Applied Mechanics and Materials Vols. 204-208

Abstract: With the rail transit project planning and construction in Qingdao, the citizen’s lives will be profoundly influenced. Rail transit will not only promote the urban lands along the railway further development, but also assemble a large number of commercial, financial and office facilities. This essay, based on the investigation of the present development and construction of the central business district along Changjiang Road in Qingdao Economic and Technological Development Zone(Qingdao ETDZ),analyzes the current land use within 500 meters on both sides of the planned railway, and the present commercial status in rail-affected area as well as investment intentions of those potential investors, discusses the form of commercial presence along the rail transit, and then predicts the further development of the central business in Qingdao ETDZ.

Abstract: The damages in two rigid base cement concrete pavement were investigated. The data analysis suggests that the void beneath curling slab resulting from the temperature gradient changing leads to pavement damages. With the benefit of the pavement curling structure numerical model established in this article, the void changing law beneath curling slab and loading stress were analyzed. The loading stress level increases dramatically due to void occurring beneath curling slab. The calculation method of loading stress in the curling slab was given. The fatigue life analysis further reveals that the void beneath curling slab caused by temperature gradient changes is the fundamental reason for the decreasing of the service life of cement concrete pavement. The service life of investigating section were predicted and analyzed according to the fatigue life prediction model established in this article and the survey data.

Abstract: In order to reduce the differential settlement and improve the stability of the subgrade when widening the old roadbed，the geosynthetics have been successfully adopted in the joint between the old and new subgrades. Based on the features of the geosynthetics-reinforced old road widening, the old and new subgrades and the pavement were regarded as a whole structure, and the numerical model was established on the basis of the assumption. By FLAC, the mechanism of geosynthetics-reinforced old road widening was discussed, the different effects under the different layer numbers of geosynthetics and roadbed filling height were studied, mainly from the aspects of displacement and surface stress of subgrade. The results show that geosynthetics not only effectively reduce the differential settlements and horizontal displacements of subgrade top, but also lessen and homogenize the average stress reflected from subgrade to pavement.

Abstract: Built on soft soil foundation, the runways settlement of Ningbo Airport has been observed since operation. Through observations respectively after one and nine years in service, we find that the post-construction settlement is directly related to the soft layer thickness and the sand drain depth; meanwhile the accumulated impact caused by landings of aircrafts is yet another factor which cannot be neglected. Post-construction settlement mostly occurs in the initial operation stage of the airport. The maximum cumulative post-construction settlement is 12.95cm one year after operation and increases to 23.70cm nine years after, which is far beyond the design value 8cm. The differential settlement is less than 4cm one year after operation, and stays below 4cm nine years after except for a few points, which basically meets the design requirements.

Abstract: Drucker-Prager linear elastic-perfectly plastic model and the associated flow rule, a numerical simulation study has been conducted on the layered asphalt concrete pavement structure, using the 2D axisymmetric finite element method (FEM). Pursuant to empirical equation of the stability, cohesion and internal friction angle of asphalt concrete, and in line with experimental test subjects on pavement material and pavement performance, the impact of mechanical parameters of each layer of asphalt concrete on the road surface deflection and the evolution law of plasticity in each structural layer under standard axle load has been studied.

Abstract: Based on a temporary shaft for construction, this paper compared two supporting patterns in the geological condition dominated by silty clay, the open-cut method with tunneling support and the bored piles supporting method, in the respects of ground surface deformation, the envelope structure deformation and the steel brace forces, using the numerical simulation method. And by comparison of the numerical results with the monitoring data, it is verified that the calculation model and methods of analysis are rational. Furthermore, the open-cut method with tunneling support is recommended as the better supporting method that can both ensure the structure safety and economy in areas of similar geological conditions. The paper has some reference value for shaft supports under similar construction conditions.

Abstract: In the process of building the ballastless track of the high speed railway from Wuhan to Guangzhou, the measuring method of the CPⅢ control network has played an extremely critical role. In this article, the form layout, measuring method, precision requirements and some other contents of the high speed railway ballastless track CP Ⅲ have been proposed. It has been proved that this control network has reliable technology basis and meets the construction requirements, which is available for other similar engineering.

Abstract: The heat stabilities of embankment on the high temperature permafrost regions in the eastern Tibetan Plateau without climate warming and with air temperature rising speed of 0.04°C/a were modeled, and the heights of embankment were discussed and figured out, comparatively and respectively for asphalt-paved, concrete and gravel road surface, according to the natural geographic and geologic conditions in the high temperature permafrost regions in the district. The different confined conditions about embankment critical heights with climate warming and without climate warming were discussed in the paper. Finally, the result had been obtained by numerical calculation: in the high temperature area, for the two types of laying of cement concrete and gravel surface road, the two critical heights of the thermal stable conditions were (road operation for 30 years), respectively, do not consider climate change as 2.5 m and 2.0 m, consideration of climate change were 3.5 m and 3.0 m.

Abstract: Freeze roadway cooling technology is delivering cold quantity to cooling underground face by storage cooling energy in strata, and the effect of storaging cold is critical. The geographical position and geological condition of coal mine in Heilongjiang Province has remarkable characteristics. The feasibility of freeze roadway cooling measure was demonstrated on temperature, geothermal, constant temperature strata and frozen soil layer, etc. by analyzed its advantage adequately. The measure provides a new idea which suits the native situation for prevent the heat-harm in coal mine, it also has the realistic reference value and is worth popularizing.

Abstract: Warm mix asphalt is a new type of environment-friendly pavement material with high energy-saving and low emission and it has been attracted a number of attentions to its pavement performance. In this paper, LRT, a viscosity and resistance reducing agent for asphalt, was selected as the warm mix agent to add into SMA-13 asphalt mixture. The high temperature and water stability, low temperature crack resistance and fatigue property of both hot and warm mix SMA-13 asphalt mixtures were evaluated, and various aspects of pavement performance of both materials were comparatively analyzed.