No abstract

No abstract

The aim of the study was to solve the problem of drainage stability of pavement base in cold and Cloudburst area. With porous concrete as the research object, an optimum design of porous concrete was determined using a step filling and orthogonal test method, and the relationship between the porosity and the connected porosity of the porous concrete was analyzed. Furthermore, drainage performance and frost resistance of the pavement, compressive strength of the porous concrete, bending strength, and compressive elastic modulus were studied. The results show that the effects of water-cement ratio on the strength of porous concrete based on the step filling method are the most significant. In addition, the connected porosity and goal porosity have a good linear relationship; that is, the drainage performance increases with the increase in connected porosity, whereas the frost resistance, compressive strength, flexural tensile strength, and compressive elastic modulus decrease with the increase in connected porosity. Based on an engineering project in Inner Mongolia (in China), it was shown that porous concrete with a goal porosity of 15% used as a pavement base could meet the requirements of cold weather, showers, and heavy traffic.

No abstract

This paper presents the results from a full-scale field study on the 3 different types of cast-in-place piles: rotary drilling piles (RDPs), manual digging piles (MDPs), and impact drilling piles (IDPs), for a bridge construction project of Wuqi–Dingbian Expressway, in Shaanxi. The results indicate that under the similar conditions, MDP exhibits the largest bearing capacity (11000 kN) in the loess area, followed by RDP (9000 kN) and IDP (8000 kN). And all tested values exceed the estimated value (7797.9 KN), indicating that the calculation formula of bearing capacity recommended by the Chinese standard is safe and conservative. During the load transfer process, the axial force attenuation rate of the pile body increases with pile side resistance. The average attenuation rate of MDP is the largest (24.2%), followed by RDP (19.72%) and IDP (16.69%). The bearing characteristics of these test piles are mainly pile side resistance, but the manual digging method created the least amount of disturbance to the soil around the pile, and due to its hole wall being rough, this enhances the pile-soil interactions. Hole-forming methods mainly affect the exertion of pile side resistance compared with pile end resistance. In view of pile side resistance and pile end resistance not taking effect at the same time, degree of exertion of these 2 resistances should be considered when designing cast-in-place piles in loess areas, and different partial coefficients should be used.