Meyerhof Method Research Articles

An approach for calculating the vertical ultimate bearing capacity of a shallow circular foundation

In this work, a new method for the vertical bearing capacity of a shallow circular foundation was proposed with the amended formula by combining the limit equilibrium method and the principle of conservation of energy. Then the vertical ultimate bearing capacity of eight different circular foundations was acquired with the above mentioned method, an empirical formula method, and the static load test to obtain comparative results. The results showed that the relative error for the proposed method was deemed as the most accurate, close to the result of Vesic method, while much less than the relative error for both Meyerhof method and Hansen method. In addition, the impact factors for vertical ultimate bearing capacity including density, cohesion, friction angle of soil, radius, and burial depth of shallow circular foundation were also discussed, indicating that the shear strength parameters and density of soil, and especially the friction angle were the main influencing factors of the bearing capacity.

PERILAKU TIANG BOR PENOPANG INFRASTRUKTUR PADA TANAH LUNAK AKIBAT BEBAN STATIK

Bored piles have been used to support transportation infrastructures (offices, a terminal building, power house, warehouses and workshop) in a harbor. The bored piles were penetrated into mostly old alluvial deposits and dilluvial deposits of very stiff marine clay with traces of shell debris. A bored pile was tested as part of this research program to verify the accuracy of the predicted pile capacities. The proposed static prediction capacity methods include Meyerhof, a, b and l methods. The results of the analysis show that Meyerhof method (1951) with inputs of laboratory test data provides closely agreement with static loading test results. The other methods give somewhat conservative prediction. This paper discusses bearing capacity analysis of bored piles based on soil characteristics and static loading test results. Results of the analysis indicate that the bored piles capable of resisting load transmitted from the upper structure. The research will be of interest to many practicing engineers using this kind of piles.

PHC 매입말뚝의 하중저항 설계정수 제안

ABSTRACT The limit states design method is replacing the allowable stress design method worldwide, e.g. the design code of ISO and various construction codes of Korea are adopting the reliability based limit state method. This paper proposed LRFD design value which is one of limit states design method for the PHC bored pile used as building foundation. This paper analysed 81 load test results and the bearing design(Meyerhof method & SPT-CPT conversion method), and proposed LRFD value for each design reliability Index 2.33 and 3.0 for PHC bored pile. LRFD value of PHC bored pile represents 0.36～0.44 for Meyerhof method and 0.24～0.31 for SPT-CPT conversion method according to the deign reliability index. Key words: PHC Pile, Bored Pile, Limit States Design Method, LRFD(Load and Resistance factored Design Method), Deign Reliability Index 본 논문은 토지주택연구원의 ‘말뚝기초의 설계법 선진화 및 시공법 다양화 연구’의 일부분을 정리한 내용입니다.1) 토지주택연구원, 수석연구원(주저자: jbpark@lh.or.kr)2) 토지주택연구원, 수석연구원(교신저자: parkyb@lh.or.kr)3) 토지주택연구원, 수석연구원

Revisiting bearing capacity analysis of MSE walls

Common design of MSE walls determines the layout and strength of reinforcement by using a synergy of various analyses. One such analysis is bearing capacity in which the reinforced mass is considered a rigid body exerting uniform pressure over reduced area due to eccentricity. In some codes, Meyerhof's method for an eccentrically loaded footing is used to assess bearing capacity and to ensure a sufficient margin of safety. In these codes, the horizontal resultant of lateral earth pressure on the reinforced mass affects eccentricity but is ignored in assessing the bearing capacity coefficients in this analysis; i.e., the analysis does not consider the impact of load inclination. Using rigorous upper bound in limit analysis of plasticity, the critical failure mechanisms of the analyzed equivalent footing are identified. It is demonstrated that for a footing subjected to a vertical eccentric load only, Meyerhof's approximation is reasonable. However, ignoring the impact of horizontal force on bearing capacity in such an equivalent footing is significantly unconservative. Conversely, it is shown that some compounded conservatism in the equivalent problem stems from ignoring the interface friction between the reinforced and retained soils while implicitly considering an unfeasible failure mechanism for bearing of the footing. With conservative selection of soil shear strength properties and a typical value of factor of safety against bearing failure, the end result is likely conservative. The use of this flawed bearing capacity analysis in design is questioned. Also questioned is the applicability of bearing capacity calculations developed for a rigid footing when dealing with a flexible reinforced mass. It is suggested to replace it with a robust and more realistic, albeit simple analysis that considers failures through the foundation soil.

Upper Bound Solution for Ultimate Bearing Capacity of Foundation Based on Unified Strength Theory

Based on unified strength theory, an upper bound solution for bearing capacity of foundation is established considering the strength of soil above the basement by using Prandtl slip model. The proposed method could be degenerated to classical slip-line method in some certain situations. A series of results could be presented by means of changing the parameters of unified strength theory. The results obtained by this proposed method are greater than those by Terzaghi method, which is mainly because the positive effects of soil strength above foundation base. Since unified strength theory could be simplified to Mohr-Coulomb strength theory in a certain situation, the results are close to those obtained by Meyerhof method. This proposed solution can consider the effects of intermediate principal stress so that we can make full use of the potential capacity of soil, which is a rigorous upper-bound solution. Other solutions are special cases of this proposed solution.

Upper Bound Solution for Ultimate Bearing Capacity of Foundation Based on Unified Strength Theory

Based on unified strength theory, an upper bound solution for bearing capacity of foundation is established considering the strength of soil above the basement by using Prandtl slip model. The proposed method could be degenerated to classical slip-line method in some certain situations. A series of results could be presented by means of changing the parameters of unified strength theory. The results obtained by this proposed method are greater than those by Terzaghi method, which is mainly because the positive effects of soil strength above foundation base. Since unified strength theory could be simplified to Mohr-Coulomb strength theory in a certain situation, the results are close to those obtained by Meyerhof method. This proposed solution can consider the effects of intermediate principal stress so that we can make full use of the potential capacity of soil, which is a rigorous upper-bound solution. Other solutions are special cases of this proposed solution.

Studi Eksperimen Pengaruh Pencampuran Serbuk Batu Bara dan Serbuk Gipsum terhadap Kuat Dukung Tanah Lempung dengan Metode Meyerhof

One of the function soil in the Civil Engineering building is to bore the burden structure will be continued from foundation, until a soil acted the part of a building structure stability Clay soil is one of various soils which have of law bearing capacity, so repair improvement the physical and soil mechanic.One of the method to improvementof clay soil stability is with mixing gypsum powder and fly ash powder as additive.This research at mixing gypsum powser and fly ash are : 2% ; 4% ; 6% ; 8% & 10%. From Triaxial UU test and Direct shear test obtainable gypsum powder which to resulted a cohesion value and maximum shear angle at 6%. of the dry weight soil and fly ash powder at 10%.The testing data will be analysis with Meyerhof method. The Triaxial UU test with gypsum powder 6% obtainable economically dimension of foundation 58,30% and 48,86% at Direct shear test The economically dimension of foundation at fly ash powder at 10% obtainable 58,30% at Triaxial UU test and 53,37% at Direct shear test The mixing gypsum powder 6% obtainable increased a soil bearing capacity 186,63% at Triaxial UU test and 72,67% at Direct shear test The mixing fly ash powder 10% can increased soil bearing capacity 188,98% at TriaxialUU test and 99,70% at Direct shear test. keyword : Experiment, fly ash powder ,gypsum powder, bearing capacity, clay soil, Meyerhof method

Estimating Relative Density of Sandy Soils

ABSTRACT The applicability of three previous empirical correlations proposed for estimating relative density of sandy soils based on the SPT N-value, effective overburden stress and soil gradation characteristics was investigated in the present study by using a data base of relative density obtained from high quality undisturbed samples of fine to medium sand with Fc≦20%, D50≦1.0 mm and Dmax≦4.75 mm. All undisturbed samples were recovered by in-situ freezing method. The relative density estimated by Meyerhof's method (1957) was in the range of +15%~-45% of the measured values. Meyerhof's method (1957) was modified by Tokimatsu and Yoshimi (1983) by considering the effect of fines content on the SPT N-value. The relative density estimated by Tokimatsu and Yoshimi's method (1983) is in the range of +25%~-20% of the measured values. The underestimation of relative density of Meyerhof's method (1957) was modified. On the contrary, the overestimation of relative density is more significant than Meyerhof's method. The relative density estimated by the method proposed by Kokusho et al. (1983) is in the range of +20% to -35% of the measured values even for dense sand with a relative density larger than 60%. Meyerhof's method (1957) and the method proposed by Kokusho et al. (1983) have a common disadvantage that they will extremely underestimate the relative density of fine to medium sand for SPT N-value lower than about 8. The errors in estimation of relative density by these methods are large. A simple empirical correlation (Eq. (10)) was proposed in the present study to estimate the relative density of fine to medium sand based on the normalized SPT N-value, N1. The relative density estimated by the proposed method is in the range of +15% to -30% of the measured values for N1 in the range between 0 and 50. As a whole, the proposed method is less in errors for estimating relative density compared with those estimated by Meyerhof's method (1957) and the method proposed by Kokusho et al. (1983). Based on a data base of undisturbed samples with data of fines content obtained from the SPT spoon samples, the method proposed by the authors is again compared with the three previous methods. The relative density estimated by the proposed method based on the above data base is in the range of +15% to -10% of the measured values. Among four methods, as a whole, the proposed method shows the least errors in estimation of relative density. The proposed method was also modified (Eq. (16)) by taking into account of the effect of fines content of SPT samples. The relative density estimated by the modified method based on the fines content is almost in the range of +10% to -10% of the measured values. Two empirical correlations proposed in the present study are less in errors of estimating relative density compared with three previous methods. The range of relative density estimated by the proposed method is well consistent with the range of the measured values (40% to 90%). The empirical correlations proposed in the present study should be applied to fine to medium sand with Fc≦20%, D50≦1.0 mm and Dmax≦4.75 mm.

각종 항타공식에 의한 말뚝의 허용지지력 연구

말뚝에 대한 지지력 평가는 재하시험에 의한 결과를 이용하는 것으로부터 정.동력학적 공식등 다양한 방법들이 사용되고 있다 최근의 국내 조사에 의하면 표준관입시험의 N치에 기초한 Meyerhof공식이 설계단계에서 빈번하게 사용되는 것으로 보인다. 본 연구에서는 국내에서 실시된 다수의 정 동재하시험자료를 가지고 말뚝기초 설계에 사용되는 이론식을 실측값과의 비교를 통해 각종 이론식에 의한 말뚝의 허용지지력 추정의 신뢰성을 알아 보고자 하였다 또한, 경시효과를 고려한 경우 말뚝의 지지력에 미치는 영향에 대해서도 연구가 이루어졌다 본 연구를 통해 얻은 주요 결과로는 Davisson 방법을 기준으로 정도를 평가한 결과, Terzaghi & Peck > Chin > Meyerhof > 수정 Meyerhof 방법순으로 기준값에 근접하였으며 동재하시험결과는 항타공식 중 수정 Engineering News 공식이 가장 실측치에 근접한 결과를 주었으나 이는 해머 효율의 불확실성이라든가 변수의 자체특성, 경시효과등이 고려된 경우에는 다른 결과를 줄 수도 있을 것으로 판단되며, 경시효과를 고려한시험 결과 선단지지력에 비해 주면마찰력이 뚜렷하게 증가하였는데 항타시 대비 주면마찰력은 평균 약 2배정도 증가하였고 Engineering News,수정 Engineering News, Hiley, Danish, Gates, CAPWAP 해석시에 대한 7일의 경시효과를 고려한 관계시은 각각 <TEX>$Q_{u(Restrike)} / Q_{u(EOID)} = 0.98t_{0.1}$</TEX> , <TEX>$0.98t_{0.1}$</TEX>, <TEX>$1.17t_{0.1}$</TEX>, <TEX>$0.88t_{0.1}$</TEX>, <TEX>$0.89t_{0.1}$</TEX>, <TEX>$0.97t_{0.1}$</TEX>.과 같은 결과를 주었다. The estimation of pile bearing capacity is important since the design details are determined from the result. There are numerous ways of determining the pile design load, but only few of them are chosen in the actual design. According to the recent investigation in Korea, the formulas proposed by Meyerhof based on the SPT N values are most frequently chosen in the design stage. In the study, various static and dynamic formulas have been used in predicting the allowable bearing capacity of a pile. Further, the reliability of these formulas has been verified by comparing the perdicted values with the static and dynamic load test measurements. Also, in most cases, these methods of pile bearing capacity determination do not take the time effect consideration, the actual allowable load as determined from pile load test indicates severe deviation from the design value. The principle results of this study are summarized as follows : As a result of estimate the reliability in criterion of the Davisson method, t was showed that Terzaghi & Peck >Chin>Meyerhof > Modified Meyerhof method was the most reliable method for the prediction of bearing capacity. Comparisons of the various pile-driving formulas showed that Modified Engineering News was the most reliable method. However, a significant error happened between dynamic bearing capacity equation was judged that uncertainty of hammer efficiency, characteristics of variable, time effect etc... was not considered. As a result of considering time effect increased skin friction capacity higher than end bearing capacity. It was found out that it would be possible to increase the skin friction capacity 1.99 times higher than a driving. As a result of considering 7 day's time effect, it was obtained that Engineering news, Modified Engineering News, Hiley, Danish, Gates, CAPWAP(CAse Pile Wave Analysis Program) analysis for relation, repectively, <TEX>$Q_{u(Restrike)} / Q_{u(EOID)} = 0.98t_{0.1}$</TEX> , <TEX>$0.98t_{0.1}$</TEX>, <TEX>$1.17t_{0.1}$</TEX>, <TEX>$0.88t_{0.1}$</TEX>, <TEX>$0.89t_{0.1}$</TEX>, <TEX>$0.97t_{0.1}$</TEX>.

Analysis of Load Tests on Piles Driven through Calcareous Desert Sands

The ultimate bearing capacity of short, precast concrete piles driven into calcareous sands was examined by pile-load tests carried out at two sites in Kuwait. The piles had a 0.3 m × 0.3 m square cross section and extended to a maximum depth of 12 m. They were driven through a loose-to-compact calcareous surface sand layer underlain by a competent dense-to-very-dense siliceous cemented sand deposit. The pile tips and part of the pile shafts were embedded in the lower layer. The base resistance and shaft friction were calculated using the Meyerhof method for a layered soil profile. The method employs the standard penetration test N values. The results indicate that a great portion of the pile capacity is due to base resistance. The skin friction mobilized is small and consists of two components corresponding to the two layers penetrated along the pile shafts. The calculated pile capacities were very close to the measured values. The unit skin friction is not constant along the pile shafts.

Energy and angular distributions of secondary electrons from 5-100-keV-proton collisions with hydrogen and nitrogen molecules

Cross sections for the ejection of electrons from hydrogen and nitrogen by protons have been measured as a function of the energy and angle of ejection of the electrons at incident proton energies of 5-70 keV and 100 keV for hydrogen. The range of angles measured was 10-160\ifmmode^\circ\else\textdegree\fi{} and the electron energy range was 1.5-300 eV. The doubly differential cross sections were also integrated over angle, over electron energy, or over both to obtain singly differential and total cross sections for electron production. Average electron energies were also calculated from the data. The angular distributions of electrons are peaked in the forward direction but become more isotropic as the proton energy decreases. Nitrogen yields a more isotropic distribution than hydrogen. In this range of proton energies the cross sections integrated over angle are found to fall off approximately exponentially with electron energy, and a simple empirical equation has been found that describes the singly differential and total cross sections within a factor of 2 for several targets. A theoretical interpretation of this result in terms of the molecular promotion model is given in which Meyerhof's method of calculating cross sections for $K$-shell excitation is applied for the first time to the ionization of outer shells of atoms.

Cone Resistance as Measure of Sand Strength

Available theories for deduction of the drained friction angle of sands from the results of static cone penetration tests were applied to data from several field sites and laboratory chamber tests. Only results obtained using a standard cone with 60 deg apex angle and 10 sq cm base area were considered. The methods of De Beer and Troffimenkov are shown to yield overconservative estimates of phi. The methods of Meyerhof, Durgunoglu and Mitchell, Janbu, and Schmertman give values of phi varying by one 2 deg to 5 deg and agree well with the results of laboratory drained triaxial tests. The methods of Meyerhof, Janbu, and Schmertmann are best suited for practical engineering applications. However, the Meyerhof method cannot be used if a limiting value of cone resistance cannot be defined, Schmertmann's method requires knowledge of K sub o, and Janbu's method is applicable only if the cone resistance increases approximately linearly with depth. /ASCE/

Bearing Capacity of a Continuous Footing Set in Two-Layered Ground

The Meyerhof method to estimate the ultimate bearing capacity of a continuous footing set in homogeneous ground is extended to the case of two-layered ground where the base of the footing is set in the supporting layer overlain by the weak layer. The extended method takes into account the effect of the shearing strength of the weak layer on the bearing capacity of the footing base and gives more precise bearing capacity than the method which assumes the shearing strength of the weak layer to be zero.