面向工程教育认证的“地基处理”课程改革

文章根据“地基处理”课程的特点和培养目标,分析了传统教学方式的不足,基于工程教育认证的要求,提出针对性的改进措施,并应用于教学过程。通过实践取得了教学相长的效果,实现“地基处理”教学的全过程质量控制,达到培养具有工程意识和创新能力应用技术型人才的目的。

Research on the Informatization Technology of Rural Residential Land Cadastral Data

Using innovative information means to form the digital management sys- tem of rural residential land is the key point to solve the difficult and hot issues in rural residential land management. In view of the diversity, large quantity, and preservation with paper of rural residential land data, a new method for automatic cutting and classification of digital images based on the image data source and us- ing the image processing algorithm and Python programming was proposed in order to achieve rapid and accurate collection and digital storage of rural residential land cadastral data. Using this method, digital image automatic cutting and classification were realized, and the efficiency and accuracy of this method was validated by comparing with the non-support free shooting method and manual image process- ing. The experimental results showed that the efficiency of the data acquisition of the fixed shooting method was 4.24 times of that of the non-support free shooting method with the accuracy rate increasing by 7.1%, and the efficiency of automatic image processing was 35 times of that of manual processing. Based on rapid and accuracy data acquisition, this method realized the automatic processing of digital images, which provided a reference for the research of informatization technology of the whole rural residential land data and has the value of popularization and appli- cation.

Key Technologies in the Design and Construction of 300 m Ultra-High Arch Dams

Starting with the Ertan arch dam （240 m high, 3300 MW） in 2000, China successfully built a total of seven ultra-high arch dams over 200 m tall by the end of 2014. Among these, the ]inping 1 （305 m）, Xiaowan （294.5m）, and Xiluodu （285.5 m） arch dams have reached the 300 m height level （i.e., near or over 300 m）, making them the tallest arch dams in the world. The design and construction of these 300 m ultra-high arch dams posed significant challenges, due to high water pressures, high seismic de- sign criteria, and complex geological conditions. The engineering team successfully tackled these chal- lenges and made critical breakthroughs, especially in the area of safety control. In this paper, the author summarizes various key technological aspects involved in the design and construction of 300 m ultra- high arch dams, including the strength and stability of foundation rock, excavation of the dam base and surface treatment, dam shape optimization, safety design guidelines, seismic analysis and design, treatment of a complex foundation, concrete temperature control, and crack prevention. The experience gained from these projects should be valuable for future practitioners.

Numerical model of soft ground improvement by vertical drain combined with vacuum preloading

The rapid development of high-speed transportation infrastructure such as highway and high-speed railway has resulted in the advancement of soft soil improvement techniques. Vacuum preloading combined with vertical drains has been proved to be an effective method in the treatment of soft foundation. A three-dimensional numerical analysis of the coupled methods was presented, in which the smear zone and the well resistance were taken into account. The variations of the basic soil parameters including the permeability coefficient and the coefficient of volume compressibility were considered in the numerical model. The result of the numerical model was then compared to the measured value. The results indicate that the decrease of coefficient of volume compressibility accelerates the consolidation of the soil while the influence of hydraulic conductivity is insignificant. A cube drain presents the closest result to the real situation compared to the other equivalent methods of prefabricated vertical drain (PVD). The case study indicates that the numerical model with variation of soil parameters is closer to the measured value than the numerical model without variation of soil parameters.

Application of CFG Pile Construction Technology for Soft Foundation Treatment

CFG pile has been widely applied as one of the common ground treatment techniques. As a concealed work, the construction quality of pile foundation not only relates to the success of the project, but also concerns the benefits of thousands of hot, seholds. Only strengthening the supervision and management during the construction and strictly designing and specifying CFG pile can ensure the construction quality of CFG pile. But most researches focus on operating mechanism and theoretical analysis, and there are fewer researches about the construction of CFG pile. The real construction of CFG pile has no specified operation and lacks of the construction guidance, which not only causes great problems and has great influence on the intensity of CFG pile, but also makes the real pile body have great difference from the design requirements. Therefore, the study on construction of CFG pile in the paper has great significance.

Laboratory investigation of axisymmetric single vacuum well point

Vacuum well point is a new but faint soft ground treatment method. This work focuses on the consolidation behavior of a reconstituted soft clayey specimen under vacuum well point combined with surcharge loading. The laboratory test was conducted through a vacuum-surcharge consolidation apparatus, and the vacuum loading scheme was adopted for vacuum pressure application to investigate the vacuum effect on soil consolidation. In the testing process, some key parameters such as vacuum pressure, pore water pressure and settlement deformation were timely recorded. Furthermore, the water content, void ratio and permeability coefficient of samples collected after loading were measured to reflect the consolidation characteristics. By comparing with the membrane system and membraneless system, something different was found for the vacuum well point method. The results indicate that the consolidation behavior of an axisymmetric single vacuum well point is almost identical to the behavior of vacuum preloading combined with prefabricated vertical drain(PVD), except for the distribution of the vacuum pressure along the well drain due to the structure of the vacuum well point. And the vacuum well point method may be useful for the improvement of soft clayey deposit in a certain depth.

Finite element analysis on impact of foundation treatment in bridgehead transition section upon bridge piles

In order to decrease relative settlement, foundation treatment plays an extremely important role in bridgehead transition section, especially, the situation of building the bridge piles firstly, and then processing piles. On the basis of engineering practice, the authors analyzed the influence of foundation treatment on bridge piles in bridgehead transition section by finite-element method (FEM). This research has positive significance in predicting displacement of bridge pile, directing construction of foundation treatment, and improving quality of engineering and so forth.

Research on pore microstructure features for dredger fill based on mercury intrusion method

The material composition and microstructure have a comprehensive influence on geological engineering properties of dredger fill.The porosity of the dredger fill is an important characteristic of microscopic structure.Taken dredger fill from Binhai New Area in Tianjin as research object,the distribution trend of pore is obtained by granularmetric analysis,mineral composition analysis and mercury intrusion method.By discussing the variation regulation of dredger fill in two different kinds of processing methods,certain theoretical basis is provided for evaluating the engineering geological properties of dredger fill.It can be concluded from the test results that after drainage treatment,the porosity decreased and the structure unit changed from the relatively loose state to aggregate state.In certain depth range,the consolidation effect of dredger fill with drainage treatment is better than that without drainage treatment.

Field study on performance of new technique of geosynthetic-reinforced and pile-supported embankment at bridge approach

Vehicle bumps at a bridge approach caused by the differential settlement between a bridge and an adjacent backfill embankment are one of the most difficult problems in geotechnical engineering. Large vehicle bumps make drivers uncomfortable and cause large impact loads on vehicles and the bridge abutment. A new ground-improvement technique called fixed-geosynthetic-reinforced and pile-supported embankment(FGT embankment) was developed and used to alleviate vehicle bumps at a trial bridge-approach site located in central China. To distribute the differential settlement between the bridge and adjacent backfill embankment over a long transition zone, the following three techniques were used at the trial bridge-approach site:(a) the FGT embankment,(b) conventional geosynthetic-reinforced and pile-supported embankment(CT embankment), and(c) geosynthetic-reinforced embankment without piles(GR embankment). The performance of all three techniques in the field trial was investigated by field measurements involving earth pressure cells, geosynthetic deformation sensors, and settlement gauges. The FGT and CT embankments exhibited better performance than the GR embankment. Compared with the CT embankment, the FGT embankment was more effective at ground improvement. At an elevation of 4.0 m from the base of the embankment, the pressures below the geosynthetic were smaller than those above the geosynthetic at the closest measurement point. The difference between the pressures between above and below the geosynthetic tended to increase with the embankment height.

Cubature Formula for Spherical Basis Function Networks

Some mathematical models in geophysics and graphic processing need to compute integrals with scattered data on the sphere.Thus cubature formula plays an important role in computing these spherical integrals.This paper is devoted to establishing an exact positive cubature formula for spherical basis function networks.The authors give an existence proof of the exact positive cubature formula for spherical basis function networks,and prove that the cubature points needed in the cubature formula are not larger than the number of the scattered data.