is studied, and the results show that:

[0118] 1. As shown in Figure 12 , with the increase of the cohesive force, the soil arch height between the waste concrete sleeper combined structure increases;

[0119] 2. As shown in Figure 13As shown, the soil arch height decreases with the increase of the internal friction angle, and when the internal friction angle is greater than 25°, the soil arch height changes little, and is below 0.9m.

[0120] Meanwhile, a finite element calculation model of the waste concrete combined structure is constructed, as shown in the accompanying drawings, Figure 14 The strength influence of the waste concrete sleeper combined structure in the collapse range is analyzed, and the results show that:

[0121] 1. As shown in the accompanying drawings, Figure 15 With the expansion of the collapse range, the load multiplier of the combined structure decreases;

[0122] 2. With the decrease of the aging load multiplier of the concrete sleeper, the strength of the new and old concrete sleepers only differs by about 0.267%.

[0123] Therefore, the spacing of the waste concrete sleeper combined structure with a spacing of 1.8m is small under the action of the soil load of 6m~10m high, and can bear the influence of the roadbed collapse hole of 2m~4m wide. According to the above calculation and analysis, the designed new roadbed is 20m wide and 6m~10m high.

[0124] Therefore, through the calculation model and the finite element limit analysis method, it is concluded that the optimal strength of the soil arch effect forming filler is that the internal friction angle is greater than 25° and the cohesive force is 8kPa.

[0125] The specific construction scheme is as follows:

[0126] 1. The combined structure adopts type IIIa waste concrete sleepers, which are 2.6m long, 0.32m wide at the bottom, 0.14m wide at the top, and 0.26m high;

[0127] 2. The four holes are all 45mm in diameter, and the spacing between the waste concrete sleepers in the first direction in each combined structure is 0.426m;

[0128] 3. The concrete sleepers between the upper and lower layers are fixed by Φ39 long screws and matching hexagonal nuts, and the steel backing plate providing the counterforce is 414mm long, 200mm wide, and 0.8cm thick;

[0129] 4. A grinder is used to open a 20mm deep notch in the upper layer sleeper, the notch is 0.14m away from the end of the waste concrete sleeper, the notch is 23cm long and 21cm wide, and it is vertically placed in the gap between the upper layer waste concrete sleepers of the combined structure;

[0130] 5. Φ32 precast long 0.8m end "S" type steel bars are used to stagger lap between each group of waste concrete sleeper combined structure and the adjacent group of waste concrete sleeper combined structure, which are fixed on the screws fixing the upper and lower concrete sleepers, and then fixed by nuts;

[0131] 6. A concrete sleeper is vertically placed in each gap of the lower concrete sleeper;

[0132] 7. The waste concrete sleeper composite structure is filled with coarse aggregate with a particle size greater than 2 cm, and the filling height is 0.55 m;

[0133] 8. A layer of geotextile is placed on the coarse aggregate;

[0134] 9. The subgrade soil filler with an internal friction angle greater than 25° and a cohesion of about 8 kPa is backfilled and compacted in layers to the design height, and finally the pavement hardening treatment is performed.

[0135] The interior of the concrete sleeper composite structure is filled with coarse aggregate, which can withstand the load of the upper subgrade. At the same time, the coarse aggregate layer forms a channel for the water in the subgrade soil to drain, which is beneficial to the rapid drainage of water, has good permeability, can quickly drain groundwater, and can prevent subgrade diseases caused by poor drainage of groundwater. The geotextile is placed on the interface between the waste concrete sleeper composite structure and the upper subgrade soil, which can filter the groundwater in the upper soil, prevent the loss of fine particles in the soil, maintain the overall structure of the upper subgrade soil, and increase the uniformity of the load of the concrete sleeper composite structure. The concrete sleeper composite structure improves the stiffness of the subgrade, makes the subgrade have better seismic performance, prolongs the service life of the road, and improves the durability of the subgrade.

[0136] The details of the present application are well known to those skilled in the art.

[0137] The above shows and describes the basic principles, main features and beneficial effects of the present application. The above is only a preferred embodiment of the present application and does not limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A design method for roadbed based on waste and abandoned concrete sleepers, characterized in that: The method comprises the following steps: S1: grooves (19) are formed at both ends of the lower surface of the upper transverse sleeper; S2: the lower structure unit (2) comprises four lower longitudinal sleepers and one lower transverse sleeper in H shape, and a plurality of lower structure units (2) are connected end to end along the long side of the foundation pit; S3: the upper structure unit (1) and the lower structure unit (2) are the same in structure, the upper structure unit (1) and the lower structure unit (2) are laid in staggered mode, the upper end through hole of the lower longitudinal sleeper is aligned with the lower end through hole of the upper longitudinal sleeper, the lower end through hole of the lower longitudinal sleeper is aligned with the upper end through hole of the upper longitudinal sleeper, the grooves (19) are connected with the middle position of the lower longitudinal sleeper, and a plurality of upper structure units (1) are laid on the lower structure units (2) in end-to-end mode along the laid lower structure units (2); S4: the pad (16) is placed at the through hole, the upper structure unit (1) and the lower structure unit (2) are connected through the screw rod (15) and the nut (18), and a strip-shaped structure unit (10) is formed; S5: a plurality of strip-shaped structure units (10) are laid in parallel to fill the entire foundation pit, and the adjacent strip-shaped structure units (10) are fixedly connected through the s-shaped steel bar (17); S6: the coarse aggregate (22) is filled in the gap between the laid sleepers and is compacted; S7: the geotextile (21) is laid; S8: the subgrade covering parameters capable of forming the soil arching effect are obtained through the calculation model and the finite element limit analysis method, and the subgrade covering is laid; The strip-shaped structure unit (10) comprises the upper structure and the lower structure arranged in a stacked mode, the upper structure comprises the upper structure units (1) connected end to end, the lower structure comprises the lower structure units (2) connected end to end, the upper structure unit (1) is connected with the lower structure unit (2) through the connecting piece one (3), and the strip-shaped structure units (10) are connected through the connecting piece two (4); the upper structure unit (1) comprises the upper longitudinal sleeper and the upper transverse sleeper, the lower structure unit (2) comprises the lower longitudinal sleeper and the lower transverse sleeper; the upper structure unit (1) and the lower structure unit (2) are arranged in a staggered mode, the upper structure unit (1) is arranged in a staggered mode in the longitudinal direction upward / downward, the upper end through hole of the lower longitudinal sleeper corresponds to the lower end through hole of the upper longitudinal sleeper, the lower end through hole of the lower longitudinal sleeper corresponds to the upper end through hole of the upper longitudinal sleeper, and the lower longitudinal sleeper is connected with the groove (19) arranged on the lower surface of the upper transverse sleeper in a clamped mode.

2. The design method of the waste and abandoned concrete sleeper subgrade according to claim 1, characterized in that: The connecting piece one (3) comprises a screw rod (15), the screw rod (15) passes through the through hole of one end of the upper longitudinal sleeper and the through hole of the other end of the lower longitudinal sleeper respectively, the screw rod (15) is in stop cooperation with the nut (18) arranged at both ends of the screw rod (15), and the connecting piece two comprises an s-shaped steel bar (17), both ends of the s-shaped steel bar (17) are connected with the strip-shaped structure unit (10) respectively.

3. The design method of the waste and abandoned concrete sleeper subgrade according to claim 2, characterized in that: The upper longitudinal sleeper and the nut (18) at the upper end of the screw rod (15) are provided with a backing plate (16), the lower longitudinal sleeper and the nut (18) at the lower end of the screw rod (15) are provided with the backing plate (16), the backing plate (16) is provided with a hole for the screw rod (15) to pass through, and the end portion of the s-shaped steel bar (17) is clamped between the backing plate (16) and the nut (18).

4. The design method of the waste and abandoned concrete sleeper roadbed according to claim 3: four lower longitudinal sleepers are longitudinal sleeper A (31), longitudinal sleeper B (32), longitudinal sleeper C (33) and longitudinal sleeper D (34), longitudinal sleeper A (31) and longitudinal sleeper B (32) are spaced apart by Xm, longitudinal sleeper C (33) and longitudinal sleeper D (34) are spaced apart by Ym, the distances X and Y are the same, longitudinal sleeper A (31) and longitudinal sleeper D (34) are spaced apart by 0.426m, longitudinal sleeper B (32) and longitudinal sleeper C (33) are spaced apart by 0.426m, one lower transverse sleeper is transverse sleeper E (35), one end of the transverse sleeper E (35) is placed in the middle of longitudinal sleeper A (31) and longitudinal sleeper D (34), and the other end of the transverse sleeper E (35) is placed in the middle of longitudinal sleeper B (32) and longitudinal sleeper C (33).

5. The design method of the waste and abandoned concrete sleeper subgrade according to claim 4, characterized in that: The surface of the notch (19) is attached to the surface of the middle position of the lower longitudinal sleeper, and the depth of the notch (19) is 20mm.

6. The design method of the waste and abandoned concrete sleeper subgrade according to claim 5, characterized in that: Through the calculation model and the finite element limit analysis method, it is obtained that the soil covering thickness capable of forming the soil arching effect is greater than or equal to 1.6m, and the optimal soil filling strength is that the internal friction angle is greater than 25° and the cohesive force is 8kPa.

7. The method for designing a waste and abandoned concrete sleeper subgrade according to claim 6, characterized in that: When the length of the abandoned concrete sleeper is 2.6m, it is obtained through calculation that X and Y are 1.5m-2.0m, which is beneficial to form the soil arching effect.

Images