岩土工程技术

Displacement Prediction About Huangci Landslide Based on Verhulst Model With Its Realization in Excel VBA

Cheng Jiangtao, Liu Li

2008, 22(5): 217-222.

[Abstract](79) [PDF 741KB](7)

Abstract:
Taking the forecast and prediction of the Huangci landslide displacement-time for example, through the analysis of landslide engineering geology condition, origin, occurring and developing process, combining with the displacement-time data of the ground monitor pile and the displacement monitor instrument, the research thought of the landslide displacement forecast and prediction by using the Verhulst model is summarized. Based on it, compiling the landslide forecast and prediction program with the inlaid VBA language in Excel, to solve the difficulty on manual computation. Through the example analysis, and comparing the Verhulst model and GM(1,1) model forecasting result with the actual monitoring result, confirming the applicability of the Verhulst model which is used in landslide displacement forecast and prediction as well as the reliability of the program. The result indicated that the Verhulst model is suitable to forecast just before sliding for the landslide, while the GM (1,1) model is suitable to the medium-short term forecast. The impending sliding time of the Huangci landslide which is forecasted by the Verhulst model is between January 26, 1995 and January 27, 1995, and the result is complied with the actual sliding time, which indicated that it's feasible to use the Verhulst model for landslide forecast and prediction.

Slope Stability Analysis Based on 3-D Nonlinear Finite Element Method

Zhang Jianli, Liu Yaoru, Yang Qiang

2008, 22(5): 223-226,231.

[Abstract](44) [PDF 734KB](6)

Abstract:
The adjustment of nonlinear stress is not taken into account in the limit equilibrium analysis of rigid body, and it is difficult to get sliding safety factor with finite element method. To solve these problems, based on multi-grid method, structure grid for nonlinear finite element method and sliding surface grid for calculating safety factor are established separately. So the sliding safety factor of arbitrary sliding surface or sliding blocks can be obtained. Thus limit equilibrium analysis can be integrated with nonlinear finite element method. This algorithm has been implemented in TFINE, a code for 3-D nonlinear finite element method. The calculation efficiency and the influence on result precision by grid are analyzed. Then it is applied to the stability analysis of Jinping high slope. The result shows that multi-grid method is effective and more reasonable.

Finite Element Analysis of Uplift Bearing Capacity of Squeezed Branch Pile

Tang Mengxiong, Li Sen

2008, 22(5): 227-231.

[Abstract](36) [PDF 660KB](7)

Abstract:
Squeezed branch pile, which has a remarkable potential in engineering practices, is a new type of pile developed in recent years. To study the load transfer mode of squeezed branch pile and bearing characteristics of branch plates in uplift forces, several two-dimensional pile-soil models of squeezed branch pile in soft soil of Guangzhou are established in ANSYS, and the effects of branch size, branch number, branch space and material parameters of pile and soil on the uplift bearing capacity of squeezed branch pile are analyzed also. The uplift bearing mechanism of single squeezed branch pile is investigated progressively,and the results provide a reference for the design and construction of similar piles.

Analysis for Seismic Dynamic Responses of Highway Tunnel in High Earthquake Intensity Area

Zhu Zhangan, Gao Bo, Suo Ranxu

2008, 22(5): 232-235.

[Abstract](41) [PDF 575KB](6)

Abstract:
Based on soil-structure dynamic interaction theory, aseismatic calculation is used for the analysis on portal section of highway tunnel for an important practical engineering project. The response of displace, acceleration and internal forces of structure are described. Results show that the locations of the basement of sidewall and the hance are weak points of aseismic under the situaition of artificial seisimic wave. The waveform of acceleration of structure is similar to the one input. These results provide some references for aseismic design.

Method for Seepage Analysis With Free Surface Based on Ansys

Chen Jiang

2008, 22(5): 236-240.

[Abstract](78) [PDF 670KB](12)

Abstract:
An improved element conductivity matrix regulative method for seepage analysis with free surface is proposed. The elements are discretized to a series of panels (cells for 3D) in local coordinate system, the weight coefficient of panel or cell is determined according to the pressure head in the center of it, then the equivalent permeability coefficient of element is obtained by weighted averaging, this method can avoid area or volume calculation near the free surface and the mesh density of panel or cell is optional, the program is simplified. The iterative process is controlled by setting convergence parameter in advance, avoiding convergent difficulty due to the enormous change of permeability coefficient between two successive iterations. Seepage analysis program is coded with APDL language of Ansys, the function of Ansys is extended and a newly approach for seepage analysis with free surface is presented. The numerical examples show that this improved method can meet engineering requirement for its better convergence and higher accuracy.

New Model and Its Validation for Calculating Limiting Bearing Capacity of CFG Pile Composite Foundation

Zhang Huile, Liu Zunping, Zhu Jintai

2008, 22(5): 241-248.

[Abstract](46) [PDF 829KB](10)

Abstract:
This article analyses vertical bearing character of CFG pile composite foundation, according to the particularity of equal settlement surface, two shear failure model about CFG pile composite foundation is brought forward, the part above equal settlement surface is considered pile's uprising shear failure of Terzaghi's mode, the part below equal settlement surface is considered pile's uprising shear failure of Meyerhof's model, through assumption, the formula of limiting bearing capacity is educed and engineering practice.

Slope Stability Analysis Based on Simulated Annealing Genetic Algorithm

Wang Xun, Li Yunhua, Yun Feng

2008, 22(5): 249-252.

[Abstract](43) [PDF 616KB](6)

Abstract:
In the slope stability analysis, the polyline slipe surface search is very important. The text will draw back the GA method and the SA unifies, and has displayed the heredity algorithm formidable overall situation search ability, simultaneously used draws back the SA method to strengthen the GA part to ask the fine ability. Through introduction SAGA very good solution landslide most dangerous sliding surface search question, for slope of the sliding surface search provides a new solution method, has overcome conventional method all sorts of malpractices.

Monitor Analysis About Super-deep Pit of Crossing-river Tunnel Working Well

Li Weitao, Wang Minhua, Zhou Wei

2008, 22(5): 253-256.

[Abstract](46) [PDF 730KB](5)

Abstract:
Working well of Shanghai crossing-river tunnel is a super-deep pit engineering. The enclosed structure and deform of pit is different from ordinary pit. According to monitor data , performance of deep pit is analyzed. Meantime, some problems in the construction are explained,which can provide reference to the design and construction of similar case.

Experimental Study on Working Properties of Soil Nailing Excavation Supporting Engineering

Xiong Bo, Liu Shuaihua

2008, 22(5): 257-259.

[Abstract](63) [PDF 355KB](17)

Abstract:
Based on the experiment and study of the soil nailing excavation supporting of Huiyayuan in Tianhe Guangzhou, the characteristic of soil nailing supporting system is analyzed. The research provides a reference for similar engineering.

Construction Technology and Quality-control Methods of Cast-in-Situ Hollow Pipe Piles

Wang Yanling

2008, 22(5): 260-262.

[Abstract](46) [PDF 406KB](6)

Abstract:
Cast-in-situ hollow pipe pile is a new type of tube-sinking piles that squeezes soil out partially, which have been applied in the soft soil treatment for some expressways and made good technical and economic benefit. As a new technology, the construction technology and quality controlling of cast-in-situ hollow pipe pile are introduced in detail.

Combined Retaining Structure of Slope Protection Micro-Pile and Soil Nailing Wall

Lin Zhongwei, Wang Xinyu, Zhang Zhenduo

2008, 22(5): 263-266,270.

[Abstract](54) [PDF 612KB](14)

Abstract:
Soil nailing is one of the widely used construction technologies of the slope protection, and the economic applicability is appreciated. But the disadvantage of poor integral rigidity limits the application range of soil nailing support structure. The combined retaining structure of slope protection micro-pile and soil nailing wall is superior to the soil nailing in the integral rigidity, and it's proved in the engineering application. The design and practical effect are analyzed, and the result is offered for the similar engineering.

Deformation Failure Mechanism of Tumenzi Landslide in Three Gorges Project Reservoir Area

Sun Donghui, Liu Jianlei

2008, 22(5): 267-270.

[Abstract](52) [PDF 784KB](7)

Abstract:
This paper studies on the basement of the characteristics of the geology and deformation of the Tumenzi landslide, then do further research on the genetic mechanism, deformation failure mode as well as starting mechanism. The research result shows as follows: first, the deformation mechanism of the landslide is Translational gliding mode; second, the landslide is in the stage of wholly creep deformation with partly slidingl third, the continually heavy rain is the main factor which may results in its broken. At last, put forward the disposing suggestions according to characters of the landslide, which has important significance in guiding the design and construction of this kind of projects.

2008 Vol. 22, No. 5