Pile raft foundation - soil parameters

G

Godfrey

New Member
Hello, I'm a bit lacking in this regard as I haven't solved a project with a pile raft foundation against many previous projects. Without further ado, how can I calculate and obtain the following parameters for data entry into IdeCAD. The geology firm that made the ground survey said that it is not our job to give these parameters and they went out of business. They've even just heard of one. - Vertical spring factor (kv) (t/m3) - Adhesion factor - Undrained shear resistance (t/m2) The data I have; - Soil type: The upper levels are large and small, the rock quality is low-medium strength, the rock quality rises towards the bottom, the unit with high strength limestone features - Soil safe bearing capacity: qem = 2.00 kg/cm2 - Soil group: B - Soil class: Z2 - Ground bearing coefficient ks: 10000 t/m3 - Internal friction angle (fi) = 35 degrees - Cohesion C = 3 kg/cm2 Thank you to everyone who has already guided me and have a good day.
 
Undrained slip resistance (strength) = Cohesion (will be effective) Adhesion factor: 1/3 of the internal friction angle can be taken. There are formulas for Kv= Vertical spring factor. If the geological engineers used the Spt test in the ground survey, you can calculate the above parameters with the N value here.
 
"levent":1zsu73fg" said:
Undrained slip resistance (strength) = Cohesion (will be effective) Adhesion factor: 1/3 of the internal friction angle can be taken. Kv= Formulas for vertical spring factor. If geological engineers used the Spt test in their soil survey You can calculate the above parameters with the N value here.
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Hello Mr. Levent. The adhesion factor in the document suggested by Hakan in the link below gives a slightly different result compared to the approach you suggested, so I am a bit confused. In my project, the internal friction angle is 35 degrees. The cohesion value is 3 kg. /cm2.Do I need to get the adhesion factor 0.40 - 0.45
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Hello again friends, I am stuck in calculating the vertical bearing coefficient for piled raft foundation. Project data; - There is only one kind of layer under the foundation. - ks = 10000 t/m3 - Pile diameter D = 65 cm - Pile length L = 10 m
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According to the vertical end bearing formula (Eq.11) in the document (pile foundations_21-bf-7silva.pdf) suggested by Hakan in the link above (D* = according to the article) normalizing pile diameter to be taken) Kvb = ks x (D/2) x L x (D/D*) = 10000 x (0.65/2) x 10 x (0.65/1.8) = 11736.11 is reached, but the value of the unit of the vertical bearing coefficient Shouldn't it be tf/m3? According to the formula, rather than the value, it turns out to be unit t/m. Was I making a mistake somewhere, I couldn't figure it out.
 
viewtopic.php?f=5&t=1085&hilit=adhesion&start=240 Again according to the vertical skin friction resistance stiffness formula (Eq.12) in the document suggested by Hakan in the above link (pile foundations_21-bf-7silva.pdf) Alpha for a single spring model at the bottom When 1 is taken (single vertical spring at bottom of piles); Es-tip : Modulus of elasticity of the end soil layer according to the soil survey report = 29319.89 kg/cm2 = 293198.9 t/m2 Ep: Elasticity modulus of piles from C20 concrete class 2909703.299 t/m2 Kvfi = 1.8 x Es-tip x (L/D) x (Ep/Es-tip)^(0.5 - (Ep/Es-tip)/(L/D)) x 1 = 1.8 x 293198.9 x (10/0.65) x (2909703/293198.9)^(0.5 - (2909703/) 293198.9)/(10/0.65)) x 1 = 1.8 x 293198.9 x 15.38 x 9.92^(0.5 - 9.92/15.38) x 1 From this formula, the unit of the other component of the vertical bearing coefficient is t/m2. As a result, I could not get out of the way of calculating the vertical bearing coefficient.
 
Hello, (pile foundations_21-bf-7silva.pdf) according to the vertical end bearing stiffness formula (Eq.11), it is explained how Kvb can be calculated as the vertical spring constant (tf/m). You don't need to make such a calculation because the program already calculates it. The value you will give in the ground layers is the parameter used to calculate this. Its unit is tf/m3. We can call it a kind of vertical horizontal coefficient. The vertical spring constant is calculated with the following formula in the program. Ki (tf/m) = LateralPileArea (m2)* Kvertical (tf/m3) You must give the K-Vertical (tf/m3) in the soil layers to the program. Regarding this, you can also check the link below.
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Thank you for your interest Mr. Hakan. Finally, is there an empirical approach or formula you can suggest for Kdusey? In the document in the link below, an approach for Kv is suggested (p-21-22), but I was not sure of its usability.
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