Water-power engineering dam foundation covering layer and construction method

Abstract

The invention relates to a hydropower engineering dam foundation covering layer and a construction method, the construction method comprises lenticular body replacement construction, and the lenticular body replacement construction comprises exploration and identification of a sand layer lenticular body existing in a dam foundation, and excavation of the sand layer lenticular body; after excavation is completed, the surface of the dam foundation is cleaned; the excavated area is rolled to be flat, pits are formed after flattening, transition materials are put into the pits for backfilling, rolling is conducted to be flat, and a backfilling layer is obtained; and the compaction density of the backfilling layer is measured, if the measured compaction density is smaller than a preset compaction density threshold value, the transition materials are repeatedly put for backfilling and rolling, and otherwise, subsequent construction is conducted. According to the construction method, the sand layer lenticular body is dug out, backfilled and replaced, so that the sand layer lenticular body can be thoroughly treated, the deformation and settlement of the foundation are reduced, the bearing capacity of the foundation is greatly improved, the settlement amount of the dam body is reduced, the stability and compactness of a foundation covering layer are improved, and the safety of the dam is ensured.

Description

Technical Field

[0001] The present disclosure relates to the technical field of hydropower engineering, and in particular to a hydropower engineering dam foundation covering layer and a construction method thereof. Background Art

[0002] The foundation covering layer of a hydropower project dam is an important foundation for the construction of the hydropower project dam. Therefore, the anti-deformation and settlement ability and bearing capacity of the foundation covering layer of the hydropower project dam are very important.

[0003] The foundation covering layer of the dam riverbed is generally thick, with the thickest part being 65m. It is mainly composed of alluvial boulder-containing sand and gravel layers, with only a small amount of landslide boulders near the foot of the slope. Among them, the particle sizes of materials in different layers of the foundation covering layer vary greatly, the layer distribution is complex, and there are a certain amount of sand lens.

[0004] The construction method in the related technology does not process the sand layer lens, resulting in limited compaction depth. It is difficult to reinforce the deep locations, and the effect of reducing foundation deformation and settlement and improving foundation bearing capacity is limited, and the reduction of dam body settlement is also limited. Summary of the invention

[0005] The purpose of the present disclosure is to provide a hydropower engineering dam foundation covering layer and a construction method to solve the problems in the above-mentioned related technologies.

[0006] In order to achieve the above-mentioned object, one aspect of the present disclosure provides a construction method for a hydropower engineering dam foundation covering layer, comprising the following steps: Lens replacement construction; Wherein, the lens replacement construction includes: S101, exploring and identifying sand layer lenses existing in the dam foundation, and digging out the sand layer lenses; S102. After the excavation is completed, clean the surface of the dam foundation; S103, rolling and leveling the excavated area to form a pit, and backfilling the pit with transition material and rolling and leveling it to obtain a backfill layer; S104, measuring the compaction density of the backfill layer. If the measured compaction density is less than a preset compaction density threshold, repeat step S103; otherwise, proceed to subsequent construction.

[0007] Optionally, the construction method further comprises: Foundation compaction construction; The foundation compaction construction includes: S201, marking the basic edge line; S202, marking multiple tamping point locations and measuring the site height; S203, setting the tamping hammer at one of the tamping points, tamping at a predetermined height, tamping the next tamping point after the tamping is completed and repeating the operation to complete the first tamping; S204, after the first round of tamping is completed, the tamping pit is filled with transition material, and steps S202 and S203 are repeated multiple times to complete multiple rounds of tamping.

[0008] Optionally, in step S203, setting the tamping hammer at one of the tamping points and tamping at a predetermined height includes: The rammer is set at one of the ramming points, hoisted to a predetermined height, and allowed to fall freely to ram the ramming point, and the amount of ramming pit sinking is measured and recorded, and this process is repeated multiple times; The difference between the average pit subsidence between the last and second last tamping is no more than 50 mm. In step S204, the number of tamping passes is set to three, the tamping energy of the first tamping pass and the tamping energy of the second tamping pass are both set to 8000 kN•m, and the tamping energy of the third tamping pass is set to 1000 kN•m.

[0009] Optionally, the construction method further comprises: Dam foundation rolling treatment construction; The dam foundation rolling treatment construction includes: S301, dividing the dam foundation covering layer into a main area and an edge area, dividing the main area into a plurality of paths arranged in parallel along the second direction, each of the paths extending along the first direction; Wherein, the first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam; S302, rolling is performed along each of the paths in a straight line and repeated for multiple times to complete the compaction of the main area of ​​the dam foundation cover layer; S303. The edge area of ​​the dam foundation cover layer is compacted using a rammer and a hydraulic vibrating plate.

[0010] Optionally, in step S302, the speed of the straight-line movement is set to 1.5 km / h-2 km / h, and the number of times each path is rolled is set to 10 times.

[0011] Optionally, the construction method further comprises: Dam foundation slope treatment construction; The dam foundation slope treatment construction includes: S401, excavate and clean the slopes on both sides of the dam foundation to form the slope foundation surface; S402, crush and clean the protruding rock mass on the slope foundation surface; S403, pouring concrete into the inverted hanging cavity of the cleaned slope foundation surface to fill the inverted hanging cavity.

[0012] Optionally, the construction method further comprises: Dam body mud treatment; Wherein, the dam body mud treatment includes: S501, screening the material source to remove the mud; S502. Clean the transport vehicles when they enter or leave the dam foundation; S503. Monitor the surface of the dam foundation. If mud or unqualified materials are found, transport them directly to the designated location.

[0013] Optionally, the construction method further comprises: Drainage construction; Wherein, the drainage construction includes: S601, digging pump pits at the upstream and downstream of the foundation pit respectively, and installing drainage pumps, wherein the drainage pumps are used to pump water in the pump pits; S602. Dig a plurality of drainage ditches in the foundation pit, wherein the plurality of drainage ditches extend in a first direction and a second direction respectively, and the plurality of drainage ditches are connected to the pump pit, wherein the first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam.

[0014] Optionally, in step S102, the number of rolling is 4-6 times; In step S103, the number of rolling is 8-10 times.

[0015] A second aspect of the present disclosure also provides a hydropower project dam foundation covering layer constructed using the above-mentioned construction method for the hydropower project dam foundation covering layer.

[0016] The above technical scheme can thoroughly treat the sand layer lenses by digging out and backfilling and replacing them, can solve the problem of insufficient compaction depth caused by the sand layer lenses, can reinforce the locations with great depth, is conducive to reducing foundation deformation and settlement, greatly improves the foundation bearing capacity, reduces the settlement of the dam body, thereby improving the stability and density of the foundation cover layer and ensuring the safety of the dam.

[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1is a process flow chart of lens replacement construction according to an embodiment of the present disclosure; Figure 2 It is a process flow chart of foundation compaction construction in one embodiment of the present disclosure; Figure 3 It is a process flow chart of dam foundation rolling treatment construction according to an embodiment of the present disclosure; Figure 4 It is a process flow chart of dam foundation slope treatment construction according to an embodiment of the present disclosure; Figure 5 It is a process flow chart of dam body mud ball treatment according to one embodiment of the present disclosure; Figure 6 It is a process flow chart of drainage construction according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0019] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0020] In the present disclosure, unless otherwise specified, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present disclosure, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0022] like Figure 1 As shown, one aspect of the present disclosure provides a construction method for a hydropower engineering dam foundation covering layer, comprising the following steps: Lens replacement construction; Wherein, the lens replacement construction includes: S101, exploring and identifying sand layer lenses existing in the dam foundation, and digging out the sand layer lenses; S102. After the excavation is completed, clean the surface of the dam foundation; S103, rolling and leveling the excavated area to form a pit, and backfilling the pit with transition material and rolling and leveling it to obtain a backfill layer; S104, measuring the compaction density of the backfill layer. If the measured compaction density is less than a preset compaction density threshold, repeat step S103; otherwise, proceed to subsequent construction.

[0023] Among them, in step S101, geological exploration and related equipment can be used to identify the sand lens in the dam foundation. It can be understood that the sand lens usually refers to a foreign body in the foundation with different properties and composition from the surrounding rock and soil, composed of soft soil, sand layer or other unfavorable geological bodies. The sand lens can be dug out by 2m 3 The hydraulic backhoe digs out the sand lens, loads it into a 25t dump truck, and transports it to the slag yard for temporary storage.

[0024] In step 102, the lens dropped during the excavation and transportation process may be cleaned.

[0025] In step 103, a 32t vibrating roller may be used for 4-6 initial rolling. The specific number of initial rolling times may be set according to actual needs.

[0026] In step 103, after leveling, a pit is formed, and the foundation is inspected and accepted. After the inspection is qualified, the pit is backfilled with transition material to achieve replacement. In some examples, the transition material is produced by blasting at the Shijiagou material yard, transported to the dam foundation by a 25t dump truck, and backfilled. A 2m³ hydraulic backhoe is used in conjunction with a loader to unload and lay the material to the designed thickness. The designed thickness can be set according to actual needs. After the transition material is backfilled, a 32t vibrating roller is used to roll it 8-10 times. It can be understood that the transition material has high strength and good stability, and can be pebbles, gravel, and coarse sand. In some examples, when the transition material is backfilled in the pit, it can be backfilled layer by layer, that is, it is gradually filled up with a thickness of 0.4 meters per layer. After one layer is backfilled, it is leveled and rolled before the next layer is backfilled.

[0027] In step S104, the compaction density is measured on-site using the ring knife pit digging and watering method. If the compaction density is equal to or greater than the preset compaction density threshold, the subsequent construction is started.

[0028] In the above technical scheme, the sand layer lens can be thoroughly treated by digging out and backfilling and replacing it, which can solve the problem of insufficient compaction depth caused by the sand layer lens. The deep position can be reinforced, which is beneficial to reduce foundation deformation and settlement, greatly improve the foundation bearing capacity, and reduce the settlement of the dam body, thereby improving the stability and density of the foundation cover layer and ensuring the safety of the dam.

[0029] Optionally, in an implementation manner of the present disclosure, in step S102, the number of rolling is 4-6 times.

[0030] In step S103, the number of rolling is 8-10 times.

[0031] like Figure 2 As shown, optionally, in one embodiment of the present disclosure, the construction method further includes: Foundation compaction construction; The foundation compaction construction includes: S201, marking the basic edge line; S202, marking multiple tamping point locations and measuring the site height; S203, setting the tamping hammer at one of the tamping points, tamping at a predetermined height, tamping the next tamping point after the tamping is completed and repeating the operation to complete the first tamping; S204, after the first tamping is completed, fill the tamping pit with transition material, repeat steps S202 and S203 multiple times to complete multiple tamping. Through the foundation tamping construction, the compaction density and uniformity of the foundation covering layer can be ensured, the formation of weak areas can be avoided, and the stability of the foundation covering layer can be improved.

[0032] In step 203, the rammer uses the impact force generated by the free fall of the heavy hammer to compact the foundation covering layer, and makes the foundation covering layer dense through multiple ramming to improve the bearing capacity of the foundation covering layer. The weight of the rammer, the falling distance and other parameters can be determined according to the actual situation of the foundation covering layer.

[0033] After step 204, the compaction density and bearing capacity of the base covering layer may be tested by in-situ testing or other methods to ensure that the design requirements are met.

[0034] Optionally, in one embodiment of the present disclosure, in step S201, in order to further improve the foundation bearing capacity of the dam foundation cover layer, the range of the strong compaction treatment should exceed the foundation edge line by 3m.

[0035] In step S203, setting the tamping hammer at one of the tamping points and tamping at a predetermined height includes: The rammer is set at one of the ramming point positions, and the rammer is lifted to a predetermined height by a lifting hook, and the hook is pulled to fix the wire rope, and the drop distance is locked. After the rammer is stably placed above the ramming point position, the rammer falls freely, rams the ramming point position, and measures and records the sinking amount of the ramming pit, and repeats multiple times. In some examples, when the rammer is stably placed above the ramming point position, the height of the top of the rammer is measured, and after the rammer falls freely, the hook is lowered, and the height of the top of the rammer is measured to obtain the sinking amount of the ramming pit. Optionally, after the ramming point position is rammed to produce a ramming pit, if the pit bottom is inclined, the pit bottom is leveled.

[0036] The specific distribution of the tamping point positions and the number of tamping times at each tamping point position can be determined by the relationship curve between the number of tamping times and the amount of tamping obtained through on-site tamping tests. The difference in the average pit settlement between the last tamping and the second last tamping is no more than 50 mm.

[0037] In order to ensure that the effects of each tamping point are consistent, the error is controlled by measuring the site height.

[0038] Optionally, in step S204, the number of tamping is set to three, the tamping energy of the first tamping and the tamping energy of the second tamping are both set to 8000 kN•m, and the tamping energy of the third tamping is set to 1000 kN•m.

[0039] Among them, the third tamping is a full tamping construction. After completing the first and second tamping, and after the interval time is met, the third tamping is carried out, and testing is carried out after the tamping is completed.

[0040] like Figure 3 As shown, optionally, in one embodiment of the present disclosure, the construction method further includes: Dam foundation rolling treatment construction; The dam foundation rolling treatment construction includes: S301, dividing the dam foundation covering layer into a main area and an edge area, dividing the main area into a plurality of paths arranged in parallel along a second direction, each of the paths extending along a first direction.

[0041] The first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam.

[0042] S302, rolling in a straight line along each of the paths and repeating for multiple times to complete the compaction of the main area of ​​the dam foundation cover layer; S303, compact the edge area of ​​the dam foundation cover layer with a rammer and a hydraulic vibrating plate. By ramming and then rolling, double compaction can be achieved, which can further improve the compaction density and uniformity of the foundation cover layer, avoid the formation of weak areas, and improve the stability of the foundation cover layer.

[0043] Among them, a 32t self-propelled vibratory roller can be used for rolling, and the path can be composed of the rolling marks produced when the vibratory roller moves.

[0044] In step S302, the vibratory roller travels at a low speed in the first direction and rolls in multiple paths in the second direction. The overlapping width of the indentation of each path and the overlapping width of the rolling of each zone junction should meet the relevant specifications and design requirements. Rolling is carried out strictly according to the designed number of times, and on-site sampling inspection is carried out according to the rolling inspection requirements. The upper layer can be backfilled only after passing the inspection.

[0045] Optionally, in one embodiment of the present disclosure, in step S302, the speed of the linear movement is set to 1.5-2 km / h, and the number of times each path is rolled is set to 10 times. The rolling method can mainly adopt the staggered method, that is, the width of the rolling wheel / number of rolling passes, that is, rolling from one side to the other side is completed in one time. The "static 2 dynamic 8" 10-pass rolling method can be adopted, that is, static rolling 2 times and dynamic rolling 8 times.

[0046] like Figure 4 As shown, since the slopes on both sides within the scope of the foundation covering layer are the original riverbed, the foundation surface in the slope range is exposed and the rock mass is protruding, in order to ensure the connection with the bank body in the later filling. Optionally, in one embodiment of the present disclosure, the construction method also includes: Dam foundation slope treatment construction; The dam foundation slope treatment construction includes: S401, excavate and clean the slopes on both sides of the dam foundation to form the slope foundation surface; S402, crush and clean the protruding rock mass on the slope foundation surface; S403, pouring concrete into the inverted hanging cavity of the cleaned slope foundation surface to fill the inverted hanging cavity.

[0047] Through this construction, the stability and safety of the dam foundation slope can be ensured, and the foundation risk caused by slope problems can be reduced. Among them, the inverted hanging cavity on the slope foundation surface is similar to an inverted triangle structure, located at the bottom of the slope.

[0048] Among them, in step 402, the protruding rock mass is crushed and cleaned on site using a hydraulic breaker. The parts that cannot be broken are manually drilled using a YT28 hand drill, and then filled with emulsion explosives for blasting. The cleaned slag is loaded into a 25t dump truck by a 2.0m³ hydraulic backhoe and transported to the slag yard.

[0049] Among them, in step 403, the template used for concrete pouring adopts a steel-wood combination, mainly P3015 and P1015 steel templates, and wooden templates are used for corners, ends, etc.

[0050] Before installing the template, first follow the design and measurement, and then spot weld and connect to form a template sample frame. After acceptance, the template can be installed.

[0051] During the formwork construction, the remaining debris is picked out manually or washed away using Feng Shui.

[0052] The filling concrete for the inverted hanging cavity on the slope foundation surface is mixed by a concrete mixing system, transported to the site by a 6m³ concrete mixer truck, and put into the warehouse by a chute. When the chute cannot be used, a 25t truck crane equipped with a 1m³ hanging tank is used to put the concrete into the warehouse.

[0053] The concrete is vibrated manually with a φ30-φ50 flexible shaft vibrator. The vibration standard is to ensure that there is no obvious sinking, no slurry overflow, and no bubbles appearing around.

[0054] In addition, before pouring concrete, the inverted cavity on the slope foundation surface was cleaned and free of debris by manual operation with a 1.2m³ hydraulic backhoe. The cleaned slag was loaded into a 25t dump truck by manual operation with a backhoe and transported to the slag yard for stacking.

[0055] like Figure 5 As shown, optionally, in one embodiment of the present disclosure, the construction method further includes: Dam body mud treatment; Wherein, the dam body mud treatment includes: S501, screening the material source to remove the mud; S502. Clean the transport vehicles when they enter or leave the dam foundation; S503. Monitor the surface of the dam foundation. If mud or unqualified materials are found, transport them directly to the designated location.

[0056] Among them, in step S501, the material source is transported to the basic covering layer by vehicles. When the material source is loaded onto the vehicle, it is screened to prevent mud lumps from being loaded onto the vehicle, thereby preventing mud lumps from being brought into the basic covering layer.

[0057] In step S502, a water tank is set outside the dam, and dump trucks or other construction machinery pass through the water tank before going up to the dam and are cleaned once in the water tank to prevent the vehicles or construction equipment from bringing mud or dirt into the dam foundation and contaminating the materials.

[0058] Among them, in step S503, a professional team equipped with a 3m³ loader is set up on the working surface of the dam foundation to load the mud and unqualified materials entering the dam foundation into trucks and transport them to the slag yard.

[0059] like Figure 6 As shown, optionally, in one embodiment of the present disclosure, the construction method further includes: Drainage construction; Wherein, the drainage construction includes: S601, digging pump pits at the upstream and downstream of the foundation pit respectively, and installing drainage pumps, wherein the drainage pumps are used to pump water in the pump pits; S602. Dig a plurality of drainage ditches in the foundation pit, wherein the plurality of drainage ditches extend in a first direction and a second direction respectively, and the plurality of drainage ditches are connected to the pump pit, wherein the first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam.

[0060] This arrangement ensures smooth drainage, avoids water accumulation in the dam foundation, and improves the overall safety of the dam. It should be noted that drainage construction begins before lens replacement construction and continues until the entire dam foundation cover construction is completed.

[0061] Among them, in step S601, the pump pit can temporarily store rainwater, which can be sucked out by a drainage pump to avoid water accumulation in the dam foundation.

[0062] In step S602, the length of the drainage ditch is 50m and the width is 1.5m. Multiple drainage ditches are arranged in the horizontal and vertical directions. Rainwater can flow into the pump pit through the drainage ditch, which can be easily pumped out by the drainage pump. In some examples, the drainage ditch is formed by hydraulic backhoe excavation, and the overburden stone is backfilled and compacted before filling. Drainage is achieved by drainage ditches and drainage pumps, and groundwater can be discharged to 2m below the foundation surface during the foundation compaction and rolling.

[0063] A second aspect of the present disclosure also provides a hydropower project dam foundation covering layer constructed using the above-mentioned construction method for the hydropower project dam foundation covering layer.

[0064] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0065] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0066] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for constructing a foundation covering layer of a hydropower project dam, characterized in that: The following steps are involved: Lens replacement construction; Wherein, the lens replacement construction includes: S101, exploring and identifying sand layer lenses existing in the dam foundation, and digging out the sand layer lenses; S102. After the excavation is completed, clean the surface of the dam foundation; S103, rolling and leveling the excavated area to form a pit, and backfilling the pit with transition material and rolling and leveling it to obtain a backfill layer; S104, measuring the compaction density of the backfill layer. If the measured compaction density is less than a preset compaction density threshold, repeat step S103; otherwise, proceed to subsequent construction.

2. The construction method of the hydropower engineering dam foundation covering layer according to claim 1 is characterized in that: The construction method also includes: Foundation compaction construction; The foundation compaction construction includes: S201, marking the basic edge line; S202, marking multiple tamping point locations and measuring the site height; S203, setting the tamping hammer at one of the tamping points, tamping at a predetermined height, tamping the next tamping point after the tamping is completed and repeating the operation to complete the first tamping; S204, after the first round of tamping is completed, the tamping pit is filled with transition material, and steps S202 and S203 are repeated multiple times to complete multiple rounds of tamping.

3. The construction method of the hydropower engineering dam foundation covering layer according to claim 2 is characterized in that: In step S203, setting the tamping hammer at one of the tamping points and tamping at a predetermined height includes: The rammer is set at one of the ramming points, hoisted to a predetermined height, and allowed to fall freely to ram the ramming point, and the amount of ramming pit sinking is measured and recorded, and this process is repeated multiple times; The difference between the average pit subsidence between the last and second last tamping is no more than 50 mm. In step S204, the number of tamping passes is set to three, the tamping energy of the first tamping pass and the tamping energy of the second tamping pass are both set to 8000 kN•m, and the tamping energy of the third tamping pass is set to 1000 kN•m.

4. The construction method of the hydropower engineering dam foundation covering layer according to claim 1 is characterized in that: The construction method also includes: Dam foundation rolling treatment construction; The dam foundation rolling treatment construction includes: S301, dividing the dam foundation covering layer into a main area and an edge area, dividing the main area into a plurality of paths arranged in parallel along the second direction, each of the paths extending along the first direction; Wherein, the first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam; S302, rolling is performed along each of the paths in a straight line and repeated for multiple times to complete the compaction of the main area of ​​the dam foundation cover layer; S303. The edge area of ​​the dam foundation cover layer is compacted using a rammer and a hydraulic vibrating plate.

5. The construction method of the hydropower engineering dam foundation covering layer according to claim 4 is characterized in that: In step S302, the speed of the straight-line movement is set to 1.5 km / h-2 km / h, and the number of times each path is rolled is set to 10 times.

6. The construction method of the hydropower engineering dam foundation covering layer according to claim 1, characterized in that: The construction method also includes: Dam foundation slope treatment construction; The dam foundation slope treatment construction includes: S401, excavate and clean the slopes on both sides of the dam foundation to form the slope foundation surface; S402, crush and clean the protruding rock mass on the slope foundation surface; S403, pouring concrete into the inverted hanging cavity of the cleaned slope foundation surface to fill the inverted hanging cavity.

7. The construction method of the hydropower engineering dam foundation covering layer according to claim 1 is characterized in that: The construction method also includes: Dam body mud treatment; Wherein, the dam body mud treatment includes: S501, screening the material source to remove the mud; S502. Clean the transport vehicles when they enter or leave the dam foundation; S503. Monitor the surface of the dam foundation. If mud or unqualified materials are found, transport them directly to the designated location.

8. The construction method of the hydropower engineering dam foundation covering layer according to claim 1, characterized in that: The construction method also includes: Drainage construction; Wherein, the drainage construction includes: S601, digging pump pits at the upstream and downstream of the foundation pit respectively, and installing drainage pumps, wherein the drainage pumps are used to pump water in the pump pits; S602. Dig a plurality of drainage ditches in the foundation pit, wherein the plurality of drainage ditches extend along a first direction and a second direction respectively, and the plurality of drainage ditches are connected to the pump pit, wherein the first direction is parallel to the axis of the dam, and the second direction is perpendicular to the axis of the dam.

9. The method for constructing a foundation covering layer of a hydropower project dam according to any one of claims 1 to 8, characterized in that: In step S102, the number of rolling is 4-6 times; In step S103, the number of rolling is 8-10 times.

10. A hydropower project dam foundation covering layer constructed by using the construction method for a hydropower project dam foundation covering layer as claimed in any one of claims 1 to 9.

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