岩土工程技术

Transfer Control and Visualization of Geotechnical Engineering Investigation Data

Zhang Peng, Zhang Zaiming, Yang Yuyou

2008, 22(2): 55-59,66.

[Abstract](45) [PDF 831KB](16)

Abstract:
In broad sense, it is believed that a large part of outcome of geotechnical investigation is achieved through the transmission and processing of the massive data. And the improving on the efficiency and quality can be ensured by the optimization of data transfer structure and the reasonable control. It is discussed that how the data of borehole distances being transmitted from an ichnographic layout to the section planes employing a computer program, and a method of merging analogy soil sub-layers to a major layer with the same statistical properties to facilitate the mechanical analysis using the fuzzy clustering is introduced. Finally a 3D geological model is coupling displayed with a three-dimensional geological software. The forenamed issues may just be limitations of present practice in data control and transfer process in most geotechnical engineering investigation organizations.

3 Dimensional Random Seepage Field Theory and Researching for Levee Construction

Wang Yajun, Wu Changyu, Ren Dachun

2008, 22(2): 60-66.

[Abstract](41) [PDF 1146KB](5)

Abstract:
Since the complicacy of practical seepage problem effected by various random factors, the three dimensional simulation and analysis for stochastic seepage field has an important meaning in engineering applications. The three-dimensional anisotropic heterogeneous steady random seepage model and designed program are developed on the basis of Finite Element Method. A statistical analysis of stratum soil characteristics and geological columns sampled from the main embankment of Yangtze Rive in southern Jingzhou zone of China is carried based on practieal engineering projects. The statistical hypothesis of Gaussian probability distribution for random permeability tensors of soils to be submitted into the stochastic seepage field simulation was verified that this assumption would be accepted by the statistical testing based on Kolomogorov-Smirnov theory. Various statistical characteristics and random natures in random seepage fields of the main embankment of Yangtze Rive in southern Jingzhou zone of China were investigated by numerical analysis for stochastic seepage fields simulations using three dimensional Finite Element Method as well as the rationality of simulated stochastic results and the developed model were also examined through statistical testing. Especially, the random variation of upstream and downstream water level as a stochastic boundary condition was taken into account of three-dimensional finite element model in practical analysis for the random seepage field simulations in order to describe disturbed effects of the boundary randomness due to variability of downstream and upstream water level over variabilities of simulated results presented by vector series of the random seepage field. Furthermore, the function of some safeguards to set up against the seepage problem, such as sheet-pile breakwater and eatch-water,as the turbulence of complex boundary condition together with the effects of variability of soil permeability have been analyzed for description of influence of them on the hydraulic potential distributed in the random seepage field and compared with the result obtained by determinate analysis for the corresponding steady seepage field problem.That presents the necessity,feasibility and practicability of employing stochastic studies in seepage field problems.The developed method provides a more detail and full stochastic algorithm to characterize and analysis for three dimensional random seepage field problems.The conclusion of simulated analysis is reliable in comparison with pertained stochastic checking and measured data from practical engineering.

Measurements and Numerical Simulation of Stress in Anchors of Tucheng Project

Zhang Qinxi, Fan Shaofeng, Wang Lei

2008, 22(2): 67-70.

[Abstract](21) [PDF 378KB](6)

Abstract:
The stress of anchor in retaining structure reflects the value of earth pressure in some degree. So carrying on in-situ measurements of anchors stress, the value and distribution of earth pressure will be investigated by analysis on actual data. It has important and practical significance in optimizing design of retaining structures of deep foundation pit. Taking the practical project for example, the actual stress of anchor during tensioning and fixation is measured and analyzed. With the FLAC numerical simulation, the calculation method of earth pressure on retaining structure is discussed.

Slope Stability Evaluation Based on GIS and Numerical Simulation

Xu Chong, Li Yanqing, Jiang Ribo

2008, 22(2): 71-74.

[Abstract](32) [PDF 641KB](8)

Abstract:
There are two main research directions in the field of slope stability evaluation. One is slope stability qualitative evaluation and zoning based on GIS, the other is single slope stability quantitive evaluation based on limit equilibrium method or numerical simulation method. The combination points of the present two research directions are summarized. The functions such as profile automatic generation and preprocessing of FLAC-2D simulation data are realized based on integrating of ArcGIS and FLAC-2D by program developing technique. A case study of certain project is presented to test the reliability of the model, including slope stability qualitative and quantitive evaluations. The result is objective and accurate.

Using Genetic Algorithm to Estimate Parameters of Van Genuchten Equation

Xu Xiaojian, Huang Xiaoping, Zhang Jinlun

2008, 22(2): 75-78.

[Abstract](25) [PDF 236KB](7)

Abstract:
The Van Genuchten Equation (VGE) which is used to describe the feature of soil water movement is super-set and nonlinear. Using traditional method calculating the VGEs parameters often results with a high margin of error because of complication and artificial factors. Genetic Algorithms (GA) is a new outstanding evolutionary computation method for solving complex nonlinear model. Therefore, application of real coding that based Poly-Population Genetic Algorithm (PPGA) on the VGE's parameters optimization is proposed. The results show that PPGA is a high effective algorithm with many good properties such as fast computing speed, high efficiency, high precision, small artificial factors and so on. Consequently, PPGA is a new method for calculating Van Genuchten equation parameters.

Research Situation of Geosynthetics and Its Reinforced Structure

Xiao Chengzhi, Liu Bo, Luan Maotian

2008, 22(2): 79-83,87.

[Abstract](30) [PDF 271KB](6)

Abstract:
With the extensive application of geosynthetics in the field of geotechnical reinforced projects, studies on engineering properties and reinforced mechanics of geosynthetics are rapidly developed. Present status and development at domestic and abroad of static load properties, dynamic load properties and theological properties of geosynthetics, as well as its reinforced mechanics are briefly discussed. At the same times, comparative analysis of various theories and computational methods is carried out and major problems existed in the study of geosynthetics are presented. The idea and suggestions of solving these problems are proposed.

Study on Anti-draw Bearing Properties of Rock-socketed Pile

Li Sen, Tang Mengxiong

2008, 22(2): 84-87.

[Abstract](24) [PDF 433KB](8)

Abstract:
There has been not enough study on anti-draw bearing properties of rock-socketed pile. The influence of pile diameter, pile length and socketed length on uplift bearing properties of rock-socketed pile is analyzed by using methods of grey system theory and non-linear finite element analysis. The results indicate that pile diameter has the strongest influence on uplift hearing capacity of rock-socketed pile, on which socketed length has much lesser influence while pile length has the weakest influence. And pile diameter and rock-socketed length shows a non-linear positive relationship with axial uplift secant stiffness of pile in certain extent, and pile length shows a non-linear negative relationship.

Study of Uplift Capacity Factor λ in Shanghai

Chen Daijie, Fan Xiangyang, Gu Guorong

2008, 22(2): 88-91.

[Abstract](33) [PDF 324KB](10)

Abstract:
The actual study of uplift capacity factor λ is reviewed. According to the load-displacement date, the limit of resistant extraction bearing capacity is forecasted by mathematical theory and the criterion method, and the results are compared. The uplift capacity factor λ and side friction f_s are discussed, the conclusions are useful for the design of resistant extraction pile.

Bracing Effect of Concrete Cushion to Lateral Deflection of Retaining Wall

Tian Yu, Wang Hongmei, Liu Dengpan

2008, 22(2): 92-96,100.

[Abstract](46) [PDF 955KB](5)

Abstract:
Controlling the lateral deflection of retaining wall has become a core problem in deep excavation, and lateral deflection during bottom excavation occupies considerable proportion of that in the whole excavation works. Based on measured data and factual work of a metro station construction in shanghai, the bracing effect of concrete cushion is analyzed. As a result, the exposure time of excavation has notable influence on the retaining wall's lateral deflection during the period of bottom excavation. In addition, concrete cushion plays bracing function on controlling lateral deflection of the retaining wall, which is similar to the reinforcement concrete bottom plate. Accelerating the construction of concrete cushion as soon as possible can make full use of bracing effect on controlling the lateral deflection of retaining wall. Bracing effect of concrete cushion depends on several factors, such as concrete cushion's strength, stiff and flatness. The effect can be weakened with debasement of concrete cushion's entirety. Some proposals for lateral deflection controlling during bottom excavation of deep pit are offered. Shortening bottom construction time is favorable of lateral deflection controlling. Increasing concrete cushion's entirety and fastening construction progress of the reinforcement concrete bottom plate can reduce retaining wall's lateral deflection on the excavation stage. The results may be reference to other deep excavation engineering.

Analysis of Side-pile Effects of CFG Composite Foundation

Zhao Songtao, Wang Fengchi, Yang Jianhua

2008, 22(2): 97-100.

[Abstract](43) [PDF 648KB](8)

Abstract:
GFG composite foundation is an effective method of handling soft ground and is widely applied. Analyzing the side-pile effect of CFG composite foundation by finite element analysis program and discussing the effect of subsidence, stress in soil mass and bearing capacity of the side-pile to CFG composite foundation. The analysis indicates that the side-pile confine the extrusion of soil and diminish vertical displacement. Meanwhile, side-pile augment the effective extension of additional stress, could enhance bearing capacity and promote exertion of the bearing potential of the soil among the piles.

Field Test of Dredger Fill Stabilized with Solidified Agent in Dongying Harbour Economic Development Area

Feng Yuguo, Zhu Jiadong, Song Binbin

2008, 22(2): 101-104,109.

[Abstract](63) [PDF 677KB](5)

Abstract:
The field stabilized test of dredger fill with a new solidified agent is made in Dongying Harbour Economic Development Area. The results indicate that the Unconfined compression strength of dredger fill increase through mixing with 2% solidified agent and 6% cement. The foundation bearing capacity may amount to 120kPa when stabilized thickness is 30-35cm and the settlement satisfies the requirements of the specifications.

Study on the Formation Age of Dalian Red Clay

Lin Shiwen, Lan Rongwang

2008, 22(2): 105-109.

[Abstract](31) [PDF 925KB](9)

Abstract:
The characteristic and the formation process of moraine hill in the Dalian area along the coast are analyzed from the phenomenon of the Quaternary incompact layer covering the Dalian red clay. The aggregation deposition, the characteristic about the terrestrial and thalassic red clay in the Dalian is demonstrated, and the formation age of the Dalian red clay is determined before the Quaternary glacial age. Furthermore, it is demonstrated that the Dalian red clay is one of the key layers of ancient geographical and climate in the Dalian area.

2008 Vol. 22, No. 2