岩土工程技术

Bearing Capacity For Upper Bound Method Analysis

Qin Huilai, Li Feng

2012, 26(3): 110-112,119. doi: 10.3969/j.issn.1007-2993.2012.03.001

[Abstract](24) [PDF 291KB](6)

Abstract:
At present, the bearing capacity calculation is based on three-items superposition method proposed by Terzaghi in study or practice. The three items which constituing the bearing capacity are the cohesion of the soil, the surcharge load beside the foundation and the weight of the soil Since the soil is neither linear nor elastic material,it is not a good choice to use the superposition method in theory. It maybe a good choice to directly calculate the bearing capacity with all the influnce factors taking into considered. To analyze the difference of the two rnothods mentioned above, the multi-block upper hound method is employed. The calculation results based on the two methods are presented here,and the difference is discussed. With the envelops obtained by the multi-block upper hound method, the cause of the difference for the two methods is demonstrated.

The Experimental Research on the seepage Law of Single Fracture Gritstone

Zuo Wei, Han Fei, Li Junniu

2012, 26(3): 113-119. doi: 10.3969/j.issn.1007-2993.2012.03.002

[Abstract](25) [PDF 2082KB](6)

Abstract:
Based on geologic background of Shi Zuishan colliery, the single rock fracture seepage tests under the triaxial stressdo exists, the relations tests between the effective confining pressure and the fracture aperture. This paper revealed the single fracture gritstone seepage law in the three dimensional stress, and established the relationship among effective confining pressure, fracture pressure and coefficient of permeability, in order to enrich the seepage theory research on fractured rock mass.

The Excavation Scheme of Shenyang Subway Optimize Technology Research

Wang Tienan, Yang Qingchao, Hao Zhe

2012, 26(3): 120-124. doi: 10.3969/j.issn.1007-2993.2012.03.003

[Abstract](22) [PDF 1301KB](5)

Abstract:
This paper based on shenyang subway project. Conceiving the weekend interval period metro tunnel construction as the background and the application of FLAC numerical simulation analysis software. According to the geological conditions, various of shenyang excavation method applicable range and characteristics of main adopts full section method, double meshshotereting firstly method, retain earth steps method are simulated and analyzed in three ways. and also according to the monitoring displacement, the surrounding elastic-plastic state, anchor axial force and lining of internal rationality of such excavation methods.

The Application of Composite Long-Short Pile Foundation in High Fill Soil Building

Zhang Songnan

2012, 26(3): 125-127,163. doi: 10.3969/j.issn.1007-2993.2012.03.004

[Abstract](38) [PDF 913KB](7)

Abstract:
The fill soil of different heights around buildings would easily lead to salty problems. In order to solve it and reduce the cost of pile foundation, the design philosophy for composite long-short pile foundation is presented when some bearing soil existing. Long piles are mainly build to control the settlement and short piles as well as soil mainly to provide bearing capacity. The 3D finite element method is used to simulate the performances of a short pile foundation and a composite long- short pile foundation by the fill soil. The results indicated that the composite long-short pile foundation can greatly cut the cost of pile foundation and effectively control the different settlements. So the composite long-short pile foundation may solve the salty problems and the design philosophy is useful.

Design and Practice of Trestle Bridge Bracing Construction in Deep Foundation pit

Zhao Shengfeng, Li Shubo, Ma Shiqiang

2012, 26(3): 128-131,144. doi: 10.3969/j.issn.1007-2993.2012.03.005

[Abstract](26) [PDF 991KB](9)

Abstract:
Because the deep-foundation-pit and the depth in the project, and it forms the supporting system of internal bracing. It makes the earthwork excavation to be speeially extremely difficult. Therefore, the first supporting system will com- bine structural designs and application of the trestle bridges. It will become the structural styles inevitably. The article based on the building structural design principles, carried on the analysis of the overall stress situation of the supporting system of inter- nal bracing through summaring the common form of trestle bridge structure. Combined with the projeet example, the design methods of supporting system of trestle bridge braeing construction in deep-foundation-pit is introduced, It provided some ref- erences for the structural designs of trestle bridge bracing.

Line of the Foundation Pit Optimization Design and Simulation of Deformation

Yao Jin, Hua Lijuan

2012, 26(3): 132-136. doi: 10.3969/j.issn.1007-2993.2012.03.006

[Abstract](56) [PDF 621KB](6)

Abstract:
This research is based on a section of subway line parking excavation programs to optimize the designs. Excluding the using of comparison and selection methods to get the study area for the excavation of each program and relevant supporting design. Thus the use of mathematical methods for fuzzy evaluation composite score for all applicable programs and selecting the optimal solutions. After checking the design of the pit and using ADINA software to simulate, the author verify the feasibility of the final programs.

The Seepage Surface in Foundation Pit Dewatering

Zhao Xiaofeng

2012, 26(3): 137-140. doi: 10.3969/j.issn.1007-2993.2012.03.007

[Abstract](36) [PDF 236KB](9)

Abstract:
This paper had discussed details of the generation mechanism of the seepage surface in foundation pit dewatering, the influential factors and calculation of its height, the harm on foundation pit and the measures adapted. The engineering practice showed that the study on the seepage surface in foundation pit dewatering provides a theoretical basis for resolving engineering problems in foundation pit dewatering.

The Engineering Properties Discussion of Dredger Fill Through the Cone Penetration Test

Liu Ju, Liu Hanpeng, Du Dongju

2012, 26(3): 141-144. doi: 10.3969/j.issn.1007-2993.2012.03.008

[Abstract](52) [PDF 243KB](9)

Abstract:
Effecting by the action of gravity hydrodynamic force and improving through the vacuum consolidition way, the dredger fill of Tianjin Binhai New Area has more complex engineering properties. Through the cone penetration test(CPT) and other way, it can be divided into Hard shell soil, Weak Clay soil and Sand soil, All together, three strata from top to bottom. The Hard shell soil on the top and sandy soil in the bottom consist high intensity, unsteadable distribution characters. Just as the soft soil, low intensity and high compressibility is the main characters of Weak Clay soil. The Dredger fill near the Water outlet, which is mainly composed by Weak Clay soil, has poor engineering properties.

Variety of Calculation Methods on Determining the Comparative Analysis of the Permeability Coefficient

Li Kaichao, Fan Hanguang, Gao Shuxiao

2012, 26(3): 145-148. doi: 10.3969/j.issn.1007-2993.2012.03.009

[Abstract](22) [PDF 239KB](7)

Abstract:
Permeability coefficient is an important engineering design precipitation of hydro--geological parameters, Due to the complexity of the hydrogeological and their diversity, resulting in the calculation of permeability coefficient values often lead to big differences. In this paper,Xi'an Metro Line't train station pumping test, the related using complete steady stream of well single well method with observation wells mathematical model, also considering the single--well well the complete loss of mathematical model of steady flow non- complete mathematical model of steady flow wells, water level recovery method mathematical model of an integrated three methods to determine the permeability of loess. Analyzing and comparing the advantages and disadvantages of various mathematical models, equations for calculating the permeability coefficient of loess more reasonable mathematical model.

The Study of Estimating the Tailings Pond's Safety Distance in Downstream

Tang Jiyu, Tang Jianyu

2012, 26(3): 149-151. doi: 10.3969/j.issn.1007-2993.2012.03.010

[Abstract](40) [PDF 186KB](8)

Abstract:
Owing to the safe distance of the tailings pond in downstream did not have an experimental mathematics model At present,which causes the safe distances hard to confirm. In this paper the mathematics model of the debris flow estimation is used to explore a more reasonable safe distance measurement. It could provide an estimating method scientifically for the selecting of the railings pond's sites, safety evaluation and the supervisor sections.

Dynamic Consolidation and Tests on Plateau Moraine Soil

Wang Tingbo, Song Dechao, Dun Zhiyuan

2012, 26(3): 152-154. doi: 10.3969/j.issn.1007-2993.2012.03.011

[Abstract](23) [PDF 172KB](6)

Abstract:
Taking Daocheng--Yading airport as an example, the effect of dynamic consolidation method for moraine soil is discussed in this paper. Using Rayleigh surface wave method and dynamic penetration test, the results proved that the foundation meets the design requirements in comparison to the load test after the reinforcement of moraine soil. As to the similar situations, it has a certain reference value to combine the two test methods.

Negative Skin Friction on Piles in Loess Collapsible Under Overburden Pressure

Shi Huaiqing, Gao Peng, Zhao Wenbo

2012, 26(3): 155-158. doi: 10.3969/j.issn.1007-2993.2012.03.012

[Abstract](38) [PDF 209KB](8)

Abstract:
Through the field in the natural state and, after vibroflotation sand compaction pile treatments on two regions of the static load test of pile and pile stress tests. The Author Had determined the different regions of the vertical ultimate carrying capacity of single pile, and the natural compaction sand pile under two different conditions of pile body side friction are analyzed. After vibroflotation sand compaetion pile treatments, the reinforced concrete filling pile side resistance and end resistance of the pile will be greatly improved, designed by the length shortened to save such projects in foundation of funds.

Technical Analysis on High-Rise Building Foundation Engineering Construction in Confined Aquifer

Zheng Ping, Wu Xujun, Du Fuzhi

2012, 26(3): 159-163. doi: 10.3969/j.issn.1007-2993.2012.03.013

[Abstract](33) [PDF 640KB](6)

Abstract:
The unfavorable effects of confined water were discussed briefly on the construction of foundation pit support, pile foundation and anti-float anchor (pile) for high-rise building. Combined with a engineering project, the design method of jet grouting cut-off wall in confined aquifer was elaborated. Key techniques, such as general construction sequence, treatment of gushing water in prospect hole and ground water--level observation, were also analysed in this Paper.

2012 Vol. 26, No. 3