防水胶结粉的使用机理和功能

防水胶结粉是一种新型水泥基多用途环保型建筑防水材料。它是在普通硅酸盐水泥基础上,加入经活化处理改性的有机高分子聚合物以及多种混合材、外加助剂等材料,经过科学配制的水泥深加工产品。它主要在以下几方面得到广泛的应用:

Positioning of grid points in wave front construction

In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods （vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms） in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.

Conservation Law Classification and Integrability of Generalized Nonlinear Second-Order Equation

This paper is concerned with the generalized nonlinear second-order equation.By the direct construction method,all of the first-order multipliers of the equation are obtained,and the corresponding complete conservation laws(CLs) of such equations are provided.Furthermore,the integrability of the equation is considered in terms of the conservation laws.In addition,the relationship of multipliers and symmetries of the equations is investigated.

Applications of airtight concrete grouting to road tunnels

Road tunnel excavation often traverses coal strata, which is at risk of firedamp explosion that usually results in disaster. Airtight concrete grouting is popularly used in this kind of tunnel project. Based on the essential theory of mechanics of fluids in porous media, the principle of improving concrete airtight property and its influential factors are investigated. The proportioning tests and monitoring method for airtight concrete are introduced, which is illustrated by a case study applied to the project of the Huayinshan Tunnel. It is proved by engineering practices that the achievement of this research work is beneficial to tunneling project across coal strata.

Analysis of a Failed Port Slope and Stabilization

A nonmetal transportation port with soft soil foundation of Tianjin New Harbor failed during construction in 1997. The soil properties and geological changes before and after landslide were in- vestigated by in situ test means. The stability of the slope was estimated with several calculation methods, such as the simplified Bishop method and the non-circle analysis method. According to the investigation and analysis results, the factors that may cause the slope failure can be deter- mined as follows: excessive excavating, violating the normal construction procedure, excessive pore water pressure during earlier piling and sudden water-level fluctuation in front of the slope. Measures to improve the soil foundation for reconstructing the port include strengthening the failed slope with vibro sand piles, filling up the crushed stone layer, dividing the excavation into four steps and driving piles by larger intervals. The port now has been successfully reconstructed and begun operation.

Dynamic Deformation Monitoring for Long-Span Bridges under Construction and EMD De-noising Method

Construction progress of long-span bridge is complicated and the quality control is strict. Any disadvantage during construction may potentially affect the internal forces and deck alignments after it is open to traffic. To exactly evaluate the periodic alignments, internal forces and safety, geometrical and physical monitoring are needed during construction. This study aims at the requirement of dynamic geometric monitoring during Sutong Bridge construction, and introduces the realization and observing schemes of the self-developed GPS real-time dynamic geometrical deformation monitoring system. Affected by wind load and construction circumstance, GPS （global positioning system） monitoring signal contains a variety of noise. And the useful signal can be extracted from the signal after de-noising the noises. A de-noising method based on EMD （empirical mode decomposition） model is introduced here to process the bridge dynamic monitoring data, and with the wavelet threshold de-noising method are compared. The result shows that the EMD method has good adaptability, is free from the choice of wavelet bases and the number of decomposition layer. The method is an effective de-noising method for dynamic deformation monitoring to large-span bridges.

Application of Snapback Chronometry Method in Calculation of Regulation

Work study is an area of construction production rationalization in which with scientific, logical, holistic and system analysis methods of the process we gain optimum in way of work and time of work. Chronometry method is one of the work study methods which is appropriate for recording shorter cyclic processes and is based on statistical sampling theory. Determination of cyclic times and work performances of standard cyclic construction machines （SCCM） is one of key assumptions of dynamic planning of machine work on every construction site. Calculation methods of SCCM work performances arc one of basic research objects in the field of construction organization and technology. Study shows applied chronometry method in work of standard cyclic construction machine. Goal of this study is to accomplish regulation through measured time cycle and compare measured effects with effects obtained with standard methodology of calculating hydraulic excavator practical achievement for gaining regulation in order to determine main reasons which effect work performance on site.

Assessing Student Learning Using the Constructor Qualification Examination in US Accredited Programs

Today, construction management programs face growing academic accountability resulting in the need to define new program outcomes to measure student learning. In most cases, student learning is analyzed only within the context of an academic program using survey methods which do not accurately quantify overall student learning. Contrary to this condition, construction management programs increasingly require students to take level lofthe nationally administered CQE （constructor qualification exam） upon graduation. However, little or no analysis of this data is conducted beyond basic interpretation of the national and program averages provided by the testing agency. Providing a statistical approach to analyze this data and to propose recommended strategies for its improvement, this research develops and investigates statistical methods to analyze the national test data as a program assessment tool for student learning. Specifically, this work seeks to develop performance standards and expectations for students when taking the CQE exam, to define correlations between student GPA （grade point average） and student performance on the CQE exam. Likewise, this work presents methods to identify program weakness and strategies for improvement by comparing the CQE Level 1 exam with ACCE （American council for construction education） accreditation standards.

A Project-Based Sustainability Rating Tool for Pavement Maintenance

Pavements require maintenance to prevent undue distress or to restore performance; however, pavement maintenance and its impacts do not receive enough attention in many cases, and are either ignored or treated as a low priority, Most current maintenance activities have budget issues and only focus on removing deteriorated pavement sections, Deferred pavement maintenance has impacts on the environment and on society, and may thus affect the costs associated with maintenance, A sustain- ability rating tool is a good way to list, explain, and evaluate such impacts, Various sustainahility rating tools have been developed for pavement; however, pavement maintenance has its own features that are different from those of the new construction, expansion, or reconstruction of pavements, This research project reviews nine sustainahility rating tools for pavement, although none of these tools fully describe maintenance features or can he directly applied to evaluate maintenance projects, A new sustainahility rating tool is then developed for pavement maintenance; this new tool can he used to evaluate individual projects and raise public awareness about the importance of pavement mainte- nance, Its details are described, and its use is demonstrated through an example to show the evaluation process and results,

Cost Climate Survey Scale in Construction:Development and Empirical Research

To develop the cost climate survey scale( CCSS) used in construction enterprises,the design concepts,principles and the process diagrams of CCSS are proposed.Through questionnaire investigation and expert interviews,314 projects are established and the CCSS that is made up of 7 dimensions framework and 30 levels is preliminarily determined.After categorized merger,pre-test analysis and multiple items refining,16 projects of CCSS are eventually compiled.In order to verify the credibility and validity of the CCSS,200 employees in Qinhuangdao construction company as the samples are tested.SPSS 21.0 is used to analyze the reliability,validity and rationality of level divisions,and Amos 22.0 is for analyzing the degree of model adaptation in this survey.Finally,the current cost climate situation of the construction site in the company is evaluated,the deficiencies of the cost culture of the construction site are pointed out.This study shows that strengthening the cost knowledge training has a significant positive effect on the cost climate cognition of the employees.Nevertheless,accumulation of work experience has a dual impact on that.The CCSS is not only an important foundation for the cost climate research and its theoretical development,but also the premise of the cost climate quantitative research.An appropriate CCSS,to some extent,can reflect the cognitive level of all kinds of employees in one enterprise and cost savings degree of the enterprise in a certain time.The development of CCSS reflects the originality and interactivity,and fills a blank of the CCSS in construction,which is considered to be an effective tool for cost climate research in construction.

Development of L-Type Fixation Equipment for Transporting Unit Modules

The unit modular technique is one in which unit modules are prefabricated in a factory and then constructed at a construction site. That is why an important process, transport of unit module, is added in this technique. However, it is not easy to transport a unit module that is high prefabrication ratio （prefab. ratio） （70-90%）, since the walls and interior and exterior materials installed in it can become broken when the unit module is fixed using general fixation tools, including ropes and fixing belts. When the external wall, windows, etc. are damaged during the transportation, the efficiency of unit modular method is deteriorated. Taking this into account, the purpose of this study is to develop an improved fixation device that is convenient for fixing a unit module with a high prefab, ratio to a vehicle and securing the safety while running. The L-type adapter block proposed in this study was evaluated the structural safety through simulation method. The result of the simulation is that it seems desirable to set the working load of the L-type adapter block as 15 kN for Case 1 and 30 kN for Case 2. Therefore, when the L-type adapter block is utilized under the conditions in which the same load is applied as in Case 2, it is expected that safety will be improved.

Design of Human Resource Performance Evaluation System for Construction Enterprises

Based on job analysis for the permanent departments of construction enterprises, by combining KPI assessment method and 360-degree evaluation method, this article establishes a set of human resource performance evaluation indicator system; by determining indicators＇ weights and evaluators＇ grading weights through analytic hierarchy process （AHP）, offering a kind of dynamic computing method for performance evaluation, and tightly linking the evaluation result to employees＇ personal interests, this article builds up a set of scientific performance evaluation system. This article takes the engineering department of construction enterprises for example to explain the calculation and application of performance evaluation result. This article provides construction enterprises with a method reference for human resource performance evaluation.

Discussion of Construction Related to Sheet-piled Wharf

In this paper, firstly, the characteristics of sheet-piled wharf construction are introduced. And then, six aspects of sheet-piled wharf construction are discussed： sheet pile, anchorage structure, guiding girder, anchor rod, backfilling behind sheet pile wall, superstructure of sheet-piled wharf etc. The construction of sheet pile involves piling on the land or piling？on？the sea, piling methods, piling patterns, guide frame, embedding sheet piles etc.

Challenges and Innovations in the Sutong Bridge Foundation Project

This article introduces three outstanding innovations, i.e. utilization of the steel casing for the piles to establish a construction platform for Sutong Bridge's large and deep-pile groups; 5000 ton steel cofferdam lowered as a whole and used as a protective structure against impact from ship collision; Permanent scour protection. This article also presents economical and reasonable design method for large bridge foundation and explains the significance of innovation and technical integration to large and complicated project construction based on the above theory.

Research on the Causes and Coping Strategies of the Land Subsidence Caused by the Tunnel Construction Projects

In this paper, we conduct research on the causes and coping strategies of the land subsidence caused by the tunnel construction projects. We analyze the issues from the following of the perspectives. （1） Analysis method. To solve large scale system of the development of computer hardware and the numerical calculation method, we use the basic analysis to deal with it. （2） The empirical of methods. Ground motion is usually leads to the basic development of the inclined tunnel surface vertical displacement, the result of the movement process can turn to a settling tank. （3） Machine learning based approaches. In one of biggest difficulties when using neural network method is to obtain all possible parameters related to ground subsidence, we use the machine learning model to handle the challenge. In the final part, we show prospect for the future research, we will combine more numerical analysis tools to optimize the current methodology.

Study on the computation method of temperature field of RCC dam

According to the construction characteristic of RCC dam cast by layers, three-dimensional finite element relocating mesh method is developed to simulate construction process and compute temperature field. The computation model of relocating mesh method is expatiated in detail; based on the thermodynamic properties of RCC materials, the feasibility and error of relocating mesh method are analyzed and demonstrated; The computation results in this article are verified by means of the temperature observation data of certain RCC gravity dam. The results show that the temperature field computed by three-dimensional finite element relocating mesh method can not only ensure the computation precision, but also improve the calculation efficiency greatly. This provides an effective method for simulating construction process and computing temperature field of RCC dam.

Verification of Seismic Performance of Pile Foundation in Composite Ground through Experimental and Numerical Methods

A new construction method of pile foundation in composite ground, in which, prior to installing piles, the ground is improved around the heads of the piles in soft ground or ground subject to liquefaction, which is introduced in this paper. This construction method uses a combination of pile foundation construction together with common ground improvement methods, including deep mixing, preloading and sand compaction piling, and it is referred to as the composite ground pile method. Since an artificial ground with relatively high rigidity comparing with that of the original ground was formed around the pile in this method, and the seismic performance has not been made clear, thus the seismic performance of piles in composite ground was systematically analyzed through a series of centrifuge model tests and numerical analyses by using dynamic nonlinear finite element method, and a verification method for the seismic performance of piles in composite ground was proposed on the basis of the experimental and numerical results.

Sustainable Design in Space Structures

The sustainable design approach presented in this paper supports an increased commitment to environmental stewardship and conservation, and results in an optimal balance of cost, environmental, societal, and human benefits while meeting the mission and function of the intended space structure. The aim of this paper is to develop the guidelines that could be applied in the design of a space structure in order to achieve the optimal overall lifetime performance of the space structure. Space structures are more than inanimate hunks of metal, glass and fabric. Every space structure that we design as structural engineers is like a child - a child that is conceived with a passionate vision of its form, structure and purpose; nurtured through the schematic design phase and the development of construction documents; and cared for during the labor pains of plan check corrections, requests for information, shop drawing review, and construction observation. Like children, our space structures mature, perform necessary functions during their lives, and eventually, grow old and die. The design of a sustainable space structure is a much more challenging and cross-disciplinary process than in the past and therefore it is necessary that the space structure is viewed as an integrated system and that all members of the design team work in a fully integrated fashion.

Performance of seven highway construction contracting methods analyzed by project size

The conventional Design-Bid-Build(DBB)construction contracting method has had various drawbacks exposed in highway construction practice, including lack of communication, inefficient design, antagonizing relationships, and increased disputes. To mitigate the negative aspects of DBB, several alternative contracting methods and alternative project delivery systems have been devised and introduced to the industry over the past30 years. Five such innovations were tested by a research team from the University of Florida under the sponsorship of the Florida Department of Transportation(FDOT). To perform a realistic assessment, this study categorized FDOT projects built between 2006 and 2015 into groups according to current contract amounts. Both absolute and relative metrics were defined and employed. For comparison purposes, a collective analysis on all gathered data was performed. Additionally, the influence of outliers on the results was examined. The results showed that analyses based on individual cost categories are more convincing because large projects tend to impose stronger influence on the analyses. In addition, outliers must be identified and screened to reach realistic and reliable conclusions. With regard to the actual performance of the contracting methods, each performs differently within different cost categories.

Real-time compaction quality monitoring of high core rockfill dam

The conventional quality control method of core rocldill dam construction exhibit difficulty controlling compaction parameters accurately or ensuring construction quality. This is because it is easily influenced by human behavior or lack of adequate management. We therefore establish the timely monitoring indexes and control criteria of compaction processes by considering the characteristics and quality requirements of high core rockffll dam construction. Based on the established indexes and criteria, integrating GPS, GPRS and PDA technologies, a real-time compaction quality monitoring method is proposed. The relevant key techniques are proposed as well, including automatic collection of information and a graphic algorithm for rolling-process visualization. By the proposed method and techniques, a real-time monitoring system is provided to realize the precise automatic online entire-process monitoring of compaction parameters, including compaction pass, rolling trajectory, nmning speed of roller, vibration status and rolled pavement thickness. The application of the Nuozhadu project shows that the proposed system can control compaction parameters effectively and ensure better construction quality. Therefore, it might become a new way towards construction quality control of high core rockfill dam.