岩土工程技术

Real-time Analysis System of Rock Stability Based on the Block Theory

Yu Yongchao

2014, 28(2): 55-59. doi: 10.3969/j.issn.1007-2993.2014.02.001

[Abstract](59) [PDF 3538KB](7)

Abstract:
Block theory is one of the commonly used methods for rock stability analysis. Different from other numerical analysis methods, block theory is essentially geometrical analysis, which required little and simple parameters, the processing is rapid and the computing results are easy and practical. Based on the above characteristics of block theory, combined with the lately development of information technology, real-time analysis system of rock stability is proposed. Firstly, the original data can be collected from the field. Then the real-time computing and analysis can be conducted through the terminal system. And after that, the original data and the results from the terminal can be transported to the remote work station at the time of computing and analysis, based on which can be evaluated and the decision can be made instantly, so as to guarantee the safety and stability of engineering rock mass. This method combined block theory with information system, which is good to the promotion and development of block theory, and plays an important role in the safe construction and stable operation for a project. This is an important direction of information geotechnical engineering in the era of internet of things.

Design and Analysis of a Deep Foundation Pit in Nanjing West

Lu Feng, Zhu Ming, Yan Ronghua

2014, 28(2): 60-63,105. doi: 10.3969/j.issn.1007-2993.2014.02.002

[Abstract](46) [PDF 4202KB](11)

Abstract:
The excavation of deep foundation pit is a very complex project, in the design and construction of foundation pit, should not only consider the security and stability of retaining structure, should also consider the effect of groundwater on the stability of foundation pit and the complexity of the engineering properties of rock and soil. In a foundation pit in Nanjing as the object, the selection of deep excavation and retaining structure is analyzed, summarized the key calculation and checking the content design of retaining of deep foundation pit. Finally comparative analysis of the calculation results with the monitoring data show the effectiveness of the results, the envelope form, can provide some reference for future similar project.

Case Study and Numerical Comparison of Deformation Based on the Composite Foundation with Different Reinforcement

Yin Chenpeng, Zhang Huaijing, Sun Hongwei

2014, 28(2): 64-69,87. doi: 10.3969/j.issn.1007-2993.2014.02.003

[Abstract](53) [PDF 3444KB](10)

Abstract:
The natural ground of a object can not meet the requirements of bearing capacity and differential settlement and there is thick filling which is based on fly ash under the foundation, so the natural ground need to be reinforced. Firstly, comparing the two different treatment schemes and considering the fly ash is good building material, the final scheme is that adopting the cement deep mixed piles to reinforce the filling layer to improve the bearing capacity of the natural ground, and using CFG piles to handle the deep soil to meet the requirement of settlement. Secondly, according the final scheme, using the finite element software PLAXIS 3D to build two models to compare and analyze the settlement, model 1:composite layer model, model 2:pile unit model. The final simulation results were compared respectively with the measurement data of settlement, and the comparison can provide some guiding significance for the future engineering.

A Formula Method to Determine Ratio of Ultimate Shaft Capability in Tension and Compression

Kang Tao, Zhang Xiaoyu

2014, 28(2): 70-72. doi: 10.3969/j.issn.1007-2993.2014.02.004

[Abstract](160) [PDF 594KB](18)

Abstract:
Uplift piles, as one type of deep foundation, have been widely used in various field. But because of lack of a solid theoretical foundation, the value of the ratio of ultimate shaft capability in tension and compression are mainly based on empirical data. Limit equilibrium equations of single pile are established when vertical compressive loading test and self-balance measurement method are carried out. Furthermore, a simple formula, taking into consideration the diameter of piles and the soil properties, is derived to caculate this ratio. Reasonable agreement has been observed between the measured and predicted values of ultimate uplift capacities of piles beared in the strata with better consolidation status.

Technology of Tunnel Curtain Grouting Method Used in Tongluoshan

Pu Huizhong, Cai Yunze, Wang Weihua

2014, 28(2): 73-75,82. doi: 10.3969/j.issn.1007-2993.2014.02.005

[Abstract](37) [PDF 4038KB](9)

Abstract:
Whe tunnel across the water-rich lamination broken rock layer, because of water pressure,it is easy to cause water gushing-out after the tunnel is excavated. By the way, mud and other sudden accident would he happened. The lamination structure of water has the long-term pressure to structure as well as the erosion of concrete which it has bad effect to the structure. Thus crossing the weak rock and broken water-saturated zone, we use curtain grouting method to improve rock, to he sure of pore water is outside of the scope of the excavation and to ensure the security of the tunnel face.

Fuzzy Evaluation Method on Rockmass Strength Parameters of Cut Slope

Li Yushu, Feng Su

2014, 28(2): 76-78. doi: 10.3969/j.issn.1007-2993.2014.02.006

[Abstract](48) [PDF 339KB](10)

Abstract:
Rockmass strength parameter is an important mechanics index in major engineering. Now many empirical rela-tionships for this parameter based on that of rock often occurs index determination difficulty and inaccurate estimating results. Fuzzy discount method for rockmass strength parameter getting from corresponding rock is introduced in this paper, and then, a deep cut slope is selected as a case, basing on rock mass quality characteristic data from in situ investigation, the rockmass strength parameter is predicted by fuzzy evaluation and verified by in field test results.

Implement Methods and Effects of Viscous-spring Artificial Boundary in Seismic Analysis of Embankments

Yang Yang, Huang Deqiang

2014, 28(2): 79-82. doi: 10.3969/j.issn.1007-2993.2014.02.007

[Abstract](60) [PDF 6717KB](6)

Abstract:
Combined with an embankment engineering on the downstream of Min River in Fujian province, a simple and convenient implementation method of viscous-spring artificial boundary, dynamic responses of the embankment by the nonlinear finite element program,and discussed the dynamic response characteristic of different boundary conditions. The results showed that, dynamic response of embankment and foundation were decelerated significantly when considering the foundation radiation damping effect of the traditional fixed boundary condition, and research demonstrated satisfactory coincidence between experimental results and these obtained by simulation described in this article. The course of computing is simplified and the precision has improvement in a certain extent.

Simulation Study of Stability of Different Store Stage of Yujiagou Tailings Dam

Liu Hengxin, Liu Haijian, Yang Anhui

2014, 28(2): 83-87. doi: 10.3969/j.issn.1007-2993.2014.02.008

[Abstract](57) [PDF 6184KB](10)

Abstract:
Using the simulation software SEEP/W of Geo-Studio and embankment stability analysis system software HH-SLOPE, the seepage stability and slope stability of different store stage of Yuiiagou tailings dam are studied. The change rules of seepage and stability of slope are researched when the elevation of the beach crest is 840 m, 875 m, 900 m and 950 m. The results show that the dry beach length, operating water level and elevation of the beach crest have certain influence on the seepage field stability of the tailing reservoir, the higher seepage gradient focused on upstream slope toe position. In different working conditions, the safety coefficient of dam slope stability is higher than the minimum safety coefficient of anti-sliding stability. It also indicates that the tailings dam is stable. The results of research provide a reasonable reference to the construction of Yujiagou tailings darn.

Analyses the Influence Factors of Building Groundwater Level for Prevention of Up-floating in Beijing Area

Kong Linglin, Liu Chun, He Jianyong

2014, 28(2): 88-91. doi: 10.3969/j.issn.1007-2993.2014.02.009

[Abstract](64) [PDF 483KB](16)

Abstract:
The analysis and research on all possible factors and influence degrees of the groundwater dynamic change of building site is the important foundation of the security, economic and reasonable building groundwater level for prevention of up-floating. In this paper, to research and analyze various influence factors on the building groundwater level for prevention of up-floating, to discuss the effects of various factors on the predicted groundwater level dynamic change rule, development trend, the basal groundwater head pressure and the groundwater level for prevention of up-floating value of building.

Application of Bored Cast-in-place Pile and SMW in Foundation Pit

Wei Renjie, Ma Jun

2014, 28(2): 92-95. doi: 10.3969/j.issn.1007-2993.2014.02.010

[Abstract](69) [PDF 4765KB](12)

Abstract:
Taken a foundation pit project in Shanghai as an example, the bored cast-in-place pile and SMW with steel bracing were used based on analysis of the characteristics of the foundation pit. The bracing method was calculated and analyzed. Problems in the construction process that should be paid attention to were mentioned. It provides some suggestions for same type of similar foundation pit projects.

Analysis and Research of Fringe Truss-Internal Supporting System in Deep Foundation Pit

Wang Tao, Yan Zhenhuan

2014, 28(2): 96-99,108. doi: 10.3969/j.issn.1007-2993.2014.02.011

[Abstract](87) [PDF 15584KB](15)

Abstract:
Based on engineering example, research is carried out on force characteristics and performance of fringe truss-internal supporting system Differences between monitoring actual value and calculated value are analyzed. Problems about design and constructions process that should be paid attention to are discussed. Reference for similar deep foundation pit is provided.

Calculation of Retaining Structure with Double-row Piles of Finite Soils

Fang Chengfei, Chu Zhenhuan

2014, 28(2): 100-105. doi: 10.3969/j.issn.1007-2993.2014.02.012

[Abstract](36) [PDF 6932KB](11)

Abstract:
Deep excavation supporting engineering which is close to the existing basement structure, the width of ground is limited. The deformation characteristic and distribution of the earth pressure of retaining structure with double-row piles which has been effected by the basement have been analyzed by the method of FEA and the analytical formula. The simplified earth pressure's calculation method of double-row piles which is applicable to such situations has been proposed, the program has been made. Based on observation data, the rationality of the recommended computational model has been tested and verified.

Analysis of Spatial Effect and Deformation of Soil Nailing Walls

Zhang Dan, Fa Liteng, Wang Jian

2014, 28(2): 106-108. doi: 10.3969/j.issn.1007-2993.2014.02.013

[Abstract](52) [PDF 5511KB](9)

Abstract:
Retaining structure with soil nailing walls which has a deformation of obvious spatial effect is the most commonly used form of foundation pit retaining structure in the Beijing area. This retaining structure usually uses the method of design that one section is applied to every part of the foundation pit; therefore, it is more unsafe and conservative relative to external corner and internal corner position. In this paper we made an analysis result with three-dimensional numerical simulation on a foundation pit in Beijing in order to study the spatial effect of deformation of the retaining structure with soil nailing walls. Through this we draw a conclusion that the maximum horizontal displacement took place in external corner of the foundation pit and around was the most unsafe position while the horizontal position of internal corner of the foundation pit turned to be significantly smaller than other parts but had little area of effect thus we could hardly consider its effects on overall deformation of the foundation pit.

2014 Vol. 28, No. 2