CN109024701B - Phosphogypsum reservoir slope seepage prevention method - Google Patents
Phosphogypsum reservoir slope seepage prevention method Download PDFInfo
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Abstract
The invention discloses a side slope seepage prevention method for a phosphogypsum reservoir, which comprises the following steps: step1, treating a slope bottom platform, a side slope and a slope top platform; step2, leveling a slope bottom platform and a side slope; step3, arranging a blind ditch, a gypsum residual water seepage guiding system and a slope bottom platform seepage preventing system on the slope bottom platform; step4, laying a three-dimensional drainage net on the side slope, and step5, performing seepage-proofing arrangement on the surface of the phosphogypsum-adhered slope layer, wherein the seepage-proofing arrangement is connected with a seepage-proofing system at the bottom of the original reservoir area, and the top of the seepage-proofing arrangement is anchored on a slope top platform; and 6, performing multi-stage modification on the phosphogypsum plaster slope. The method not only can achieve the aim of preventing seepage of the steep side slope of the phosphogypsum reservoir, but also greatly reduces the excavation amount of the original side slope under the condition of comprehensively utilizing the phosphogypsum to paste the slope by changing waste into valuable.
Description
Technical Field
The invention relates to a side slope seepage prevention method for a phosphogypsum reservoir, which is an seepage prevention treatment method suitable for valley type phosphogypsum storage yards, and is particularly suitable for phosphogypsum reservoir extension projects.
Background
Phosphogypsum is a solid waste discharged during the production of phosphate fertilizer and phosphoric acid, and 4.5-5t of phosphogypsum is produced every 1t of phosphoric acid. The resource utilization condition of the phosphogypsum is unsatisfactory both at home and abroad, and the effective utilization rate of the phosphogypsum all over the world is only about 4.5 percent. At present, the treatment mode of phosphogypsum treatment is mainly stockpiling.
The phosphogypsum storage yard mainly comprises a flat-land type storage yard and a valley type storage yard, and the flat-land type storage yard and the valley type storage yard can become pollution sources and cause serious environmental problems if the storage and the treatment are not proper.
The phosphogypsum is improperly stockpiled and treated, and can cause the following harm to the environment:
(1) the phosphogypsum waste residue has the pH value of 2.5-4.5, is a strong acid waste residue, and can cause soil acidification if being stored improperly;
(2) phosphogypsum leachate is acidic wastewater, contains soluble phosphorus, fluoride and the like, and can cause eutrophication pollution of underground water, surface water and lakes and reservoirs if not treated properly.
Therefore, the ardealite storage yard needs to be subjected to anti-seepage treatment.
Chinese utility model patent that the bulletin number of authorizing is CN202989864U, and the bulletin date of authorizing is 2013 6 months 12 days discloses a catch basin structure in ardealite stock dump, including the interior side slope of ardealite stock dump storehouse, laid HDPE prevention of seepage membrane, its characterized in that on this side slope: the method comprises the steps of piling up a position, needing to be provided with a cut-off ditch, on a side slope in a phosphogypsum storage yard on an HDPE anti-seepage film by using a filling bag to form a short wall body, paving a U-shaped HDPE film on the short wall body to cover the short wall body, and connecting two lower ends of the U-shaped HDPE film and the HDPE anti-seepage film into a whole through a single-rail welding line. The utility model discloses a through improving current catch basin, make full use of prevents that osmosis membrane easily welded characteristic makes the construction of catch basin more convenient in the ardealite store yard storehouse, saves the investment to the safe and reliable of ardealite store yard anti-seepage system has been guaranteed.
Chinese utility model patent that the bulletin number of authorizing is CN202672195U, and the bulletin date of authorizing is 2013 1 month 16 discloses a spread device of membrane prevention of seepage ardealite stock dump bottom row ooze, including the ardealite stock dump initial dam of having laid the HDPE membrane in the slope of upstream, its characterized in that: the dam heel of the upstream face of the initial dam is provided with a reinforced concrete box culvert, a plastic blind ditch is filled in the reinforced concrete box culvert, the tail part of the reinforced concrete box culvert is provided with a stainless steel pipe which can lead out water seepage to the outside of the reinforced concrete box culvert, and the stainless steel pipe is connected with an HDPE pipe buried at the bottom of the initial dam. The utility model discloses a drainage system oozes the moisture that the phosphogypsum that deposits in the storehouse basin below the initial dam elevation of yard contains moisture and precipitation and accumulates is derived and is followed the dam foundation and lead to low reaches to the storehouse and transfer the water sump outward to discharge as early as possible the moisture in the phosphogypsum, accelerate the drainage of phosphogypsum to solidify, ensure the stability of phosphogypsum yard.
The invention discloses a device for solving the problem of seepage guide at the bottom of a wet-discharge film-paving seepage-proofing phosphogypsum storage yard, which is disclosed by a Chinese patent with an authorization notice number of CN103669550B and an authorization notice date of 2015, 12 and 30, and belongs to the technical field of chemical facilities. The seepage guiding blind ditch comprises an initial dam, seepage guiding blind ditches, stainless steel pipes and solid-wall pipes, wherein each seepage guiding blind ditch consists of two transverse seepage guiding blind ditches parallel to the axis of the initial dam and a longitudinal blind ditch perpendicular to the transverse seepage guiding blind ditches, the distance between the first transverse seepage guiding blind ditch and the dam foot of the initial dam is not less than 50m, and the distance between the second transverse seepage guiding blind ditch and the first transverse seepage guiding blind ditch is not less than 50 m. The invention effectively leads the saturated water in the phosphogypsum in the yard to a downstream water pool under the condition of not damaging an anti-seepage system of the phosphogypsum yard, accelerates the drainage consolidation of the phosphogypsum, increases the physical and mechanical indexes of the phosphogypsum and ensures the operation safety of the phosphogypsum yard.
The Chinese patent application with the application publication number of CN102182209A and the publication date of 2011, 9, and 4 discloses a side slope water seepage isolation system of a phosphogypsum storage yard, which comprises tensile and puncture-resistant geotextile paved on the surface of a rock side slope and a high-density polyethylene film paved under phosphogypsum and having a smooth outer surface, wherein a plurality of tooth-shaped bulges which are arranged at intervals are combined between the tensile and puncture-resistant geotextile and the high-density polyethylene film in a hot melting mode to form gaps as channels for downward flowing of side slope seepage water, so that the risk that the HDPE high-density polyethylene film is supported and bulged by the side slope seepage water top is reduced, good protection is provided for preventing the high-density polyethylene film from being burst by rocks and other bulges on the side slope, and the high-density polyethylene film with the smooth outer surface is adopted, so that the friction force between the high-density polyethylene film and the phosphogypsum is reduced to the maximum extent, and the downward dragging caused by the settlement of the phosphogypsum, Tearing and the like. The side slope water seepage isolation system can reliably provide guarantee for isolating phosphogypsum from side slope water seepage for a long time.
Although the prior art has certain improvement on the anti-seepage treatment of the phosphogypsum storage yard, the prior art has the following defects:
1. the above patents relate to the drainage, seepage-guiding and seepage-proofing membrane anchoring of the phosphogypsum storehouse, and are important components of the seepage-proofing of the phosphogypsum storehouse. However, it cannot solve the problems of slope seepage control, installments and the like.
2. The seepage-proofing direction of the prior art achieves the aim of seepage proofing of the phosphogypsum storage yard by using other materials and products, and phosphogypsum is not utilized at all, so that the construction cost of the ardealite side slope seepage-proofing is high.
Disclosure of Invention
The invention provides a phosphogypsum storehouse side slope seepage prevention method for solving the technical problems in the prior art, not only can the aim of phosphogypsum side slope seepage prevention be achieved, but also the excavation amount of the original side slope is greatly reduced under the condition of comprehensively utilizing phosphogypsum to paste the side slope by changing waste into valuable, and the method has the greatest advantages of easily realizing 'construction by times' by completing seepage prevention construction once after clearing the foundation, and distributing the capital construction investment, thereby greatly reducing the construction cost of the phosphogypsum storehouse.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a phosphogypsum reservoir slope seepage prevention method is characterized by comprising the following steps: the method comprises the following steps:
step1, constructing a slope bottom platform at the slope bottom, constructing a slope top platform at the slope top (the slope top platform is constructed according to the construction progress, the construction is not required), and the slope bottom platform and the slope top platform are required to be flat and need to be dug to an old soil layer;
step2, removing floating soil and sundries on the surface layer of the side slope, digging to an old soil layer, and forming a down slope from the top to the bottom of the slope;
step3, leveling the foundation of the slope bottom platform by using clay to enable the slope bottom platform to form a down slope which is 1% of the down slope in the direction of the blind ditch, and then paving an HDPE film; manually leveling the side slope; arranging an anchoring ditch on the slope top platform;
step4, arranging an underdrain at the joint of the slope bottom platform and the side slope, wherein the underdrain is used for guiding and draining the concentrated water seepage on the side slope; installing a modified phosphogypsum residual water guiding and permeating system on the HDPE film at the bottom of the slope, wherein the modified phosphogypsum residual water guiding and permeating system is arranged close to the slope;
step5, laying a geotechnical drainage net on the side slope, wherein one end of the geotechnical drainage net extends to the slope top platform and is fixed on the slope top platform through an anchoring ditch; the other end of the modified phosphogypsum seepage guiding system extends to the slope bottom platform, and the seepage water of the modified phosphogypsum can be guided into the modified phosphogypsum seepage guiding system through a three-dimensional drainage network;
and 6, from the slope bottom platform to the slope top platform, carrying out modified phosphogypsum slope pasting and compacting, wherein the modified phosphogypsum slope pasting is divided into multi-period modified phosphogypsum slope pasting, and the modified phosphogypsum slope pasting of the next period is carried out only after the modified phosphogypsum slope pasting of the previous period is finished. The specific process of the modified phosphogypsum plaster slope in each period is as follows: firstly, sticking a slope with modified phosphogypsum, paving an HDPE film on the slope surface of the modified phosphogypsum sticking slope after the slope sticking is finished and anchoring the HDPE film in an anchoring groove at the top of the modified phosphogypsum sticking slope at the period, then paving an HDPE film (temporary) on the top surface of the modified phosphogypsum sticking slope, wherein one end of the HDPE film on the top surface of the slope is connected with the HDPE film on the slope surface in a welding mode, and the other end of the HDPE film on the top surface of the slope is provided with a temporary drainage groove (inverted trapezoid) and extends to the side slope; HDPE films on the slope surfaces of adjacent modified phosphogypsum sticking slopes are connected in a welding mode; when the modified phosphogypsum clinging slope at the next stage is constructed, a temporary HDPE film and a temporary drainage ditch at the top of the slope at the previous stage are removed, and the connectivity of the modified phosphogypsum at each stage is ensured; the HDPE film on the slope surface of the first-stage modified phosphogypsum plaster is connected with the HDPE film on the slope bottom platform in a welding mode, and the HDPE film laid on the left lower side of the clay cushion layer on the slope bottom platform is welded with the HDPE film on the slope surface of the first-stage modified phosphogypsum plaster; and the HDPE film on the top surface of the final stage modified phosphogypsum slope is fixed in the anchoring ditch together with the geotechnical drainage net.
The modified phosphogypsum in the modified phosphogypsum plaster slope is phosphogypsum which is subjected to neutralization treatment by lime to enable the pH value to be 6-9.
The middle of the blind ditch is provided with a floral tube wrapped by geotextile, the floral tube for guiding and discharging the water seepage of the side slope (the floral tube is wrapped by the gravel and the geotextile and embedded in the side slope) is communicated with the floral tube in the blind ditch, then the gravel is filled between the blind ditch and the floral tube, and finally, clay is filled above the floral tube.
The modified phosphogypsum residual water guiding and seepage system comprises a geotechnical drainage net, a floral tube and geotechnical cloth, wherein the floral tube is positioned above the geotechnical drainage net, and the floral tube and the geotechnical drainage net are wrapped by the geotechnical cloth.
And the floral tube in the modified phosphogypsum residual water seepage-guiding system is guided into a downstream regulating water tank for purification treatment. And the water in the temporary drainage ditch and the blind ditch at the top of the sub-dam in each period is clean water and is directly discharged outside.
And a layer of unidirectional geogrid is added every 2m in the modified phosphogypsum plaster slope in each period.
In step6, when the modified phosphogypsum is pressed, the initial compaction width of the modified phosphogypsum is obtained by subtracting the width of a reserved HDPE film welding operation platform from the width of a slope raising platform at the position; before the next slope pasting, the smooth top surface of the previous stage is planed and loosened, the thickness of loose filling is controlled within 30cm, and the modified phosphogypsum slope pasting construction of the next stage can be carried out.
In step6, the water content of the modified phosphogypsum is required to be 16-24% after compaction, and the minimum compaction degree is 95%.
The slope ratio of the modified phosphogypsum plaster slope at each stage is 1: 1.5-2.5, and is determined according to the arrangement of the overall plane and the section.
The clay used for the clay cushion layer and the backfill clay is required to be the clay with the particle size of less than 5mm, the clay needs to be compacted in a layered mode, the thickness of each layer of compaction is not more than 300mm, and the degree of compaction is not less than 90%.
Compared with the prior art, the invention has the following beneficial effects:
the invention is improved compared with the prior art in that: changing waste into valuable, modifying by using the phosphogypsum in the reservoir area, using the modified phosphogypsum for slope pasting, slowing slope gradient, reducing the seepage-proofing height of one-time construction, and adjusting the one-time construction into multi-stage construction so as to better ensure the seepage-proofing effect; the compactness of the impermeable cushion layer is ensured by rolling; geomembranes are arranged at the bottom of the slope layer and the outer slope for seepage prevention, and a three-dimensional drainage net is arranged between the slope layer and the mountain body for drainage of water seepage of the slope, so that environmental pollution can be prevented; a seepage guide system is arranged on an anti-seepage film at the bottom of the modified phosphogypsum plaster slope layer to collect percolate and then guide the percolate to enter a downstream regulating water tank, so that the environmental pollution can be prevented; temporary drainage ditches are arranged at the top of each period to guide and drain rainwater, so that the amount of the warehouse-in flood is reduced; after the multi-stage modified phosphogypsum slope construction is completed, the geomembrane is anchored in the top anchoring ditch, so that the safety of the geomembrane is ensured; the impermeable membranes of the side slopes at each stage are communicated, so that the integrity and the sealing property of the side slope geomembranes are ensured; therefore, the whole seepage prevention mode of the modified phosphogypsum plaster slope is communicated and complete, and the requirement of the phosphogypsum warehouse on seepage prevention is met.
The modified phosphogypsum slope-pasting process greatly reduces the excavation amount of the mountain side slope on the premise of ensuring the anti-seepage effect; the construction can be realized in multiple stages from one construction, and one-time investment is shared to the investment of multiple years, so that the capital pressure and financial burden of enterprises are greatly relieved.
Compared with the prior art, the method has the advantages that the modified phosphogypsum is used for slope pasting, the HDPE film is coated after slope pasting by the modified phosphogypsum, and when the reservoir area formed after treatment is opposite phosphogypsum, two layers of seepage prevention of the HDPE film and the modified phosphogypsum are carried out, so that the seepage prevention effect is better, the phosphogypsum is fully utilized, local materials are used, and the seepage prevention cost is greatly reduced. The water in the modified phosphogypsum plaster slope is guided into the water return tank for treatment under the action of the mounting of the perforated pipe and the solid-wall pipe, so that the surrounding environment is not polluted. The HDPE film laying position and the connection mode are both used for achieving a better anti-seepage effect and preventing harmful substances in the phosphogypsum from permeating into a mountain or the surrounding environment.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is an enlarged view of FIG. 1 at A;
FIG. 3 is a schematic view of the anchoring groove structure;
FIG. 4 is an enlarged view of FIG. 1 at B;
FIG. 5 is an enlarged view of FIG. 1 at C;
FIG. 6 is an enlarged view of FIG. 1 at D;
FIG. 7 is an enlarged view of FIG. 1 at E;
FIG. 8 is an enlarged view at F of FIG. 1;
fig. 9 is a schematic structural view of a second stage modified phosphogypsum plaster slope.
The reference numbers are 1, a slope bottom platform, 2, a slope top platform, 3, a side slope, 4, a foundation leveling layer, 5, an underdrain, 6, a modified phosphogypsum residual water seepage guiding system, 7, a clay cushion layer, 8, an HDPE film, 9, a geotechnical drainage net, 10, an anchoring ditch, 11, a first-stage modified phosphogypsum plaster slope, 12, a second-stage modified phosphogypsum plaster slope, 13, a third-stage modified phosphogypsum plaster slope, 14, a fourth-stage modified phosphogypsum plaster slope, 15, a fifth-stage modified phosphogypsum plaster slope, 16, a sixth-stage modified phosphogypsum plaster slope, 17, geotextile, 18, a floral tube, 19, clay, 20, a geogrid, 21, an inverted trapezoid temporary drainage ditch, 22 and broken stones.
Detailed Description
The present invention will be further described with reference to the following examples, which are intended to illustrate only some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, other embodiments used by those skilled in the art without any creative effort belong to the protection scope of the present invention.
The invention provides a side slope seepage prevention method for a phosphogypsum reservoir, which has the main improvement point that modified phosphogypsum is used for slope pasting, and then a HDPE film is covered after slope repairing. The specific method comprises the following steps:
step1, constructing a slope bottom platform 1 and a slope top platform 2
Constructing a slope bottom platform 1 at the slope bottom of the side slope, constructing a slope top platform 2 at the slope top (the last implementation), wherein the slope bottom platform 1 and the slope top platform 2 are required to be flat and are dug to an old soil layer; the constructed slope bottom platform and the constructed slope top platform are approximately flat and cannot have the conditions of step shape, unevenness, reverse slope and the like;
step2, slope 3 foundation clearing
Removing the floating soil and impurities on the surface layer of the side slope 3, digging to an old soil layer, and forming a down slope from the top of the slope to the bottom of the slope (namely forming the down slope from the top of the slope to the bottom of the slope, no counter slope can be generated, rainwater and sewage can be discharged conveniently, and the phosphogypsum is prevented from entering (Step 1 and Step2 can be exchanged in sequence and can be operated simultaneously);
step3, laying a foundation leveling layer 4 on the slope bottom platform 1 and the side slope 3 for foundation leveling, and avoiding the situations of unevenness and reverse slope;
step4, digging an underdrain 5 at the joint of a slope bottom platform 1 and a side slope 3 (the underdrain of the original platform can be generally utilized in the extension project), installing a modified phosphogypsum residual water guiding and permeating system 6 on the slope bottom platform 1, arranging the modified phosphogypsum residual water guiding and permeating system 6 close to the side slope 3, laying a clay cushion layer 7 on a basic leveling layer 4 of the slope bottom platform 1, and then laying an HDPE film 8 on the clay cushion layer 7; when the clay cushion layer 7 is laid, firstly, the HDPE film 8 is laid on the left lower side (shown in figure 8) of the clay cushion layer 7, then, the clay cushion layer 7 is laid, and the thickness of the clay cushion layer 7 is 300 mm;
step5, paving a geotechnical drainage net 9 on the side slope 3, wherein one end of the geotechnical drainage net 9 extends to a position 1.0m above the top of the slope in the period-changing period, then fixing the geotechnical drainage net on the side slope, and the other end of the geotechnical drainage net extends to the slope bottom modified phosphogypsum residual water seepage guiding system 6;
step6, performing modified phosphogypsum slope pasting and compacting from a slope bottom platform 1 to a slope top platform 2, wherein the modified phosphogypsum slope pasting is divided into multiple-stage modified phosphogypsum slope pasting (as shown in fig. 1, the modified phosphogypsum slope pasting is divided into six stages totally, namely a first-stage modified phosphogypsum slope pasting 11, a second-stage modified phosphogypsum slope pasting 12, a third-stage modified phosphogypsum slope pasting 13, a fourth-stage modified phosphogypsum slope pasting 14, a fifth-stage modified phosphogypsum slope pasting 15 and a sixth-stage modified phosphogypsum slope pasting 16 respectively), the height of each-stage modified phosphogypsum slope pasting is not more than 6m, the next-stage modified phosphogypsum slope pasting is performed only after the previous-stage modified phosphogypsum slope pasting is completed, and the specific flow of each-stage modified phosphogypsum slope pasting is as follows: firstly, sticking the slope with the modified phosphogypsum, repairing the slope after finishing the slope sticking, leveling the slope, adding a layer of one-way geogrid 20 every 2m in the modified phosphogypsum sticking slope in each period when the modified phosphogypsum is stuck, wherein the initial compaction width of the modified phosphogypsum is the width of a slope starting platform minus the width of a reserved HDPE film welding operation platform, the thickness of a loose filling part before compaction is controlled within 30cm, and the smooth compaction surface in the previous period is subjected to loosening treatment before implementation in each period, so that the modified phosphogypsum sticking slope in the next period can be constructed. The rolling control indexes of the modified phosphogypsum are as follows: layer thickness is less than or equal to 50cm, water content = (20 ± 4)%, minimum degree of compaction =95% (corresponding to a dry density of 1.26 g/cm); laying an HDPE film 8 on the slope surface of the modified phosphogypsum sticking slope and anchoring the HDPE film to the top of the modified phosphogypsum sticking slope; the other end of the slope top surface is provided with an inverted trapezoidal temporary drainage ditch 21 which extends to the side slope 3; paving a clay layer with the thickness of 30cm at the top between the anchoring end of the side slope impermeable membrane and the edge of the inverted trapezoidal temporary drainage ditch to isolate rainwater from entering the slope adhering layer; HDPE films on the slope surfaces of adjacent modified phosphogypsum sticking slopes are connected in a welding mode; the HDPE membrane on the slope surface of the first-stage modified phosphogypsum patch slope is connected with the HDPE membrane on the slope bottom platform in a welding mode, the HDPE membrane laid on the upper side of the clay cushion layer on the slope bottom platform is welded with the HDPE membrane on the slope surface of the first-stage modified phosphogypsum patch slope together, the welding seam interval of two welding points is not less than 300mm, and the HDPE membrane on the top surface of the last-stage modified phosphogypsum patch slope is fixed in the anchoring ditch 10 together with the geotechnical drainage net.
The modified phosphogypsum in the modified phosphogypsum plaster slope is phosphogypsum which is subjected to neutralization treatment by lime to enable the pH value to be 6-9.
A floral tube 18 wrapped by geotextile 17 is arranged in the middle of the underdrain 5, then gravel 22 is filled between the underdrain 5 and the floral tube 18, and finally clay 19 is filled above the floral tube 18.
The modified phosphogypsum residual water seepage guiding system 6 comprises a geotechnical drainage network 9, a floral tube 18 and geotechnical cloth 17, wherein the floral tube 18 is positioned above the geotechnical drainage network 9, and the geotextile 17 wraps the floral tube 18 and the geotechnical drainage network 9 together.
The floral tube 18 in the modified phosphogypsum residual water seepage-guiding system is communicated with the floral tube 18 embedded in the side slope, and is guided into a downstream regulating reservoir through a solid-wall tube for purification treatment.
The slope ratio of the modified phosphogypsum plaster slope at each stage is 1: 1.5-2.5.
The clay used for the clay cushion layer 3 and the backfill clay 19 is required to have the particle size of less than 5mm, the clay needs to be compacted in a layered mode, the thickness of each layer is not more than 300mm, and the compactness is not less than 90%.
The anchoring ditch is as shown in fig. 3, a ditch is dug on the top of the slope platform 3, then the geotechnical drainage net and the HDPE film are bent and placed in the ditch, and then the ditch is backfilled with clay 19 and compacted.
The HDPE film is a 2.0 mm-thick single-rough-surface or double-rough-surface HDPE film, the width of the HDPE film can be properly adjusted, and the number of overlapping times is reduced as much as possible.
The HDPE film has the following specific requirements when laid:
a. the method comprises the following steps that a laying worker starts to lay a film, the film is temporarily anchored by a sand bag immediately after being laid, whether the lapping width of a film piece meets the requirement of about 100mm or not is checked, and the film is adjusted in time when needing to be adjusted so as to make full preparation for the next procedure;
b. before construction, power supply line maintenance and smoothness are well carried out, maintenance of construction machines is in place, labor force arrangement is ready, and other preparation works are carried out;
c. rolling and paving the coiled material from top to bottom during paving, and ensuring the smooth paving;
d. the amount of HDPE films laid every day is reasonably arranged according to the welding capacity, and the amount of the expanded HDPE films is reduced when severe weather comes;
e. smoking is prohibited on the laid HDPE film, and the use of matches, lighters and chemical solvents or similar items is prohibited in the area where the HDPE film is laid;
f. the installed impermeable membrane cannot be damaged when the position of the laid HDPE membrane is adjusted, and only a clamp which is permitted to be used can be used in the adjustment process of the HDPE membrane;
g. in the construction process, enough temporary ballast or ground anchors (sand bags or geotextile coiled materials) are needed to prevent the paved HDPE films from being blown up by strong wind, the ballast or ground anchors used are permitted to adopt articles which cannot damage the HDPE films, and under the condition of strong wind, the HDPE films need to be temporarily anchored, and the installation work needs to be stopped;
h. the film spreading is reduced to the minimum or the maximum in the air temperature in the day.
The HDPE film welding method comprises the following specific requirements:
a. production welding can be carried out only after the trial welding is passed;
b. the on-site film connection is carried out in a dry environment on a compacted and flat cushion surface, and soil, dust, dirt or other foreign matters are prevented from entering a welding line; in the welding process, the welding quality is ensured not to be affected by any sundries in the overlapping range of the welding line;
c. in welding, the overlapping width of the welding seam is kept enough to carry out destructive test;
d. except in the place of repair and patching, the slope is more than 1:10, no transverse seam can be formed, and the welding seam at the bottom of the side slope extends from the slope toe to the bottom of the field by at least 1.5 m;
e. each HDPE film must be welded on the day of laying, and if proper protection measures are taken to prevent rainwater from entering the ground surface below, the welding seam is connected at the bottom, which can be exceptional;
f. only approved tool boxes or tool bags may be used, and equipment and tools may not be placed on the surface of the HDPE film unless in use;
g. the lap width of the HDPE film seams is about 100mm, no lap width of less than 75mm is allowed anywhere, and for double track fusion welding the lap width should not exceed 150 mm; the possibility of wrinkles and fish mouth formation at the seam is avoided as much as possible;
h. in the welding process, if the width of the lap joint part does not meet the requirement or a welding missing place occurs, a marking pen needs to be marked at the first time so as to make repair;
i. when extrusion welding is required, surface oxides are removed from the HDPE film welding area, the HDPE film welding area is strictly limited to be only carried out at the welding area, and the grinding operation must be carried out within one hour before welding.
After welding, the HDPE film meets the following requirements in the process of acceptance:
a. and (3) detecting the air pressure of the hot melting welding: aiming at the characteristics that double-track welding seams are formed by hot melting welding and an air cavity is reserved in the middle of each welding seam, air pressure detection equipment is mainly adopted to detect the strength and the air tightness of each welding seam. After one welding line is constructed, two ends of a welding line air cavity are blocked, the welding line air cavity is pressurized to 180kPa by using air pressure detection equipment, the pressure is maintained for 3-5 minutes, the air pressure is not lower than 150kPa, the welding line air cavity is qualified, each welding line is detected, and the qualification rate is 100%.
b. Vacuum test (or spark test) of extrusion welding: for a monorail weld formed by extrusion welding, a vacuum detection method (or electric spark detection) is mainly adopted for detection; and (3) directly applying negative pressure to the part to be detected of the welding line by using vacuum detection equipment, judging that the welding line is qualified without any leakage when the air pressure in the vacuum cover reaches 25-35 kPa, detecting each welding line, and ensuring that the qualified rate is 100%.
c. Destructive sampling detection of weld strength: a destructive sample is taken for each welding device for welding a certain length for indoor experimental analysis (the sampling position must be repaired immediately), the strength quality of the welding seam is quantitatively detected, and the qualification rate is 100%. The sampling size is 0.3mX0.5m, 10 standard test pieces with the width of 25.4mm are cut from each sample, and 5 shearing experiments and 5 stripping experiments are respectively carried out. Of the test results of 5 specimens per experiment, 4 must meet the requirements in the above table, and the strength test is regarded as passed when the average value must meet the standard in the table and the lowest value must not fall below 80% of the standard value.
The slope bottom and the slope top in the invention do not necessarily refer to the slope bottom or the slope top of the whole slope, but only refer to a relative description of the slope in the construction reservoir area, for example, if the selected reservoir area relates to a section of the slope with the height of 325m to 365m, 325m of the slope is the slope bottom, 365m of the slope is the slope top, the platform constructed at 325m is the slope bottom platform, and the platform constructed at 365m is the slope top platform.
Claims (9)
1. A phosphogypsum reservoir slope seepage prevention method is characterized by comprising the following steps: the method comprises the following steps:
step1, treating a slope bottom platform and a side slope
Constructing a slope bottom platform at the slope bottom, wherein the slope bottom platform is required to be flat and needs to be dug to an old soil layer, removing floating soil and sundries on the surface layer of the side slope, and digging to the old soil layer to form a slope top to slope bottom downslope;
step2, leveling a slope bottom platform and a side slope;
step3, firstly, arranging an underdrain on the slope bottom platform, wherein the underdrain is positioned at the joint of the slope bottom and the side slope; and then, performing anti-seepage arrangement on the slope bottom platform to construct an anti-seepage layer, wherein the anti-seepage arrangement specifically comprises the following steps: paving a clay cushion layer on the slope bottom platform, and then paving an HDPE film on the clay cushion layer; after the seepage-proofing arrangement is finished, arranging a modified phosphogypsum residual water seepage-guiding system, wherein the modified phosphogypsum residual water seepage-guiding system is arranged close to a side slope;
step4, laying a geotechnical drainage net on the side slope, wherein one end of the geotechnical drainage net extends to the top of the slope and is fixed on the top of the slope through an anchoring ditch, and the other end of the geotechnical drainage net extends to and is in lap joint with the modified phosphogypsum residual water guiding and seepage system at the bottom platform of the slope;
step5, performing multi-stage modification on phosphogypsum plaster slope
The method comprises the following steps of (1) carrying out modified phosphogypsum slope pasting and compaction from a slope bottom platform to the top of a side slope, dividing the modified phosphogypsum slope pasting into multi-period modified phosphogypsum slope pasting, carrying out the next-period modified phosphogypsum slope pasting after the previous-period modified phosphogypsum slope pasting is finished, wherein the specific flow of the modified phosphogypsum slope pasting in each period is as follows: firstly, sticking a slope with modified phosphogypsum, paving an HDPE film on the slope surface of the modified phosphogypsum sticking slope after the slope sticking is finished, paving an HDPE film on the top surface of the modified phosphogypsum sticking slope, connecting one end of the HDPE film on the top surface of the slope with the HDPE film on the slope surface in a welding mode, and arranging a temporary drainage ditch at the other end of the HDPE film and extending the HDPE film to the side slope; HDPE films on the slope surfaces of adjacent modified phosphogypsum sticking slopes are connected in a welding mode; when the next-stage modified phosphogypsum sticking slope is constructed, removing the HDPE film and the temporary drainage ditch on the top surface of the last-stage modified phosphogypsum sticking slope; the HDPE film on the slope surface of the first-stage modified phosphogypsum plaster is connected with the HDPE film on the slope bottom platform in a welding mode, and the HDPE film laid on the left lower side of the clay cushion layer on the slope bottom platform is welded with the HDPE film on the slope surface of the first-stage modified phosphogypsum plaster; and the HDPE film on the top surface of the final stage modified phosphogypsum slope is fixed in the anchoring ditch together with the geotechnical drainage net.
2. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: the modified phosphogypsum in the modified phosphogypsum plaster slope is phosphogypsum which is subjected to neutralization treatment by lime to enable the pH value to be 6-9.
3. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: and an impermeable layer constructed on the slope bottom platform extends 1m to the side slope.
4. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: the modified phosphogypsum residual water guiding and seepage system comprises a geotechnical drainage net, a floral tube and geotechnical cloth, wherein the floral tube is positioned above the geotechnical drainage net, and the floral tube and the geotechnical drainage net are wrapped by the geotechnical cloth.
5. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: the height of the modified phosphogypsum plaster slope in each period is not more than 6m, and a layer of unidirectional geogrid is added in each modified phosphogypsum plaster slope every 2 m.
6. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: and 5, when the modified phosphogypsum is compacted, the initial compaction width of the modified phosphogypsum is the width of the slope raising platform minus the width of a reserved HDPE film welding operation platform, the loose filling thickness before compaction is controlled within 30cm, the smooth compaction surface is planed and loosened after compaction, and the next-stage modified phosphogypsum slope construction can be carried out.
7. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: in step5, the water content of the modified phosphogypsum is required to be 16-24% after compaction, and the minimum compaction degree is 95%.
8. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: the slope ratio of the modified phosphogypsum plaster slope at each stage is 1: 1.5-2.5.
9. The phosphogypsum-reservoir slope seepage-proofing method according to claim 1, which is characterized in that: the clay used for the clay cushion layer is required to be the particle size of less than 5mm, the clay needs to be compacted in a layered mode, the thickness of each layer of compaction is not more than 300mm, and the degree of compaction is not less than 90%.
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| CN110016939B (en) * | 2019-05-16 | 2024-03-01 | 中国电建集团贵阳勘测设计研究院有限公司 | Structure of HDPE pipe penetrating phosphogypsum dam |
| CN112663627A (en) * | 2020-12-10 | 2021-04-16 | 瓮福（集团）有限责任公司 | Method for dissolving and applying phosphogypsum raw slag engineering |
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| CN201924381U (en) * | 2011-02-01 | 2011-08-10 | 深圳市胜义环保有限公司 | Side slope film paving structure for ardealite slag field |
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