2017 Vol. 31, No. 4

Development and Creation
Study on Foundation Treatment Method for Open Cut Section of Loess Tunnel in High-speed Railway
Liu Pengfei
2017, 31(4): 163-166,199. doi: 10.3969/j.issn.1007-2993.2017.04.001
Abstract:
The choice of foundation treatment method for open cut section of high-speed railway tunnel in loess area should focus on eliminating double standards of collapsibility and controlling settlement and deformation.In this paper,Yuzhong county,Lanzhou city,taking a loess high-speed railway tunnel excavation section of the foundation treatment as an example,the use of cement-soil compaction pile for foundation treatment occurs when the hole collapsed and shrinkaged,changed to bored pile,and reinforced concrete rigid support plate is set to the top of the pile,the pile-plank structure has good effect of foundation treatment.It is shown that the method of foundation treatment in loess tunnel should be selected rationally according to the technical and economical comparison with the factors such as water content,collapsibility and so on.
Characteristic Analysis of Expansive Soil (Rock) in Angola
Wang Yingbing, Liao Yanhong, Xia Yuyun
2017, 31(4): 167-169,210. doi: 10.3969/j.issn.1007-2993.2017.04.002
Abstract:
In this paper,the macroscopic characteristics,mineral composition,expansibility and bearing capacity of expansive soil(rock) in Angola are analyzed and summarized by field investigation,indoor and field tests combining with engineering examples.The result reveals that the expansive soil(rock) in Angola is mainly distributed in the western coastal areas,where the geomorphic unit is dominated by denudation hills.This soil contains many hydrophilic mineral components and has large discreteness of expansibility index.It is sensitive to water that leads to the phenomenon of expansibility and strength attenuation after humidification which are the prominent characteristics of the expansive soil(rock) in Angola.
The Seepage Stability Analysis of the Process of Anqing Product Pipeline Crossing River
Zhang Yi
2017, 31(4): 170-172,179. doi: 10.3969/j.issn.1007-2993.2017.04.003
Abstract:
In the construction process of Anqing product pipeline crossing river course project,pipeline crossing will affect the seepage of river channel and embankment.In this paper,the finite difference method is used to analyze and calculate the seepage stability of the embankment after the pipeline crossing,and groundwater flow numerical simulation model is established.Based on the analysis of numerical simulation results of groundwater flow and the application of critical hydraulic gradient method,the possibility of seepage failure by directional drilling crossing river course is analyzed quantitatively.
Technology Probe and Research
Research on Design of Retaining Structure System for Foundation Pit Adjacent to Building
Wang Duli, Kuang Jian, Shen Yupeng
2017, 31(4): 173-179. doi: 10.3969/j.issn.1007-2993.2017.04.004
Abstract:
ABAQUS sottware is used to establish the model ot excavation of soft soft foundation pit approaching building in Huining Jiayuan residential quarte,Tianjin.The maximum inclination of building is taken as the criterion to analyze the features of influence of each element in the support structure system on the deformation of the adjacent building.Several conclusions were drawn:①Increasing the distance between the building and the foundation pit can effectively control the settlement and inclination of the building.②Increasing the height of the inner support or the prestress of the internal support can effectively control the settlement and deformation of the adjacent building.③The concrete strength,the diameter and length of pile have little influence on the settlement and inclination of building.④Increasing the cohesion and angle of internal friction of the soil can effectively control the settlement and inclination of the building,which can be used as an option for the protection of building under certain circumstances.
Scanning Electron Microscopy Analysis of Soil Body after Vacuum Preloading and Deep Soil Foundation Treatment in a Shipbuilding Base Hydraulic Reclamation Area
He Longfei
2017, 31(4): 180-185. doi: 10.3969/j.issn.1007-2993.2017.04.005
Abstract:
Combined with the reinforcement principle of soil-cement mixing method,SEM was used to analyze the microstructure of undisturbed soil and treated soil in a shipbuilding base hydraulic reclamation area.From the microscopic point of view,this paper describes and analyzes the advantages and disadvantages of using the method of cement soil mixing to reinforce the deep foundation of the site under different conditions(including the original soil,the depth,the type of curing material,etc).Some suggestions are put forward to improve the strength of cement soil mixing pile,and so as to guide the actual project.
Measurements and Numerical Simulation of Extended Service Foundation Pit
Zhang Qinxi, Wu Hao, Chao Zhe
2017, 31(4): 186-191. doi: 10.3969/j.issn.1007-2993.2017.04.006
Abstract:
During the engineering construction period,due to the design adjustment,land transfer,lack ot tunds and other reasons,the extended service of support structures often occurs,thereby increasing the risk of construction,but numerical simulation analysis about this is rare till today.Based on practical engineering example,by using the MIDAS software and choosing rea.sonable constitutive models,the numerical simulation for supporting structure for excavation is performed.The findings show that the final maximum horizontal displacement appears at the place of the second anchors,and decreases as the axial forces decrease.With the increase of excavation depth,the ground surface settlement and the bottom uplift of excavation increase at the same time.The decay of axial forces fluctuates from 9% to 37%,and the decay is still distinct after reducing axial forces.The result of numerical simulation coincides basically with that of measurement in the trend,showing that extended use of supporting structure should arouse people’s attention.
Support Design and Practice of a Deep Foundation Pit Project in Shanghai Area
Sun Yingxin, Liu Xiaoyong
2017, 31(4): 192-195,204. doi: 10.3969/j.issn.1007-2993.2017.04.007
Abstract:
Taking a deep foundation pit support engineering in Putuo District,Shanghai Zhenda Road as an example,giving full consideration to the characteristics of this project,combined with safety,economy and other aspects,to determine the bored pile with supporting a concrete form of the retaining,the shallow parts of the gravity retaining.This paper introduces the support scheme selection,design and calculation,and provides relevant information monitoring results,practice shows that the support effect is good,and provides some reference for the later similar projects.
Study on Acoustic Emission Energy Characteristics of Rocks with Different Brittleness
Ma Yunpeng, Zhao Wanchun, Chen Yanqiu
2017, 31(4): 196-199. doi: 10.3969/j.issn.1007-2993.2017.04.008
Abstract:
The conventional uniaxial test for four kinds of rocks with different brittleness is carried to obtain the acoustic emission energy characteristics of rocks with different brittleness.In the process of loading,the acoustic emission(AE) signal is detected by the acoustic emission detection system.Stress-strain curves and acoustic emission energy curves are gotten from this test.The results show that the brittleness of samples increase with the increasing of the sand ratio.The stress-strain curve shapes of the samples are similar and there are no obvious plastic stages before the peak value,while the acoustic emission curves have the obvious plastic stage and the plastic stage becomes shouter as the brittleness increases.The acoustic emission energy reaches the maximum value at the peak value and the maximum value follows a power function relationship with the brittleness index of the samples.After the peak,the stress decreases at a moment,but the acoustic emission energy will last for a short time and the duration of acoustic emission activity is shortened with the increasing of sample’s brittleness.
Design and Application of Double Row Pile in Foundation Pit Support in Nanjing Area
Wei Tianle
2017, 31(4): 200-204. doi: 10.3969/j.issn.1007-2993.2017.04.009
Abstract:
The tension in urban construction land has accelerated the development of underground space.Deep foundation pit support in protecting underground space construction has gradually been taken seriously.They were widely used in foundation pit support due to the advantages of double row pile having large lateral stiffness,small lateral deformation and with no need for support inside.Based on a case project in Nanjing,this paper introduces the design,calculation analysis and construction attention points of double row pile,which can provide reference for the application of double row pile in this area in the future.
Evaluation on Treatment Effect of Deep Artificial Filled Ground
Ji Jianhua
2017, 31(4): 205-210. doi: 10.3969/j.issn.1007-2993.2017.04.010
Abstract:
During the engineering construction in the deep fill areas,the major problems are the selection ot the ground treatment methods and the evaluation of the effects.Through the detection cases of the engineering application of the dynamic consolidation,it is proved that the dynamic consolidation can improve the deep fill ground effectively.By the regression analysis,the linear regression equation is established,which can be used in the preliminary assessment of the ground bearing capacity.This method has important reference value to the similar engineering applications.
The Application of Post Grouting Technology for Post-inserted Steel Piles
Yuwen Bin
2017, 31(4): 211-216. doi: 10.3969/j.issn.1007-2993.2017.04.011
Abstract:
Through an engineering example,the paper introduces the advantages and characteristics oi post grouting technology for post-inserted steel piles,design method and construction process.According to the comparative analysis of test data before and after the grouting pile foundation,proved that the technology can significantly improve the bearing capacity of pile and reduce the pile settlement.The technology has guiding significance for similar projects.