CN114687323A - Seepage-prevention construction method for semi-reservoir seepage-prevention high-fill silty loam homogeneous dam - Google Patents
Seepage-prevention construction method for semi-reservoir seepage-prevention high-fill silty loam homogeneous dam Download PDFInfo
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- E—FIXED CONSTRUCTIONS
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- E—FIXED CONSTRUCTIONS
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Abstract
The invention discloses an anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam, which comprises the following steps of: 1) testing a rolling process; 2) construction of external drainage; 3) filling a dam body; 4) constructing a toe wall; 5) performing internal drainage construction; 6) laying a composite geomembrane; 7) the composite geomembrane is connected with the toe wall; 8) secondary construction of toe walls; 9) and (5) constructing a protective layer. The method aims to solve the problem that in the construction of a homogeneous earth dam, a geomembrane is only laid on a dam body aiming at a place where the dam bottom does not seep water, and the joint of the geomembrane and the dam bottom is sealed so as to meet the leakage requirement. According to the invention, the composite geomembrane is only laid on the slope surface of the dam body, the dam bottom is only simply leveled, and the composite geomembrane is not required to be laid at the dam bottom; on the premise that the dam body meets the design requirements, the construction links are reduced, the construction period is shortened, and the construction cost is greatly reduced.
Description
Technical Field
The invention belongs to the technical field of dam construction, and particularly relates to an anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam.
Background
The single soil dam is also called homogeneous soil dam and is formed by filling single soil material. The dam shape has simple structure, convenient construction and better adaptability to the geological conditions of the dam foundation. Based on the characteristics, the homogeneous earth dam is a dam type which is most applied in the current water conservancy and hydropower reservoir projects in China, but often, the homogeneous earth dam has design defects or quality problems of different degrees because detailed treatment and node measures are not in place. The control of seepage prevention of the high-fill silty loam homogeneous soil dam is a key and difficult problem in construction. Through the rolling of the high-fill silty loam dam body, overpressure and underpressure are avoided by optimizing a quality control means, internal and external drainage measures and an anti-seepage construction process of the dam body are optimized, the seepage risk of the homogeneous soil dam is greatly reduced, and later-period maintenance and maintenance costs are effectively reduced.
In order to prevent water leakage, the common homogeneous earth dam needs to be paved with geomembranes on the dam body and the dam bottom. When the geomembrane is laid on the dam body and the dam bottom, the side slope of the dam body and the dam bottom need to be compacted and leveled, so that the laying requirement of the geomembrane can be met, the geomembrane is prevented from being broken due to the defects of bulges, depressions and the like, the construction period of the existing process is long, and the construction cost is high. When the construction is carried out on the site where part of the dam bottom does not seep water, the dam bottom can be free from geomembrane laying operation so as to shorten the period and save the cost. However, only the geomembrane is laid on the dam body, the sealing treatment difficulty of the joint of the geomembrane and the dam bottom is large, and the leakage requirement is difficult to meet. The water in the dam body is easy to permeate through the gap at the joint of the geomembrane and the dam bottom to seep out, thereby threatening the safety of the dam body.
Disclosure of Invention
The invention provides an anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam, and aims to solve the problem that in the construction of the homogeneous dam, a geomembrane is only laid on a dam body aiming at a field without water seepage at the bottom of the dam, and the joint of the geomembrane and the bottom of the dam is sealed to meet the seepage requirement.
Therefore, the invention adopts the following technical scheme:
an anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam comprises the following steps:
1) and (3) rolling process test: drawing relation curves between different paving thicknesses and rolling times and the optimal water content and the maximum dry density respectively through a rolling process test; calculating to obtain optimal rolling process parameters, namely optimal soil paving thickness, rolling times and optimal water content according to the designed dry density and by combining the curves;
2) and (3) external drainage construction: the outer drainage perforated pipe is arranged along the periphery of the dam body, the drainage perforated pipe is embedded into the reservoir bottom impervious foundation layer, the periphery of the drainage perforated pipe is provided with a gravel reverse filter layer, and the position of the drainage perforated pipe, which is connected with the dam body backfill materials, is provided with reverse filter geotextile;
3) filling a dam body: performing dam filling operation according to the optimal rolling process parameters determined in the step 1); filling each layer of earthwork to construct a closed loop, and paving by adopting an occupation method; before the next layer of filling, the surface of the previous layer of filling is subjected to roughening treatment; after filling, carrying out slope cutting treatment, and leveling and compacting the slope surface of the dam body;
4) constructing a toe wall: excavating toe wall grooves at the positions of the toes of the dam body to finish the concrete pouring of the toe walls, wherein the top surfaces of the toe walls are arranged in grooves and tongues;
5) and (3) internal drainage construction: arranging an inner drainage perforated pipe along the toe part of the dam body, and filling a gravel water filtering layer around the drainage perforated pipe;
6) laying a composite geomembrane: the composite geomembrane is laid from the top of the dam body to the bottom of the dam body, so that the composite geomembrane is smooth and straight; splicing the seams of the adjacent composite geomembranes by a hot-melt welding method;
7) connecting the composite geomembrane with a toe wall:
a. polishing and removing impurities on the top surface of the toe wall to ensure that the surface of the concrete is smooth and flat;
b. coating hot melt adhesive on the top surface of the toe wall, adhering strip-shaped lower rubber sheets, and sequentially splicing the lower rubber sheets along the length direction of the toe wall until the whole toe wall is fully paved;
c. separating the head end of the composite geomembrane positioned at the bottom of the reservoir, stripping the geotechnical cloth layers on the upper and lower surfaces of the composite geomembrane, and exposing the plastic layer between the two geotechnical cloth layers;
d. coating hot melt adhesive on the upper surface of the lower rubber sheet, adhering the exposed plastic layer on the lower rubber sheet, and sealing the front end of the plastic layer by using sealant, wherein the front end of the plastic layer extends to the internal corner position of the tongue and groove of the toe wall;
e. coating hot melt adhesive on the upper surface of the composite geomembrane plastic layer, and fixedly adhering an upper layer rubber sheet above the plastic layer, wherein the upper layer rubber sheet is opposite to the lower layer rubber sheet in position, and the lower layer rubber sheet and the upper layer rubber sheet fixedly adhere the plastic layer of the composite geomembrane into the upper layer rubber sheet;
f: placing a steel plate with holes on the upper rubber sheet, and anchoring the rubber sheet and the plastic layer in the toe wall concrete through a belt rear expansion bolt;
8) and (3) secondary construction of toe walls: pouring concrete at the top of the toe wall for secondary sealing, wherein the concrete seals the upper layer rubber sheet and the lower layer rubber sheet into the toe wall, and the top elevation of the toe wall after secondary construction is higher than the designed reservoir bottom elevation;
9) construction of a protective layer: and filling a protective layer above the composite geomembrane on the slope.
Further, after the connection construction of the composite geomembrane and the toe wall in the step 5) is finished, a perforated steel plate is placed on the upper rubber sheet, holes are vertically punched downwards through the holes in the perforated steel plate, the holes penetrate through the upper rubber sheet, the plastic layer and the lower rubber sheet and extend into concrete, and the upper rubber sheet, the plastic layer and the lower rubber sheet are anchored in the toe wall concrete through expansion bolts.
And further, coating a polyurethane sealant anticorrosive layer on the surfaces of the steel plate with the holes and the expansion bolts.
Further, in the step 5), the end part of the plastic layer extends to the position of the internal corner of the tongue-and-groove of the toe wall, and is sealed by polyurethane sealant.
Further, in the step 5), after the front end of the plastic layer extends to the position of the concave angle of the tongue-and-groove of the toe wall, the plastic layer is sealed by polyurethane sealant.
Further, in the step 2), the outer drainage floral tube is buried below 1.0m of the impermeable basement rock layer at the bottom of the reservoir, and the gradient of the outer drainage floral tube is not less than 0.3% so as to ensure that the underground water is naturally drained.
Furthermore, the inner drainage perforated pipe is connected with PE vent pipes at intervals, and the PE vent pipes are arranged along the slope of the dam body; the lower end of the PE vent pipe is communicated to the inner drainage perforated pipe, and the upper end of the PE vent pipe is positioned at the top of the dam body and extends out of the composite geomembrane.
Furthermore, the interval between adjacent PE ventilation pipes is 20-30 meters.
The invention has the beneficial effects that:
1. according to the invention, the composite geomembrane is only laid on the slope surface of the dam body, the dam bottom is only simply leveled, and the composite geomembrane is not required to be laid at the dam bottom; on the premise that the dam body meets the design requirements, the construction links are reduced, the construction period is shortened, and the construction cost is greatly reduced;
2. the annular outer drainage perforated pipe and the annular inner drainage perforated pipe are additionally arranged to form an inner and outer independent drainage system, so that the homogeneity of backfilling at the bottom of the homogeneous earth dam is ensured, the external water and the inner water in the original design scheme are effectively prevented, and a water seepage channel is easily formed, so that major quality potential safety hazards such as dam body main body structure damage and the like are avoided;
3. the composite geomembrane is connected with the toe wall and is sealed, so that the problem of damage or infirm bonding during the construction of the composite geomembrane is fundamentally solved; the composite geomembrane has good sealing performance in a connection mode with the toe wall, meets the design requirement, greatly reduces the leakage risk of the homogeneous earth dam, and effectively reduces the later maintenance cost;
4. according to the invention, through a rolling process test, according to the soil quality type, the soil paving thickness, the rolling times and the optimal water content are reasonably determined, and bump rolling is selected, so that the interlayer combination is good; the rolling parameters and the rolling process are optimized by combining selected mechanical equipment, and a closed-loop rolling scheme is adopted, so that the problems of uneven filling of the dam body, uneven settlement, formation of cracks, permeation and the like caused by improper treatment of under-rolling, over-rolling and joint of a working surface of the dam body are solved.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is an enlarged view of a portion of FIG. 1 of the present invention;
FIG. 3 is a schematic view showing the layout of the zinciferous coated steel sheets in step 5) of the present invention.
Detailed Description
The invention will be further described with reference to the accompanying drawings, as shown in figures 1 and 2:
an anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam comprises the following steps:
1) and (3) rolling process test:
drawing relation curves between different paving thicknesses and rolling times and the optimal water content and the maximum dry density respectively through a rolling process test; calculating to obtain optimal rolling process parameters, namely optimal soil paving thickness, rolling times and optimal water content according to the designed dry density and by combining the curves; so as to achieve the rationality of the design filling standard of the backfill soil material and determine the compaction method and the optimal water content control range which achieve the design filling standard.
2) And (3) external drainage construction: the outer drainage perforated pipe is arranged along the periphery of the dam body, the drainage perforated pipe is embedded into the reservoir bottom impervious foundation layer, the periphery of the drainage perforated pipe is provided with a gravel reverse filter layer, and the position of the drainage perforated pipe, which is connected with the dam body backfill materials, is provided with reverse filter geotextile; the outer drainage perforated pipe is buried below 1.0m of the impermeable basement stratum at the bottom of the reservoir, and the gradient of the outer drainage perforated pipe is not less than 0.3% so as to ensure the natural drainage of the underground water.
3) Filling a dam body: performing dam filling operation according to the optimal rolling process parameters determined in the step 1);
a. partitioning and blocking of dam filling: and each layer of earthwork filling of the dam body of the reservoir achieves closed-loop construction, each block is divided into three construction blocks according to engineering characteristics, and the construction is organized by adopting a flow process, namely, one construction block is paved and filled, one construction block is rolled, one construction block is sampled and accepted, and the three construction blocks are uniformly distributed and divided along the axis of the dam.
b. Treating the original ground: all filling base surfaces and contact surfaces are correspondingly cleaned according to design requirements, humus soil and sundries on the surface of the foundation are removed, compaction ditches and groove pits are filled, and the surface of the foundation is ensured to be flat. The ground transverse slope is steeper than 1: and 5, the original ground is dug into steps and then filled, and the transverse slope of the ground is steeper than 1: 2.5, special treatment should be done to prevent slipping along the substrate.
c. And (3) backfill paving: when the substrate is backfilled, the backfill materials are transported to a filling position by a dump truck and directly discharged by adopting a retreating method. And (3) paving a plurality of layers of fillers at the bottom of the filling part by adopting artificial thin layers, paving the fillers by adopting an occupancy method after filling the fillers to be 0.5m above the foundation, and manually leveling the fillers, wherein the layer thickness is determined according to relevant specifications and field tests. When the dike is built and filled, in order to ensure the rolling quality of the side slope, when each layer of material is paved to the slope side, the paving width has a certain margin, and the filling sideline of the dam body after compaction and slope cutting meets the requirement of 0-30cm (mechanical construction). And (3) uniformly lifting the adjacent segmental operation surfaces, reducing construction joints, and if the height difference between the segments is inevitable, connecting the segments by adopting slopes of 1: 3-1: 5, and processing according to related technical requirements.
d. Compacting backfill materials: the bottom of the filling position is compacted by a light machine (a vibrating plate tamper, a frog tamper and the like) at the positions where several layers of manually paved fillers are arranged and the positions where the fillers are jointed with the concrete structure; the packing layer paved by the loader is compacted by adopting a road roller to vibrate and roll. The compaction method adopts a forward and backward offset method, rolling is carried out for 4-10 times, the rolling speed is not more than 2km/h, and the specific rolling parameters are determined by a rolling process test. The spreading and compacting processes of the backfill should be continuously carried out, and the soil is loosened not overnight. So as to prevent the non-return filler from being dried in the sun and influencing the filling quality. And (5) performing water spraying and wetting treatment on the soil layer with the air-dried surface. After each layer of soil material is rolled, the upper layer of soil can be paved only after the dry volume weight is determined to meet the design requirement.
e. Shaving operation: and after the compaction inspection is qualified, performing debristling treatment on the surface of the previous layer of filling before the next layer of filling, and debristling by repeatedly walking on the filling layer surface by adopting a loader crawler. Loose soil and sundries scattered on a filling surface feeding transportation line and a dry and hard smooth surface formed by vehicle running, manual trampling and an inner platform are thoroughly removed before soil paving, and are watered and moistened. And the convex block can be ground, so that the debristling operation is saved, and the compaction quality can be ensured.
f. Leveling and slope cutting: after the embankment is built and the filling is finished, a backhoe is adopted to assist the manual slope cutting treatment, and the whole slope is compacted; and leveling and compacting the surface of the steel pipe strictly according to the design gradient.
g. And (3) construction of an outer drainage perforated pipe: the outer drainage floral tubes are arranged along the periphery of the dam body, the outer drainage floral tubes are buried below 1.0 meter in the reservoir bottom impervious basement rock layer, and natural drainage of underground water is guaranteed according to the gradient of 0.3%. Gravel reverse filtering layers are arranged around the outer drainage perforated pipes, reverse filtering geotextile is arranged at the joint position of the gravel reverse filtering layers and the dam backfill materials, and the gravel reverse filtering geotextile extends to the underground water level by more than 1.0 m.
4) Constructing a toe wall: excavating toe wall grooves at the bottom in the dam body and the boundary position of the reservoir bottom according to design requirements to finish toe wall concrete pouring; in order to improve the integral waterproof effect of the anchoring node part of the geomembrane, the tongue-and-groove form is kept on the top surface of the toe wall by one-step pouring, the opening is positioned on one side far away from the dam body, and the opening height is not less than 300.
5) Performing internal drainage construction; and an inner drainage perforated pipe is arranged along the bottom of the dam body, the inner drainage perforated pipe is connected by adopting DN100 polyethylene PE pipes in a hot melting way, gravel water filtering layers are filled around the inner drainage perforated pipe, and underground water in the dam is discharged through a drainage gallery through the inner drainage perforated pipe. The inner drainage perforated pipe is connected with PE vent pipes at intervals, and the PE vent pipes are arranged along the slope of the dam body; the lower end of the PE vent pipe is communicated to the inner drainage perforated pipe, and the upper end of the PE vent pipe is positioned at the top of the dam body and extends out of the composite geomembrane. The interval between adjacent PE ventilation pipes is 20-30 meters.
Finishing reservoir dam body filling and slope building procedures according to design drawings, and carrying out supporting layer construction, wherein the supporting layer is generally made of fine sand with the thickness of 150mm and is used as a cushion layer, manual leveling is carried out, and a sand layer is kept from being damaged in the construction process; the surface of the support layer should be flat and straight, the flatness is controlled within +/-2 cm, the tamping coefficient must reach 94 percent, and the composite geomembrane can be paved on the support layer after rolling.
6) Laying a composite geomembrane: the composite geomembrane is laid from the top of the dam body to the bottom of the dam body, so that the composite geomembrane is flat and straight, the two composite geomembranes are aligned and overlapped, and the overlapping width is about 30cm generally according to the design requirement. And splicing the joints of the adjacent composite geomembranes by a hot-melting welding method.
When the composite geomembrane is welded, the ground surface is dried, the splicing adopts a hot-melting welding method, and the welding tool adopts an automatic temperature-regulating (speed-regulating) electric heating wedge type double-channel plastic heat sealing machine and a hot-melting extrusion welding machine. Before the formal welding operation, the equipment parameters are set, and a small film with the thickness of 300 multiplied by 600mm is taken for trial welding. Then, a shearing and peeling test of the weld is carried out on a stretcher, if the shearing and peeling test is not lower than a specified value, the parameters are locked, and formal welding is started according to the parameters. Otherwise, the parameters are re-determined until the test is qualified. When the temperature and the wind speed are greatly changed, the parameters should be adjusted in time.
7) Connecting the composite geomembrane with a toe wall:
a. and (4) polishing and removing sundries on the top surface of the toe wall to ensure that the surface of the concrete is smooth and flat.
b. Coating KS hot melt adhesive on the top surface of the toe wall, and sticking a strip-shaped lower layer rubber sheet of 150 x 10cm at the position where the KS hot melt adhesive is coated; the lower rubber sheets are sequentially spliced along the length direction of the toe wall until the whole toe wall is paved.
c. And (3) separating the head end of the composite geomembrane positioned at the bottom of the reservoir, stripping the geotechnical cloth layers on the upper and lower surfaces of the composite geomembrane, and exposing the plastic layer between the two geotechnical cloth layers.
d. And brushing KS hot melt adhesive on the upper surface of the lower rubber sheet, adhering the exposed plastic layer on the lower rubber sheet, extending the front end of the plastic layer to the internal corner position of the tongue and groove of the toe wall, and sealing the connection position of the front end of the plastic layer and the internal corner position of the tongue and groove of the toe wall by adopting polyurethane sealant.
e. The KS hot melt adhesive is coated on the upper surface of the plastic layer, an upper rubber sheet is pasted and fixed above the plastic layer, the upper rubber sheet is opposite to the lower rubber sheet in position, the upper rubber sheet is sequentially spliced until the whole toe wall is paved, and the lower rubber sheet and the upper rubber sheet paste and fix the plastic layer of the composite geomembrane into the plastic layer.
f: placing a steel plate with holes on the upper rubber sheet, wherein the steel plate with holes is a galvanized steel plate; vertically and downwards punching holes in the steel plate with the holes, wherein the punched holes penetrate through the upper layer rubber sheet, the plastic layer and the lower layer rubber sheet and extend into concrete, and expansion bolts are installed in the punched holes to fix the steel plate with the holes; coating 2 times of reinforced epoxy coal tar pitch anticorrosive layers on the surfaces of the steel plates with holes and the expansion bolts, wherein the thickness of the coating is 600 mu m; and after the expansion bolt is installed in the hole, polyurethane sealant is coated on the surface of the expansion bolt. In order to improve the connection strength, the perforated steel plates may be arranged in a left-right staggered manner, as shown in fig. 3.
The expansion bolts are preferably M16 x 150, the perforated steel plates are preferably 150 x 300 x 10; the upper layer rubber sheet and the lower layer rubber sheet are 150-10 strip-shaped rubber sheets.
8) And (3) secondary construction of toe walls: and pouring concrete at the top of the toe wall for secondary sealing, wherein the concrete seals the steel plate with the holes, the upper layer rubber sheet and the lower layer rubber sheet, and the top elevation after secondary construction of the toe wall is higher than the design bottom elevation.
9) Construction of a protective layer: after the composite geomembrane is laid and welded to be qualified, a protective layer is filled in time, and the speed of filling the protective layer is matched with the speed of laying the geomembrane, so that the geomembrane is prevented from being exposed to the sun for a long time in the burning sun.
In the invention, the composite geomembrane is a high-density polyethylene geomembrane, and the density is not lower than 0.94g/cm2The longitudinal and transverse tensile yield strength is not less than 7N/mm, the longitudinal and transverse tensile breaking strength is not less than 10N/mm, the right angle tearing load is not less than 56N, the puncture resistance strength is not less than 120N, and the water vapor permeability coefficient is not more than 1.0 x 10-11g cm/(cm)2S.pa), dimensional stability ± 2%, others subject to meeting the specification requirements. The geomembrane adopts and strictly executes 'geosynthetic filament spun-bonded needle-punched non-woven geotextile' GB/T17639-. The geomembrane adopts a wide (not less than 6 m) filament spun-bonded needle-punched non-woven geomembrane with the specification of 500g/m2The longitudinal and transverse breaking strength is not less than 20.0KN/m, the tearing strength is not less than 0.7KN, the bursting strength is not less than 3.2kN, and the hydrostatic pressure resistance is 1.0 MPa.
The field embodiment is as follows: the first stage project of the Yiganouyi reservoir in the Hening county is located in the Yiganouyi town, the total reservoir capacity of the reservoir is 92 ten thousand cubic meters, the shape of the reservoir is a regular rounded rectangle, the dam body is a composite geomembrane seepage-proofing rolling type homogeneous earth dam, the size of the reservoir bottom is 180m multiplied by 160m, the size of the reservoir opening is 285m multiplied by 265m, the designed water depth is 19.20m, the highest water level is 21.0m, and the reservoir bottom is located in a waterproof foundation layer. In the construction, through a rolling process test, the water content is reasonably determined according to the soil property category, the bump rolling is selected, the interlayer combination is good, the rolling parameters and the rolling process are optimized by combining selected mechanical equipment, and a closed loop rolling scheme is adopted, so that the phenomena of under-rolling and over-rolling of dam earthwork and improper joint processing of a working surface are prevented, and the dam body is unevenly filled, the settlement is uneven, cracks and permeation are formed; the annular external drainage perforated pipe is additionally arranged to form an internal and external independent drainage system, so that the homogeneity of backfill at the bottom of the homogeneous earth dam is ensured, the external water and internal drainage of the original design scheme are effectively avoided, a water seepage channel is easily formed, and major quality safety hazards such as dam body structure damage are caused; the quality monitoring of an anti-seepage system is strengthened, anti-seepage membrane node measures are perfected, the requirements of dam body safety and use functions are met, the requirements of reservoir opening and water storage are good, the dam body is not seepage, the design requirements are met, overpressure and underpressure are eliminated, the internal and external drainage measures of the dam body and the anti-seepage membrane quality monitoring measures are optimized through a high-fill silty loam dam body rolling scheme, anti-seepage membrane node connection is innovated, the seepage risk of a homogeneous soil dam is greatly reduced, and later maintenance cost is effectively reduced.
Claims (8)
1. An anti-seepage construction method for a semi-reservoir anti-seepage high-fill silty loam homogeneous dam is characterized by comprising the following steps:
1) and (3) rolling process test: drawing relation curves between different paving thicknesses and rolling times and the optimal water content and the maximum dry density respectively through a rolling process test; calculating to obtain optimal rolling process parameters, namely optimal soil paving thickness, rolling times and optimal water content according to the designed dry density and by combining the curves;
2) and (3) external drainage construction: the outer drainage perforated pipe is arranged along the periphery of a dam butt of the dam body, the drainage perforated pipe is embedded in a reservoir bottom impervious base rock layer, a gravel reverse filter layer is arranged around the drainage perforated pipe, and a reverse filtration geotechnical cloth is arranged at the joint position of the gravel reverse filter layer and the dam body backfill soil;
3) filling a dam body: performing dam filling operation according to the optimal rolling process parameters determined in the step 1); filling each layer of earthwork to construct a closed loop, and paving by adopting an occupation method; before the next layer of filling, the surface of the previous layer of filling is subjected to roughening treatment; after filling, carrying out slope cutting treatment, and leveling and compacting the slope surface of the dam body;
4) constructing a toe wall: excavating toe wall grooves at the positions of the toes of the dam body to finish the concrete pouring of the toe walls, wherein the top surfaces of the toe walls are arranged in grooves and tongues;
5) and (3) internal drainage construction: arranging an inner drainage perforated pipe along the toe part of the dam body, and filling gravel water filtering layers around the drainage perforated pipe;
6) laying a composite geomembrane: the composite geomembrane is laid from the top of the dam body to the bottom of the dam body, so that the composite geomembrane is smooth and straight; splicing the seams of the adjacent composite geomembranes by a hot-melt welding method;
7) connecting the composite geomembrane with a toe wall:
a. polishing and removing impurities on the top surface of the toe wall to ensure that the surface of the concrete is smooth and flat;
b. coating hot melt adhesive on the top surface of the toe wall, adhering strip-shaped lower rubber sheets, and sequentially splicing the lower rubber sheets along the length direction of the toe wall until the whole toe wall is fully paved;
c. separating the head end of the composite geomembrane positioned at the bottom of the reservoir, stripping the geotechnical cloth layers on the upper and lower surfaces of the composite geomembrane, and exposing the plastic layer between the two geotechnical cloth layers;
d. coating hot melt adhesive on the upper surface of the lower rubber sheet, adhering the exposed plastic layer on the lower rubber sheet, and sealing the front end of the plastic layer by using sealant, wherein the front end of the plastic layer extends to the internal corner position of the tongue and groove of the toe wall;
e. coating hot melt adhesive on the upper surface of the composite geomembrane plastic layer, and fixedly adhering an upper layer rubber sheet above the plastic layer, wherein the upper layer rubber sheet is opposite to the lower layer rubber sheet in position, and the lower layer rubber sheet and the upper layer rubber sheet fixedly adhere the plastic layer of the composite geomembrane into the upper layer rubber sheet;
f: placing a steel plate with holes on the upper rubber sheet, and anchoring the rubber sheet and the plastic layer in the toe wall concrete through a belt rear expansion bolt;
8) and (3) secondary construction of toe walls: pouring concrete at the top of the toe wall for secondary sealing, wherein the concrete seals the upper layer rubber sheet and the lower layer rubber sheet into the toe wall, and the top elevation of the toe wall after secondary construction is higher than the designed reservoir bottom elevation;
9) construction of a protective layer: and filling a protective layer above the composite geomembrane on the slope.
2. The antiseep construction method for semi-reservoir antiseep high fill silty loam homogeneous dam of claim 1, wherein after the construction of connecting the composite geomembrane and the toe wall of step 5), a steel plate with holes is placed on the upper rubber sheet, holes are vertically punched downwards through the holes on the steel plate with holes, and the holes are punched through the upper rubber sheet, the plastic layer and the lower rubber sheet and extend into the concrete and are anchored in the concrete of the toe wall by expansion bolts.
3. The seepage-proofing construction method of the semi-reservoir seepage-proofing high-fill silty loam homogeneous dam as claimed in claim 2, wherein the surfaces of the steel plate with holes and the expansion bolts are coated with a polyurethane sealant anticorrosive layer.
4. The seepage-proofing construction method of half-warehouse seepage-proofing high-fill silty loam homogeneous dam according to claim 1, characterized in that in the step 5), the end part of the plastic layer extends to the internal corner position of the rabbet of the toe wall and is sealed by polyurethane sealant.
5. The seepage-proofing construction method of the semi-reservoir seepage-proofing high-filling silty loam homogeneous dam as claimed in claim 1, wherein in the step 5), the front end of the plastic layer extends to the position of the groove and corner of the toe wall, and is sealed by polyurethane sealant.
6. The anti-seepage construction method of the semi-reservoir anti-seepage high-fill silty loam homogeneous dam according to claim 1, wherein in the step 2), the outer drainage floral tube is buried below 1.0m of the reservoir bottom impervious basement stratum, and the gradient of the outer drainage floral tube is not less than 0.3% so as to ensure the natural drainage of underground water.
7. The seepage-proofing construction method of the semi-reservoir seepage-proofing high-fill silty loam homogeneous dam according to claim 1, wherein the inner drainage floral tube is connected with PE gas permeable tubes at intervals, and the PE gas permeable tubes are arranged along the slope of the dam body; the lower end of the PE vent pipe is communicated to the inner drainage perforated pipe, and the upper end of the PE vent pipe is positioned at the top of the dam body and extends out of the composite geomembrane.
8. The seepage-proofing construction method of the semi-reservoir seepage-proofing high-fill silty loam homogeneous dam of claim 7, wherein the interval between adjacent PE gas permeable pipes is 20-30 m.
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