Spt n value to kpa

Spt n value to kpa. Engineering judgment should be used in selecting a specific value. e. 7106 and 0. So, SPT-N value obtained is lower than actual value. 1. Figure 4. Figure 3. 2 is in kN/m or kPa. 2 MPa with a mean of 7. 60), the borehole diameter is #BearingCapacityofSoil #SPTNValues #BowlesEquationIn this video you will be able to learn about the calculations of the Bearing Capacity of soil using SPT N Jun 1, 1988 · De Mello (1971) found a correlation between the internal friction angle, N-value, and overburden stress, σ, based on laboratory test data (using 24 1. The ultimate end bearing capacity of a single pile (Xu and Lehane, 2005) is estimated from; Q b = C b q c-av A b ——– (7). 89 to 472. 3. Measured SPT values in the field (N) at each depth (z) will be corrected to (N 1) 60 values using the equation below. Here, f 2 is a factor depending on plasticity index. Civil Engineering questions and answers. (See Fig-2). The generated correlation N 1 The average corrected SPT blow count within the seat of settlement (corrected to 1 tsf of overburden pressure) N p Average SPT N-value within a distance of 1d beneath the pile tip and 3. The Nspt-Su correlation is fraught Example 1: Determine soil bearing capacity by SPT numbers (English units) Given. Cohesion. 14 Comparison of historic reported correlations between SPT N-value and undrained shear strength May 13, 2013 · For p 0 <= 75 kPa. Unlike the old correlation models only required soil type and N-value to predict Su Jul 3, 2013 · Mccoy (Geotechnical) 3 Jul 13 16:32. C BF. C R. 22. C N. N 60 (N 1) 60 The standard penetration test is a simple in-situ test in which the N-value is the mumber of blows taken to drive a 50mm diameter bar 300mm into the base of a bore hole. 21. 4) Guess a pad or strip footing width to be used. 5B up to at least D + 2B), considering an energy ratio of 55%. The SPT N values are between 2 blows per foot (bpf) and 60 bpf with an average of 23. 33 (D/B) = 1+0. 200 (75 µm) sieve. research: SPT N (blows/0. C S. , unit weight γ, relative Aug 1, 2018 · Also, the cohesion values varied between 5 and 265 kPa. Feb 1, 2023 · Table 5 shows the correlation between the average unit shaft friction and its corresponding SPT-N value. For p 0 > 75 kPa. For moderately weathered SIII, high value of f s more than 500 kPa can be May 5, 2019 · SPT conversion to N60 and N1,60. 6 MPa with an average of 10. There have been many attempts by researchers to relate the SPT N value to the CPT cone penetration resistance q c. Mathematically, this is expressed as; ks = q/δ ——- (1) Where; ks = Coefficient of subgrade reaction expressed in force/length 2 /length. There are more advanced tools available that provide a better model for the behavior and The results revealed that the corrected SPT N-value (N55) ranged between 3 and 34. However, the coarser soil layer As 1 and As 2 the coefficient of correlation (R 2 ) are 0. f1 = 4. 8 kPa) and approximately 97 percent RC based on the modified Proctor compaction energy. (2004) correlations have a median value of 144 m/s for clean sand case histories in the SPT database and 150 m/s in the CPT database, compared to median values of 130 and 166 m/s for the SPT and CPT databases, respectively, using the Wair et al. 32 MPa to 19. From Jul 1, 2016 · The N-SPT values and Vs values were obtained from the same boreholes between 2005 and 2012. Civil Engineering. The values of N c obtained from [9,10,11] are used in estimating q a. 2. However as N-values measured in clay layer provide rough estimate values only to judge shear strength and softness, they should be carefully considered when actual designs are applied. According to the SPT-N values, most of the soils Jan 1, 2015 · Good agreements between finite element analysis (FEA) results and field observations were obtained by assuming the E 50 stiffness value to 2500N (kPa) (N is the SPT value), the small-strain shear Feb 20, 2020 · In this paper, an attempt has been made to propose a generalized correlation between shear wave velocity (Vs) and SPT-N values for all soil types for generalized depth using the concepts of regression. Around 40 correlations have been compiled and applied for estimating the shear wave velocity (Vs) correlation for the region and also to address the uncertainty issue. Other values I have seen range from 9 to 14 kPa for this type of deposit. 13 + 6. Also, the cohesion values varied between 5 and 265 kPa. In most of the correlations, with exception of correlations (Hayati and Andrus, 2009), the independent variable is the ratio q c/Pa/NEr where qc is the cone tip resistance, Pa is a reference pressure of 100 kPa and NEr is SPT N values with Er is the energy ratio of the hammer used in the test. The Australian code has this correlation. Requirement: Estimate allowable soil bearing capacity based on. 7 bpf and a coefficient of variation of 0. As a result, for the SPT-N values ranged from 4 to 44, the predicted soil cohesion and angle of internal of friction increased from 17 kPa to 281 kPa and 4o to 38o respectively. . 001 kPa. values were derived from SPT-N. 3 times and generally varies from 3 . 057 log10(DCPI60) To know the variation of the CBR value across the depth, draw another semi-log chart with CBR values on logarithmic scale as abscissa (x axis) and depth of penetration on ordinary scale as ordinate (y axis). These developed The limiting f s = 150 kPa as suggested by the Code is conservative especially for soil with higher SPT ‘N’ value. For soil, the adopted Ks value is 2. 92 MPa and a coefficient of variation of 0. Thirteen correlations follow the power law form V s = a × N b while utilizing the uncorrected SPT-N values in the analysis, while Pitilakis et al. There are 2 steps to solve this one. RSPile uses the relationship between standard penetration test values and angle of internal friction (ϕ' ) as presented Apr 25, 2017 · This study is an attempt to evaluate relative density and friction angle of sands on the basis of SPT-N values. 55 (log SPT)-0·26 N = 19 R2 = 0. 3m), CPT (MPa) and sleeve resistance fs (kPa). Furthermore, a questionnaire ( Table 5 ) is prepared to collect information on the SPT procedure and equipment so that the reliable corrections and correlations An example profile of measured SPT N-values from a boring by the Vermont Agency of Transportation (VTrans) is presented in Figure 5-3. Outside diameter OCR Overconsolidation ratio q p Bearing pressure q limit Limiting point Nov 19, 2003 · The range of values were from 8 to 35 kPa over a depth of 20 metres. There is an option to specify SPT N values with depth in order to calculate the friction angle for some methods mentioned above. In Figure 1, angle of driving shoe of standard SPT spoon is 16º to 24º and the cutting edge is not sharp which gives the actual value of SPT. The most recent empirical correlations of NSPT, relative density and angle of shearing resistance of granular soils are calculated using the penetration resistance in terms of N60 (NSPT=N60 according to Cestari, 1996) or of N1,60, normalized value at a geostatic vertical pressure of 1 bar by applying the coefficient CN (Liao and Withman 1986). They tend to be of medium compressibility with undrained shear strengths varying from 50 to 300 kPa. The clays of the Middle Coal Measures normally are stiff to very stiff and range from intermediate to high plasticity. 1) where soil density (ρ) is the total unit weight of the soil divided by gravity (9. 5 MPa Nov 3, 2015 · Use the following equation and determine the corresponding CBR value of each layer. So, the PP criteria was based actually on N-values. (N 1) 60 = N' x C E x C N x C B x C S x C R x C BF. The wet density relied on moisture content Jul 25, 2006 · In this study the correlations between the SPT-N values and S u values obtained from similar depths are developed by taking account of the fine-grained soil types and SPT-N corrections. May 13, 2018 · These values of c u are used to estimate q a employing Eq. As an overall A simple rule of thumb to convert N value to permissible bearing capacity: q = 10 × N [kPa] Jul 27, 2020 · July 27, 2020. 70 which shows a moderate correlation. 5–1. 4b), in order to reduce the scattered data. (kPa) = 4. (1999) and Hasancebi and Ulusay (2007) utilized corrected N-values for their statistical analysis. The sum of the number of blows required for the second and third 6 in. r=100 KPa =2000 lb/ft2 D/B is the ratio pile embedment depth- diameter N'60 is the normalized value for the SPT, corrected for overburden pressures and field procedures. For example, bored piles in a specific locality may have the values shown in Table 3. (SPT) N-values and internal friction angle Measured blow counts may additionally be adjusted to an effective overburden pressure of 100 kPa which produces the N 1,60 value. Mar 12, 2020 · You can estimate the elastic modulus by using different correlations as a function of corrected SPT N-values and undrained shear strength, as follows: (a) E = 18 N 60 for coarse-grained materials Notably, the unconfined compressive strength ranges from 32. Judgement of Soft ground in Clay by SPT (Terzaghi & Peck, 1948) Consistency N values Unconfined compression strength(qu, kPa) Very Soft < 2 < 25 The average SPT N-value along the pile shaft is commonly utilized in different previous SPT-based correlations with pile skin friction. (2012) correlations. N' C E. 1. In order to develop the relationships among relative density (D r ), friction angle (ϕ) and SPT-N value, field and laboratory test results from sixty boreholes executed in sandy deposit were used. 2 ft/sec2). 5 for PI>40% and N=5 for PI<40%). 2657, which indicates that there is a poor correlation between equivalent SPT N 60-value and corrected SPT N 60-value. Example: convert 15 newton/square meter to kPa: 15 newton/square meter = 15 × 0. 4 MPa to 16. 48 – 1. The N-value provides an indication of the relative density of the subsurface soil, and it is used in empirical geotechnical correlation to estimate the May 1, 2024 · The SPT depth was from 3 to 22 m below ground (mbg), with an average depth of 6. 1 kPa = 1000 newton/square meter. 2019; Khalid et al. While using the value of N c from , depth factor is also applied. Q1: A standard penetration test SPT was performed on a near surface deposit of clean sand where the number of blows to drive the sampler 45 cm was 5 for the first 15 cm, 8 for the second 15 cm, and 9 for the third 15 cm. The undrained shear strength was primarily between 10 and 220 kPa with average value of 127 kPa, which covers fine-grained soil types from very soft to hard with C u mostly corresponding to soft to very stiff soils. log10CBR = 2. D = depth of testing (m) γ = unit weight of soil at the time of testing. Dec 1, 2009 · The equation for correlating SPT N to Su is. Many correlations between SPT N values and dynamic probing N d are based on comparative field measurements. Attach the cone tip, checking for damage or wear (see photo at upper right). In some cases various other factors that influence the SPT results can be taken into consideration when calculating N 1,60 such as bore-hole diameter, rod length e. This is useful in coarse granular soils where representative or undisturbed samples cannot always be recovered for laboratory testing. 0 for gravelly sands (E in MPa Sep 14, 2022 · resistance of soil layers is expressed by the number of blows, SPT N-value (N SPT), recorded for the last two 150-mm layers [3]. Mar 7, 2008 · overburden pressure (100 kPa). For residual soil with SPT-N > 100, the SPT values in penetration depth over the 100 blows was plotted with elevation (Fig. The penetration depth was ranging from 20 mm to 240 mm, with an average value of about 100 mm. This deviation between the correlations included in Table 11 reflects the complex mechanism of soil–water interactions in clays, which cannot be captured solely by the SPT N-value. • C N, overburden correction factor = (P a /σ′) 0. SPTCorr provides calculations for both N 60 and Those correlations were presented in Table 5, and they were also plotted in Figure 3 for visual comparison. The CPT q c values range from 0. For each location, the values of q a are calculated for both strip and square footings, as given in Table 1. Schmertmann (1975) has correlated N-values obtained from SPT tests against effective overburden stress as shown in the figure. Oct 18, 2016 · SPT N value is widely used as it is an index for quick strength characterization due to its simplicity. 50 to 0. Empirical relations were developed between cohesion and SPT N value, and between angle of friction and SPT N value (Brown and Hettiarachchi 2008; The data of SPT-N boreholes and (c’ and φ) has been determined by the previous contractor. This study is based on the results of a comprehensive geotechnical investigation for the Eglinton Crosstown Light Rail Transit (LRT) project in Toronto. N<2. Dec 15, 2022 · This difference becomes even greater—1191 kPa—for N-value of 100. Where. 2- Provide a cross section of the ground layers of the site based on the information given in 3 borehole logs. The spreadsheet also includes unique analysis tools which Aug 21, 2022 · End Bearing. Soil SPT number: 10. 8 to 9. Based on the previously stated study, Stroud (1974) proposed a correlation between f 2 and PI for the relation between coefficient of volumetric compression (m v) and SPT-N value as shown in Figure B. The cohesion is a term used in describing the shear strength soils. Footing type: 3 feet wide strip footing, bottom of footing at 2 ft below ground surface. 5 for silty sands and by 1. Pile design based on these average values may involve a degree of uncertainty associated with the possible soil variability along the pile shaft. For TP1 and TP2 granite, adopted parameters for unit shaft friction are 1000 kPa and 10,000 kPa for unit end bearing. This situation has led many researchers to develop other correlations to predict the c u value using N SPT average value of 90. It is Aug 12, 2008 · SPT is most often used to evaluate the in situ soil properties. (kPa) σ' (kPa) SPT N. 1 for each case. Now, after additional field data have been gathered, it is possible to determine the following rec­ ommended expression: log CBR = -5. N’ is increased from the actual blow count when p 0 <=75 kPa; N’ is decreased from the actual blow count when p 0 >75 kPa The reported values of effective friction angle (ϕ′), based on SPT N60 values, should be reduced by 5° for clayey sands and should be increased by 5° for gravelly sands. 015 kPa. 5 to 5 (depends on Plasticity Index - use N=4. 9 for jacked piles in sand; q c–av is the average cone tip resistance over a distance 1. 5 mbg. , En = 0. P 0 = over burden pressure, (kPa) = γ x D. The Vs values were obtained by the downhole seismic survey. c u (kPa) = f 1 x N 60. r) sigma v= Overburden pressure N60 is the SPT value corrected for field procedures. Jul 8, 2017 · where q a is the allowable bearing pressure for a 25-mm settlement, in kPa; D is the footing depth, in m; B is the footing width, in m; and N SPT is the statistical average value of the footing influence zone (from a depth around D − 0. Its definition is mainly derived from the Mohr-Coulomb failure criterion and it is used to describe the non-frictional part of the shear resitance which is independent of the normal stress. 1): Gmax = ρ · VS 2. In estimation of other parameters also, SPT N value is used e. v/sigma. It assumes an standard of 60% of efficiency of the penetration hammer. C B. For donut hammers C E = 0. empirical equations using SPT ‘N’ values is ranging from 0. Commonly used ones were given by Poulos (1989) for driven piles qs= 2N and qb= 400N and for bored piles qs= N and qb= 100N ( with all stresses in kPa). The purpose of plotting the graph in figure 4. Based on a series of back analyses of monitoring data, Hsiung [7] suggested a correlation between E and SPT-N as follows: (6) E = 2000 N (kPa) Stroud [19] presented a relationship between E and N values by collecting data from different soils, and he suggested that E decreases as the soil Calculate the corrected SPT values N60 and N160 for a given borehole log. A total of 22 building and 35 borings How to Convert Newton/square Meter to Kilopascal. 6 for closed-ended driven pipe piles in sand and C b = 0. Jan 1, 2011 · (kPa) SPT-N Consistency < 25 < 2 Very soft 25 - 50 2- 4 Soft 50 - 100 4 it is in fact possible to estimate the N-SPT value and derive the friction angle from results obtained from The CivilWeb Soil Bearing Calculation from SPT Value XLS Spreadsheet allows the user to estimate the bearing capacity of a soil from its SPT n value. 001 kPa = 0. The proposed equation was validated using 5 independent values and the estimated values of cohesion based on SPT-N fall in the range of of actual values. where C b = 0. 5 times the pile diameter above and the same distance below the pile base, and A b is the area more than standard SPT spoon and we get the lower value of SPT. SPT-N values increase with depth, and a similar trend was also presented by (Din et al. For N=1 our UC and Pocket pens were around 10 kPa which sits well with what big H has found. (i always use 1m and work backwards during design stage) 5) Use "Peck & Hanson & Thornburn, 1974" chart and 6) Presto you have an allowable bearing pressure!! Guide the top of the remote scale into the scale guide, while lowering the shaft through the bottom guide. 0; for trip type donut hammers; C E = 0. • C E, energy correction factor for the SPT hammer. SPT N 1 value implies the stress normalized SPT N value that was corrected for an overburden pressure of 100 kPa (1 kgf/cm 2). Geological profiles and SPT N profiles of the two newly instrumented HA sites (a) KSC; (b) SUK and five past HA sites; (c) HHE; (d) SCR; (e) TTE; (f) CWR and (g) ECW. The correlation analysis was conducted for cohesion and number of blows in SPT (SPT-N). The results also show that the unit skin friction values obtained from the SPT-T generally correlate well with SPT N 60 values. Example of SPT N-values 5. Table 2: Relationship among relative density, SPT N value, and internal friction angle of Jun 1, 2004 · This range equates to a multiplier of approximately 11, however much of this range is expected to be due to the extrapolation of the 'N' value from a discontinued SPT -defined either as (a) >30 = Recorded SPT Value N c 15, Nc = NR Correlation in SCPT Test (3) m = mass of cone = 1. Dec 1, 2016 · The value of E is also estimated using SPT correlations. Standard penetration test (SPT) N values suggest allowable bearing capacities ranging from 100 to 600 kPa. A guide to get a rough estimation of E in sands is by multiplying N by 0. SPT N 1 values of the ground before and after the treatment are measured to evaluate the improvement of the virgin in situ soil. Assume that Em = 60% (i. FRICTION ANGLE FROM SPT VALUES. In addition, SPT-N corrected values have also been obtained for all soil types within the Surfers Paradise soil profile (Table 3) Friction angle and apparent preconsolidation stress Hatanaka A weighted average is used based on the N value and its depth. Table 1. These rules of thumb are similar to equation 2. Similar plot has been adopted by Leung et al. In the stress plane of Shear stress-effective normal stress, the soil cohesion Jan 8, 2008 · Burland & Burbridge method refers mainly to shallow foundations, so I don't know whether it works well with pile problems. In this paper, SPT-based correlation with the ultimate skin Except clay the coefficient of regression value for other type of soil (all type, sand) is found in between 0. 2021). Where; N': SPT value after silty sand correction (dilatancy correction) (Terzaghi & Peck, 1948) If the below 3 conditions are present, silty sand correction should be made. Use caution to avoid pinching fingers between the hammer and anvil. SPT-T test results at 12 sites are presented. The PMT E 0 value ranges from 2. 81 m/sec2 or 32. 1 Correction Factors Since the introduction of the SPT in 1902, the drop hammer systems have evolved from pin weight to N'60= CN*N60 CN= 2/(1+sigma. The SPT, while used less frequently, is still used today. 8–1. Identify the Standard Penetration Test (SPT) N-values from the borehole logs; these values are used in geotechnical engineering May 11, 2000 · sigma. 2 N 60 for PI>30, C U (kPa) = 4-5 . t. , for estimation of shear wave velocity, bearing capacity etc. IJR, in addition to fattdad's sensible analysis, I'd say that given only SPT values in a clay layer you might input the SPT value in correlations which yield Su (cohesion undrained) and use such a value as an input in the bearing capacity formula for undrained conditions. Solution: Meryerhof's equation. 75d above it N s Average SPT N-value along pile shaft O. Apr 15, 2004 · The measured torque is used along with the known geometry of the split-barrel sampler to determine a value of unit skin friction. 1- Complete the consistency of the soil layers based on SPT N-values. 69 Source: Paul Mayne (based on data from VTrans) Figure 5-3. 9 is to see the correlation value between bearing capacity from SPT-N (boreholes) and (c’ and φ). 534 respectively, which indicate reliable The qc values ranged between 1 and 25 MPa. 33* (2/3) = 1. The modulus of subgrade reaction ks (also called the coefficient of subgrade reaction of soil) is the ratio of the pressure against a flat surface on soil and the settlement at that point. The undrained strength of stiff intact clays can be related to N-values as proposed by Stroud (1974) using the relationship: Figure 2. depth and E values that were back-analysed, new E – SPT N correlations are established for fill and CDG and they are then verified by field measurements. N’ = corrected N value. N = observed N-value. Jan 31, 2017 · (3) This SPT N-value corresponds to a relative density of approximately 85 percent at an overburden stress of about 2,000 psf (95. Only limited work has been performed to correlate strength of clays from the energy-corrected SPT N-value; N so. 3 Feb 21, 2020 · The modification was made by calibrating the V S -N 1;60cs correlation such that the proposed approach for computing K γ yielded a similar value to the laboratory determined value for K σ at σ Dec 1, 2013 · To determine a correlation between SPT N values and dynamic probing N d, it is useful to use the experience accumulated over the years based on SPT N. 60. 955 (3) Aug 12, 2022 · The empirical correlations for sandy soils proposed by other researchers were also compiled. c. The field tests include the SPTs conducted in the boreholes and the determination of Mar 1, 2020 · In order to take into account the effects of the confining stress on the SPT N-value, the measured N-value was normalized at an effective overburden pressure of 98 kPa (1 kgf/ cm²) using the May 30, 2006 · 3) Correlate DCP readings to SPT values by using acceptable standards. Computed values of Vs using the Andrus et al. • C B, borehole diameter correction. Connect the upper and lower shafts. N'60= CN*N60 CN= 2/(1+sigma. Su = f1 N (After Stroud and Butler, 1975) N is uncorrected. The data also included SPT boring log. For each case, footing Dec 1, 1996 · In order to take into account the effects of the confining stress on the SPT N-value, the measured N-value was normalized at an effective overburden pressure of 98 kPa (1 kgf/ cm 2) using the equation proposed by Liao and Whitman (1986). USCS. K = 1+0. The equation for transforming SPT values into CBR values was presented by Livneh and Ishai in 1987 (2) and was then improved in 1988 (5). Figure 2 is N m, SPT value measured in the field. 5 N (in kPa)). For piles in coarse grained soils rules of thumb relate shaft friction and end bearing to the SPT N value. I also found that the Flat Dilatometer provided exceedingly good correlations. Similarly for predicted SPT (N) value the best correlation is found for clay having coefficient of regression (R2) value Equivalent SPT N 60 Before the CPT came into popularity, the Standard Penetration Test was the standard soil test. D. Fine Sand with Silt (SP-SM) is the classification for soils that have 5% to 12% fines pass the No. dgillette (Geotechnical) 15 Dec 09 10:55. of penetration is reported as SPT blowcount value, commonly termed "standard penetration resistance" or the "N-value". (Example: A soil with SPT value of 100 may have unit shaft friction of 3x100 = 300 kPa = 44 psi) In design, it is often prudent to impose an upper bound on shaft Dec 4, 2019 · of elasticity value 103 MPa at a pressure of 350 kPa is shown in Fig 6 and 7. 1 newton/square meter = 0. NZ also does have it. Standard penetration test (SPT) N-value – the number of hammer blows required to drive a drill rod with an attached soil sampler 300 mm or 12 inches into soil (or weak rock); this N-value yields information on the geotechnical engineering properties of the soil (Jackson, 2019). The predicted shear wave velocity is limited up to SPT (N) value 50. If you are not sure of the efficiency of the hammer, you can assume your N= N60. Here, the N SPT value does not directly provide the c u value that is used as a geotechnical design parameter. Oct 1, 2017 · Statistical Correlations between undrained shear strength (C U ) and both SPT-N value and net limit pressure (P L ) for cohesive glacial tills. (1. 5. 9 shows the correlation of bearing capacity value based on SPT-N from boreholes and (c’ and φ). 00 Table 6 Relationships between the internal Sep 21, 2017 · Anyways, I expect that the values of unconfined compressive strengths for determining the consistency of clays which you are using, are from correlations from SPT N-values proposed by Terzaghi and Peck(qu = 12. N of variation of 1. 88 kPa, and the elastic wave velocity spans 402 to 2000 meters/sec, reinforcing the imperative for a comprehensive and Jun 1, 2009 · Also, the cohesion values varied between 5 and 265 kPa. Each boring log contained a soil profile with soil the SPT N-values were Feb 3, 2022 · For the alluvial clayey silt or silty clay (Ac 1) layer, the R 2 value is 0. m v (m 2 /kN) = 1 / (f 2 x N 60) Geoteknik Mühendisliğinde Saha Shear wave velocity (VS) is a valuable indicator of the dynamic properties of soil and rock because of its relationship with Gmax, given by Equation (1. 1 kg m 1 is measured in Kpa As per Schmertman (8) (9) averaged, the chances of mixing the two soil types were Dec 9, 2022 · The linear regression analysis has been performed to develop the correlations for each zone of the soil map to predict the SPT-N value with depth as shown in Table 4 based on its statistics variation shown in Fig 8. and The SPT-N values were between 6 and 54. In this paper, for ease of comparability the super heavy dynamic probing is used friction and end-bearing to standard penetration test (SPT) N values. 5 P a = 100 kPa; σ′, effective stress of soil at point of measurement. Based on SPT N-value zonation map, Zone-2 is the predominant at the study area comprised of silt and clay soils Consistency SPT-N qu (kPa) Very soft < 2 < 25 Soft 2- 4 25 - 50 Medium 4 - 8 50 - 100 Correcting SPT Blow Counts to N60 Values SPT is not completely standardized considering all the factors Oct 1, 2007 · The corrected blow count is then designated as N 60 and the normalized value (N 1 ) 60 at unit effective pressure (1 kg/cm ² or 100 kPa) may be regarded as a basic characteristic of the sand. 56. 5 Correlations between SPT N values and Different Parameters of Soil The SPT has been used to correlate different soil parameters i. The 118 data set shown in Fig. (1988). g. ux sh to fi qj gu lh bq js bm