Schmertmann.xls

SECTION 2.0 SETTELMENT CALCULATION 2.1 Schmertmann's Method ◈ Schmertmann's method (Schmertmann, 1970, 1978; and Schmertmann et al., 1978) is a popular and useful technique for computing the settlement of footings on cohesionless soils. ◈ This method is more precise than either th Modified Meyerhof or Burland and Burbidge methods because: - It is based on cone penetration test (CPT) data, which has much greater resolution and precision than the standard penetration test (SPT). (It's also possible to use this method with other data, including the SPT) - It allows the engineer to divide the soil into layers and assign a different modulus to each layer, while the other methods require a single N60 value. This is especially useful in complex soil profiles. - This method considers the relative importance of each layer through the use of strain influence factors. (Eq. To compute the magnitude of this factor for each layer.σ'vo) σ'zp= effective overburden pressure at foundation level (depth = Df + B/2 for square and circular footings. D + B for continuous footings) zf = depth below bottom of footing . whicherer is shallower. as shown in Fig. 1) Izp = peak strain influence factor q' = net bearing pressure (= q .5 + 0. it is first necessary to determine the peak value. of the soil and its variation with depth.1. STEP-2 Consider the soil from the base of the footing to the depth of influence below the base of to an incompressible strata.2 Schmertmann's Procedure STEP-1 Perform appropriate in-situ tests to determine the modulus.1 √ (q' / σ'zp) where.2. STEP-3 The strain influence factor varies with depth. Es. Izp : ▶ Izp = 0. . STEP-4 Compute the strain influence factor at the midpoint of each layer: STEP-5 Compute the settlement ▶ δ = C1 x C2 x C3 x q ' x Σ (Izi x Hi / Esi) where. 2) .03 .1) C3 = shape factor = 1.5 (σ'vo / q') C2 = creep factor = 1 + 0.73 q' = net bearing pressure (q .0.0. δ = settlement of Footing C1 = depth factor = 1 .2 log10(time in years / 0.03 L/B ≥ 0.σ'vo) Hi = thickness of soil layer I Esi = modulus of soil layer i Izi = Iz at midpoint of soil layer i σ'vo = effective stress at a depth Df below the ground surface (Eq. 0 m 18 kN/m3 - 2 Weathered Limestone (WSL) > 10. and Simsima Limestone "SL".5 m .0 m 20 kN/m3 50.8m) during site construction work. . tall tower.0 MPa 3 Simsima Limestone (SL) 24 kN/m3 4900. etc. 99.95 QNHD (= EL. Sect. The most of the "RS" layer will be removed to the level of +2. 3. Weathered Simsima Limestone "WSL".3 Soil Design Parameters ◈ For Soil Properties (refer to Foundation Design Basis.2. "RS" is a thin layer of unconsolidated gravely sand overlying limestone.1. Therefore. ◈ Also. Engineering fill will be used to replace the deleterious natural material or to raise natural ground surface elevations to required levels. they are Residual Soil "RS".0 MPa ◈ Three different types of strata exist at the project site. Table 1) Layer Description thick of layer Bulk Density Elastic Modulus 1 Residual Soil (RS) 0. settlement for important equipment (heavy equipments.) will be occurred in this filling layer. 0 MPa 3 Simsima Limestone (SL) > 10. (Soil Design Parametes for Settlement Calculation) Layer Description thick of layer Bulk Density Elastic Modulus 1 Engineering Fill ≤ 5.0 m 19 kN/m3 25.◈ Conclusion On the basis of the above mentioned.0 m 20 kN/m3 50.0 m 24 kN/m3 4900.0 MPa 2 Weathered Limestone (WSL) > 10. the soil design parameters for settlement calculation will be taken as following Table.0 MPa . : Square (SQU) and Circular Footings (CIR) L/B ≥ 10.00 m 2.2.50 m 30.00 m 2. : Continuous Footings (CON) 1< L/B < 10.3 Settlement Calculation ▶ Footing dimension Width (B) Length (L) Depth (Df) hf L/B Footing Shape 2.00 m 12 CON ▶ Footing shape L/B = 1. : Rectangular Footings (REC) . hf) : For hf < Df + B σ'zp(con) = γs x (Df + B) : For hf > Df + B ▶ Bearing pressure at bottom of footing (q) -q= 150.σ'zp(con) = where.σ'vo = 38.γw) x (Df .00 where.00 kN/m2 .0 m ▶ Effective stress at a depth Df below the ground surface (σ'vo) . 12. σ'zp(squ) = (γs x hf) + (γs .00 kN/m2 .hf) ▶ Initial vertical effective stress at a depth of Izp (σ'zp) .γw) x (Df + B/2 . For Case-1 : σ'vo = (γs x Df) kN/m2 For Case-2 : σ'vo = (γs x hf) + (γs .σ'zp = 61.hf) : For hf < Df + B/2 σ'zp(squ) = γs x (Df + B/2) : For hf > Df + B/2 61.γw) x (Df + B .50 kN/m2 : (For Square Shape Footing) where. .0 m Square or Rec Shape = Df + 2B = 7.▶ Depth of influence = where.0 m Continuous Shape = Df + 4B = 12.00 kN/m2 : (For Continuous Shape Footing) σ'zp(con) = (γs x hf) + (γs .σ'zp(squ) = 49. 0.830 ▶ Secondary creep factor (C2) .C2 = 1 + 0.▶ Peak strain influence factor (Izp) .340 ▶ Time since application of load (yr) -t= 50.03 (L / B) ≥ 0.730 .5 (σ'vo / q') = 0.1 √ (q' / σ'zp(squ)) = 0.Izp(con) = 0.650 .1) = 1.0.0 year (t ≥ 0.0.1 √ (q' / σ'zp(con)) = 0.73 = 0.636 ▶ Depth factor (C1) .5 + 0.5 + 0.1 yr) ▶ Shape factor (C3) .03 .C1 = 1 .C3 = 1.Izp(squ) = 0.2 log10 (t . 9 6.6 8.79E-06 1.8 4.66E-06 1.0000 0.5844 0.6 9.0 5.2963 0.25E-06 1.08E-06 4.5379 0.1947 0.1 7.3 7.8 10.20 0.3916 0.0000 0.1562 0.0000 0.6 5.4 8.5164 0.9 8.4317 0.6179 0.08 3.2 7.8 5.28 0.51740 0.24 0.0000 0.Top Bottom Es (m) (m) (kN/m ) 0.0 3.1 3.6007 0.2793 0.92 1.5 7.9 1.3978 0.81E-06 5.2950 0.20 0.2963 0.2523 0.20 0.4 4.41E-06 3.09486 0.36 2.20E-06 2.27E-06 2.38161 0.16 1.1 6.20 0.2 2.2 6.11E-07 6.04 2.27976 0.20 0.1778 0.2624 0.96 2.24581 0.3 4.9 3.20 0.2256 0.1947 0.1778 0.3640 0.44 2.13610 0.20 0.4317 0.6 2.2871 0.3219 0.4148 0.25E-06 4.32E-06 1.2624 0.60214 0.43E-07 0.0 9.0000 0.5841 0.1 4.19384 0.3644 0.20 0.0 7.20 0.6349 0.22683 0.4148 0.00 3.2116 0.4656 0.1 1.6 3.0 4.44 0.13E-06 2.8 4.23508 0.4 3.55135 0.93E-06 1.12 2.00E-06 1.18559 0.6 7.41556 0.4 5.05E-06 9.5333 0.5727 0.5658 0.1215 0.0000 0.5671 0.59E-06 1.8 7.20 0.21034 0.19E-06 1.7 6.5032 0.2286 0.4 7.9 4.6010 0.2 4.24 1.3568 0.8 6.6349 0.16 3.46E-06 1.94E-06 4.2 4.2116 0.48345 0.56 1.11960 0.3297 0.0 3.20 0.4 7.0000 0.68 2.3568 0.20 0.3219 0.5502 0.7 3.73E-06 1.8 9.3471 0.20 0.2 3.20 0.20209 0.2 6.9 7.2 9.5 0.8 10.4656 0.1 5.2 5.8 5.3 6.76 2.81E-06 2.0000 0.16909 0.0 8.5 4.3 0.20 0.3 5.58E-06 2.4994 0.6 5.4 6.6 3.6007 0.3202 0.20 0.8 3.0000 0.20 0.0000 0.08661 0.0 6.02E-06 2.04 0.20 0.5 3.1608 0.85E-06 3.46E-07 7.4 9.12E-06 1.4685 0.2 3.2 7.4486 0.24333 0.58564 0.7 2.53E-06 4.21858 0.88 1.3301 0.20 0.6 8.6179 0.21186 0.5658 0.8 8.28457 0.4961 0.3 1.30E-06 2.36 0.4082 0.6 6.3991 0.82E-07 9.2455 0.84 0.20 0.69E-06 3.72 1.8 9.16084 0.39E-06 1.80 1.07E-06 2.2455 0.4265 0.20 0.0000 0.1608 0.2 2.2321 0.5310 0.5671 0.5 1.52 2.07836 .2174 0.48 1.0000 0.4 4.4338 0.3132 0.8 8.5 2.4 6.6 2.20 0.20 0.3471 0.1 0.4613 0.6010 0.0 2.20 0.5333 0.52 0.8 7.44951 0.64 1.58530 0.61863 0.13E-06 3.3916 0.6421 0.84 2.4963 0.2871 0.2603 0.0 7.7 4.3809 0.12 0.1909 0.34766 0.4 3.86E-06 1.0 2.9 2.6 4.3301 0.4825 0.2174 0.15260 0.20 0.3809 0.3978 0.20 2.1440 0.92 3.5164 0.5502 0.8 6.00 1.74E-06 2.6 9.20 0.7 1.20 0.14435 0.20 δ (mm) 1.20 0.4994 0.0 4.4825 0.76 0.6 6.2 5.20 0.7 5.4 2.25158 0.5 5.11135 0.2 8.27632 0.0 9.60 0.2286 0.20 0.2793 0.5841 0.7 7.0868 0.1 2.3640 0.4265 0.0521 0.6074 0.0000 0.17734 0.5310 0.6 7.0174 0.20 0.28 2.6 4.4 2.2 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 25000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 zf / B Iz(squ) Iz(con) Izi (m) Hi Izi Hi / Es (m) 0.0 zf 2 2.0 5.26807 0.20 0.25983 0.20 0.1 0.0000 0.10311 0.20 0.4613 0.4 9.5 6.20 0.20 0.20 0.60 2.4 8.14E-07 8.0 2.4 5.8 3.79E-07 7.2 8.40 1.4486 0.34E-06 2.4961 0.08 1.31371 0.97E-06 4.3132 0.0 10.0000 0.7 0.68 0.3 3.20 0.0 6.3 2.20 0.2523 0.52E-06 1.32 1.20 0.0000 0.20 0.9 5.12785 0.0 8.2 9. 0 11.72 3.69E-07 1.20 0.96 #VALUE! #VALUE! 0.3 8.1100 0.7 8.64 3.20 #VALUE! #VALUE! 5.06186 0.20 0.8 11.1 9.20 0.7 9.6 10.76E-07 5.0000 0.0000 0.0762 0.0000 0.20 0.40 3.0000 0.40E-07 3.8 11.6 11.2 10.03712 0.72E-07 3.05E-07 2.4 10.0931 0.9 #VALUE! #VALUE! 3.8 12.4 11.2 11.0000 #VALUE! #VALUE! 0.00412 #VALUE! #VALUE! 11.0931 0.39E-08 #VALUE! #VALUE! Σtotal δ = 0.0423 0.1439 0.1270 0.2 11.04537 0.20 0.642 mm .1100 0.5 9.0085 #VALUE! #VALUE! 0.0593 0.3 9.0423 0.0254 0.6 11.8 12.08E-07 4.37E-07 1.4 11.20 0.88 3.01237 0.0593 0.0254 0.0085 #VALUE! #VALUE! 0.0000 0.80 3.0 N/A ! 10.20 0.0 11.10.1270 0.4 10.56 3.0762 0.05361 0.9 9.48 3.02062 0.0000 0.0000 0.02E-07 3.0 N/A ! N/A ! 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 50000 8.6 10.02887 0.07011 0.5 8.20 0.32 3.0000 0.1439 0. 0 RESULT SUMMARY FOR SETTELMENT CALCULATION .SECTION 3. Story drift with maximum inelastic response displacement have been checked as per UBC 97 1630. Due to above revision. 2 2. TSP/PJ/013-HS/TP-M0037 dated December 22. The revised piping loading data have been incorporated. 0 3. . 1999 and the revised loading data.1) have been made to incorporate TSP comments.REVISION NOTES This revised calculation notes (Revision No. 9. the computer output and review results of structural analysis have been partially revised. Major revision are as follows : 1. which led to a change of member size and geometry in Rev.