The shaft capacity of pipe piles in sand

2003 ◽  
Vol 40 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Kenneth G Gavin ◽  
Barry M Lehane
Keyword(s):  
Design Method ◽  
Test Chamber ◽  
In Situ Stress ◽  
Simple Expression ◽  
Cone Penetration ◽  
Factors Affecting ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Shaft Capacity

This paper describes results from an experimental programme that investigated factors affecting the shaft capacity of open-ended (pipe) piles in sand. A number of jacked pile installations in a test chamber filled with loose sand were performed using both open- and closed-ended, 114 mm diameter piles. The test series was designed to investigate the effects of in situ stress level, pile end condition, and degree of plugging on the development of pile shaft resistance. The results indicate that the maximum local shaft resistance that can develop at a given location on a pipe pile may be expressed as a function of the incremental filling ratio of the soil plug during installation, the cone penetration test (CPT) qc value, and the relative position of the pile toe. The experimental results allowed a simple expression to be developed for the plug resistance during pile installation, and this is used in conjunction with a popular design method for closed-ended piles to provide a means of estimating the shaft capacity of open-ended piles. The new approach is shown to provide good estimates of overall shaft capacity and skin friction distribution.Key words: shaft capacity, pipe piles, sand.

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

scholarly journals Exploring Deep-Rock Mechanics through Mechanical Analysis of Hard-Rock In Situ Coring System

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jianan Li ◽  
Heping Xie ◽  
Ling Chen ◽  
Cong Li ◽  
Zhiqiang He
Keyword(s):  
Rock Mechanics ◽  
Hard Rock ◽  
Design Method ◽  
Drill Pipe ◽  
In Situ Stress ◽  
Drilling Depth ◽  
Innovative Design ◽  
The Core ◽  
Deep Rock

Exploration of deep-rock mechanics has a significant influence on the techniques of mining and rock mechanics. Rock coring technique is the basic method for all rock mechanics study. With the increase of the drilling depth and increasing strength of the hard rock, how to obtain high-quality rock core through various coring techniques is an eternal work. Here an innovative method is applied to design the new coring system to maximize the efficiency of operation. The stress conditions or parameters of rock core in the coring are analyzed, and the mechanism of the core with in situ stress is shown in this paper. The conflict of the core and coring tool chamber is proposed for the innovative design. The innovative design method is fulfilled by the theory of inventive problem solving (TRIZ). An improved coring system for the full-length core with in situ stress was obtained with the solutions of improved coring mechanism, cutting mechanism, and spiral drill pipe.

Design and performance evaluation of vertical shafts: rational shaft design method and verification of design method

1988 ◽  
Vol 25 (2) ◽  
pp. 320-337 ◽  
Author(s):  
R. C. K. Wong ◽  
P. K. Kaiser
Keyword(s):  
Design Method ◽  
Three Dimensional ◽  
Earth Pressure ◽  
In Situ Stress ◽  
Cohesive Soils ◽  
Strength Parameters ◽  
Yield Zone ◽  
Ground Deformations ◽  
And Performance

Ground deformations around axisymmetric shafts cannot be determined with the design approaches currently available, which are mostly based on plasticity methods. The convergence–confinement method (usually applied to tunnels), with consideration of gravitational effects and the three-dimensional conditions near a shaft, is proposed as a tool to predict formation pressure on a shaft and radial ground displacements. It is shown that the behaviour of a shaft is governed by (1) the mode of yield initiation dominated by the in situ stress state and the soil strength parameters and (2) the extent of the yield zone that develops if wall displacements are allowed to occur during construction.Closed-form solutions are presented to approximate the pressure–displacement relationship for cohesionless and cohesive soils. Results from this approach compare well with those obtained by finite element analyses. The conventional design methods that provide the minimum support pressures required to maintain stability are not conservative. These pressures are generally less than those actually encountered if ground movements during construction are restricted with good ground control. Key words: shaft, design method, support, interaction, yielding, stress, displacement, earth pressure, arching.

Influence of placement method on the in situ density of hydraulic sand fills

1989 ◽  
Vol 26 (3) ◽  
pp. 453-466 ◽  
Author(s):  
J. A. Sladen ◽  
K. J. Hewitt
Keyword(s):  
Key Words ◽  
Cone Penetration Test ◽  
Penetration Test ◽  
Cone Penetration ◽  
Hydraulic Fill ◽  
Factors Affecting ◽  
Placement Method ◽  
Method Of Placement ◽  
Hydraulic Fills

The range of densities achievable by hydraulic placement of sand straddles the boundary between values giving acceptable potential performance and those giving unacceptable potential performance. This has led to concerns over the safety of structures using hydraulic fills, such as the artificial drilling islands in the Canadian Beaufort Sea. Liquefaction failures of hydraulically placed sand have occurred at four or more of these islands. Until recently, the factors affecting in situ density were little understood. Data obtained from several artificial islands are presented and these are used to demonstrate the overwhelming influence of method of placement on in situ density. The possible reasons for this influence and the implications for design are discussed. Recommendations are made for research that, together with conclusions drawn in the paper, should allow hydraulic fills to be used with more confidence in the future. Key words: sand, hydraulic fill, liquefaction, cone penetration test.

Geotechnical parameters of reclaimed sandfill from the cone penetration test

2005 ◽  
Vol 42 (1) ◽  
pp. 91-109 ◽  
Author(s):  
Yung-Mook Na ◽  
Victor Choa ◽  
Cee-Ing Teh ◽  
Ming-Fang Chang
Keyword(s):  
Stress Level ◽  
Cone Penetration Test ◽  
In Situ Stress ◽  
Load Test ◽  
Penetration Test ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Geotechnical Parameters ◽  
Cone Resistance

Sandfill at reclaimed sites is usually formed by more than one placement method. Reclaimed sandfill is often highly variable, and the cone penetration test is most commonly used for site characterization. Correlations among the cone resistance and geotechnical parameters for sand are influenced by the in situ stress level, and it is important to incorporate the stress-level effect. In this study, cone penetration tests were performed at several levels from the top of a 10 m high surcharge, which was later removed step by step, and in situ density was determined layer by layer at the Changi East reclamation site in Singapore. Different ways of normalizing the cone resistance by the corresponding in situ stress were investigated. Specialized in situ tests including the self-boring pressuremeter test, the cone pressure meter test, the seismic cone penetration test, and the plate load test were conducted to provide the reference deformation characteristics of sandfill. Results of the in situ tests indicate that the sand density and the cone resistance profiles vary between areas formed by different sand placement methods. Site-specific correlations developed based on comparison of normalized cone resistance with the reference data obtained from laboratory tests and other in situ tests are found to be suitable for the evaluation of relevant soil parameters.Key words: stress normalization, cone resistance, correlations, geotechnical parameter, in situ characterization, granular soil.

scholarly journals Design Method for Specific Charge in Deep Mining considering Influence of In Situ Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Fengpeng Zhang ◽  
Qiqi Hao ◽  
Xiulong Wang ◽  
Zhaoguo Qiu
Keyword(s):  
Design Method ◽  
High Stress ◽  
In Situ Stress ◽  
Quantitative Relation ◽  
Correction Coefficient ◽  
Explosion Crater ◽  
Specific Charge ◽  
Rock Blasting ◽  
Test Results

In situ stress has a large influence on blasts in deep mines and should be considered in blasting design. In this study, explosion crater tests were conducted to investigate the variation of specific charges under different stress loading conditions. It was revealed that rock blasting under high stress is different from that under low stress. A correction coefficient for specific charge was defined to consider the influence of in situ stress on blasting. A quantitative relation between the correction coefficient, stress-to-strength ratio, and lateral stress coefficient was presented. Based on the explosion-crater test results, a design method for specific charges was proposed with the consideration of in situ stress. Finally, the design method was applied to a field blasting test at Hongtoushan Copper Mine. The test results indicate that the proposed design method can effectively use the high in situ stress at depth for rock fragmentation. Compared with the original blasting design, the specific charge is reduced by 19.8% and the average block rate is reduced from 6.8% to 2.84%. At the same time, the blasting boundary is well controlled and the ore loss and dilution rates are reduced. This research has important guiding significance to deep mine blasting design.

Sign in / Sign up

Export Citation Format

Share Document