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采用预应力管桩(PHC)作为路基挡土墙基础,可发挥PHC桩质量保证率高、抗压性能好的优势,挡土墙承担水平荷载的要求也给PHC桩基础与基底的连接模式提出了问题。依托广东广清高速公路扩建工程进行现场试验,研究PHC桩基础分别采用有盖板的垫层式和无盖板的嵌入式承连挡土墙基底模式的作用机制。研究表明:垫层式与嵌入式连接的PHC基础桩间土均承担主要荷载,嵌入式连接外桩与桩间土应力比更大,是垫层式两倍左右,嵌入式内、外桩承载力发挥率差别更加明显;垫层式连接基础不能阻止墙体发生偏转,嵌入式连接通过桩体的约束作用控制墙体保持位置状态稳定;垫层式与嵌入式连接的挡墙受力主要表现为底板底面沿路基方向承受拉应力,在垂直路基方向底板底面未出现零压力区;两种连接模式墙体水平位移差别不大,桩间土是承担水平荷载的主体。
The use of prestressed tubular piles (PHC) as the foundation of subgrade retaining walls can give a high quality guarantee of PHC piles and good compressive strength, and the requirement of retaining walls for horizontal loads also puts forward the connection mode between PHC piles and foundation The problem. Relying on Guangdong Guangqing Expressway expansion project for field experiments to study the PHC pile foundation were covered with a cushioned and without cover embedded bearing retaining wall base mode of action mechanism. The research shows that the main load between the cushion type and the embedded PHC foundation piles is the main load. The stress ratio between embedded connection piles and soil between piles is larger, which is about two times that of the cushion type. The embedded inner and outer pile bearing Force play rate difference is more obvious; cushion type connection foundation can not prevent the wall deflection, embedded connection through the pile body constraints to control the wall to maintain the position state stability; cushion type and embedded connection wall force main performance The bottom of the floor is subjected to tensile stress along the direction of subgrade, and there is no zero pressure zone on the bottom of the subgrade in the direction of vertical subgrade. The horizontal displacement of the two connection modes is not obvious, and the soil between the piles is the main body responsible for the horizontal load.