岩土工程技术

Large Shaking Table Test for Portal Section of Huangcao Ping NO.2 Tunnel

Li Yushu, Li Tianbin, Wang Dong

2009, 23(3): 109-114,118. doi: 10.3969/j.issn.1007-2993.2009.03.001

[Abstract](76) [PDF 428KB](6)

Abstract:
The entry portal of NO. 2 Huangcao Ping Tunnel located on State Highway of NO. 318 is selected as the prototype to make large shaking table test. Firstly, the similarity relation, the moulding material, the mouldcase design, the test scheme and the load subsequence is introduced, and then the dynamic response of acceleration, earth pressure, displacement and strain occurred on the portal lining, the portal structure and the portal slope is systematically analyzed, and finally give the evaluation on seismic safety of the NO. 2 Huangcao Ping Tunnel.

Base on Different Freezing Experiment Model Analying Heave-Preventing Mechanism

Cheng Jinyuan, Zhou Jinsheng, Shang Xiangyu

2009, 23(3): 115-118. doi: 10.3969/j.issn.1007-2993.2009.03.002

[Abstract](45) [PDF 292KB](5)

Abstract:
For heave-preventing problem of freezing technique application, the amount of heave was compared between frozen-depth-controlled intermittent freezing mode and tranditional continuous freezing mode by experiments. The results showed that: the heave amount of intermittent mode was 48.8% that of continuous mode,and its equivalent heave amount was about 71.2% that of continuous mode,which meant frost heave was partially prevented. For heave-preventing mechanism of this intermittent mode, final ice lens was suggested as key ice lens. From qualitative analysis of experiments, heave-preventing menchanism for frozen-depth-controlled intermittent mode was indicated. Segragation temperature of final lens increased during intermittent phase for intermittent freezing mode slowed and even stopped the growth of final lens,and frost heave was thus controlled. Finally, frozen-depth-controlled intermittent freezing mode was indicated as the only applicable heave-preventing mode for engineering,and its more economic than traditional continuous freezing mode was also pointed.

Comparative Study of Shear Test Between Sand and Steel

Yang Dafang, Liu Xiliang, He Jun

2009, 23(3): 119-121,126. doi: 10.3969/j.issn.1007-2993.2009.03.003

[Abstract](34) [PDF 240KB](5)

Abstract:
In order to study the shear properties of the interface between the sand and steel, the result of a series simple shear test and direct shear test of interface between dry, saturated sand and smooth, rough steel on the DSJ-2 electric four-joint equal stress direct shear apparatus and after reffitted is constrastively analyzed. The result shows that the shear stess-shear displacement curve of interfaces presents misalignment elastic ideal plasticity relations when the vertical stress is 50,100kPa or presents rigidity-plasticity relations when the vertical stress is 200,400kPa with the simple shear test, the shear stess-shear displacement curve of interfaces presents misalignment relations when the vertical stress is 50,100kPa or presents hyperbolic curve relations when the vertical stress is 200,400kPa with the direct shear test. In addition, the experience reduction formula of contact surface shearing strength target(the interface shear strength index with the direct shear test multiplied by a factor less than 1) are proposed to revise the direct shear test result in design.

Back Analysis of Road Foundation Based on Structural Character of Soft Soil

Li Xiance, Fan Shaofeng, Zhang Tiezhuang

2009, 23(3): 122-126. doi: 10.3969/j.issn.1007-2993.2009.03.004

[Abstract](48) [PDF 292KB](7)

Abstract:
Embarking from the structural character of soft soil,this paper studied on the high void ratio,strong permeability and the compression curve of soft soil to discussed the settlement's calculation method in express way foundation. The back analysis method already became one effective way to forecast the later settlement. This method is to analysis and carries on the feedback to the engineering from room and time. It is a dynamic process. It not only includes various static state analysis carried on in normal regulations design period, but also includes the construction process, and according to the real settlement or other information carries on a series of feedback processing. It connects the design and construction closely. For estimating the later settlement,this paper analyzed the model parameters,and forecast the settlement curves. This paper also compares the real curves with the theory curves and forecast curves to evaluate the treatment methods.

Method Study Based on Entropy Weight Law for Stability of Loess Slope

Yao Yong, Yao Wenhua, Gao Jiacheng

2009, 23(3): 127-129. doi: 10.3969/j.issn.1007-2993.2009.03.005

[Abstract](48) [PDF 157KB](5)

Abstract:
In the comprehensive assessment, the establishment of assessment system and the determination of weight are both very important and difficult. In view of this situation, a new loess slope stability evaluation model is established. Loess slope stability condition will be divided into state-level 5.. stability, more stable, less stability, instability, unstable in this model. The evaluation factors are height of slope, gradient of slope, severe, internal friction angle and cohesion. Aiming at the difficulty of defining weight value, the Entropy Weight Law is used in the comprehensive assessment,which avoids the subjectivity of artificial weight.. The engineering example indicates that the new assessment method is reasonable and feasible, and it provides a new idea for slope assessment.

GIS-based Slope Stability Evaluation Using Extension Matter-element Model

Xu Chong, Cao Jiangang, Mo Yanhe

2009, 23(3): 130-134. doi: 10.3969/j.issn.1007-2993.2009.03.006

[Abstract](59) [PDF 390KB](6)

Abstract:
The stability of slopes is affected by many factors. A multi-index extension matter-element model is developed to evaluate the stability of slopes. This model is then programmed using ArcGIS Engine development platform and VB programming language. The functions, including data collection and management,and visualization of stability evaluation,are also implemented. A case study is presented to test the reliability of the model, including data input, extension matter-element model evaluation and visualization.

Impactions of Groundwater on Excavation and Preventive Measures

Fan Jiadong, Zhang Linggang

2009, 23(3): 135-138. doi: 10.3969/j.issn.1007-2993.2009.03.007

[Abstract](64) [PDF 259KB](12)

Abstract:
Based on different types of groundwater and its characteristics, the impaction of of vadose zone water, diving water as well as confined water and their preventive measures are analyzed. The results show that the vadose zone water and diving water's impaction is mainly caused by seepaging Through the cut-off pile,good results can be received; and the confined water is mainly caused by the irnpaction of sudden foundation chung. The traditional preventive method (river drainage, deep well water and so on) and their disadvantages are analyzed. In the study of new ways, we studied the Mechanical properties of unsaturated soils under the condition of flexibility based on spherical particles loose accumulation of the most idealized model show that there are two main damage modes, bending and shear damage. The materials mechanicsare applicated to calculate separately the minimum riser h and h_min, through theoretical analysision we know that, as long as change the value of maximum bending moment the thickness could be reduce to the minimum by adopting additional plates.

Mechanical Behavior of Interface Between Sand and Steel in Simple Shear Tests Under High Normal Stress

Guo Jiaqi, Liu Xiliang

2009, 23(3): 139-142,154. doi: 10.3969/j.issn.1007-2993.2009.03.008

[Abstract](31) [PDF 275KB](4)

Abstract:
Vertical additional force outside surface of the shaft lining caused by dewatering settlement of bottom aquifer in the thick alluvium induced shaft fracture in east china. The study on sheafing property of interface between soil and structure under high stress is key to solve this engineering problem. A series simple shear tests about interface were carried out on the manufactured, modified simple shear system under high stress. The analysis of testing data demonstrates that the relationship of stress and shearing displacement can be described as nonlinear elastic-ideal plastic model, and that the strength criterion of interface accords with Mohr-Coulomb through origin.

Deformation Features and Evolution of Slope Geological Disaster Mass After Strong Earthquake

Xu Wending, Wu Yunying, Zhang Shubao

2009, 23(3): 143-146. doi: 10.3969/j.issn.1007-2993.2009.03.009

[Abstract](49) [PDF 339KB](4)

Abstract:
After Wenehuan "5. 12" earthquake of Siehuan province, there are many secondary geological disasters such as tallings,slides and mudrock flows in denudation hill areas valley in low mountain slopes, there are many important projects, villages and densely populated areas. After earthquakes the stability of lase rock and soil mass is decrease sharply with the distroy of rain fall and external. Disaster proveting must aeorrding to the geological environment, deformation history, deformation characties of the status and evolution,give us a economic and scientific, reasonable ways to prevent disasters and decrease disaster and governance programs.

Stablization Technical Research on Coastal Mud of Cao Feidian

Qin Pengfei, Zhou Ke, Gao Huadong

2009, 23(3): 147-149. doi: 10.3969/j.issn.1007-2993.2009.03.010

[Abstract](31) [PDF 189KB](6)

Abstract:
Cao Feidian Tangshan Industrial District is now being seriously exploited, the stabilization of the generous mud on the surface is the preliminary thorny problem. Reaches indicate that the chemical stabilization is an effective method. By library tests, the preferable prescription of cement, Na₂SO₄ and Na₂SiF₆ is obtained, and the anti-pressure has been checked. Result shows that this prescription is superior, and could provide scientific guide for the construction.

Theoretical Analysis and Numerical Simulation of Embankment Reinforced With Geosynthetics and Pile-wall

Luo Ruiping, Chen Baoguo

2009, 23(3): 150-154. doi: 10.3969/j.issn.1007-2993.2009.03.011

[Abstract](19) [PDF 268KB](5)

Abstract:
The construction of high embankments on soft ground faces several challenges, such as potential bearing capacity failure, intolerable total or differential settlements. Horizontal geosynthetic reinforcement combined with vertical reinforcement using piles or pile walls can provide an economical and effective solution to ground improvement to support high embankments. Theoretical and numerical analyses were conducted to investigate the interaction among the embankment fill, geosynthetics,pile-walls and soft soil. The variation laws of the soil arch efficiency, the pile-wall efficiency, the differential settlement at the embankment bottom and the tension in geosynthetics are also discussed. Research results show that the soil arch effect in fill combined with the tension membrane effect of geosynthetics can considerably enhance the pile-wall efficiency, and minimize the yielding of the soft soil; the distribution of tension in geosynthetics is not uniform and the maximum value of tension generates at the edge of pile-wall.

Application of Dynamical Compaction Method Treating Detritus Filled Ground

Peng Manhua, Zhang Haishun, Tang Xiangda

2009, 23(3): 155-158. doi: 10.3969/j.issn.1007-2993.2009.03.012

[Abstract](32) [PDF 244KB](5)

Abstract:
The dynamical compaction method treating filled ground is expounded. Dynamical compaction method is proved an effective method to treat detritus filled ground through many tests. At the same time,it is suggested that communication construction method be introduced during dynamical compaction constructin.

Geotechnical Engineering Investigation Record to Shijiazhuang Tiesij u Beiguo-kaiyuan Project

Liang Jinguo, Tian Pengcheng, Zhou Wensheng

2009, 23(3): 159-163. doi: 10.3969/j.issn.1007-2993.2009.03.013

[Abstract](22) [PDF 307KB](8)

Abstract:
Through the introduction of engineering investigation of Shijiazhuang Tiesiju Beiguo-kaiyuan project, the effective method and technical approach were summed up to geotechnical engineering analysis. The results of the analysis were verified through measurement, and can be available for reference.

2009 Vol. 23, No. 3