岩土工程技术

Study on Time Effect of Static Pressure Pipe Pile in Zhoushan District

Tu Yinjiu, Bao Limin, Zhang Wei

2009, 23(6): 271-275. doi: 10.3969/j.issn.1007-2993.2009.06.001

[Abstract](35) [PDF 263KB](6)

Abstract:
Study is done on time effect of static pressure pipe pile in Zhoushan district by repress and statical loading test. The character of piling force changing with different soil is pointed out. Relationship of piling force vs truce time and recovery coefficient vs lataral soft soil property is discovered.

Research on Uniaxial Consolidation Test of the Typical Reticulate Red Clay Around Dongting Lake Area

Yan Luchao, Li Jianzhong, Tang Xiqing

2009, 23(6): 276-279,283. doi: 10.3969/j.issn.1007-2993.2009.06.002

[Abstract](37) [PDF 315KB](5)

Abstract:
To research the uniaxial consolidation property of the typical reticulate red clay around Dongting lake area, uniaxial consolidation tests were performed on the undisturbed and disturbed sample under different vertical pressure. By analyzing the laboratory results, the authors drew following conclusions: the compressibility of undisturbed sample is much more insignificant than that of disturbed sample;in secondary consolidation stage, the creep curves of undisturbed sample is rough, and the undisturbed sample has no obvious steady creep stage, while the creep curves of disturbed sample are smooth and there is obvious steady creep stage in disturbed sample;the undisturbed sample comes to the end of creep deformation much earlier. The authors also found that uniaxial consolidation of unsaturated reticulate red clay has the linear rule, and the authors deduced a empirical equation of uniaxial consolidation, a parameter in this equation can help us forecast the ultimate settling amount of reticulate red clay.

Study on Deep-hole Pre-grouting for Shallow Tunnelling in Gravel Stratum

Wu Jiangbin

2009, 23(6): 280-283. doi: 10.3969/j.issn.1007-2993.2009.06.003

[Abstract](57) [PDF 337KB](6)

Abstract:
Gravel stratum is a kind of one with loose structure, poor arching capacity and strong permeability; meanwhile it is eementingless and low in self-stability. At present, construction technique and method of shallow tunnelling in this stratum are not so perfect, such as conduit pore-forming process, grouting material selection, grout proportion, grouting pressure and grouting capacity parameter, which are less of experience for reference during construction. Based on the engineering background of the Shallow tunnelling test section in Beijing Metro Line 9, deep-hole pre-grouting experiment was done under the condition of gravel stratum. This paper compares and analyses the laws and different characteristics of pore-forming effect, drilling efficiency, grouting pressure,grouting capacity, grout proportion and grouting reinforcement effect among five pore-forming methods as well as two grouting methods, which are progressive style and retrograde style, and proposes a deep-hole pre-grouting method which is suitable for gravel stratum. The research conclusions will provide useful reference for following construction of the Beijing Metro Line 9 and deep-hole pre-grouting in similar strata.

Study of Choice Behavior on the Super-long Uplift Piles in Mollisol Area

An Jingbo, Zhao Siyuan, Deng Zhihui

2009, 23(6): 284-287. doi: 10.3969/j.issn.1007-2993.2009.06.004

[Abstract](37) [PDF 260KB](7)

Abstract:
The long uplift piles are researched in this paper through the comparative analysis of conventional straight piles, grouting piles and under-reamed piles. The theoretical equation of load-displacement is derived by a mathematical model. The mechanism of increasing load-carrying capacity and load transfer law of the different piles are studied by analysising the load-carrying capacity when the displacement of the pile top is 30 mm, and the distribution of frictional resistances of different style of piles in a mollisol area of coastal. The grouting straight piles should be the priority selection because of the increase of safety probability.

Numerical Simulation of Pit Excavation on Constructed Main-Buildings

Wu Chao, Ye Chaohan, Fan Xiangyang

2009, 23(6): 288-291,295. doi: 10.3969/j.issn.1007-2993.2009.06.005

[Abstract](39) [PDF 404KB](5)

Abstract:
Protection of adjacent important buildings is an essential subject during pit excavation. As for a wide foundation pit with underground garage and main buildings, the excavation and construction of main buildings may precede underground garage. In general, the underground garage is often close to main buildings, which would lead to such serious problem inevitably, the excavation of underground garage has great influence on main buildings constructed or under-construction. Based on practical engineering,finite element method is utilized to simulate this problem.

Identification of Abnormal Attribute for Observed Stress in Foundation Pile Based on Wavelets

Li Xiaoyan, Ruan Huaining, Chen Zhijian

2009, 23(6): 292-295. doi: 10.3969/j.issn.1007-2993.2009.06.006

[Abstract](44) [PDF 213KB](4)

Abstract:
Wavelet has good localization characteristic in time and frequency domain. Strangeness index of data serial can be calculated simply and conveniently with wavelet to detect stochastic jump value. The detected method is correct and effectual by validating test data. Abnormity attribute can be identified automatically, according to distribution rules of jump value of multi-sensors. It states that identification of abnormality attribute based on wavelet analysis is a novel and valid method.

Influence Factors and Sensitivity Analysis of Stability for Bank Involved in Water

Wang Hao, Xia Liquan

2009, 23(6): 296-300. doi: 10.3969/j.issn.1007-2993.2009.06.007

[Abstract](47) [PDF 338KB](7)

Abstract:
In this paper, the author analyzed the influence factors of bank ruin in the Three Gorges of the Yangtze River area and summarized the type and feature of the factors. And we analyzed the factors with the numerical simulation software to get the impact of various factors and the sensitivity with Orthogonal test. The production will provide the reliable basis for the Three Gorges area which has the similar geological condition.

Punching-cutting Safety Evaluation in the Pile Tip Hard-bearing and Application in the Red Beds

Luo Zhaohua, Jiang Zhongxiao

2009, 23(6): 301-303. doi: 10.3969/j.issn.1007-2993.2009.06.008

[Abstract](65) [PDF 214KB](4)

Abstract:
For hard rock-socketed pile tip bearing layer thickness less than 3 times actually, in order to ensure safe and cost savings, base on the analysis of pile-rock and soil system load transfer mechanism and failure mode of rock, we establish the punching capacity formula of pile tip hard-bearing stratum, then use the formula to calculate pile-end hard-bearing stratum anticutting capacity,and it was divided by the pile design load to obtain the of safety K, using the safety factor K to determine whether pile bearing stratum thickness can meet the load requirements. Project examples show: the method in the apply of the red layer region is good and reference.

The Application of EXCEL in Slope Stability Analysis

Deng Dongping, Li Liang, Zhao Lianheng

2009, 23(6): 304-308. doi: 10.3969/j.issn.1007-2993.2009.06.009

[Abstract](230) [PDF 295KB](30)

Abstract:
By exploiting Excel's powerful data-processing and convenient formula for support functions and of object-oriented programming language VBA, it applies to the stability analysis of some slopes. The basic method is that first Swedish slices method which is the traditional method, is used to calculate and analyze this slope, and at the basis of former method obtaining the most dangerous sliding surface, the safety factor Fs will be improved through simplified Bishop method. In this process, the unknown variable of the limit equilibrium method can be easily obtained by Excel add-VBA subroutine, and factor of safety (Fs) of the most dangerous sliding surface is calculated. At the same time,a visualization button is designed to draw the location of the most dangerous sliding line of this slope. This method make the calculation procedure simplify, and it can not only achieve easily in the Excel, but also the results are proved to be very close when the data obtained from this method, is compared with the simplified Bishop method, so it can meet demand for project.

Application of the Method of Reflect Wave in Detection of Cement Mixed-in-place Pile of Lian-lin Highway roadbed

Xu Baotian, Yan Zhanghong, Xia Wenjun

2009, 23(6): 309-312. doi: 10.3969/j.issn.1007-2993.2009.06.010

[Abstract](21) [PDF 277KB](5)

Abstract:
The method of reflect wave is used to examine the cement mixed-in-place pile in the roadbed of Lian-lin Highway. The reflect wave signal has 4 types, which are differently corresponding to the reflect features of the pile top, pile body defect and the pile bottom. Based on theoretical study and practical experiments, we believe that the reflection wave method is effective in examining the cement mixed-in-place piles.

A Method to Describe Characteristics Feature of Microstructure for Soil

Li Shunqun, Chai Shouxi, Wang Yinghong

2009, 23(6): 313-315,320. doi: 10.3969/j.issn.1007-2993.2009.06.011

[Abstract](28) [PDF 339KB](4)

Abstract:
The techniques of correlation analysis and principal component analysis are utilized to study leature microstructure parameters extracted from SEM photos of the three kinds of soil. The study shows that message superposition is clear and severe among microstructure parameters for feature analysis, and that is same for field analysis. Therefore, it is reasonable to construct a lower parameter matrix to substitute the original higher parameter matrix for microstructure. The minority representative principal components can approximately synthesize the overall meaning of microstructure according to the desired value of contribution by the method of principal component analysis, and this makes extensive use of mierostructure theory in soil mechanics expediently and potentially.

Study on the Loess-like Saline Soil as Backfill Material in Xining

Wang Zhiming

2009, 23(6): 316-320. doi: 10.3969/j.issn.1007-2993.2009.06.012

[Abstract](29) [PDF 345KB](7)

Abstract:
Based on the investigation of distribution of the loess-like saline soil foundations in Xining, engineering characteristics and the damages to the building, respectively, from three characteristics of the settlement by soaking, salt expansion and causticity of the loess-like saline soil, the author research into the effects on the nature of the foundations from the changes of salinity in the backfill in the loess-like saline soil foundations in Xining. Some of the points raised by the practice has achieved a certain degree of social effects and economic benefits.

The Technology for Pipe Jacking of the Second Water-pipeline Engineering in Shantou

Zhong Junbin, Wang Zuomin, Cao Yuping

2009, 23(6): 321-323. doi: 10.3969/j.issn.1007-2993.2009.06.013

[Abstract](43) [PDF 211KB](7)

Abstract:
The distance of pipe Jacking is 2080m in the second water-pipeline engineering across Shantou gulf. The pipe successfully got across the sea wall and weathering granite in sea. The length is the longest in the world. The completion means the progress of the technology of design and construction in pipe jacking engineering.

2009 Vol. 23, No. 6