AU2020100940A4

AU2020100940A4 - Method For Protecting Soil Slope From Shallow Landslide By Using Phosphogypsum

Info

Publication number: AU2020100940A4
Application number: AU2020100940A
Authority: AU
Inventors: Zhiqing Li
Original assignee: Institute of Geology and Geophysics of CAS
Current assignee: Institute of Geology and Geophysics of CAS
Priority date: 2020-04-20
Filing date: 2020-06-04
Publication date: 2020-07-23
Anticipated expiration: 2028-06-04
Also published as: CN111424688A

Abstract

The present invention provides a method for protecting an expansive soil slope from a shallow landslide by using phosphogypsum. The method includes: preparing an improver with anionic polyacrylamide and potassium chloride; preparing a mixture with phosphogypsum, fly ash and soil, and mixing the mixture with the improver and water to prepare an improving mixture slurry; laying a three-dimensional vegetation net on the face of the slope from top to bottom, and fixing the three-dimensional vegetation net; spraying the improving mixture slurry by wet spraying to the face of the slope twice; mixing the improving mixture slurry with grass seeds well, and spraying to the face of the slope once; covering with a non-woven fabric by tying and fixing, and watering every day. The method meets the requirements of greening protection and shallow landslide protection for expansive soil slopes. The method reduces the stock of phosphogypsum, thereby reducing the occupation of cultivated land and reducing environmental pollution. In addition, the method promotes plant growth with available phosphorus in the phosphogypsum

Description

METHOD FOR PROTECTING SOIL SLOPE FROM SHALLOW LANDSLIDE BY USING PHOSPHOGYPSUM

TECHNICAL FIELD The present invention relates to the field of slope engineering, and in particular to a method for protecting a soil slope from a shallow landslide by using phosphogypsum. BACKGROUND Expansive soil contains rich clay minerals such as montmorillonite and illite, and has the characteristics of swelling with water and shrinking with water loss. Therefore, the excavation of slopes during rains is prone to gradual cracking, resulting in the landslide of the expansive soil slopes. The conventional slope protection methods include arched slope protection, grid beam slope protection, mortar rubble slope protection and other engineering measures. These methods have high cost, and their gray protection design is inharmonious with the surrounding landscape, and easy to cause secondary collapse. Phosphogypsum is a byproduct produced in the production of phosphoric acid with apatite and sulfuric acid by wet process in chemical plants. The production of 1 ton of phosphoric acid yields about 5 tons of phosphogypsum. Phosphogypsum is a powdery material with little plasticity. It is slightly acidic due to the residual phosphoric acid, sulfuric acid and hydrofluoric acid. In addition, phosphogypsum is rich in available phosphorus, which can be used for plant growth. China produces more than 8 million tons of phosphogypsum every year. By the end of 2011, China had overstocked more than 300 million tons of phosphogypsum. If the phosphogypsum is applied to engineering design through technical measures, the overstocked phosphogypsum will be greatly reduced. This will save the land resources, avoid the collapse of phosphogypsum dams, and turn waste into treasure to give play to the benefits of phosphogypsum. Reference to cited material or information contained in the text should not be understood as a concession that the material or information was part of the common general knowledge or was known in Australia or any other country. Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. SUMMARY The present invention provides a method for protecting a soil slope from a shallow landslide by using phosphogypsum. The present invention protects the soil slope from a landslide, and reduces the stock of solid phosphogypsum waste, thereby saving the land resources and harmonizing with the surrounding ecological environment.

The present invention adopts the following technical solution: a method for protecting a soil slope from a shallow landslide by using phosphogypsum, including the following steps: (1) preparing an improver including anionic polyacrylamide and potassium chloride: weighing 1 part of anionic polyacrylamide and 1-10 parts of potassium chloride by mass to prepare the improver, where the anionic polyacrylamide and potassium chloride are solid powder; the anionic polyacrylamide has an ion exponent of greater than 20% and a molecular weight of not greater than 3 million; (2) preparing a mixture including phosphogypsum, fly ash and soil: weighing 19 parts of phosphogypsum, 1part of fly ash and 40-50 parts of soil by dry mass, and mixing well to obtain the mixture, where the soil in the mixture is expansive soil, cohesive soil, silt, loam or planting soil; (3) preparing an improving mixture slurry: blending each 1 m 3 of the mixture with 5-27.5 kg of improver to obtain an improving mixture, and adding water to prepare the improving mixture slurry, where not less than 2.5 kg of anionic polyacrylamide is added to each 1 m3 of the mixture, and the water is added until the improving mixture slurry is thin enough to be sprayed from a spray pipe by greening wet spraying; (4) laying a three-dimensional vegetation net: leveling an excavated slope; constructing an intercepting ditch on a crest of the slope, a drainage ditch on a toe of the slope and a drainage groove on a face of the slope; laying the three-dimensional vegetation net on the face of the slope from top to bottom, and fixing the three-dimensional vegetation net, where the three-dimensional vegetation net extends 40-80 cm on the crest of the slope to be buried in the soil and compacted; a longitudinal/transverse tensile strength of the three-dimensional vegetation net is greater than 1.0 kN/m; and (5) spraying the improving mixture slurry and sowing: spraying the improving mixture slurry by wet spraying to the face of the slope twice from top to bottom and left to right with a thickness of 4 1 cm each; then mixing the improving mixture slurry with grass seeds well, and spraying to the face of the slope once with a thickness of 4 1 cm; covering with a non-woven fabric by tying and fixing, and watering every day, where the total thickness of the sprayed improving mixture slurry on the face of the slope is not less than 10 cm; not less than 25 g of grass seeds are sown per square meter of the face of the slope. Advantages of the present invention: The protection method is simple in construction. The method meets the requirements of greening protection and shallow landslide protection for soil slopes, such as expansive soil, red clay, silt and gravelly soil slopes. The method reduces the stock of solid phosphogypsum waste, thereby reducing the occupation of cultivated land and reducing environmental pollution. In addition, the method promotes plant growth with available phosphorus in the phosphogypsum, thereby turning waste into treasure.

Applications of the present invention: Greening protection and shallow landslide protection of slopes in highway and railway engineering, etc. DETAILED DESCRIPTION Example: a method for protecting a soil slope from a shallow landslide by using phosphogypsum, including the following steps: (1) Prepare an improver: weigh 300 kg of anionic polyacrylamide and 600 kg of potassium chloride to prepare 900 kg of improver. (2) Prepare a mixture: weigh 38 t of phosphogypsum, 2 t of fly ash and 94 t of loam by dry mass, and mix well to obtain 134 t of mixture. (3) Prepare an improving mixture slurry: mix 134 t of mixture with 900 kg of improver to prepare an improving mixture, and add water to obtain the improving mixture slurry, where the mixture has a bulk density of 1.4 g/cm3 .

(4) Lay a three-dimensional vegetation net: level an excavated slope; construct an intercepting ditch on a crest of the slope, a drainage ditch on a toe of the slope and a drainage groove on a face of the slope; lay and fix a three-dimensional vegetation net on the face of the slope, where the three-dimensional vegetation net is laid on the face of the slope from top to bottom, and extends 60 cm on the crest of the slope to be buried in the soil and compacted. (5) Spray the improving mixture slurry and sow: spray the improving mixture slurry by wet spraying to the face of the slope twice from top to bottom and left to right with a thickness of 4 cm each; then mix the improving mixture slurry with grass seeds well, and spray to the face of the slope once with a thickness of 3 cm; then cover with a non-woven fabric by tying and fixing, and water every day.

Claims

What is claimed is: 1. A method for protecting a soil slope from a shallow landslide by using phosphogypsum, comprising the following steps: (1) preparing an improver comprising anionic polyacrylamide and potassium chloride: weighing 1 part of anionic polyacrylamide and 1-10 parts of potassium chloride by mass to prepare the improver, wherein the anionic polyacrylamide and potassium chloride are solid powder; the anionic polyacrylamide has an ion exponent of greater than 20% and a molecular weight of not greater than 3 million; (2) preparing a mixture comprising phosphogypsum, fly ash and soil: weighing 19 parts of phosphogypsum, 1part of fly ash and 47 parts of soil by dry mass, and mixing well to obtain the mixture, wherein the soil in the mixture is expansive soil, cohesive soil, silt, loam or planting soil; (3) preparing an improving mixture slurry: blending each 1 m3 of the mixture with 5-15 kg of improver to obtain an improving mixture, and adding water to prepare the improving mixture slurry, wherein not less than 2.5 kg of anionic polyacrylamide is added to each 1 m 3 of the mixture, and the water is added until the improving mixture slurry is thin enough to be sprayed from a spray pipe by greening wet spraying; (4) laying a three-dimensional vegetation net: leveling an excavated slope; constructing an intercepting ditch on a crest of the slope, a drainage ditch on a toe of the slope and a drainage groove on a face of the slope; laying the three-dimensional vegetation net on the face of the slope from top to bottom, and fixing the three-dimensional vegetation net, wherein the three-dimensional vegetation net extends 40-80 cm on the crest of the slope to be buried in the soil and compacted; a longitudinal/transverse tensile strength of the three-dimensional vegetation net is greater than 1.0 kN/m; and (5) spraying the improving mixture slurry and sowing: spraying the improving mixture slurry by wet spraying to the face of the slope twice from top to bottom and left to right with a thickness of 4 1 cm each; then mixing the improving mixture slurry with grass seeds well, and spraying to the face of the slope once with a thickness of 4 1 cm; covering with a non-woven fabric by tying and fixing, and watering every day, wherein the total thickness of the sprayed improving mixture slurry on the face of the slope is not less than 10 cm; not less than 25 g of grass seeds are sown per square meter of the face of the slope.