A connecting method of new and old dams in garbage dam extension

Abstract

The application belongs to the field of building, and particularly discloses a connecting method for connecting a new dam and an old dam in extension of a garbage dam, which first reinforces the old dam body to form a reinforced part; the method comprises the following steps: (1) constructing a steel flower pipe-steel pipe-reinforced geotextile system; (2) constructing a pile anchor system; then constructing an increased part above the reinforced part and the old dam body to form a new dam body. The connecting method for connecting the new dam and the old dam in extension of the garbage dam can not only improve the anti-sliding force of the potential sliding surface of the old dam body, but also can enhance the connection between the new dam body and the old dam body, and improve the common working performance and the coordinated deformation capacity of the two, so as to achieve the purpose of in-situ expansion.

Description

Technical Field

[0001] This invention relates to the field of construction, specifically to a method for connecting old and new dams in the expansion of a waste retaining dam. Background Technology

[0002] With the rapid increase in the amount of municipal solid waste, existing landfills will be unable to continue to handle the ever-increasing volume of waste. Given the limited land available for landfills and the limited capacity of existing municipal solid waste landfills, it is necessary to expand existing landfills to increase their waste storage capacity.

[0003] In the process of raising, reinforcing, and expanding a landfill, it is necessary to construct a higher landfill dam along the existing old one. Landfill dams are typically homogeneous earth dams, and the dam body can be considered a homogeneous slope. According to calculations and engineering experience, the connection between the old and new dam bodies is the weakest point of the slope, and the most unfavorable sliding surface is located here. However, as an earth dam, if existing technology is used to create anti-slip steps on the old dam before backfilling and reinforcement, the dam body cannot maintain coordinated deformation between the old and new dam bodies. This can easily lead to cracks between the old and new dam bodies, affecting the overall stability of the dam and making it prone to landslides in the future. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for connecting the old and new dams in the construction of a garbage dam. The method can reduce the generation of cracks between the new and old dams when reinforcing and expanding the old dam, strengthen the connection between the old and new dams and enhance the integrity of the old and new dams, so that the two can deform in coordination and work together, thereby improving the stability of the garbage dam.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0006] A method for connecting old and new dams in the expansion of a waste retaining dam includes the following steps:

[0007] S1. Reinforce the old dam body to form a reinforced section; including the following steps:

[0008] S11; Construct a steel pipe-steel pipe-reinforced geotextile system;

[0009] S12: Construct a pile-anchor system;

[0010] S2. Construct a raised section above the reinforced section and the old dam body to form a new dam body.

[0011] Preferably, in step S1, the reinforcement includes multiple reinforcing layers stacked along the height direction of the old dam body, and each reinforcing layer is provided with a steel pipe-steel pipe-reinforced geotextile system. The construction steps of the steel pipe-steel pipe-reinforced geotextile system are as follows:

[0012] S111. On the slope surface in the old dam body that comes into contact with the new dam body, holes need to be drilled for positioning first. After drilling the installation holes, the steel pipes and anchor cables are then installed alternately in the installation holes, one after the other.

[0013] S112. A steel pipe is welded to the end of the steel pipe that extends out of the old dam body to hold the reinforced geotextile; wherein, the steel pipe has grouting holes on its wall. When the steel pipe is anchored into the old dam body, cement mortar is injected into the steel pipe. After the cement mortar solidifies, the steel pipe is anchored to the old dam body.

[0014] S113. Next, reinforced geotextile is laid to cover the bottom surface of this fill layer. After the fill layer is filled and compacted, the top surface of this fill layer is covered again with reinforced geotextile. The reinforced geotextile surrounds the fill layer in the vertical direction and is weighed down by bagged gravel.

[0015] S114. The upper and lower layers of reinforced geotextile are filled with soil and rock mixture to form the reinforced layer.

[0016] Preferably, in step S112, before injecting cement mortar into the steel pipe, the MICP binder and bacterial solution are mixed and injected into the old dam body through the grouting hole of the steel pipe; the injected MICP binder and bacterial solution penetrate into the pores and cracks in the old dam body, and then the MICP technology is used to induce calcium carbonate deposition to fill the pores and repair the cracks.

[0017] Preferably, in step S113, the upper and lower reinforcing geotextiles of the fill layer need to be fixed to the ground or the upper and lower fill layers using nails.

[0018] Preferably, in step S113, the backfill layer needs to have an embedded structure at the lower layer of reinforced geotextile, the embedded structure being a trench on the bottom surface of the backfill layer; then the lower layer of reinforced geotextile is placed in the trench and filled with soil-rock mixture.

[0019] Preferably, in step S12, the construction steps of the pile-anchor system are as follows:

[0020] S121. Drill holes at the toe of the old dam body, use a rotary drilling rig to drill the grouting holes, and clean the grouting holes;

[0021] S122. Erect a template on the ground at the pile hole, and make the template flush with the top of the old dam body;

[0022] S123. After hoisting the prepared steel cage to the top of the formwork and aligning it with the pile hole, place the steel cage into the pile hole.

[0023] S124. Select concrete to be poured into the formwork to form a cast-in-place pile until the cast-in-place pile is flush with the top of the old dam body;

[0024] S125. Install a concrete cover plate between the top of the old dam body and the top of the cast-in-place piles;

[0025] S126. A concrete waist beam is installed on the pile segment at the same horizontal plane as the anchor cable in the cast-in-place pile for tensioning and anchoring the anchor cable.

[0026] Preferably, in step S125, a concrete cover plate is constructed on the top of the old dam body. The concrete cover plate extends from the top of the old dam body towards the cast-in-place pile until the bottom surface of the concrete cover plate is flush with the top of the cast-in-place pile, and then the concrete cover plate is connected to the top of the cast-in-place pile.

[0027] Preferably, in step S126, the free section of the anchor cable needs to be fitted with a PVC pipe; then the PVC pipe is installed in the installation hole, and cement mortar is injected into the gap between the PVC pipe and the hole wall, so that the cement mortar reaching the anchoring section of the anchor cable can fix the anchoring section of the anchor cable and connect the anchoring section of the anchor cable and the soil around the installation hole into a whole; after the grouting of the anchoring section of the anchor cable is completed, grouting should continue to fill the space between the PVC pipe and the hole wall of the installation hole; after the cement mortar has solidified and its strength is qualified, the anchor cable needs to be tensioned and anchored on the waist beam.

[0028] Preferably, in step S3, the PVC pipe is coated with an anti-corrosion and lubricant.

[0029] Preferably, in step S3, the heightened section does not directly contact the old dam body, and the dam is formed by backfilling the soil-rock mixture in layers and then compacting it.

[0030] Compared with existing technologies, it has the following advantages:

[0031] 1. The new and old dam connection method for the expansion of the garbage retaining dam of the present invention uses the locking connection effect of the pile anchor system to lock one end of the anchor to the cast-in-place pile and the other end to the old dam body. On the one hand, it can directly improve the anti-sliding force of the potential sliding surface of the old dam body. On the other hand, due to the tensioning effect of the anchor, it can hold the cast-in-place pile in the new dam body to enhance the connection between the new dam body and the old dam body, thereby improving the joint working performance and coordinated deformation capacity of the two, and achieving the purpose of in-situ expansion.

[0032] 2. The new and old dam connection method for the expansion of the garbage retaining dam of the present invention adds a pile anchor system to the steel pipe-steel pipe-reinforced geotextile system. The anchor cables in the pile anchor system are arranged alternately and adjacently with the steel pipe-steel pipe-reinforced geotextile system, so as to strengthen the old dam body and improve the connection strength between the new and old dam bodies.

[0033] 3. The construction method of connecting the old and new dams in the construction of the garbage dam of the present invention is convenient and helps to improve the connection stability between the new dam body and the old dam body, so as to enhance the working performance of the dam body. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the connection structure between the old and new dams in the construction of the garbage retaining dam according to the present invention.

[0035] Figure 2 This is a schematic diagram of a steel pipe-steel pipe-geotextile system.

[0036] Figure 3 This is a schematic diagram of the installation of the reinforcement components.

[0037] Figure 4 This is a detailed drawing of the slope treatment.

[0038] Figure 5 This is a sample diagram of the cross-section of a steel perforated pipe.

[0039] Figure 6 This is a sample diagram of the anchor cable cross-section. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0041] See Figures 1-6 The new and old dam connection structure for the construction of a garbage dam of the present invention is used to reinforce and expand the old dam body 13. The new and old dam connection structure includes a reinforcement part and a heightening part 5. The reinforcement part is connected to the side wall of the old dam body 13, and the heightening part 5 is disposed on the top surface of the reinforcement part and the old dam body 13. The reinforcement part includes a plurality of reinforcing layers stacked along the height direction of the old dam body 13. The side of the reinforcing layer closest to the old dam body 13 is connected to the old dam body 13 by a traction member. The heightening part 5 does not need to be in direct contact with the old dam body 13, so it can be directly backfilled with soil and rock mixture in layers and compacted to form a dam.

[0042] See Figures 1-6 The traction component includes a steel pipe 4 and a steel pipe 2; one end of the steel pipe 4 is inserted into the old dam body 13, and the other end extends out of the old dam body 13 and is connected to the steel pipe 2; the axial direction of the steel pipe 2 is perpendicular to the axial direction of the steel pipe 4; the reinforcement layer includes reinforced geotextile 3 and bagged crushed stone 7.

[0043] In this embodiment, the reinforced geotextile 3 is an engineering material used for reinforcing soil for its long-term design life. It has the characteristics of corrosion resistance, chemical resistance, and good permeability. Using the reinforced geotextile 3 can not only ensure the stability of the soil, but also play a role in filtering and isolating (the landfill has leachate, which will erode the dam body). Under the tension of the steel pipe 2, the reinforced geotextile 3 above and below each layer of fill 11 can tightly connect the current layer of fill 11 with the steel pipe 4 to form a steel pipe 4-steel pipe 2-geotextile connection system, thereby strengthening the connection between the old and new dam bodies. In addition, the steel pipe 2 is welded to the steel pipe 4 to hold the reinforced geotextile 3 of the upper and lower layers. The length direction of the steel pipe 2 is consistent with the direction of the dam body.

[0044] See Figures 1-6 The reinforcement section also includes a reinforcement component for strengthening the connection strength between the new dam body 12 and the old dam body 13. The reinforcement component includes cast-in-place piles 1 and waist beams 8 installed on the cast-in-place piles 1. There are multiple sets of cast-in-place piles 1 and waist beams 8. The multiple sets of cast-in-place piles 1 are arranged in parallel and are all driven vertically into the ground. The multiple sets of waist beams 8 are arranged vertically, and each set of waist beams 8 is connected to multiple sets of cast-in-place piles 1. The old dam body 13 is connected to the waist beams 8 by anchors.

[0045] The anchoring components include an anchor cable 17, an anchor plate 16, an anchor 15, and a PVC pipe 18. The old dam body 13 has mounting holes for the PVC pipe 18, which is installed in the mounting holes and extends horizontally. Cement mortar 19 fills the space between the PVC pipe 18 and the mounting holes. One end of the anchor cable 17 is fixed to the waist beam 8 via the anchor 15, and the other end passes through the PVC pipe 18 and connects to the old dam body 13. The anchor plate 16 is positioned between the anchor 15 and the waist beam 8. During the entire tensioning process, the anchor plate 16 primarily functions to transmit and distribute the pressure from the tensioning equipment; that is, it bears the compressive stress transmitted from the anchor 15 and transfers it to the waist (crown) beam, which is then distributed among the individual cast-in-place piles 1.

[0046] In this embodiment, the cast-in-place pile 1 has a specification of Φ1000@1500, uses C30 concrete, and is constructed to the top of the old dam by erecting formwork. Furthermore, each cast-in-place pile 1 is connected by a tie beam 8 to enhance the working performance of each pile 1 and the locking connection with the anchor cable 17, thereby strengthening the connection between the old and new dam bodies. The tie beam 8 is a C30 concrete tie beam used to lock one end of the anchor cable 17 onto the cast-in-place pile 1 and to connect each cast-in-place pile 1... The piles are connected as one unit, so that each pile can share the tension of the anchor cable 17, thereby enhancing the connection between the old dam body 13 and the new dam body 12. The anchor cable 17 is a steel strand anchor cable 17, which is fixed at its outer end to the waist beam 8 located on the pile 1, and the other end is anchored in the old dam body 13. In this way, on the one hand, the anti-sliding resistance on the potential sliding surface of the old dam body 13 can be directly increased, and on the other hand, the connection between the new dam body 12 and the old dam body 13 can be enhanced.

[0047] In addition, the anchor 15 is an OVM15 anchor 15. In post-tensioned structures or components, the anchor 15 is an anchoring tool used to maintain the tension of the prestressed steel strands and transfer it into the concrete.

[0048] In addition, the PVC pipe 18 is sleeved on the free section of the anchor cable 17 to separate the cement mortar 19 from the free section of the anchor cable 17, so that the free section of the anchor cable 17 is not solidified by the cement mortar 19 and thus cannot perform its tensioning function; the inside of the PVC pipe 18 is coated with anti-corrosion and lubricant.

[0049] See Figures 1-6 The steel pipe 4 has a diameter of 48mm and is provided with grouting holes 9 along its circumference. These grouting holes 9 are arranged along the axis of the steel pipe 4, and a grouting channel communicating with the grouting holes 9 is provided inside the steel pipe 4. During the initial reinforcement of the old dam body 13, MICP technology can be used to mix the cementing liquid and bacterial solution and inject them into the old dam body 13 through the grouting holes 9. The generated calcium carbonate fills the pores and cracks within the old dam body 13, thus achieving seepage prevention for the old dam body 13. Requirements: During backfilling, the steel pipe 4 should be grouted. Cement mortar 19 should be injected into the soil around the steel pipe 4 through the grouting hole 9 to solidify the soil and make the steel pipe 4 form an anchor. This will allow the grouted steel pipe 4 to remain in the old dam body 13 and be firmly anchored thereto, providing sufficient anchoring and anti-sliding effect, improving the stability of the old dam body 13, and enhancing the connection between the old and new dam bodies through the steel pipe 4-steel pipe 2-geotextile system. In other words, the steel pipe 4 simultaneously serves as both a soil nail and a grouting pipe.

[0050] See Figures 1-4The upper backfill layer 11 and the concrete cover plate 6 together press down on the cast-in-place pile 1, preventing it from being crushed by the backfill layer 11 or pulled down by the anchor cable 17; the concrete cover plate 6 serves as the cushion layer for the heightened part of the new dam body 12, and together with the old dam body 13, it bears the pressure of the overlying soil.

[0051] See Figures 1-6 Except for the bagged crushed stone 7, the reinforced geotextile 3 is filled with soil and stone mixture to form a backfill layer 11; the upper and lower layers of the reinforced geotextile 3 are fixed to the backfill layer 11 by nails 10.

[0052] See Figures 1-6 The lower layer of reinforced geotextile 3 has an embedded structure, which is a ditch 14 set on the bottom surface of the fill layer 11. The reinforced geotextile 3 located in the ditch 14 is pressed into the ditch 14 by the soil-rock mixture.

[0053] See Figures 1-6 The construction method of the new and old dam connection structure for the expansion of the garbage dam according to the present invention is as follows:

[0054] S1. Before expanding the new dam body 12, the old dam body 13 needs to be reinforced before it can be filled and expanded. When reinforcing the old dam body 13, holes need to be drilled on the slope surface of the old dam body 13 that is in contact with the new dam body 12 for positioning. After drilling the installation holes, the steel pipe 4 and the anchor cable 17 are installed into the holes alternately at the upper and lower holes.

[0055] S2. A steel pipe 2 is welded to the end of the steel pipe 4 that extends out of the old dam body 13 to hold the reinforced geotextile 3. The steel pipe 4 has grouting holes 9 on its wall. When the steel pipe 4 is anchored into the old dam body 13, cement mortar 19 is injected into the steel pipe 4 to fix the steel pipe 4 to the old dam body 13 and to inject grout into the old dam body 13.

[0056] S3. Since the old dam body 13 located in the landfill also has seepage prevention requirements (the leachate from the landfill will erode the dam body), it can be reinforced using MIP technology (i.e., microbial induced calcium carbonate precipitation technology). Before filling the soil-rock mixture and drilling the dam toe, the MIP cementing liquid is mixed with the bacterial liquid and injected into the old dam body 13 through the grouting hole 9 of the steel pipe 4. Since the bacteria are very small, they can seep into deeper places through the pores and cracks in the old dam body 13. In these pores and cracks, the MIP technology is used to induce calcium carbonate deposition, fill the pores and repair the cracks, improve the density of the old dam body 13, and thus improve its seepage resistance.

[0057] S4. Drill holes at the toe of the old dam body 13. Use a rotary drilling rig to align the drill bit with the intersection of the crosshairs. After meeting the deviation requirements, drill the grouting hole and clean it. Then, erect a template on the ground at the original location of the grouting hole. The template extends upward until it is flush with the top of the old dam body 13. Lift the prepared steel cage to the top of the template and align it with the position of the grouting hole. After installation, pour C30 concrete into the template to form grouting pile 1 (Φ1000) until the grouting pile 1 is flush with the top of the old dam body 13.

[0058] S5. During the construction of the cast-in-place pile 1, the construction of the C20 concrete cover plate 6 begins on the top of the old dam body 13. The concrete cover plate 6 extends from the top of the old dam body 13 toward the concrete column (i.e., the cast-in-place pile 1) until the bottom surface of the concrete cover plate 6 is flush with the top of the concrete column (i.e., the cast-in-place pile 1) and then connects it to the top of the concrete column (i.e., the cast-in-place pile 1).

[0059] S6. A concrete waist beam 8 is installed on the pile segment of the cast-in-place pile 1 at the same horizontal plane as the anchor cable 17 for tensioning and anchoring the anchor cable 17. The anchor cable 17 is divided into an anchoring section and a free section. The free section of the anchor cable 17 needs to be fitted with a PVC pipe 18. The PVC pipe 18 is coated with anti-corrosion and lubricant to improve the working performance of the free section of the anchor cable 17. During pressure grouting, cement mortar 19 should be injected into the space between the PVC pipe 18 and the hole wall of the installation hole. Under pressure, the cement mortar 19 will flow to a deeper position, i.e., the anchor cable 17. At the anchoring section, the cement mortar 19 flowing into the anchoring section of the anchor cable 17 can fix the anchor cable 17 and connect it with the soil around the installation hole to form a whole, so as to play an anchoring role; after the grouting of the anchoring section of the anchor cable 17 is completed, grouting should continue to fill the space between the PVC pipe 18 and the hole wall of the installation hole; after the strength of the cement mortar 19 is qualified, the anchor cable 17 needs to be tensioned and anchored on the waist beam 8 to provide anchoring and anti-sliding effect for the potential sliding surface of the old dam body 13, and at the same time strengthen the connection between the new dam body 12 and the old dam body 13.

[0060] S7. The new dam body 12 is constructed and compacted in layers using a mixture of soil and rock. Before each layer is filled, the bottom surface of the filling layer 11 is covered with a reinforced geotextile 3. After the filling and compaction of the filling layer 11 is completed, the top surface of the filling layer 11 is covered with a reinforced geotextile 3 again. The upper and lower layers of reinforced geotextile 3 are held in place by steel pipes 2 (which are welded to steel pipes 4) on the slope of the old dam body 13. Therefore, the steel pipes 2 hold the reinforced geotextile 3 in place and prevent the reinforced geotextile 3 from being pulled out of place or detached from the filling layer 11 by the displacement of soil particles in each filling layer 11, thus forming a steel pipe 4-steel pipe 2-geotextile system.

[0061] S8. The upper and lower layers of reinforced geotextile 3 of each fill layer 11 need to be fixed to the ground or fill layer 11 using fixing nails 10; the lower layer of reinforced geotextile 3 needs to be set with an embedded structure, that is, a small trench 14 is dug on the bottom surface of the fill layer 11, the lower layer of reinforced geotextile 3 is placed in the trench 14 and filled with soil and rock mixture, so as to limit and strengthen the fixing of the reinforced geotextile 3, thereby strengthening the integrity of the steel pipe 4-steel pipe 2-geotextile system and each fill layer 11, and further enhancing the connection strength between the new dam body 12 and the old dam body 13;

[0062] S9. Since the steel pipe 4 and the anchor cable 17 are installed alternately and adjacently, each time a backfill layer 11 is filled, if there is an installation hole corresponding to that backfill layer 11 (i.e., when the anchor cable 17 or steel pipe 4 needs to be installed), grouting should be performed in time to lock the anchor cable 17 to make it an anchor or grouting should be performed using the steel pipe 4. Among them, the cement mortar 19 can effectively fill the steel pipe 4 and can be injected into the surrounding soil through the grouting hole 9 of the steel pipe 4 to achieve the purpose of solidifying the soil. After the cement mortar 19 is solidified, it will firmly anchor the steel pipe 4 into the old dam body 13 to form an anchor, thereby improving the anchoring capacity of the steel pipe 4, so that the steel pipe 2 can further tighten the reinforced geotextile 3, enhance the connection between the new dam body 12 and the old dam body 13, and strengthen the old dam body 13 at the same time.

[0063] S10. The ends of the reinforced geotextile 3 at the bottom of each fill layer 11 are pressed down with several bags of crushed stone 7. The edge of the lower layer of reinforced geotextile 3 is rolled up to the other side of the bag of crushed stone 7 and pressed down by the fill layer 11. The edge of the upper layer of reinforced geotextile 3 is rolled down and pressed down by the bag of crushed stone 7 to prevent the reinforced geotextile 3 from shrinking or misaligning, thereby further strengthening the integrity of the steel pipe 4-steel pipe 2-geotextile system and each fill layer 11, so as to enhance the connection between the new and old dam bodies.

[0064] S11. Due to the slope requirement of the new dam body 12, the amount of soil filling in each fill layer 11 is inconsistent; and because the reinforced geotextile 3 wraps around each fill layer 11, there will be areas between upper and lower fill layers 11 where fill layers 11 are missing due to the slope design. Therefore, these areas need to be filled and compacted with soil-rock mixture (see details). Figure 4 );

[0065] S12. The part above the concrete cover plate 6 belongs to the heightened part 5 of the new dam body 12. This heightened part 5 does not need to be in direct contact with the old dam body 13, so it can be directly backfilled with soil and rock mixture in layers and then compacted to form a dam.

[0066] Finally, the construction method of the new and old dam connection structure for the expansion of the garbage dam according to the present invention has the following advantages:

[0067] (1) This method is convenient to construct, beneficial to the connection between the new dam body 12 and the old dam body 13, and enhances the working performance of the dam body;

[0068] (2) The pressure grouting equipment injects grout into the installation hole to form an anchor. The waist beam 8 on the cast-in-place pile 1 uses the anchor 15 to lock the anchor cable 17, and connects the anchor cable 17 to the cast-in-place pile 1 to form a pile-anchor system.

[0069] (3) On the basis of the steel pipe-steel pipe-reinforced geotextile system, a pile anchor system is added. The anchor cable 17 in the pile anchor system is arranged alternately with the steel pipe-steel pipe-reinforced geotextile system, which can strengthen the old dam body 13 and improve the connection strength between the new and old dam bodies. In addition, the steel pipe 4 also has the functions of soil nail and grouting pipe.

[0070] (4) By utilizing the function of the steel pipe 4 as a soil nail, the sliding resistance of the potential sliding surface of the old dam body 13 can be improved, and the old dam body 13 can be anchored. By utilizing the function of the steel pipe 4 as a grouting pipe, the impermeability of the old dam body 13 can be effectively improved by MICP technology and pressure injection of cement mortar 19, and the old dam body 13 can be reinforced so that the steel pipe 4 is tightly anchored in the old dam body 13, thereby extending the service life of the old dam body 13.

[0071] (5) The anchor can lock one end of the anchor cable 17 to the cast-in-place pile 1 and the other end to the old dam body 13 through the tight locking connection of the pile anchor system. On the one hand, the anchor section directly improves the anti-sliding force of the potential sliding surface of the old dam body 13. On the other hand, the tensioning effect of the anchor cable 17 pulls the cast-in-place pile 1 in the new dam body 12, strengthens the connection between the new dam body 12 and the old dam body 13, improves the joint working performance and coordinated deformation capacity of the two, and achieves the purpose of in-situ expansion.

[0072] (6) The end of the reinforced geotextile 3 is pressed with bagged crushed stone 7 to ensure that the reinforced geotextile 3 does not shift.

[0073] (7) The concrete cover plate 6 can enhance the ability of the cast-in-place pile 1 to withstand the tension of the anchor cable 17 and the pressure of the soil-rock mixture backfill layer 11, so that the cast-in-place pile 1 will not collapse or tilt. At the same time, the combination of the concrete cover plate 6 on the top of the old dam body 13 and the cast-in-place pile 1 can serve as the foundation for the heightened part of the new dam body 12, enhancing the stability of the heightened part.

[0074] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for connecting old and new dams in the expansion of a garbage-retaining dam, characterized in that, Includes the following steps: S1. Reinforce the old dam body to form a reinforced section; the reinforced section includes multiple reinforcing layers stacked along the height direction of the old dam body, and each reinforcing layer is equipped with a steel pipe-steel pipe-reinforced geotextile system. Includes the following steps: S11; Construct a steel perforated pipe-steel pipe-reinforced geotextile system; wherein, the construction steps of the steel perforated pipe-steel pipe-reinforced geotextile system are as follows: S111. On the slope surface in the old dam body that comes into contact with the new dam body, holes need to be drilled for positioning first. After drilling the installation holes, the steel pipes and anchor cables are then installed alternately in the installation holes, one after the other. S112. A steel pipe is welded to the end of the steel pipe that extends out of the old dam body to hold the reinforced geotextile; wherein, the steel pipe has grouting holes on its wall. When the steel pipe is anchored into the old dam body, cement mortar is injected into the steel pipe. After the cement mortar solidifies, the steel pipe is anchored to the old dam body. S113. Next, reinforced geotextile is laid to cover the bottom surface of this fill layer. After the fill layer is filled and compacted, the top surface of this fill layer is covered again with reinforced geotextile. The reinforced geotextile surrounds the fill layer in the vertical direction and is weighed down by bagged gravel. S114. The upper and lower layers of reinforced geotextile are filled with soil and rock mixture to form the reinforced layer; S12: Constructing a pile-anchor system, wherein the construction steps of the pile-anchor system are as follows: S121. Drill holes at the toe of the old dam body, use a rotary drilling rig to drill the grouting holes, and clean the grouting holes; S122. Erect a template on the ground at the pile hole, and make the template flush with the top of the old dam body; S123. After hoisting the prepared steel cage to the top of the formwork and aligning it with the pile hole, place the steel cage into the pile hole. S124. Select concrete to be poured into the formwork to form a cast-in-place pile until the cast-in-place pile is flush with the top of the old dam body; S125. Install a concrete cover plate between the top of the old dam body and the top of the cast-in-place pile. Specifically, the concrete cover plate is constructed on the top of the old dam body. The concrete cover plate extends from the top of the old dam body to the cast-in-place pile until the bottom surface of the concrete cover plate is flush with the top of the cast-in-place pile. Then, the concrete cover plate is connected to the top of the cast-in-place pile. S126. A concrete lintel is installed on the pile segment at the same horizontal plane as the anchor cable in the cast-in-place pile for tensioning and anchoring the anchor cable. The free section of the anchor cable needs to be fitted with a PVC pipe. The PVC pipe is then installed in the installation hole, and cement mortar is injected into the gap between the PVC pipe and the hole wall. This ensures that the cement mortar reaching the anchoring section of the anchor cable can fix the anchoring section and connect it to the surrounding soil. After the grouting of the anchoring section is completed, grouting should continue to fill the space between the PVC pipe and the hole wall. Once the cement mortar has hardened and reached the required strength, the anchor cable needs to be tensioned and anchored on the lintel. S2. Construct a raised section above the reinforced section and the old dam body to form a new dam body.

2. The method for connecting the old and new dams in the expansion of a garbage-retaining dam according to claim 1, characterized in that, In step S112, before injecting cement mortar into the steel pipe, the MICP binder and bacterial solution are mixed and injected into the old dam body through the grouting hole of the steel pipe. The injected MICP binder and bacterial solution penetrate into the pores and cracks in the old dam body, and then the MICP technology is used to induce calcium carbonate deposition to fill the pores and repair the cracks.

3. The method for connecting the old and new dams in the expansion of a garbage-dammed retaining dam according to claim 1, characterized in that, In step S113, the upper and lower layers of reinforced geotextile in the fill layer need to be fixed to the ground or the upper and lower layers of fill layer using nails.

4. The method for connecting the old and new dams in the expansion of a garbage-dammed retaining dam according to claim 1, characterized in that, In step S113, the backfill layer needs to have an embedded structure at the lower layer of reinforced geotextile, the embedded structure being a trench on the bottom surface of the backfill layer; then the lower layer of reinforced geotextile is placed in the trench and filled with soil-rock mixture.

5. The method for connecting the old and new dams in the expansion of a garbage-dammed retaining dam according to claim 1, characterized in that, In step S126, the inside of the PVC pipe is coated with an anti-corrosion agent and a lubricant.

6. The method for connecting the old and new dams in the expansion of a garbage-dammed retaining dam according to claim 1, characterized in that, In step S2, the heightened section does not directly contact the old dam body; the dam is formed by backfilling the soil-rock mixture in layers and then compacting it.

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