岩土工程技术

Application of Pure-Concrete-Pile in Mixed Soils of Venezuela

Wu Xuelin, Tang Guoyi, Dai Yanxiong

2014, 28(1): 1-4. doi: 10.3969/j.issn.1007-2993.2014.01.001

[Abstract](37) [PDF 2879KB](7)

Abstract:
The topography and geomorphology of which surrounded by mountains is the material sources of mixed soils in Caracas,Venezuela.The project in this paper is located in Caracas with the mixed soils that contain sand,gravel,silt and silty clay.And the mixed soils with lower bearing capacity is unhomogeneous which represented by discrete SPT blow counts.Through the PLTs on nature ground and pure-concrete-pile composite ground,this paper indicates that the beating capacity of the mixed soils is more increased by ground improvement.And feasible construction technology of pure-concrete-pile is also tested.The application of pure-concrete-pile composite ground in Caracas mixed soil is successful and perfect.

Experimental Study on Deep Soft Ground of High Speed Railway Treated with Bored Pile-continuous Thin Plate Structure

Sun Honglin

2014, 28(1): 5-9. doi: 10.3969/j.issn.1007-2993.2014.01.002

[Abstract](40) [PDF 2909KB](6)

Abstract:
The settlement and the long-term dynamic stability of soft ground were the key technical problems,when the low subgrade of high speed railway with ballastless track was constructed in deep soft soil region.The soft ground will have large residual settlement under embankment load because of its high compressibility and the foundation soil may have greater plastic deformation arise from long-term large dynamic load in the operation process,which can seriously affects the ride comfort of ballastless track.In order to decrease settlement and improve the long-term dynamic stability of the low embankment on deep soft ground in Shanghai Hongqiao area of Beijing-Shanghai High Speed Railway,the bored pile-continuous thin plate structure was firtstly used with detailed monitoring and testing.The analysis results indicate that this structure has the characteristic of smaller post-construction settlement and better resistance capacity to dynamic load deformation,so it can meet the controlling requirements of ballastless track on high speed railway.

Design and Construction of Deep Excavation Support in Shenzhen East Gate No. 61 Compound

Cao Xiaopin

2014, 28(1): 10-13. doi: 10.3969/j.issn.1007-2993.2014.01.003

[Abstract](33) [PDF 2799KB](10)

Abstract:
The project of shenzhen east gate No.61 compound is located in east gate commercial street,Luohu,Shenzhen,it is adjacent to the subway and existing shallow foundation buildings.The depth of excavation is 17.15 m and 18.60 m.According to surrounding environmental requirements and geologic conditions,various types of bracing system such as secant pile,punching pile,rotary jet grouting pile,internal supporting system and anchor cable were selected.The construction of deep excavation were seriously simulated by the three-dimensional numerical simulation method.Based on the results of numerical analyses,foundation pit deformation and its impact on subway were studied.Design and construction has been completed and proved to be effective,which provide valuable references for similar projects in the future.

Discussion about Anti-floating Design of Subway Station

Yang Hongmei, Li Ling, Wang Shengjun

2014, 28(1): 14-19. doi: 10.3969/j.issn.1007-2993.2014.01.004

[Abstract](54) [PDF 1163KB](14)

Abstract:
Anti-floating design is very important for subway design,and it greatly affects the cost of construction.There are several controversy about design parameters,anti-floating calculation.The writer researches on latest codes and expert opinions,and introduces the confirmation of waterproof location,anti-floating design and measures of anti-floating.The writer states personal views about the divergences,and propose personal methods and advices about problems of subway station antifloating design on the basis of features of subway engineering.

Experimental Study on the Effects of Water Content and Clay Material on Stability of Sliding Zone Soils

Li Hongbo

2014, 28(1): 20-23,28. doi: 10.3969/j.issn.1007-2993.2014.01.005

[Abstract](26) [PDF 1932KB](9)

Abstract:
In order to analysis the stability of a Nanjing slope,a quantitative analysis through test method was carried out.Using test method to reveal change in clay minerals and water content of structural plane influence the strength parameters c、φ and F of rock slope.Some results were present:1) the safety factor was decreased with the increase of clay minerals; it reaches the minimum between 45%~55%; 2) the safety factor was decreased with the increase of water content.Using the particle swarm algorithm analysis the test results、it showed that with the increase in the content of clay minerals,the safety factor of change is non-linear,but always showed a good correlation,the correlation coefficients ranging from small to large; the safe coefficient values and water content showed a negative correlation linear relationship and maintain at a high correlation,the correlation coefficient reached 0.90 or more,it is in line with the general laws of nature.

The Discussion of Calculation to Water & Earth Pressure and the Preferred Shear Strength Index

Zhang Haidong, Liu Xu

2014, 28(1): 24-28. doi: 10.3969/j.issn.1007-2993.2014.01.006

[Abstract](32) [PDF 605KB](9)

Abstract:
The shear strength index is very important in geotechnical calculations,how to use the shear strength indices under different test conditions in engineering practice concerns whether the project is secure and stable,this problem has long been a rather hot debate in engineering rield.From the fundamentals,this paper elaborates some specious concepts,presents a thesis that calculating the water and the earth pressure together is insignificant in engineering,and the effective self-weight stress is not equal to the effective stress,meanwhile,it generalizes a basic idea that is how to choose the shear strength index in engineering practice Hope to have significance to accurately understand the theory of soil mechanics and direct engineering practice

The Analysis of the Seepage and the Stability of the Zhangjiawan Reservoir Dam

Guo Jiapeng

2014, 28(1): 29-32. doi: 10.3969/j.issn.1007-2993.2014.01.007

[Abstract](79) [PDF 1468KB](9)

Abstract:
This paper takes Zhangjiawan reservoir dam as an example to analyse the seepage stability by using finite element method and the slope stability by using the Swedish circle method and the Bishop method of the homogeneous earth darr.On this base evaluating the safety and the seepage and slippage resistivity of the Zhangjiawan reservoir dam.

Numerical Simulation Research on Spatial Variation of Displacement of Underground Pipeline During Excavation of Deep Foundation Pit in Tianjin Soft Soil Area

Ji Kuixiang, Guo Jinjing, Zhou Yuming

2014, 28(1): 33-36,50. doi: 10.3969/j.issn.1007-2993.2014.01.008

[Abstract](34) [PDF 4615KB](8)

Abstract:
Taking a deep foundation pit engineering of a research building in Tianjin as an example,analysis adjacent pipeline displacement rule caused by foundation pit excavation with the finite element simulation.Simulation results show that different excavation sequence will lead to different displacements of pipeline,the influence on pipeline from middle to both sides excavation is smaller than that from both sides to the middle excavation,and at the end of the foundation pit is the maximize curvature change of the pipeline.The soil reinforcement can effectively reduce the displacement of pipeline caused by foundation pit excavation.Different depth and width of reinforced soil will result in different restrictions on pipeline displacement function.In combination with the practical situation of the project,believe that when the strengthening depth is 7 m and the width is 7 m is the most economic under the premise of best reinforcement effect.

Reinforcement Technology of Foundation Pit Engineering on Miscellaneous Fill Soil Rich in Water

Liu Hailong, Zhang Zhihua, He Xiaofei

2014, 28(1): 37-40. doi: 10.3969/j.issn.1007-2993.2014.01.009

[Abstract](25) [PDF 1266KB](6)

Abstract:
A project faces a problem which is water burst and sand boil between the piles on miscellaneous fill soil when digging the soil and settig up anchors after constructing the slop shield piles,and now we need to reinforce its foundation pit on the miscellaneous fill soil.After detailed demonstration,we use the methods of grouting reinforcement and adding anchor.We calculate the two anchoring parameters according to the specification,and do the anchor test,at last we find out the anchor reinforcement design meeting the requirements according to the basic test results.We successfully solve the shutdown problem caused by groundwater influence and ensure the project completed.

Research on Permeability of Compacted Bentonite with Fracture

Chen Jie, Zhang Yonghao, Wang Qinghai

2014, 28(1): 41-44. doi: 10.3969/j.issn.1007-2993.2014.01.010

[Abstract](24) [PDF 853KB](7)

Abstract:
In order to evaluate the self-healing effect of bentonite fracture,researches were carried on to find the changing rules of permeability coefficient for the compacted bentonite samples,which have different fracture configurations and numbers,by permeated-saturated experiments.The statistical methods were used to analyze the differences of different permeability coefficient samples.The results show that permeability coefficient of compacted bentonite with fractures (dry density 1.2 g/cm³) gradually decreased with time during the saturated process,and the permeability coefficients have no significant differences between the samples with or without fractures.It also shows that configurations and numbers of fracture have no significant influence on the permeability of compacted bentonite.The compacted bentonite has good self-healing performance.

Application of Vacuum Preloading in the Pearl River Basin of a Dredger Fill Site

Qin Jiao

2014, 28(1): 45-47,55. doi: 10.3969/j.issn.1007-2993.2014.01.011

[Abstract](30) [PDF 3044KB](8)

Abstract:
This paper based on the Pearl River Basin of a dredger fill site case,introduces the construction parameters and the application effect of vacuum preloading,and makes a quantitative analysis of the formation strength in mud deep mixed column.The results show that the vacuum preloading is applicable to these sites,and the reinforcement effect is obvious,but the strength in the mud deep mixed wall decline larger,this position needs to take a replacement for another times after the treatment to use,which can offer some references for other similar engineering.

The Application of Dynamic Compaction Ground of Liquefaction

Wang Tienan, Li Jun

2014, 28(1): 48-50. doi: 10.3969/j.issn.1007-2993.2014.01.012

[Abstract](37) [PDF 2862KB](7)

Abstract:
Liquefaction mechanism of geotechnical investigation about saturated sand and silt in the article are expounded,the paper mainly analyzes the influence factors that can eliminate the dynamic compaction,which work with similar liquefied sites in geotechnical investigation.

Experimental Reserch on Engineering Characteristics of Carbon Mudstone in Liupanshui, Guizhou Province

Liu Ziang, Man Li, Bie Jiangbo

2014, 28(1): 51-55. doi: 10.3969/j.issn.1007-2993.2014.01.013

[Abstract](79) [PDF 3405KB](15)

Abstract:
Compared with ordinary mudstone,carbon mudstone in Liupanshui has special engineering characteristics.The mechanical characteristics of the area of carbon mudstone are researched in detail through fall cone test to determine liquid limit and plastic limit,compaction tests,shear strength test,and compression test in laboratory.The research results show that ①Carbon mudstone is of good plasticity,under the influence of water softening,it easily comes to disintegrate and lower the intensity; ②The moisture content of carbon mudstone can significantly affect on the compaction performance,dry density changed a lot when moisture content is between 12.5 0% and 15%; ③The cohesive force of carbon mudstone decreases rapidly with the increase of moisture content when it is leas than 11%,and changes little when it is between 11% and 15%; ④Compreasion settlement of carbon mudstone appears after the loading in a short period of time,it can quickly compress and achieve a stable state after the loading.

2014 Vol. 28, No. 1