A construction method for using phosphogypsum in an embankment, comprising:
- (1) preparing a phosphogypsum-containing embankment mixture, including:
- weighing 90 parts by weight of phosphogypsum and 10 parts by weight of cement, and uniformly mixing and stirring the phosphogypsum and the cement to obtain a base material mixture;
- and
- weighing 2-4 parts by weight of sodium silicate, dissolving the sodium silicate in water, and adding an obtained solution to the base material mixture to obtain the phosphogypsum-containing embankment mixture;
- (2) mixing the phosphogypsum-containing embankment mixture with water, including:
- acquiring a part of the phosphogypsum-containing embankment mixture by using an isostatic pressing method, adding water to prepare samples with different water content, and obtaining maximum dry density and optimal moisture content of the phosphogypsum-containing embankment mixture in a same compaction energy condition, wherein moisture content of the phosphogypsum-containing embankment mixture is defined as a mass percentage of water lost when heating is conducted at a temperature between 120-130° C. for 9-12 hours to form a dried phosphogypsum-containing embankment mixture at the temperature;
- (3) adding water to the phosphogypsum-containing embankment mixture according to the optimal moisture content obtained in (2) above to make moisture content of the phosphogypsum-containing embankment mixture reach the optimal moisture content, to obtain an embankment filler, where mixing of the phosphogypsum-containing embankment mixture is conducted in a plantmix manner by using a stock bin of a cement stabilized soil mixing station and a forced mixer;
- and
- where an anti-seepage cushion layer is an anti-seepage geotechnical cloth or an anti-seepage geomembrane with a thickness not less than 1.0 mm;
- and
- (4) transporting the embankment filler to a construction site, and installing the embankment filler according to a method that includes:
- 1) leveling and compacting original ground, and layering a soil filler above a groundwater level and a surface water level, wherein a loose layering depth of each layer of laid soil filler is not greater than 40 cm, and compactness is not less than 90%;
- 2) layering a first anti-seepage cushion layer on a full section of a top surface of a compacted soil-filled embankment;
- 3) layering a first soil filler layer on a full section of the first anti-seepage cushion layer, wherein a loose layering depth of the first soil filler layer is not greater than 40 cm;
- conducting compaction and densification on the first soil filler layer in a condition of optimal moisture content;
- and
- layering a second anti-seepage cushion layer on a full section of the top surface of the first soil filler layer;
- 4) layering a second soil filler layer on a full section of the second anti-seepage cushion layer, wherein a loose layering depth of the second soil filler layer is not greater than 40 cm;
- conducting compaction and densification on the second soil filler layer in a condition of optimal moisture content;
- and
- layering a third anti-seepage cushion layer on a full section of the top surface of the second soil filler layer;
- 5) layering the phosphogypsum-containing embankment mixture on a full section of the top surface of the third anti-seepage cushion layer, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
- conducting isostatic compaction and densification in a condition of optimal moisture content;
- reversely layering the third anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the third anti-seepage cushion layer on each side along an embankment section direction is not less than 1.5 m;
- and
- layering a fourth anti-seepage cushion layer with a same width as the third anti-seepage cushion layer on the third anti-seepage cushion layer;
- 6) layering the phosphogypsum-containing embankment mixture on the top surface of the phosphogypsum-containing embankment, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
- conducting isostatic compaction and densification in a condition of optimal moisture content;
- reversely layering the fourth anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the fourth anti-seepage cushion layer on each side along the embankment section direction is not less than 1.5 m;
- and
- layering a fifth anti-seepage cushion layer with a same width as the fourth anti-seepage cushion layer on the fourth anti-seepage cushion layer;
- 7) layering the phosphogypsum-containing embankment mixture on the top surface of the phosphogypsum-containing embankment, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
- conducting isostatic compaction and densification in a condition of optimal moisture content;
- reversely layering the fifth anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the fifth anti-seepage cushion layer on each side along the embankment section direction is not less than 1.5 m;
- and
- layering a sixth anti-seepage cushion layer with a same width as the fifth anti-seepage cushion layer on the fifth anti-seepage cushion layer;
- 8) continuously layering the phosphogypsum-containing embankment mixture according to the above method until reaching an upper embankment, wherein a loose layering depth of each layer of phosphogypsum-containing embankment mixture is not greater than 40 cm;
- conducting isostatic compaction and densification in a condition of optimal moisture content;
- and
- reversely layering an nth anti-seepage cushion layer on a full section of the embankment from its two sides to its center;
- and
- 9) layering a third soil filler layer on a full section of the nth anti-seepage cushion layer, wherein a loose layering depth of the third soil filler layer is not greater than 40 cm;
- and
- conducting compaction and densification on the third soil filler layer in a condition of optimal moisture content, so as to form a filling embankment.