Anti-seepage method for earth-rock mixed dam type to cope with differential settlement

Abstract

The invention discloses an anti-seepage method for an earth-rock mixed dam type to cope with differential settlement, and relates to the technical field of building construction methods.A thorn wall is poured in a preset position between a concrete dam section and an earth dam section of a mixed dam connecting section, one end of the thorn wall is fixedly connected with the concrete dam section 1, and the other end of the thorn wall is inserted into the earth dam section; longitudinal grooves are prefabricated in the end face of one end, close to the earth dam section, of the thorn wall and the two side faces in the insertion direction, the longitudinal grooves are formed in the height direction of the thorn wall in a penetrating mode, the depth of the grooves is 50 mm + / -2 mm, and the width of the grooves is 50 mm + / -2 mm; and the thorn wall is formed by layered pouring. According to the anti-seepage method for coping with differential settlement of the earth-rock mixed dam type, when a crack between a thorn wall and an earth dam section caused by differential settlement is smaller than or equal to 5 mm, the water swelling rubber strip can completely block within three days after absorbing water and swelling, and manual intervention is not needed; for a disengagement area which is not compacted sufficiently, the rubber strip can expand to block the disengagement area when seepage contacts with the rubber strip, and a seepage channel which is invisible to naked eyes is eliminated.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a seepage prevention method for a soil-rock hybrid dam type to address uneven settlement. Background Technology

[0002] Hybrid dams are widely used due to their economic efficiency and adaptability to terrain. When a dam site simultaneously presents a narrow bedrock section and gently sloping covered terraces on both banks, hybrid dams can maximize the use of the terrain. For example, the Maopingxi protection dam in the Three Gorges Project, with its earth-rock dam on the left bank and concrete gravity dam on the right, is suitable for the transitional sections between the Yangtze River canyon and wide valley. Hybrid dams are structures that balance engineering safety and economy under complex terrain and geological conditions. The piercing wall, as a key structure for seepage control in the connecting section of a hybrid dam, mainly addresses issues such as deformation coordination, seepage control, and structural stability. Its design rationality directly affects the seepage safety of the dam structure. While the piercing wall can effectively control seepage in the connecting section... However, the compression modulus of the spiked wall and the earthen dam differs significantly. Under the weight of the dam body, reservoir water pressure, or foundation deformation, uneven settlement is likely to occur at the connection section. Furthermore, because the stiffness of the spiked wall is approximately 20-30 GPa, which is significantly different from the stiffness of the soil and rock material (0.1-1 GPa), uneven settlement can lead to stress concentration between the spiked wall and the earthen dam section, resulting in cracks. This damages the structural integrity of the connection section, forming direct seepage channels and causing the spiked wall structure to lose its original seepage prevention function. Uneven settlement can also lead to local voids between the spiked wall and the soil. Even without visible cracks, insufficient compaction can create hidden seepage channels.

[0003] Therefore, it is necessary to propose a seepage prevention method for earth-rock hybrid dams to address uneven settlement and solve the above problems. Summary of the Invention

[0004] Technical problem to be solved: The purpose of this invention is to provide a seepage prevention method for earth-rock hybrid dams to cope with uneven settlement, so as to solve the problem mentioned in the background art that stress concentration occurs between the spiked wall and the earth dam section in existing hybrid dams, resulting in cracks, destroying the structural integrity of the connection section and forming a direct seepage channel, causing the spiked wall structure to lose its original seepage prevention function.

[0005] Technical Solution: To achieve the above objectives, the present invention provides the following technical solution: a seepage prevention method for earth-rock hybrid dams to address uneven settlement, comprising the following steps: 1. Precasting and Casting of the Spike Wall: A spike wall is cast at a predetermined position between the concrete dam section and the earth dam section of the hybrid dam connection segment, so that one end of the spike wall is fixedly connected to the concrete dam section 1, and the other end is inserted into the earth dam section; longitudinal grooves are precast on the end face of the spike wall near the earth dam section and on both sides along the insertion direction. The longitudinal grooves are set through the height direction of the spike wall, with a groove depth of 50mm±2mm and a groove width of 50mm±2mm; the spike wall is formed by layered casting, with each layer having a casting height of 2-3m, and each layer is vibrated during the casting process; 2. Installation of expansion rubber strips: Cut the expansion rubber strips to the size that matches the length of the longitudinal groove and leave an overlap allowance. Use expansion inhibitors to prevent premature expansion when exposed to moisture during construction. Mark anchor points every 200mm along the longitudinal groove direction. After drilling holes at the bottom of the groove, use a high-pressure blower to blow away the dust in the holes. Inject epoxy resin anchoring adhesive into the holes to 2 / 3 of the hole depth. Use 12mm diameter 304 stainless steel nails to press the expansion rubber strips into the groove and align the anchor points. 3. Synergistic effect of sealing reinforcement and seepage prevention: Water-swellable sealant is injected at the interface between the expansion rubber strip and the longitudinal groove, and the surface is covered with a PE protective film; when cracks or hidden seepage channels are generated in the wall and earth dam section due to uneven settlement, the expansion rubber strip absorbs water and expands after contacting the seepage, sealing the cracks and hidden seepage channels.

[0006] Preferably, the water absorption and expansion rate of the expanding rubber strip in step 3 is ≥200%, and after expansion, it can fill the crack with a width of 3-5mm, and its water pressure resistance is >0.5MPa.

[0007] Preferably, in step 3, when the mixed dam is a low dam (dam height H≤30m), 1-3 expansion rubber strips are arranged along the entire length of the top of the spiked wall, 1-3 expansion rubber strips are arranged vertically on both sides, and 1-3 expansion rubber strips are arranged along the entire length of the end face near the earth dam section.

[0008] Preferably, in step 3, when the mixed dam is a medium dam (30m < dam height H ≤ 70m), 3-5 parallel expanding rubber strips are arranged at intervals of 300mm on the top of the spiked wall; 3-5 vertical expanding rubber strips are arranged at intervals of 500mm on both sides; and 3-5 expanding rubber strips are arranged at intervals of 300mm along the entire length of the end face near the earth dam section.

[0009] Preferably, in step 3, when the hybrid dam is a high dam (dam height H > 70m), 5-7 expansion rubber strips are arranged at intervals of 200mm on the top of the spiked wall; 5-7 vertical expansion rubber strips are arranged at intervals of 400mm on both sides; and 5-7 expansion rubber strips are arranged at intervals of 250mm along the entire length of the end face near the earth dam section.

[0010] Preferably, the grooves on the end face and both sides of the spiked wall near the earth dam section are provided with multiple layers of expanding rubber strips. Each layer of expanding rubber strip is wrapped with a geomembrane, and each layer of expanding rubber strip is provided with a stainless steel nail. Both ends of the nail penetrate the corresponding expanding rubber strip. The exposed ends of the nails in the two outermost layers of expanding rubber strips are fixedly installed with lining plates, and the ends of the nails near the adjacent expanding rubber strips are bent vertically and have a blade at the end. Both ends of the nails in the middle expanding rubber strips are bent vertically and also have a blade at the end.

[0011] Beneficial effects: Compared with the prior art, the present invention provides a seepage prevention method for earth-rock hybrid dams to cope with uneven settlement. This seepage prevention method for earth-rock hybrid dams to cope with uneven settlement has a unique structure and is easy to use. When uneven settlement causes cracks in the wall and earth dam section to be ≤5mm, the water-swellable rubber strip can completely seal the cracks within three days without manual intervention. For voids due to insufficient compaction, the seepage will expand and seal the voids upon contact with the rubber strip, eliminating seepage channels that are invisible to the naked eye.

[0012] The expansion pressure (0.3~0.8MPa) of the expanding rubber strip continuously compresses the crack wall. Even if settlement continues to develop, the rubber strip can still seal the crack and prevent the formation of seepage channels (suitable for settlement ≤30mm). It can also eliminate stress concentration. The flexible material can buffer shear force and reduce the risk of cracking in the pierced concrete wall.

[0013] The thorn wall itself serves as the first rigid seepage barrier, while the water-swelling properties of the rubber strips act as the second barrier. This effectively prevents water from carrying away fine particles from the dam body through the seepage channels, extending the dam's lifespan and reducing secondary damage to the earth dam caused by uneven settlement. Attached Figure Description

[0014] Figure 1 This is a three-dimensional schematic diagram of the present invention.

[0015] Figure 2 This is a schematic diagram showing the installation position of the spiked wall according to the present invention.

[0016] Figure 3 This is a perspective view of the spiked wall structure of the present invention.

[0017] Figure 4 This is a longitudinal cross-sectional schematic diagram of the spiked wall structure of the present invention.

[0018] Figure 5 This is a schematic cross-sectional view of the present invention.

[0019] Figure 6 This is a schematic cross-sectional view of the spiked wall structure of the present invention.

[0020] Figure 7This is a cross-sectional schematic diagram of the expanded rubber strip structure in Embodiment 2 of the present invention.

[0021] In the diagram: 1. Concrete dam section; 2. Earth dam section; 3. Spike wall; 4. Expanded rubber strip; 5. Through nail; 6. Geomembrane; 7. Lining plate. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Example 1: This example provides a seepage prevention method for earth-rock hybrid dams to address uneven settlement. Its core lies in the use of a rigid-flexible composite structure design of "rigid spiked wall 3 + flexible expansion rubber strip 4" to solve the seepage failure problem caused by the stiffness difference between the traditional spiked wall 3 and the earth dam section 2. The following detailed description of the implementation of this invention, combined with specific engineering scenarios and construction details, allows those skilled in the art to apply the technical solution.

[0024] I. Preliminary Preparations By combining foundation bearing capacity tests and finite element simulations, the maximum possible settlement of the connection section is predicted (usually controlled within ≤30mm, which is within the scope of this invention).

[0025] II. Specific Construction Implementation Steps (a) Casting of the piercing wall 3 and prefabrication of the longitudinal groove 1. Design of Spike Wall 3 parameters: Based on the connection length between the concrete dam section 1 and the earth dam section 2 of the hybrid dam, design the height and thickness of spike wall 3, which is usually 1 / 3 to 1 / 2 of the dam width to ensure structural stability.

[0026] 2. Construction of the Spike Wall 3: Excavate the groove of the earth-rock dam, install rigid formwork on both sides of the earth dam section 2, and reserve anchor bar holes. Using the treated groove surface as a template on the side of the earth-rock dam, fill the material in layers along the height, with each layer being 2-3m. During the pouring process, vibrate each layer to ensure that the material is evenly distributed, and ensure that a groove is left on the side of the spike wall 3 near the earth dam section 2. The groove depth is 50mm±2mm, the groove width is 50mm±2mm, and the groove length extends through the height of the spike wall 3. Lay a plastic film to isolate the contact surface between the template and the earth dam section 2 to prevent the concrete from sticking to the soil during pouring.

[0027] (III) Installation stage of expansion rubber strip 4 1. Rubber strip selection and pretreatment: Select expansion rubber strip 4 made of natural rubber and water-absorbing resin. After testing, its water absorption expansion rate is 220%. After expansion, it can fill a 5mm wide crack and withstand water pressure of 0.6MPa. Cut the rubber strip according to the longitudinal groove length (25m), leaving a 50mm overlap allowance for each strip. Immediately after cutting, apply a special expansion inhibitor (main component is organosilane) and place it in a dry and ventilated construction shed for later use.

[0028] 2. Anchoring System Construction: Mark anchoring points every 200mm along the longitudinal groove length using a stone pencil. Drill vertical holes 80mm deep in the bottom of the groove using an impact drill (14mm diameter). After drilling, use a high-pressure blower (0.8MPa) to blow away dust from the holes to ensure the hole walls are clean. Inject epoxy resin anchoring adhesive (compressive strength ≥60MPa) into the holes to 2 / 3 of the hole depth. Then, use 12mm diameter 304 stainless steel nails to press the rubber strip into the groove, with the top of the nail flush with the bottom of the groove to ensure a tight fit between the rubber strip and the bottom of the groove.

[0029] 3. Rubber strip arrangement scheme: Low dam: Two parallel rubber strips are arranged along the entire length of the top of the spiked wall 3, with a spacing of 80cm; two rubber strips are arranged vertically on each of the left and right sides, with a spacing of 1.5m; and two rubber strips are arranged along the entire length of the front end face, with a spacing of 60cm.

[0030] Zhongba: Four rubber strips are arranged at intervals of 300mm on the top of the spiked wall 3; four vertical rubber strips are arranged at intervals of 500mm on each of the left and right sides; and four rubber strips are arranged at intervals of 300mm on the front end face.

[0031] High dam: Six rubber strips are arranged at intervals of 200mm on the top of the spiked wall 3; six vertical rubber strips are arranged at intervals of 400mm on each of the left and right sides; and six rubber strips are arranged at intervals of 250mm on the front end face.

[0032] (iv) Stage of coordinated sealing and seepage prevention 1. Interface sealing treatment: All rubber strip overlaps are bonded with a special adhesive, with an overlap length ≥100mm. A layer of water-swellable sealant is applied to the joints. One-component polyurethane water-swellable sealant is injected into all contact interfaces between the rubber strip and the longitudinal groove. The injection pressure is controlled at 0.3MPa to ensure that the sealant fills the interface gaps. Immediately after injection, a 0.1mm thick PE protective film is covered on the surface of the rubber strip. The edges of the protective film are fixed with tape to prevent concrete slurry from contaminating the rubber strip during subsequent dam filling.

[0033] 2. Subsequent maintenance and monitoring: After the piercing wall 3 is poured, it will be cured for 28 days according to standard. During the curing period, the surface should be kept moist and the condition of the rubber strip in the groove should be monitored regularly to ensure that there is no premature expansion or damage. When filling the earth dam section 2, a small rolling equipment should be used to lightly compact within 1m around the piercing wall 3 to avoid the impact load of large machinery on the piercing wall 3.

[0034] (v) Verification of seepage prevention effect After implementation of this embodiment, monitoring by a settlement observation instrument showed that the maximum settlement difference at the connection between concrete dam section 1 and earthen dam section 2 was 8 mm, and no visible cracks appeared at the interface between the spiked wall 3 and earthen dam section 2. A water injection test was used to detect the seepage coefficient, and the results showed that the seepage coefficient of the connection section was ≤1×10⁻. 7 The flow rate (cm / s) meets the seepage prevention design requirements for low dams. When the simulated reservoir water level rises suddenly and seepage occurs, the expansion rubber strip 4 completely expands and seals the micro-cracks at the interface within 72 hours, and no seepage concentration occurs.

[0035] In this invention, the longitudinal grooves are set continuously along the height of the spiked wall 3, breaking through the limitation of the traditional spiked wall 3 in "local seepage prevention". During implementation, a customized groove template is used to ensure that the verticality deviation of the groove is ≤1‰, avoiding uneven stress on the rubber strip due to the inclination of the groove; the continuous design allows the rubber strip to respond to settlement deformation along the entire height of the dam. Even if multi-level cracks appear in the dam body, the continuous expansion of the rubber strip can still form an overall sealing strip, solving the problem of "local crack leakage" in the prior art.

[0036] To address the seepage pressure and settlement characteristics of dams of varying heights, the following innovations were employed during implementation to achieve precise adaptation: For low dams, the focus was on "basic seepage prevention," using a sparse layout to meet basic sealing requirements; for medium dams, "deformation adaptation" was strengthened, balancing seepage prevention efficiency and material costs through optimized spacing; and for high dams, "dual protection" was emphasized, combining denser layout with dual anchoring to enhance resistance to high water pressure. This differentiated approach avoided material waste or insufficient seepage prevention caused by a "one-size-fits-all" design, demonstrating a deep adaptation to the actual needs of the project.

[0037] During implementation, an innovative three-in-one process of "nail anchoring + sealant filling + protective film protection" was adopted: the high-strength bonding of epoxy resin anchoring adhesive ensures that the rubber strip does not fall off during settlement and deformation; the secondary sealing of water-swellable sealant eliminates gaps at the anchoring points; and the PE protective film effectively isolates construction pollution. This process solves the pain points of "weak fixation" and "interface leakage" in traditional rubber strip installation, allowing the expansion and sealing function of the rubber strip to be fully utilized, forming a composite seepage prevention system of "rigid wall reinforcement + flexible sealing".

[0038] Example 2: The difference between Example 2 and Example 1 is that, as Figure 7As shown, the grooves on the end face and both sides of the pierced wall 3 near the earth dam section 2 are provided with multiple layers of expanding rubber strips 4. In this scheme, there are three layers. Each layer of expanding rubber strip 4 is wrapped with a geomembrane 6, and each layer of expanding rubber strip 4 is provided with a stainless steel nail 5. Both ends of the nail 5 penetrate the corresponding expanding rubber strip 4. The exposed ends of the nails 5 in the two outermost layers of expanding rubber strip 4 are fixedly installed with a liner 7, and the ends of the nails 5 near the adjacent expanding rubber strip 4 are bent vertically and have a blade at the end. Both ends of the nails 5 in the middle expanding rubber strip 4 are bent vertically and also have a blade at the end. By setting multiple layers of expanding rubber strips 4, when one of the outermost expanding rubber strips 4 expands when it comes into contact with water, the expanding rubber strip 4 can straighten the bent nail 5 and pierce the geomembrane 6 on the outside of the adjacent expanding rubber strip 4, so that the expanding rubber strips 4 can expand sequentially to achieve the effect of multiple sealing.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A seepage prevention method for earth-rock hybrid dams to cope with uneven settlement, characterized in that, Includes the following steps: 1) Precasting and casting of the spiked wall (3): The spiked wall (3) is cast at a predetermined position between the concrete dam section (1) and the earth dam section (2) of the hybrid dam connection section, so that one end of the spiked wall (3) is fixedly connected to the concrete dam section 1 and the other end is inserted into the earth dam section (2); longitudinal grooves are precast on the end face of the spiked wall (3) near the earth dam section (2) and on both sides along the insertion direction. The longitudinal grooves are set through the height direction of the spiked wall (3), with a groove depth of 50mm±2mm and a groove width of 50mm±2mm; the spiked wall (3) is formed by layered casting, with each layer having a casting height of 2-3m, and the layers are vibrated during the casting process; 2). Installation of expansion rubber strip (4): Cut the expansion rubber strip (4) to the size that matches the length of the longitudinal groove and leave an overlap allowance. Use expansion inhibitor to prevent premature expansion when exposed to moisture during construction. Mark anchor points every 200mm along the longitudinal groove direction. After drilling holes at the bottom of the groove, blow the dust out of the holes with a high-pressure blower. Inject epoxy resin anchoring glue into the holes to 2 / 3 of the hole depth. Use 304 stainless steel nails with a diameter of 12mm to press the expansion rubber strip (4) into the groove and align the anchor points. 3) Sealing reinforcement and seepage prevention synergy: Water-swellable sealant is injected at the interface between the expansion rubber strip (4) and the longitudinal groove, and the surface is covered with a PE protective film; when the piercing wall (3) and the earth dam section (2) generate cracks or form hidden seepage channels due to uneven settlement, the expansion rubber strip (4) absorbs water and expands after contact with seepage, sealing the cracks and hidden seepage channels.

2. The seepage prevention method according to claim 1, characterized in that, The expansion rubber strip (4) mentioned in step 3 has a water absorption expansion rate of ≥200%, and after expansion it can fill the crack with a width of 3-5mm, and has a water pressure resistance of >0.5MPa.

3. The seepage prevention method according to claim 1, characterized in that, The number and spacing of the expansion rubber strips (4) in step 3 are determined according to the height of the mixed dam: when the mixed dam is a low dam (dam height H≤30m), 1-3 expansion rubber strips (4) are arranged along the entire length of the top of the spike wall (3), 1-3 expansion rubber strips (4) are arranged vertically on both sides, and 1-3 expansion rubber strips (4) are arranged along the entire length of the end face near the earth dam section (2).

4. The seepage prevention method according to claim 1, characterized in that, The number and spacing of the expansion rubber strips (4) in step 3 are determined according to the height of the mixed dam: when the mixed dam is a medium dam (30m < dam height H ≤ 70m), 3-5 parallel expansion rubber strips (4) are arranged at intervals on the top of the spike wall (3) with a spacing of 300mm; 3-5 vertical expansion rubber strips (4) are arranged at intervals on both sides with a spacing of 500mm; 3-5 expansion rubber strips (4) are arranged at intervals along the entire length of the end face near the earth dam section (2) with a spacing of 300mm.

5. The seepage prevention method according to claim 1, characterized in that, The number and spacing of the expansion rubber strips (4) in step 3 are determined according to the height of the mixed dam: when the mixed dam is a high dam (dam height H>70m), 5-7 expansion rubber strips (4) are arranged at intervals on the top of the spike wall (3) with a spacing of 200mm; 5-7 vertical expansion rubber strips (4) are arranged at intervals on both sides with a spacing of 400mm; 5-7 expansion rubber strips (4) are arranged at intervals along the entire length of the end face near the earth dam section (2) with a spacing of 250mm.

6. The seepage prevention method according to claim 1, characterized in that, The grooves on the end face and both sides of the spiked wall (3) near the earth dam section (2) are provided with multiple layers of expansion rubber strips (4). Each layer of expansion rubber strip (4) is wrapped with a geomembrane (6), and each layer of expansion rubber strip (4) is provided with stainless steel nails (5). Both ends of the nails (5) penetrate the corresponding expansion rubber strips (4). The exposed ends of the nails (5) in the two outermost layers of expansion rubber strips (4) are fixedly installed with lining plates (7). The ends of the expansion rubber strips (4) near the adjacent side are bent vertically and have a blade at the end. Both ends of the nails (5) in the middle expansion rubber strips (4) are bent vertically and also have a blade at the end.

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