Applied Mechanics and Materials Vols. 178-181

Abstract: The finite-element method is adopted to analyze the impact of foundation pit construction on close-by railway lines, and related measures are studied to ensure the safety of railway operation during the pit construction. Eventually, cost-effective reinforcement method is recommended, therefor providing a reference for construction of similar foundation pit close to railway lines to determine reinforcement method. The conclusions indicate that under the existing structure design and basal reinforcement design of the foundation pit, the largest settlement of high-speed railway lines is 23.48mm, which does not meet the relative requirements. To reduce the settlement, three rows of high pressure jet grouting piles reinforcement outside the foundation pit and 0.15m away from waterproof curtain is recommended, and 18.0m is considered as the cost-effective reinforcement depth. With the effect of the proposed reinforcement measures, the largest settlement magnitude of high-speed railway subgrade is reduced by 25% to 14.0mm, which meets the relative requirement.

Abstract: The melting point of polypropylene geotextile is 170 centigrade. However, during the repaving design of the old cement concrete pavement, the paving temperature of the asphalt mixture is often 160-170 centigrade or above. Therefore, it is very important to verify that whether the polypropylene geotextile can be paved under a high temperature. Through the modeling and analysis of temperature fields and relevant temperature tests in the laboratory, the paper has tested the surface temperatures of the polypropylene geotexile when the asphalt mixture is paved under a high temperature. The results show that, under a simulated paving temperature of over 190 centigrade, the highest temperature of polypropylene geotextile is only about 160 centigrade, which is lower than its melting point. Therefore, the polypropylene geotextile can be used for the paving under a high temperature.

Abstract: Seepage in the roof is one of main reasons resulting softening rock and roadway deformation, in order to make sure about the influence of seepage on the roadway stability, we established corresponding models by using numerical simulation software, and analyzed the stress distribution, the deformation of surrounding rock, and the distribution range and shape of the plastic zone, the results show that water is one of the key factors to influence the stability of roadway, seepage makes the strength of surrounding rock sharply reduce, and the roof, two ribs and floor appear serious deformation.

Abstract: The road safety has close relation to road alignment, and operation speed is the key factor of the road traffic safety. We should make an evaluation on the safety of the road alignment indexes after finishing the design of the road alignment to judge the reasonability of the road alignment indexes. This paper studies the traffic safety of the road alignment based on the idea of operation speed, evaluates the quality of the road alignment by the operation speed, make further improvement for the road alignment indexes, and test the rationality of this idea through engineering examples.

Abstract: In order to solve the problem of the glare avoidance on flat road, studying the high-grade highways' planting model through field measurements and modeling methods. Based on the flat road model and geometric rules, putting up an anti-'s’ shape planting model. According to the measured data of the City Second Ring Road (Two stage highway) of Jinhua, verifying the feasibility of the model. Depending on the results, a series of suggestions were provided to reduce planting cost, expand the shielding angle and to solve the security problem.

Abstract: For asphalt pavement performance evaluation, pavement roughness, which is subject to cracks, potholes, road repairs and so on, is a major factor to influence riding quality. Therefore, riding quality is partly correlated with pavement distress, and the relationship can be transformed to that between pavement roughness and distress rate. However, this relationship is not clear, and not reflected in existing evaluation models. Thus, correlation analysis and non-parametric test of independent samples were applied in this paper to find that, international roughness index and pavement distress rate are significantly different due to different grades of roads, then, linear and nonlinear regression were used to analyze the relationships between international roughness index and pavement distress rate for different road grades. Furthermore, original data were processed by logarithmic transformation, radical transformation, exponential transformation and so on, based on which, corresponding relationships were analyzed by linear and nonlinear regression. Finally, best models to describe relationships between international roughness index and pavement distress rate for different road grades were solved out, and corresponding 90% confidence intervals were computed. Research in this paper offers a reference for improving asphalt pavement performance evaluation system and models, which is conducive to further theoretical research and practice.

Abstract: The access road slope of Shuiluo River 500KV transmission project has a loose earth-rock structure which is in a continuous state of slight creep deformation in natural conditions. Road construction period was coincided with the rainy season. On August 18, 2011, after several days of continuous rain, dramatic deformation of engineering slope occurred in the road K0 +305 ~ K0 +345 segment. Gradually a sliding deformation body was formed that vertical length is about 80m, horizontal width is 30 ~ 50m, the front and back edge height difference is 50m, the total volume is about 6.0 million m3. Finite element numerical simulation and limit equilibrium calculation show that the overall deformation and local landslide collapse of the engineering slope was caused by two factors: paring slope and concentrated rainfall. On the one hand, the position of engineering slope was mainly in the anti-sliding section of the potential sliding body, slope excavation reduced the effective stabilizing force; On the other hand, construction was coincided with the period of concentrated rainfall, groundwater level raised significantly due to excess supply of rainfall (120mm/d), the state of slip soil changed from unsaturated to saturated. Slip soil strength decreased due to softening of water, and effective stress of sliding surface lowered due to the raise of pore water pressure, so slope stability was leaded to a sharp decrease.

Abstract: This paper studied the lime-fly ash bound macadam mixed with different proportions of lime fly-ash and aggregates which is often used in construction projects, analyzed the impacts of the aggregate content to the unconfined compressive strength, modulus of compressive resilience property with various lime content and is showed that dense skeleton lime-fly ash bound macadam reached the desirable strength property and had good effect on pavement performance Therefore, it is concluded that lime-fly ash bound macadam with desirable property, replacing fine aggregates is achievable, Test results show that coarse aggregate of lime fly-ash stabilized aggregate can form skeleton structure and has the advantage of high strength and other better material properties which can meet the requirements pavement.

Abstract: Taking the unconventional roundabout of Huancheng West Road and Huancheng North Road in Jinhua City an example, a research about the existing roundabout is carried on. Through the project’s development, some problems have been discovered, and we put forward some optimized measures for the unconventional roundabout by way of keeping headway exactly. In addition, we optimize the object of study by utilizing the VISSIM software, with which the traffic capacity of roundabout is to develop. Afterwards, a conclusion is drawn that if the vehicles keep the time headway of 0.6S, the traffic capacity of roundabout will be four times as large as it was, with which a new way of thinking about optimizing the roundabout will be provided.

Abstract: FDM simulation and the monitoring data for the right exit of GuanYinPing tunnel on the Gu-Zhu expressway are presented. The FDM model is established to simulate the deformation behaviors and deformation tendency of the tunnel. According to the unsymmetrical loading geological conditions, the excavation and lining program can be corrected timely. Comparative analysis of the simulation results and monitoring data can optimize the supporting system, which also can take technical support for the rational construction. It is proposed that the combination of monitoring and FDM analysis be important for successful construction of the tunnel.