• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.277-284
• /
• 2000

Using the large diameter (D ＝ 2,500mm, L ＝ 40m) batter steel pipe piles, designed as compression piles but used as reaction piles during the static compression load test of socketed test piles (D ＝ 1,000mm, L ＝ 40m), static pile load tests for large diameter instrumented rock-socketed piles were performed. The reaction steel pipe piles were driven 20m into the marine deposit and weathered rock layer and then l0m socketed with reinforced concrete through the weathered rock layer and into hard rock layer. Steel pipe and concrete in the steel pile part, and concrete and rebars in the socketed parts were instrumented to measure strains in each part. The pullout amounts of reaction pile heads were also measured with LVDT. During the static pile load test, total compressional load of about 20MN was loaded on the head of test piles, but load above 20MN was not loaded due to lack of loading capacity of loading system. Over the course of the study, maximum pullout amount up to 7mm was measured in the heads of reaction piles when loaded op to 10MN and 1mm of pullout amount was measured. More than 85% of pullout load was transfered in the residual weathered rock layer and about 10% in the soft rock layer, which was somewhat different transfer mechanism in the static compressional load tests.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.307-314
• /
• 2001

The bearing capacity of drilled shafts that take excavation by Percussion Rrotary Drilling(PRD) into consideration was evaluated using static and dynamic pile load tests. The emphasis was on quantifying the allowable bearing capacity and point load-transfer at the pile tip on seven instrumented steel piles. Of the seven instrumented piles, five piles are placed to the bottom of the excavation by rotary and pushing into the final depth of the excavation, as opposed to the two driven piles. Based on the results obtained, it is shown that the skin friction mobilized by PRD is much greater than point resistance, whereas in driven piles, the point resistance is greater than skin friction. It is also found that much greater pile capacity was proved in the case of drilled shafts, compared to the driven piles and thus, the excavation by rotary drilling gives reliable pile capacity required to design axially loaded piles.

• 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.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.03a
• /
• pp.249-258
• /
• 1999

Dynamic load and static load tests are performed on steel pipe piles and concrete piles at five construction sites in highway to compare the difference of load bearing mechanisms. At each site, one steel pile is instrumented with electric strain gages and dynamic tests are performed on the pile during installation. Damages of strain gages due to the installation are checked and static test is performed upon the same pile after two or seven days as well. It shows that load transfer from side friction to base resistance behaves somewhat differently according to the results of load-settlement analysis obtained from PDA and static load test. Initial elastic stage of load settlement curves of two load tests is almost similar. But after the yielding point, dynamic resistance of pile behaves more stiffer than static resistance, thus, dynamic load test result might overestimate the real pile capacity compared with static result. Analysis of gage readings shows that unit skin friction increases exponentially with depth. The skin friction is mobilized at the 1∼2m above the pile tip and contributes to the considerable side resistance. Comparison of side and base resistances between the measured value and the calculated value by Meyerhof's bearing capacity equation using SPT N value shows that the calculated base resistance is higher than the measured. Therefore, contribution of side resistance to total capacity shouldn't be ignored or underestimated. Finally, based upon the overall test results, a construction control procedure is suggested.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.1C
• /
• pp.27-35
• /
• 2010

Instrumented steel sheet piles being driven by vibratory pile driver were installed in granular soil deposit and behaviors of the sheet piles were investigated. One of the instrumented steel sheet pile was installed without clutch and the other was installed with clutch. Sheet pile with clutch means that of installed in connection with pre-installed sheet pile. Penetration rates of sheet piles measured from depth measuring drum has shown that interlock friction had great effect on penetration speed of sheet pile. Clutch friction shows irregular distribution along the depths of penetration and its magnitude was estimated as 19.1kN/m. According to the accelerations obtained from accelerometer, it was seen that steel sheet pile behaviored nearly as a rigid body. Efficiency factor of an isolated sheet pile was 0.42 and that of the connected sheet pile was 0.71. Shapes of dynamic load transfer curves obtained from analysis of measuring devices was similar to those suggested by Dierssen.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.397-404
• /
• 2002

The bearing capacity of open-ended piles is affected by the degree of soil plugging, which is quantified by the IFR. There is not at present a design criterion for open-ended piles that explicitly considers the effect of IFR on pile load capacity In order to investigate this effect, model pile load tests using a calibration chamber were conducted on instrumented open-ended piles. The results of these tests show that the IFR increases with increasing relative density and increasing horizontal stress of soils. The unit base and shaft resistances decrease with increasing IFR. Based on the results of the model pile tests, new empirical relations for base load capacity and shaft load capacity of open-ended piles are proposed. In order to check the accuracy of predictions made with the proposed equations, the equations were applied to the full-scale pile load test preformed in this study, Based on the comparisons with the pile load test results, the proposed equations appear to produce satisfactory predictions.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.1
• /
• pp.5-16
• /
• 2002

The pullout behavior of large-diameter steel pipe piles(diameter = 2,500mm, length = 38~40m), which were designed as compression piles but used as reaction piles during a static compression load test on a pile(diameter = 1,000m, length = 40m), was investigated. The steel pipe piles were driven by 20m into a marine deposit and weathered soil layer and then socketed by 10m into underlying weathered and soft rock layers. The sockets and pipe were filled with reinforced concrete. The steel pipe and concrete in the steel pipe zone and concrete and rebars in the socketed zone were fully instrumented to measure strains in each zone. The pullout deformations of the reaction pile heads were measured by LVDTs. Over the course of the study, a maximum uplift deformation of 7mm was measured in the heads of reaction piles when loaded to 10MN, and 1mm of residual uplift deflection was measured. In the reaction piles, about 83% and about 12% of the applied pullout loads were transferred in the weathered rock layer and in the soft rock layer, respectively. Also, at an uplift force of 10MN, shear stresses due to the uplift in the weathered rock layer md soft rock layer were developed as much as 125.3kPa and 61.8kPa, respectively. Thus, the weathered rock layer should be utilized as resisting layer in which frictional farce could be mobilized greatly.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.107-116
• /
• 2000

Dynamic and static load tests are conducted in four construction sites by using steel pipe piles(SPP) and concrete piles to compare differences of load bearing mechanism. Steel pipe piles are instrumented with electric strain gages and are subject to dynamic load tests during driving. The damage of strain gages attached is checked simultaneously. Static load test is also conducted on the same piles after two to seven days' elapse. Then load-settlement behavior and shaft and/or tip resistances are measured. As a result, the allowable bearing capacity calculated by the Davisson's offset method of CAPWAP analysis shows 2~33% larger than that of static load test. The average value of allowable bearing capacity of static load test is closer to the allowable capacity obtained at the safety factor of 2.5 applied on ultimate bearing capacity than to the one obtained from the Davisson's offset method. The analysis of strain gage readings shows that unit skin friction increases with depth. Furthermore, the friction mobilized around the 1~2m above the pile tip considerably contributes to the total shaft resistance.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.913-922
• /
• 2009

Fourteen model pile load tests using a calibration chamber and instrumented model pile were preformed to investigate the variation of the behaviors of driven piles in sands with soil and lateral cyclic loading conditions. Results of the model tests showed that the first loading cycle generated more than 70% of the pile head rotation developed for 50 lateral loading cycles. Lateral cyclic loading also made an increase of the ultimate lateral load capacity of piles for $K_0$=0.4 and an decrease for $K_0$ higher than 0.4. Higher portion of the increase or decrease in the ultimate lateral load capacity by lateral cyclic loading was generated for the first loading cycle due to densification of loosening of the soil around the pile by lateral cyclic loading. It was also observed that a two-way cyclic loading caused higher ultimate lateral load capacity of driven piles than a one-way cyclic loading. When the pile was in the ultimate state, the maximum bending moment developed in the pile increased with increasing $K_0$ value of soil and was insensitive to the magnitude and number of lateral cyclic loading.

• The Journal of Engineering Research
• /
• v.6 no.1
• /
• pp.83-96
• /
• 2004

A soil mailed wall is adapted as road widening measure and is constructed under a miniature abutment built on steel pipe piles. The soil nailed wall called for removal of the existing embankment slope to permanently retain the fill behind the abutment. The soil nailed wall is fully instrumented and is monitored. A 3D finite element analysis is used to study further the behavior of the soil nailed wall. The complete sequence of construction is simulated. The numerical model is calibrated against the instrumented nailed wall. Then a parametric study is conducted. The results provide valuable information related to the effect of the excavation and nailing on the following: axial load and bending moment in the piles, load in the nails, and wall deflections.