公路工程质量管理之我见

公路工程质量管理以项目建设为依托，理论与实践相结合，在公路设计、施工、监督、行业技术水平等方面广泛开展全面质量管理。从上述方面对公路工程质量管理进行分析，其对公路工程建设具有很高的实用价值和指导意义。

浅析公路路面工程

路面直接承受各种车辆传递的车轮荷载以及自然气候的作用,因此路面结构是公路很重要的组成部分。根据公路等级和公路环境合理选择路面结构和路面形式,不仅可以提高公路的使用效率,并且可以节约资源和降低成本,最终提高公路的运输效益。因而,对路面工程的研究室公路工程建设中很重要的内容。

Research on the different content of weathered sand influence on expansive characteristic of a highway expansive soil in Yichang

This paper aims at widespread presence of expansive soil which can be obtained in the project from Xiaoxita to Yaqueling first-class highway rebuilding engineering in Yichang City of Hubei Province and weathered sand which can be made full use locally,many experiments have been made. Compaction experiments and expansibility index indoor experiments of undisturbed expansive soil and expansive soil mixed with sand ranging from 10 % to 50 % have been made. Through the test mixing undisturbed expansive soil with different content of weathered sand,it can change the expansive soil water characteristics and compaction characteristics. It can influence the expansibility of the expansive soil index and significantly inhibit the expansibility of the expansive soil and reach the standard of roadbed filler.

Study on range interval distance of prestressed anchor bars using update backpropagation neural network

Taking the practical reinforced engineering of a reinforced soil retaining wall as an example, which located in Shandong Province and set on 104 national highway, the stress spread behaviors of the anchor bars in the preforced proceeding were tested. According to the test data, and by use of the update backpropagation (BP) algorithm neural network(NN), the test method and it’s mechanism were studied by the network, then the learning results show the mean square error(MSE) only at the 2 55% level, and the proof testing results show the MSE at 4 38% level (the main aim is to build a NN directly from the in situ test results (the learning phase)). Ipso facto, the learning and adjustment abilities of the NN permit us to develop the test data, subsequently, 36 test data were acquired from the NN. By use of the provide data, as well as the failure situation and carried loading capacity of the retaining wall, finally, the choice the reasonable range interval distance of prestress cement grouting anchor bars were carried out, and the result was 2 m×2 m.

A speed-flow relationship model of highway traffic flow

In the view that the generally used speed-flow relationship model is insufficient in the traffic analysis under over-saturated conditions, this paper first establishes the theoretical models of speed flow relationship for each highway class based upon a large number of traffic data collected from the field. Then by analyzing the traffic flow dissipation mechanism under peak hour over-saturated traffic conditions, the speed flow relationship model structures for each highway class are reviewed under different traffic load conditions. Through curve-fitting of large numbers of observed data, functional equations of general speed-flow relationship models for each highway class under any traffic load conditions are established. The practical model parameters for each highway class under different design speeds are also put forward. This model is successful in solving the speed-forecasting problem of the traffic flow under peak hour over-saturated conditions. This provides the theoretical bases for the development of projects related to highway network planning, economic analysis, etc.

Research on the evaluation and mechanism of socio-economic benefit of highway projects

Based on the theory of system dynamics, the paper analyzes the mechanism of socio-economic benefits of highway projects and establishes the system dynamics model of regional economic-highway development. Then taking Jinji（Tianjin--Jixian） Highway of Tianjin as an example, the errors of system simulation are tested, and the system dynamics model built is verified to be quite stable, which has a high performance. Through the comparison of simulation results with and without Jinji Highway, the paper simulates and predicts the socio-economie benefit of each year from 2003 to 2013. Thus the quantification evaluation of socio-economic benefit of highway project is realized and will provide the theory instructions for similar projects in the future.

Preliminary study on the highway-related human activities

In this paper, highway-related human activities are defined as well as the human activities related to highway for keeping a normal production and livelihood. They include highway research, highway education, highway legislation, administration of justice of highway case and enforce the law, assessment, planning, design, construction and management, decision-making of highway projects. Therefore, highway-related human activities are not equal to construction of highway projects.

Concrete Placement for Bridge Decks on an Expressway Extension Project

The paper presents examples of technological designs for concrete placement in road bridges constructed during the S5/S 10 expressway extension in Poland. The project included eight concrete or composite bridge structures with different numbers of decks. The concrete placement technology is presented for the following bridge decks： slabs cast-in-situ, composite with precast or VFT （prefabricated composite beam） beams and mixed with cast in situ slabs and VFT-WIB （filler beam） beams. Continuous concrete placement was adopted for almost all the bridge superstructures except the mixed-type decks where construction joints were necessary. To control shrinkage, formwork deformations and existing restraints, the concrete was poured in layers and in stages. The design pace of concrete placement was moderate to be regulated at site without compromising safety and quality. The placement methods enabled both efficient and safe concrete pours.

Use of Innovative Contracting Methods by Dots - Project Managers Speak

Alternative contracting techniques have been frequently used in highway construction in the United State and have played an important role in the effort to improve construction project performance. However, it is still unknown whether which project factors have significant influence on project performance. It is essential to learn from the experiences and opinions of construction project managers who had executed innovative or alternative contracts in order to improve and refine the usage of alternative contracting methods. Innovative contracting methods have been used by state Departments of Transportation for many years, so there is now sufficient data to measure the effectiveness of these innovations. Working under a grant from the Florida Department of Transportation （FDOT）, the research team used the experiences and opinions of construction field engineers who had executed innovative contracts on FDOT projects to measure the effectiveness of these systems. To that end, interviews were conducted with FDOT and consultant personnel from across Florida. All interviewed were project managers who had overseen at least one project using an innovative contracting method. Discussions brought enthusiastic responses from those interviewed, both for and against certain innovations. This paper will focus on the experiences and opinions of those experienced construction field engineers dealing with well-known innovations, as well as newer innovations such as ＂Detour Rental＂ and ＂Damage Recovery＂.

Geotechnical and Mineralogical Evaluation of Soils Underlying a Failed Highway Section in South Eastern Nigeria

The Port Harcourt Enugu expressway is part of a national road grid that links parts of southern and northern Nigeria. The severe pavement failure between Umuahia and Okigwe section of the expressway covering a distance of about 30 km was investigated by geotechnical and mineralogical assessment of disturbed and undisturbed samples of the underlying soils. Also vertical electrical sounding was performed at the failed sections. Results indicate that the section is underlain by shales of the Imo Formation, and soils are composed of 27% and 74% sand and fines respectively. The Atterberg limit values are moderate to high, with liquid limit in the range of 49-54%, plasticity index 11.1-24.4% and linear shrinkage 17.86-23.57% respectively. Abrasion test results of 0.58 to 16% indicate shales of low durability. The 24 hour free swell tests results range from 33-70% implying soils of moderate to high hydro-affinity and volume change. These data corroborate the X-ray diffraction analyses results which show montmorillonite and kaolinite as the main clay minerals present in the soils. Undrained cohesion range from 9 to 54 kPa and frictional angle from 13° to 29°. High settlement amounts and field observation of intense failure correlated well with the engineering properties and the clay minerals. The soils indicate mainly MI-MH and A-7-5 soils on the USC and AASHTO classification system respectively, implying poor quality soils as subgrade materials. stabilisation. Result of the study will be useful in remedial works areas underlain by the shales. The engineering properties may be modified and upgraded by on the failed sections of the road and future pavement design in

Stability evaluation and protection of slope for Laosongling-Yanji Highway

The authors analyzed the engineering geological characteristics of the slope of the study area (K75+840-K76+340). Two typical cross-sections have been chosen to analyze the failure modes after the excavation of the highway. Different types of the failure modes have been calculated and analyzed. The results show that some dealing methods have been advised to ensure the stability of the slopes.

Design of an Enhanced Sensitivity FBG Strain Sensor and Application in Highway Bridge Engineering

The theoretical design method of enhanced sensitivity fiber grating （FBG） strain sensors was given, and moreover high qualified strain sensors were developed and fabricated, whose sensing properties were good for practical applications. The strain sensor with cylindrical shell encapsulation contained three tubular structures, due to the uneven surface structure, in the area of the strain concentration, improving the sensitivity. It could achieve the embedment strain measurement and surface measurement and had the advantages of the easy installation. The good agreement was obtained between the measurements and theoretical simulation results. After each calibration test, twenty-four FBG strain sensors and six FBG temperature compensation sensors have been installed on the undersurface of the box girder of Diaoshuiyan bridge in Yongtaiwen highway. Finally, we built up a long-term structure health system for the highway bridge.

Back-Analysis of the Response of Shield Tunneling by 3D Finite Element Method

This paper presents a numerical back-analysis of the response of a shield tunnel during construction. An important issue in the construction of shallow tunnels, especially in soft ground conditions, is the surface settlement caused by shield tunneling. The tunnel test system with 10 m length, 7 m width and 6.7 m height, which was completed in China in 2009, is a research shield tunnel system. Using shield tunneling technique known as earth pressure balance (EPB) and slurry shield method, it could be excavated in a region consisting of original soft soils, such as silty clay, and different types of underlain soft soils. Based on the test results, the real-life tunnel response can be analyzed by back-analysis technique. The back-analysis technique is adapted to the three-dimensional finite element method (FEM). Parameter analyses are calibrated to study the behavior of the multi-scale diameter tunnel under various conditions. The suggested multi-scale model results show a well agreement between the prediction and the measurement.