• Title, Summary, Keyword: 표준관입시험

Search Result 114, Processing Time 0.044 seconds

Prediction of End Bearing Capacity for Pre-Bored Steel Pipe Piles Using Instrumented Spt Rods (SPT 에너지효율 측정 롯드를 이용한 매입말뚝의 선단지지력 예측)

  • Nam, Moon S.;Park, Young-Ho;Park, Yong-Seok
    • Journal of the Korean Geotechnical Society
    • /
    • v.29 no.12
    • /
    • pp.105-111
    • /
    • 2013
  • The standard penetration test (SPT) has been widely used because of its usability, economy, and many correlations with soil properties among other factors. In SPT, hammer energy is an important factor to evaluate and calibrate N values. To measure hammer energy, an instrumented SPT rod was developed considering that stress waves transferring on rods during SPT driving are the same as stress waves transferring on piles due to pile driving. Using this idea, an instrumented SPT rod with a pile driving analyzer was applied as a pile capacity prediction tool in this study. In order to evaluate this method, SPT and dynamic cone tests with the instrumented SPT rod were conducted and also 2 pile load tests were performed on pre-bored steel pipe piles at the same test site. End bearings were predicted by CAPWAP analysis on force and velocity waves from dynamic cone penetration tests and SPT. Comparing these predicted end bearings with static pile load tests, a new prediction method of the end bearing capacity using the instrumented SPT rod was proposed.

Correlations between the CPT and the SPT for the Residual Soil in Korea (국내 잔류토층에서 CPT와 SPT와의 상관관계에 대한 연구)

  • Koo, Ja-Kap;Yi, Chang-Tok
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.7 no.3
    • /
    • pp.231-239
    • /
    • 2003
  • Many foundation jobs have been designed and constructed in Korea with the sole information obtained from the SPT. The use of the CPT to estimate equivalent SPT values is becoming a common application for foundation design. The relationship between the CPT and the SPT has been determined in a number of studies over the past three decades. However a few papers have been published on the relationship between the CPT and the SPT in residual soil. Due to the large variation in published correlations between qt and N in residual soil, local correlations should be developed wherever possible. CPT tests have been carried out in the residual soil classified by SM in accordance with USCM and compared with SPT. Value of qt/N = 0.3 have been suggested for residual soil in Korea.

Analysis of Geophysical and Geotechnical SPT Data for the Safety Evaluation of Fill Dam (필댐 안정성 평가를 위한 물리탐사와 SPT 자료의 분석)

  • Oh, Seok-hoon;Sun, Chang-Guk
    • Journal of the Korean Geophysical Society
    • /
    • v.7 no.3
    • /
    • pp.171-183
    • /
    • 2004
  • Electrical resistivity survey is widely used to investigate the stability of center-core type fill dam against the seepage phenomenon. In this study, we analyze the resistivity information obtained on a earth fill dam and compare it with the geotechnical SPT result. The analysis shows that the zones showing low resistivity value generally have low N value. However, some zones with high resistivity pattern do not accompany the increase of N value, and even showing low N value. These results imply that the direct identification of resistivity value to the real status of the core material of fill dam is impossible, and a highly resistive zone may be in serious status due to the effect increasing the resistivity value by the piping condition. Therefore, multiple exploration should be planned to reduce the uncertainty in application of geophysical methods to dam safety evaluation.

  • PDF

Assessment of Liquefaction Potential on Non-Plastic Silty Soil Layers Using Geographic Information System(GIS) and Standard Penetration Test Results (지리정보시스템 및 표준관입시험 결과를 이용한 비소성 실트질 지반의 액상화 평가)

  • Yoo, Si-Dong;Kim, Hong-Taek;Song, Byung-Woong;Lee, Hyung-Kyu
    • Journal of the Korean Geoenvironmental Society
    • /
    • v.6 no.2
    • /
    • pp.5-14
    • /
    • 2005
  • In the present study, the liquefaction potential in the area of the Incheon international airport was assessed by applying the data of both standard penetration tests and laboratory tests to the modified Seed & Idriss method. The analysis was performed against the non-plastic silty soil layer and silty sand soil layer existing within the depth of 20m and under the ground water level, having the standard penetration value(N) of below 20. Also, each set of data was mapped using the GIS(Geographic Information System) and the safety factor against the liquefaction potential ($FS_{liquefaction}$) was obtained by overlapping those layers. Throughout the analysis, it was found that there exists a potential hazard zone for the liquefaction, showing partially that the safety factor against the liquefaction potential is 1.0 to 1.5 below the standard safety factor criterion. It is further thought to be necessary that the liquefaction potential for the corresponding hazard zone be additionally assessed in detail.

  • PDF

Evaluation of Maximum Shear Modulus of Silty Sand in Songdo Area in the West Coast of Korea Using Various Testing Methods (다양한 시험 방법을 이용한 서해안 송도 지역에 분포하는 실트질 모래의 최대 전단탄성계수 평가)

  • Jung Young-Hoon;Lee Kang-Won;Kim Myoung-Mo;Kwon Hyung-Min;Chung Choong-Ki
    • Journal of the Korean Geotechnical Society
    • /
    • v.21 no.9
    • /
    • pp.65-75
    • /
    • 2005
  • Maximum shear modulus of soil is a principal parameter for the design of earth structures under static and dynamic loads. In this study, the statistical data of maximum shear moduli of silty sands in Songdo area in the west coast of Korea evaluated by various field and laboratory tests - standard penetration test (SPT), cone penetration test (CPT), self-boring pressuremeter test (SBPT), downhole test (DH), seismic cone penetration test (SCPT) and resonant column test (RC) were analyzed. Based on the measurement of shear moduli using DH which is known as maximum value at very small strain, the new empirical correlations between shear moduli and SPT or CPT values were proposed. Predictions of maximum shear moduli using the proposed correlations were compared with the data obtained from DH. The good agreement confirmed that the proposed correlations reasonably predicted the maximum shear moduli of silty sands in the area.

Evaluation of the Falling Velocity of SPT Hammer via Actual Measurement (실측에 의한 표준관입시험 함마의 낙하속도 분석)

  • 이명환;이원제
    • Geotechnical Engineering
    • /
    • v.8 no.1
    • /
    • pp.59-66
    • /
    • 1992
  • The SPT If value has been known to be influenced by various factors, among which the actually delivered energy level of the falling ram has the most significant effect. If N values of different energy levels are to be applied in the general analysis which is based on N values of standard energy levee the safety of the foundation might be in danger or the design might be overestimated. In this study the actual falling velocity of the ram has been measured so that the energy level could be estimated. The results Indicated that the energy level should be considered in the analysis or the design in this country, since the measured values are different from the internationally accepted scandard value, N60

  • PDF

A Study on the Modified N-value by the Comparison Plate Load Test with Calculated Settlement (평판재하시험과 이론적 침하량 예측식의 비교를 통한 N치 보정방법 검토)

  • Ahn, Chang-Yoon;Kim, Won-Cheul;Hwang, Young-Cheol;Nam, Hyun-Woo
    • Journal of the Korean Geoenvironmental Society
    • /
    • v.6 no.3
    • /
    • pp.25-34
    • /
    • 2005
  • The governing design point of shallow foundation is not its bearing capacity but its settlemen and N-value by the SPT is one of the key parameters for settlement estimation. However, if the N-value is more than 50/30, such as 50/10 or 50/20, the N-vlaues are not blow count of 30cm depth penetration. In these cases, the estimated settlements have big difference with the measured values because the applied maximum N value for the settlement estimation is 50. Therefore, in this study, the modified method for N-value estimation is suggested. The settlements by four methods, which are based on Elastic Theory with application of modified N-value, are compared with the Origina Plate Load Test data. The same comparision was carried out with another seven Empirical Methods. The result of this study showed that the error range of settlement is decreased from 260.4~2136.5% to 20.3~272.7%. Among four methods which are based on Elastic Theory, the original method by Elastic Theory is the most accurate with the application of modified N-value. Among Empirical Methods, Terzaghi-Peck's(1948, 1967) modified method 1 is the most accurate with the application of modified N-value. The differences between the original method by Elastic Theory and Terzaghi-Peck's(1948, 1967) modified method 1 are neglectable.

  • PDF

A Comparative Study on the Tensile Strength of Frozen Soil according to Test Methods (시험 방법에 따른 동결토의 인장강도)

  • Seo, Young-Kyo;Kang, Hyo-Sub
    • Journal of the Korean Geotechnical Society
    • /
    • v.24 no.4
    • /
    • pp.57-66
    • /
    • 2008
  • In this study, the blast-induced vibration effects on the structural stability of the adjacent tunnel and the stability were estimated with respect to the allowable peak particle velocity (PPV). The blasting distance from the tunnel satisfying the allowable PPV was estimated based on the analytical solutions, United States Bureau of Mines (USBM) suggestions, and the equations used in the subway in Seoul. The allowable blasting distance was estimated by using finite difference analysis (FDA) and the behavior of the concrete lining and rock bolts was examined and the stability of those was estimated during the blast. Research results show that the blast-induced vibration effects on the structural stability are negligible for the concrete lining but relatively large for the rock bolts.

Analytical Studies for Application of SPT Dynamic Signals to Estimate the Elastic Property of the Soil Deposit (표준관입시험의 동적신호를 이용한 지반 물성치 추정의 해석적 연구)

  • 이병식;김영수
    • Journal of the Korean Geotechnical Society
    • /
    • v.18 no.4
    • /
    • pp.167-177
    • /
    • 2002
  • A test method has been attempted to estimate the soil stiffness by measuring and analyzing dynamic signals of stress waves reflected at the bottom end of the SPT rod contacting a soil deposit. Before conducting a real size testing, a series of parametric studies were conducted in this paper to examine the applicability and the theoretical adequacy of the test method. As a result of these studies, it has been shown that the most significant influence factor affecting the amplitude ratio of the reflected wave to the incident wave at the rod-soil interface was the variation of soil stiffness. Also, the variation of the amplitude ratio was found to be closely related with the variation of impedance ratio of the soil deposit to the SPT rod. As a result, a potential of the test method could be proved to estimate the impedance and the elastic modulus of the soil deposit interfaced with the SPT rod using the test method.

Case Study of Correlation between the SPT-N Value and PMT Results Performed on Weathered Granite Zone in Korea (국내 화강 풍화대 지반의 표준관입시험 N 값과 프레셔미터시험 결과의 상관관계에 대한 사례 분석)

  • Lee, Seung-Hwan;Baek, Sung-Ha;Song, Young-Woo;Chung, Choong-Ki
    • Journal of the Korean Geotechnical Society
    • /
    • v.35 no.12
    • /
    • pp.15-24
    • /
    • 2019
  • Weathered granite zone exists in most regions of Korea and it is often used as a bearing stratum of geotechnical structures. So it is very important to estimate the characteristics of weathered granite zone. SPT (Standard penetration test) is usually performed to investigate the characteristics of the weathered zone because undisturbed samples suitable for laboratory testing are hardly retrieved. PMT (Pressuremeter test) can reliably evaluate the in situ stress-strain behavior, but it is rarely conducted because of their high cost and time-consuming procedure. In this study, the correlation between the SPT-N values and the PMT results, obtained from the weathered granite zone, was analyzed. Empirical equations for pressuremeter modulus (Em) and limit pressure (PL) were suggested and compared with the previous research.