Journal of Railway Engineering Society

Research methods: First the description was given theoretically about frozen soil and permafrost, and then the result was presented based on the analysis of various types of water disasters occurred in subgrade construction, culvert construction and bridge construction for the second phase project of Qinghai-Tibet Railway.

Research results: Although various types of water disasters occurred in constructions of subgrade, culvert and bridge were different, but all of them would influence the service of Qinghai-Tibet Railway in future in different extents, so the relevant measures should be taken.

Research conclusions: The principles of engineering design and construction of railway in permafrost area should suitable for various geologic characteristics of permafrost. The scientific analysis should be made and concrete treatment measures should be taken in order to guarantee economic rationality, safety and reliability of construction of Qinghai-Tibet Railway. Also the rational preventive measures should be taken for subgrade, culvert and bridge during the period of service in order to guarantee the quality and normal traffic of Qinghai-Tibet Railway, and fundamentally restrain the occurrence and development of water disasters, such as deformation and crack.

Research methods; the mechanism of fracture of structural soft clay by vibrating road roller is compared to that by dynamic compaction on soft ground. And the reason of failure of highway embankment is analyzed based on the physical and mechanical properties and microstructure characteristics of soft clay in the Pearl River Delta.

Research conclusions: The depositional structure of soft clay is mainly characteristic of flocculent structure with high void ratio, lower shear strength and higher sensitivity. Dynamic vibration's effect on soft ground is similar to dynamic compaction's effect. The added number of void ratio by dynamic compaction on soft ground is 7 times as much as that by static load. The reason of failure of highway embankment is that the low embankment is placed by a dynamic vibrating roller with 16 t weight, roller compaction for 10 times. It is suggested that the parameters of shear strength of soft clay should be reduced or doing design computation of construction stability of highway embankment on structural soft ground road in the condition of vibration vibrating.

Research methods: Analyzed the soil's structure characteristic and the liquid-limit & plastic-limit test characteristic, we propose to use chipper to make the improvement. And we also do considerable contrast tests for the soil with lower containing water rate higher liquid-limit.

Research results: Through the statistical contrast of the testing steps time and test results, we can see that the above method greatly shortens soil marinated time, mixture time, and then shortens the period of the test to ensure test datum all the same.

Research conclusions: Use the chipper, we can improve the efficiency of liquid-limit & plastic-limit tests that with lower containing water rate higher liquid-limit soil. And the method is very economic and useful. In the meantime, this method can debase the operators’ physical force.

Research methods: Based on several experiments, the relevant construction parameters were obtained and suitable construction method was found out through practices of organization and management, in combination with changeable situations on site.

Research conclusions: The first stair had to have enough width and the operation of all links to constructional tension had to be normalized when constructing on high side slope. In this way, the good result could be obtained.

Research methods: In combination with the subgrade test project of Hefei-Nanjiang railway, the indoor experimental research is made on improving expansive soil with lime, the comparison and analysis are made of physical and mechanical properties and the swell-shrink characteristics of expansive soil before and after improvement.

Research conclusions: It is feasible to use lime as ameliorant of expansive soil. The component of granule, physical and mechanical properties and the swell-shrink characteristics of expansive soil with lime are obviously ameliorated, the mechanical strength and water stabilization are improved, and the requirement of the backfill of the railway subgrade can be met. The ratio of the lime is 6% in the medium-grade expansive soil and 5% in the weak-grade expansive soil. The higher-grade lime over third-grade should be used and more lime should be used when using low-grade lime.

Research methods: Based on the elastic and plastic theory, the stress distribution of soil cave in foundation can be deduced in karst region. With the action of self-weight stress of soil mass and additional contact pressure, the stress concentration will be taken place in soil mass around soil cave periphery. By the Mohr-Coulomb yield criteria, whether the soil mass around soil cave is destroyed can be determined. When subgrade bearing capacity is calculated according to the item 5.2.5 of “Code for design of building foundation" GB 50007-2002, it should assured simultaneously that the soil mass around soil cave cannot be had the plastic failure, and the P value of contact allowable pressure can be obtained, the less value between fa and P is the subgrade bearing capacity for soil cave.

Research results: The calculation formula for subgrade bearing capacity of soil cave has been deduced.

Research conclusions: Through analysis and calculation, this paper points out that the groundwater has great influence on subgrade bearing capacity，and the bearing capacity will be decreased with the decline of groundwater; The bearing capacity will be increased greatly when soil cave is filled full with some materials.

Research methods: Research method: Using bridge analysis software, the paper calculated web principle tensile stress in different change fashion of web thickness. At the same time, aiming at disadvantage of general vertical prestressed reinforcement, other two layout imagination of vertical prestressed tendon was put forward in paper. Space finite element method was adopted to analysis web principle stress comparing each conformation form of vertical prestressed reinforcement by using Ansys software.

Research results: The paper deduced principle stress curves in different change fashion of web thickness; principle stress change curve in different construction form of vertical prestressed reinforcement; and node’s first principle stress contour of local beam segment.

Research conclusions: (1) the adoption of web thickness change fashion was thought an important influence factor in crack control, and transitional change fashion should be used to the full. (2) comparing the general vertical tendon, the advantage of U type vertical tendon represent to bring monolithic precompression stress on web concrete in the U region, which restrict the appearance and magnitude of web principle tensile stress. The influence analysis for new conformation form of vertical prestressed tendon offered referenced opinion for continuous system box girder in reasonable arrangement of vertical.

Research methods: The performances of concrete with the anticorrosive mixture were investigated in the experiments, such as concrete chloride diffusivity, sulfate resistance and drying/wetting cycle in corrosive environments, etc. Its mechanism was analyzed and discussed.

Research results: (1) Anticorrosive modulus of cement with the anticorrosive mixture was more than 1.0 after 90d in sulphate/water liquid; (2) Modulus of drying and welling cycle in corrosive environments of normal concrete was only 0.79 and one of the concrete with the anticorrosive mixture was 1.28. (3)The coefficient of chloride diffusivity in concrete with the anticorrosive mixture at the age of 28d and 90d is 43.1% and 9.3% of one in the normal concrete at age 28d respectively.

Research conclusions: It is effective to improve interface structure between cement and aggregate and cavity structure in the concrete with the anticorrosive mixture.

Research results: The relative construction technique was applied in construction of pile foundation and cap of pile trestle of Kaixinling Bridge 1# on Qinghai-Tibet Railway and solved the difficult problem of drilling on the pile foundation of bridge in permafrost area.

Research conclusions: In construction of pile foundation of bridge in permafrost area, it was better to use big power rotary drilling machine for rapid cavity making, but the following things should be noted: the process of concrete grouting had not to be interrupted, full preparation would be done, the connection of procedures would be short after excavation (drilling) would be quick, the time of soil exposure would be short after excavation(drilling) and the measure against sunshine would be taken if necessary, the speed of grouting concrete would be as quick as possible and the measure for maintaining concrete would be reliable.

Research methods: The mechanical behavior characteristics of rock mass of slope under load are the basis of bridge foundation position determining. In this paper, the influences of load on rock mass stress in different geometric conditions of slope are analyzed with numerical method.

Research results: According to the change characteristics of influence range of rock mass stress under load, a principle of determining safe bridge foundation position on high steep slope is put forward. The stress influence range of rock mass slope is mainly related with load intensity, bride foundation width, slope angle, bridge foundation position. According to the relations between the maximum influence coefficients of rock mass stress on sloping surface and each influencing factor, a formula determining safe bridge foundation position on high steep slope is put forward at last when the influence coefficient of rock mass stress is limited by rock mass quantity.

Research conclusions: Engineering practice shows the method of determining bridge foundation on high-steep slope in this paper is convenient and applicable.

Research methods: In this paper, a free span of an SFT body is simplified as a simple beam. On considering the conditions of the non-linear fluid damping and the structure viscous damping, the dynamic response for an SFT subjected to wave and current is analyzed by virtue of the bending vibration function on simple beam and by means of the Galerkin method and numerical integration.

Research results: The results of analyzing calculation show that the influence of the first-order modality on displacement response is the most active, and that the first-order modal response oscillation of tunnel body increases markedly as the wave frequency equals the first-order natural frequency of tunnel and harmonic vibration takes place.

Research conclusions: The dynamic response of tunnel is influenced obviously by the shape of tunnel section, the length of supporting span, and the depth of tunnel under water surface.

Research methods: In order to research the deformation characteristic and behaviors of the surrounding rock during the tunnel excavating, with the help of the computer technology and numerical simulation method. This paper introduces two tunnel excavation methods (step-method and CD-method) and plans, model building, calculation result and so on.

Research results: By executing the survey of surface deformation, the paper recommends relying on the dynamic information feedback of deformation survey to ensure the construction safety and optimal design of tunnel excavation.

Research conclusions: There are many techniques which can be applied in the construction process of passenger dedicated railway line. To make the safety of the whole construction process under the range of controlling, different tunnel excavation techniques should be analyzed by numerical method before it is applying.

Research methods: This paper researched the preventive measures and construction methods on TBM construction accidents in terms of Taohuapu No.1 tunnel construction practice of Xi'an-Nanjing Railway.

Research conclusions: This paper proposed a 20-Chinese-word principle, "Advance prediction, lining construction, data adjustment, proper promotion, and disturbance reduction", How to deal with landslide was also described in the paper, in conclusion, "Anchor spraying in time, steel-rack sealing, steel pipe lap-welding, otter board combining, slump blocking, and dense refilling". TBM excavating through the section of unfavorable geological condition smoothly and safely was validated in Taohuapu No. 1 tunnel construction.

Research methods: The experiment was done in order to make research on settlement changes caused by construction. In experiment, the same matter as that in construction scheme for tubal curtain and the similar stratum of geological condition were used. The tubal curtain was jacked in by level by diauxic dry screw drilling machine with level guidance by long support. The unit of tube shed with diameter of 600 mm was adopted for tubal curtain with I steel occlusion. The theoretical calculation was made before the experiment for making comparison with that after experiment.

Research results: The support measures in advance were proposed in construction scheme for large-diameter advanced tubal curtain in order to control the displacement of stratum. The experiment was done smoothly and found out the influence on slum by construction of tubal curtain, and the expected goal was achieved basically.

Research conclusions: The experiment proves the influence on slum by construction of large-diameter tubal curtain is small, the real tested data are close to the result of theoretical calculation and the support measures in advance for large-diameter tubal curtain can be used in real construction.

Research methods: Based on the research and analysis of the features of railed carrier vehicle and railway signal blocking equipment, the technical measures were proposed for long-distance centralized automatic dispatch and control of railed carrier vehicles inside tunnel by dispatch centralization control system. It was decided to adopt single-track transport railed line to undertake transport with some fixed passing stations at a certain interval for construction of extreme-long tunnel based on the transport value and transport system capacity.

Research results: The introduction was given to equipment composition and control principle of dispatch and control system of railed carrier vehicle for construction of extreme-long tunnel, and the technology of realizing section blocking with station interlocking control and switching. Two control modes were presented for train entering control and section blocking control of arriving and departing trains. It proposed to adopt the Geld bus distribution control system with optical cable transmission, computer interlock and PLC control.

Research conclusions: The dispatch and control system of railed carrier vehicle used for construction of extreme-long tunnel could much increase transport capacity and efficiency of single-track railed line and provide technical reference to long-distance railed transport system for the rapid construction of TBM driven long tunnel.

Research methods: The track materials can be delivered inside and outside working site under condition of no lining and moving track and the number of blocking line can be reduced by adopting the method of one-time manually laying trans-section continuously welded rail instead of the method of replacing and laying track with track panel.

Research results: The contradiction has been solved between laying track in cause of innovation of existing line and traffic of existing line.

Research conclusions: The method of manually laying continuously welded rail, conducted in short operational interval is an effective way for guaranteeing the traffic safety and construction safety in electrification innovation of existing line.

Research methods: By analyzing the influential factors of reliability allocation, the method of fuzzy synthesis evaluation based on fuzzy mathematical theory was presented to carry through optimum allocation of catenary system in this paper. Namely, appointed reliability index is distributed rationally to subsystem of catenary system by establishing factor collection of reliability level and the weight of factor and further synthesis decision-making based on attachment degree of every factor. Both reliability of whole system and economic benefit are ensured, its arithmetic was programmed simultaneously.

Research results: It proves that reliability of catenary suspension is the biggest, secondly holding setting, orientation setting and support setting respectively.

Research conclusions: It provides a feasible method for railway department's reliability optimum design of catenary system, and need to be further perfect in the design practice.

Research methods: By comparing the metro projects in Shenyang with the built metro projects in other cities, the paper compared, analyzed and demonstrated the investment decision-making and control.

Research results: According to the economical level in our country nowadays, it was economical and suitable that the unit cost per kilometer of the economical metro should be controlled under 450 million RMB.

Research conclusions: It should be effective measures to fully prepare the studying and planning work, enhance the program and control of land, adopt domestic equipment, design within quota, enhance the whole process management of the metro projects.

Research methods: This paper analyzes all kinds of factors which influence choosing rail joint schemes. From the view of fuzziness on choosing optimum scheme from those to be demonstrated, fuzzy synthetic evaluation in theory are carried out for each factor by means of principle and way on Fuzzy Math.

Research results: Through the testing of the newly-built railway between Tiandong and Debao, the recommended scheme is put forward and the feasibility and practicability of the method is demonstrated.

Research conclusions: The fuzzy synthetic evaluation method is valuable for choosing the rail joint scheme, and can provide decision-making to designers. In practical application, the method could be optimized according to the different schemes.

Research methods: On the base of the on-the-spot investigation, an introduction is given in this paper to the management made of occupational safety and health for construction industry in Germany, UK and USA, also the analysis and comparison are made, and finally the exploration and thinking are presented on how to improve management works for safe production and keeping health of labourer for Chinese construction industry.

Research results: There is a certain gap in the supervision work for safety and health for Chinese construction industry compared with the developed countries and the work should be regulated and improved.

Research conclusions: The government shall strengthen its supervision function and weaken its management function with policy, support the development of intermediate institution and play their service function, regulate the construction market, make sure the special funds for occupational safety and health improve the quality of entire people and strengthen the consciousness of safe production for whole society.

Research methods: The employer and the contractor's rights and duties under “Conditions of Contract for Construction" of FIDIC are analyzed. And the following five aspects are penetrated studied especially; financial condition, claim procedure, engineer, bid guarantee and reconnaissance material.

Research results: Some unequal situations between the employer and the contractor under “Conditions of Contract for Construction" of FIDIC are found. The further studies show the basic reason for the inequality is that FIDIC persists forming a buyer market.

Research conclusions: Establishing a market in which the employer and the contractor are completely equal and establishing the engineer in the neutral position from the beginning to the end of the work is the new system, which embodies the fair principle.