The transitions of poor ground
Poor grounds, will be examined by project study in case they will be determined grounds.
1: Poor Grounds.
2: According to YFŞ (Roads Scientific Specification ), are all diggings materials which are not suitable for given conditions in table 14/1 at 14th Section (fillings)
2: Poor grounds are the grounds that they do not carry without problems in safe and economic way during plant of the upper composition of the road and road compositions (filling,splitting, bridge, viaduct, tunnel etc. ) with considering to be showed in Ground Mechanic and Geotechnical report.
3: Poor grounds are artificial fillings that formed without controls and loose thin sandy alluvion , where the YASS ( underground water level) is high, and includes clayey, siltly organic grounds.
Determination poor grounds
The poor grounds, in general, have been located where the slope of the road is small in length and in width, and formed surface laking , and realized the discharge of underground and surface waters in long tulle. The poor grounds must be examined as follows.
According to the performed studies for Geotechnical (drilling, the research sunk, the surface geology) the poor grounds under the railway and railway buildings that will locate, primarily; must be determined :
-their attributes (CL, CH, OH),
-Sitting properties depend on time,
- resistance, state of leaning parameters that affect the stability,
- and inflated potential.
Advanced rehabilitation methods that explained in the article 5.4, must be projected in case by removing poor ground layer and its thickness could not be lifted and not to be thrown (the diggings stability, the difficulty of studying under water, the increasing cubage in long tulle )
In case, seeing shallow thickness of poor grounds where locateed under substructures of art bases or, at the bases of splitting or wadding, at the project stage.
-Abrasion with excavation,
-Putting new materials instead of it,
-Supporting with Geotextile, geocomposit or geogrid.
etc. suggestions must be indicated in report by making their dimensions.
In case, the level of underground water is shallow and close to the surface, in order to protect from water effect at road base (wadding or splitting road), primarily, forming drainage of mattress must be recommended.
1-Filteration criteria: ground grains which are provided their drainage, must not be blocked the drainage material.
The filteration criteria:
D15F £ 5 D85Z (D60Z / D10Z £ 1.5 ise D15F £ 6 D85Z)
D15F £ 20 D15Z (D60Z / D10Z ³ 4 ise D15F £ 40 D15Z)
D50F £ 25 D50Z
2-Permeability Criteria: The drainage material should have conductible property.
Permeability Criteria: D15F ³ 5 D15Z will be able to use.
Procerumenting the necessary material for drainage layer, one of the materials that indicated as follows by considering the its economicness.
a) thin and coarse filter materials that are given their gradiations at YFŞ.
b) in case, within boundaries project or at is round, natural thin materials is not enough, can not be available; instead of thin filter material and (at the regions of clay having high plasticity, in case there are not natural materials economicaly ) when is used half-breeded stone, geotextile that aimed drainage, in case instead of coarse filter materials, by using the following Type-I and Type-II materials which their gradiations are given:
Sieve (mm) The percentage of Passed materials:
2 1/2” (63 mm) 100
1 1/2” (37.5 mm) 85-100
3/4” (20 mm) 0-25
3/8”(10 mm) 0-5
Sieve (mm) The percentage of Passed materials:
3” (74 mm) 100
1 1/2” (37.5 mm) 70-100
3/4” (20 mm) 40-100
3/8”(10 mm) 20-70
No:4 (5 mm) 0-40
No:8 (2.5 mm) 0-12No:200 (0.074 mm) 0-3
c) By using Sand Mattress that its gradiation is given at YFŞ Section 11, in case sand mattress is not economic, with the determining distributions of drainage material and ground grain dimension, economic drainage materials which are satified filteration and permeability criteria, must be used.
Note: The kinds and properties of geotextile, geocomposite, geogrid and seperators, will be selected according to the kinds and properties of grounds that they will apply.
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