桩顶加筋灰土垫层理论分析与工程设计探讨

目前,加筋垫层的工程实践超前于其理论研究,桩顶加筋灰土垫层设计方法受到普遍关注.以郑-西客运专线深厚湿陷性黄土地基处理为工程背景,建立了桩顶加筋灰土垫层理论模型,分析了桩顶垫层荷载特征,提出了灰土垫层设计极限状态理论.考虑不同桩径、不同桩间距、不同路基高度和不同格栅强度情况,对灰土垫层厚度等进行了参数影响性分析.建议高速客运专线路基桩顶垫层设计中宜采用双层、双向土工格栅结构形式,并优先选用延伸率小的筋材.

Theoretical analysis of reinforced lime soil cushion above pile and its engineering design

Up till now, the theories of reinforced cushion cannot meet the needs of practice, the designing method of reinforced lime-soil cushion attracts most researchers’ attention. According to the ground treatment of the deep collapsible loess in the Zhengzhou-Xi’an Passenger Dedicated Railway Engineering, the limit state theory model of the reinforced lime-soil cushion above pile is established; the loading feature is analyzed; and the design method is presented. Considering pile diameter, pile space, subgrade height and geogrid strength, the parameters such as the cushion thickness etc., are analyzed. It is suggested that the double layer structure and the double direction reinforced geogrid with small elongation rate should be used first to reinforced lime-soil cushion in the Passenger Dedicated Railway.