Obviously, in this case, the anti-seepage of the dam body is unsafe.
For homogeneous earth dam, clay anti-seepage is the best choice of traditional methods.
At this time, the permeability line decreases slightly after passing through the geomembrane.
Contact telephone: fifteen billion eight hundred and sixty-five million nine hundred and thirty-two thousand one hundred and eighty-six fifteen billion one hundred and sixty-six million nine hundred and twenty-three thousand two hundred and sixty Email: 3627924241@qq.com (1) When the geomembrane is relatively complete, it is assumed that the equivalent permeability coefficient of the impervious layer is k = 5e-8m / s, which is equivalent to the 50cm thick impervious clay inclined wall on the upstream dam slope.
(2) When the geomembrane is seriously damaged, it is assumed that the equivalent permeability coefficient of the impervious layer is k = 5e-5m / s.
For reservoir dams with medium and low water heads, composite geomembrane can also be used for anti-seepage (composite geomembrane is also used for horizontal cladding and covered with clay “sand”.
After passing through the geomembrane, the phreatic line has dropped to a very low elevation, and the elevation of the seepage overflow point is 489.19m, which is lower than the elevation of the downstream reverse pressure flat abutment top.
The seepage flow per unit width is only 2.54-4m3/s, which is the daily seepage flow of the whole dam length The volume is 10350m3.
The traditional anti-seepage method of reservoir dam is closely related to the geological conditions of dam foundation and the form of dam structure.
There is leakage at 500.38m of the downstream slope, which is 5.38m higher than the reverse pressure platform.
Taking the water level of the water surface elevation of the sump at 488m as the boundary condition, the elevation of the escape point, flow per unit width and long-term seepage of the whole dam under three working conditions of intact, serious damage and complete damage are calculated.
(3) When the geomembrane is completely damaged, it is assumed that the equivalent permeability coefficient of the impervious layer is the same as that of the rockfill body, k = 6e-4m / s, that is, without the impervious layer, the seepage escapes at 503.70m on the downstream slope, 8.70m higher than the reverse pressure platform.
at this time, the impervious layer is moderately permeable, but the thickness is only 0.5m, and the water blocking effect is very limited and almost completely damaged.
The seepage flow per unit width is 1.03-3m3/s, and the daily seepage flow of the whole dam length is 41957m3, so the seepage flow is large and the dam anti-seepage is unsafe.
The anti-seepage of sand gravel dam or sand dam shall be compared with the planning scheme of local building materials, such as excavating foundation trench and filling clay core wall and clay inclined wall for anti-seepage; There is also high-pressure jet grouting to prevent leakage; There are also diaphragm walls and clay core walls (or inclined walls) to prevent leakage; However, due to the development of geotechnical building materials, a new choice is provided for us, that is, composite geomembrane for anti-seepage, including underground diaphragm wall and composite geomembrane (the foundation part adopts underground diaphragm wall and the dam part adopts composite geomembrane), or high-pressure jet grouting composite geomembrane (the foundation part adopts high-pressure jet grouting and the dam part adopts composite geomembrane).
The seepage flow per unit width is 8.43-4m3/s, the whole The daily seepage flow of each dam length is 34413m3, which is relatively large.
(4) According to the leakage at the downstream of the dam, the leakage escape point is on the slope of the back pressure platform, the escape elevation is relatively low, and the daily leakage is only about 12000m3 / day, which is close to the relatively complete geomembrane calculation results, indicating that the geomembrane is not seriously damaged…
