岩土工程技术

The Design and Application of Single Pile Composite Foundation Static Loading Testing Set

Gong Tianzhen, Chang Jiyu, Han Pengju

2011, 25(1): 1-4. doi: 10.3969/j.issn.1007-2993.2011.01.001

[Abstract](51) [PDF 610KB](10)

Abstract:
In order to obtain the composite foundation practical work state, which acts by cushion adjusting and by pile and soil bearing load together, single pile composite foundation static loading testing set is designed. It is used to test composite foundation characteristic value of composite foundation bearing capacity, characteristic value of pile and characteristic value of soil in piles containing cushion. This set can obtain the settlements of pile, soil in piles, and composite foundation and load severally, and can make the results of distribution of load in piles and soil in piles under composite foundation load, and can acquire the pile-soil stress ratio, which displays working mechanism of composite foundation. At last, through the practical testing used single pile composite foundation static loading testing set, the composite foundation, pile and soil in piles working state are discussed respectively, which can be used practically in scientific research, practical design and technical testing of composite foundation.

Experimental Study on the Effect of Adding a Hoop Beneath the PHC Pile Endpoint

Chen Liang

2011, 25(1): 5-9,37. doi: 10.3969/j.issn.1007-2993.2011.01.002

[Abstract](35) [PDF 1093KB](8)

Abstract:
In the course of power driving, damage to the PHC pile head and body often occur because of the exorbitant blow count or blow energy, the compacting effect and vibration effect also have an evil influence to the surroundings. By adding a hoop beneath the PHC pile endpoint, the influence of frictional force of pile side can be reduced. Based on the comprehensive test pile in a power plant project, through the research to the total blow count, final injection depth, soil plugging height, vibration test and high-strain test, we show that adding a hoop beneath the PHC pile endpoint has better effect to keep the pile integrity and reduce the vibration effect, the final ultimate bearing capacity of single pile is not be affected, the effect to compacting effect is also weak. This research results have references to pile driving in the construction of the power plant and similar porjects.

Experimental Study on Bearing Capacity of Bored Piles Using Post-grouting Technology

Xiao Jian, Zhao Gang

2011, 25(1): 10-12,16. doi: 10.3969/j.issn.1007-2993.2011.01.003

[Abstract](58) [PDF 642KB](7)

Abstract:
Post-grouting technology can improve the disadvantage of bored piles. It has been proved that post-grouting technology can advance the bearing capacity and reduce the settlement of pile markedly by some post-grouting experimentation. Side frictional resistance distribution map of pile has been gained according to distributed optical fibre detection, and post-grouting effect and mechanism of action are also analysed.

Study on Layered Settlement Prediction of Soft Soil Foundation Which Reinforced by Vacuum Preloading Based on Gray System

Zhao Pengzhou, Yin Zhangjun

2011, 25(1): 13-16. doi: 10.3969/j.issn.1007-2993.2011.01.004

[Abstract](44) [PDF 591KB](6)

Abstract:
Gray Theory is used to predict layered settlement of soft soil foundation,which reinforced by vacuum-surcharge preloading.The result shows that:Verhulst model can accurately predict layered settlement of well-distributed soil,with error of less than ten precent,but for uneven soil of foundation,the error of Verhulst model compared greatly,so the Verhulst model was modified,modified Verhulst model can accurately predict layered settlement of uneven soil of foundation.Then predict the layered settlement of foundation by different points of real datas,compared with the measured datas found that,when the settlement which out of the vacuum affected is known,Gray Model can accurately forecast the layered settlement of ground.

Application of Centre Filler PHC Pipe Pile in Soft Soil Pit Supporting

Kang Juren

2011, 25(1): 17-22. doi: 10.3969/j.issn.1007-2993.2011.01.005

[Abstract](59) [PDF 760KB](15)

Abstract:
PHC pipe pile mainly bears vertical load in foundation engineering. While PHC pipe pile is applied in pit supporting, mostly bears horizontal load.Centre filler PHC pipe pile to increase its flexural capacity.By the analysis of engineering examples, authors discussed the feasibility of PHC pipe pile's application in pit supporting, fill in the core of PHC pipe pile foundation pit supporting application has certain directive significance.

Monitoring and Analysis of Pile-anchor Retaining Structure for a Deep Foundation Pit in Beijing

Zhou Chen, Li Xudong, Sun Yuanping

2011, 25(1): 23-25,31. doi: 10.3969/j.issn.1007-2993.2011.01.006

[Abstract](59) [PDF 597KB](6)

Abstract:
Based on supporting a deep foundation pit by adopting pile-anchor retaining structure.During the constrction,the displacement of pile head,the surface settlement,the axial load of anchor rope are monitored and analyzes the main monitoring data.The results indicate that the pile-anchor retaining structure can control the horizontal displacement of foundation pit and the surface settlement of surrounding structure effectively,and there are some laws in variation of horizontal displacemen and surface settlement.The losses of prestresses of anchors is large,it's about 30%~50%,and the range of variation is about 15% during the constrction;the first anchor rope play an important role in controlling displacement and settlement,the third anchor rope is the key of controlling the maximum bending moment in pile.Giving advice for the design of similar pile-anchor retaining structure combine with the reasons of the calculating data different from the measuring data.

The Application of Combined Method of the Soldier Piles and the Composite Soil Nailing Wall in Deep Foundation Pit

Shen Yiye, Guo Miwen

2011, 25(1): 26-31. doi: 10.3969/j.issn.1007-2993.2011.01.007

[Abstract](61) [PDF 680KB](8)

Abstract:
This paper introduces a retaining project of deep foundation pit.Around the pit there are many buildings with different characteristics such as newly built or already existed,for temporary use or for permanent use.The surrounding environment and the geological condition are complex,the pit-depth veries from 9.0 m to 16.0 m.Limited by the constraints such as the duration and the construction arrangement,the shallow part of the foundation must be constructed prior to the deeper parts.According to project goals on security,economic and duration,the combined method of the soldier piles and the composite soil nailing wall was adopt.The actual construction and the monitoring result shows,the combined method meet all the requirements,and may provide useful reference for the similar projects.

Monitoring and Analyses of the Foundation Pit Deformation for Suzhou Oriental Gate

Xu Juan, Ding Haiping

2011, 25(1): 32-37. doi: 10.3969/j.issn.1007-2993.2011.01.008

[Abstract](54) [PDF 736KB](9)

Abstract:
The foundation pit of Suzhou Oriental Gate is an open-type and specially big & deep one in plane with length of about 205 m, width of about 103 m and depth of 20.5 m except local deeper areas. In this paper, the information of the surrounding soil and underground pipelines deformation as well as upright post settlement obtained in construction monitoring are sorted out and analyzed, and some beneficial conclusions are obtained that can be provided as reference of deep foundation pit design, construction and monitoring in soft soil area.

Application of Root Piles to Foundation Treatment of Powerhouse Extension Project

Zhang Liang, Gao Feng

2011, 25(1): 38-40. doi: 10.3969/j.issn.1007-2993.2011.01.009

[Abstract](44) [PDF 495KB](7)

Abstract:
In order to properly deal with asymmetric settlement for new and old melting furnace areas of south of Jiangsu one Industry powerhouse extension project, through the selection of different programs, finally adopt root piles underpinning technique to improving the foundation. Moreover, apply chemical planting steel bar and aging-resisting treaments for the foundation of new and old melting furnace areas.

Cause Analysis of Soil Test Common Wrong Results

Luo Lanying, Hu Shulin, Zhang Wei

2011, 25(1): 41-43. doi: 10.3969/j.issn.1007-2993.2011.01.010

[Abstract](28) [PDF 499KB](10)

Abstract:
Basing on the common misunderstandings and questions in geotechnical investigations soil test results, it comprehensive analyzes them from the aspects of experimental principle, test method and calculation process. This paper points out probable causes of above mentioned misunderstandings and questions and lists the major concerns of such tests, to provide advice and reference for geotechnical investigations professions and soil test techniques.

Analysis on Reliability of Excavation Face Stability in Shallow Circular Tunnel

Wang Junfeng, Gao Guangyun, Zhang Lei

2011, 25(1): 44-48. doi: 10.3969/j.issn.1007-2993.2011.01.011

[Abstract](30) [PDF 816KB](7)

Abstract:
Support pressure is a significant factor which influences on stability of excavation face in a shallow circular tunnel driven by a pressurized shield, which is also a key point in reliability analysis. FLAC3D simulation and response surface methodology is utilized for the reliability index β for ultimate state. Both soil shear strength parameters are considered as random variables as the ultimate state studying and also taking into account the statistical correlation between cohesion and internal friction angle. Finally, the assumption of uncorrelated variables was found conservative in comparison to the assumption of negatively correlated variables.

The Design and Application of Multi-type-pile Composite Foundation

Chen Tianlin

2011, 25(1): 49-52. doi: 10.3969/j.issn.1007-2993.2011.01.012

[Abstract](38) [PDF 595KB](7)

Abstract:
Based on the design calculation of Single pile composite foundation,the computational method of multi-type-pile composite foundation's bearing capacity,compression deformation and soft underground stratum checking are discussed, and it is confirmed by the practical instances. At the same time, in order to eliminate the collapsibility of loess and increase the strength of foundation, the ram dry concrete pile and CFG pile are being used in the ground treatment of collapsible loess zone for the first time, remarkable economic results and application effects have been achieved.

Technical Feasibility of Open Anti-underground Water Curtain in Coarse Sand Stratum for Construction Pit Retaining

Liu Zhijun

2011, 25(1): 53-55. doi: 10.3969/j.issn.1007-2993.2011.01.013

[Abstract](20) [PDF 604KB](5)

Abstract:
In the article the author discusses application of open anti-underground water curtain for earth retaining wall of construction pit in deep sandy soil with plenty of underground water supply。

2011 Vol. 25, No. 1