What are the dam materials and filling standards?

Damming material

(1) Seepage body 1) Permeability coefficient of impervious soil ①: homogeneous dam is not more than 1× 10-4 cm/s, and core wall and inclined wall are not more than 1× 10-5cm/s②. ③ Organic matter content: the homogeneous dam is not more than 5%, and the core wall and inclined wall are not more than 2%. If you exceed this requirement, you need to demonstrate. ④ It has good plasticity and permeability stability. ⑤ The volume changes little when soaking in water and losing water. 2) Gravel soil impervious body Gravel soil, or gravel cohesive soil, is a mixture containing a large amount of coarse gravel soil (particle size greater than 5mm) and a certain amount of elutriation soil (particle size less than 5mm). The content of particles larger than 5mm shall not exceed 50%, the maximum particle size shall not be greater than 150mm or 2/3 of the paving thickness, and the content of particles below 0.075mm shall not be less than 15%. In addition, the phenomenon of concentrated overhead of coarse materials is not allowed during filling. Practice has proved that well-graded gravel soil has good compactness, high shear strength, low compressibility and convenient construction, and is an excellent dam building material. 3) In general, other impervious materials, such as alluvial clay, expansive soil, hard clay, frozen soil and dispersed clay with plasticity index greater than 20 and liquid limit greater than 40%, are not suitable as impervious filling materials for dams. When they must be used, corresponding measures should be taken according to their characteristics.

(2) The dam shell material should have high strength. Good drainage performance is required. Cohesionless soil materials, such as sand, gravel, pebbles, boulders and crushed stones, as well as mined stones and excavated slag materials, can be used as dam shell materials, but they should be arranged in different parts of the dam shell according to their properties.

(3) Filter material, filter material and drainage material 1) The filter material, filter layer material and drainage material shall be dense, hard, water-resistant and weather-resistant. Weathered materials generally cannot be used as filter materials. 2) The material shall have the required gradation and water permeability, and the content of particles with the particle size less than 0.075mm in the filter material and drainage material shall not exceed 5%. 3) Natural gravel materials should be used as much as possible for screening. When natural gravel materials are lacking, manual rolling can also be used, but parent rock materials with strong water resistance and weathering resistance should be selected. 4) Geotextile can be used as the filter layer of the third-stage low dam.

Filling standard

(1) The filling standard of cohesive soil should take compactness and optimum water content as design control indexes. The design dry density shall be obtained by multiplying the maximum dry density of compaction by the degree of compaction. The compactness of cohesive soil shall meet the following requirements: 1) 1 grade, the compactness of grade 2 dam and high dam shall be 98% ~ 100%, and the compactness of grade 3 middle dam and middle dam below grade 3 shall be 96% ~ 98%; 2) In areas where the designed seismic intensity is 8 degrees and 9 degrees, the above specified values shall be taken;

(2) The filling standard of gravel, gravel and sand should take the relative density as the design control index and meet the following requirements: 1) The relative density of gravel should not be less than 0.75, the relative density of sand should not be less than 0.70, and the relative density of filter material should be 0.70. 2) When the content of coarse particles in gravel is less than 50%, the relative density of fine particles (particles with particle size less than 5mm) should also meet the above requirements.

(3) Taking porosity as the design control index in the rockfill filling standard, the following requirements should be met: 1) The porosity of rockfill materials for earth impervious partition dams and asphalt concrete core dams should be 20% ~ 28%; 2) When soft rock and weathered rock are used for dam construction, the porosity should be determined according to the requirements of dam deformation, stress and shear strength. 3) In areas where the design seismic intensity is 8 degrees and 9 degrees, the small value of the above porosity can be taken.

I believe that after the above introduction, everyone has a certain understanding of dam construction materials and filling standards. Welcome to Zhong Da for more information.

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