超深基坑复合土钉支护结构原位试验研究

In-situ test of composite soil nailing for a deep foundation pit

通过对深圳假日广场超深基坑预应力锚索复合土钉支护结构进行全方位的原位测试试验,收集了关于土钉拉力、锚索应力、孔隙水压力、面层土压力的大量数据,旨在研究钉—锚—土三者的工作性状、相互作用机理,以及随基坑开挖、锚索张拉、降雨、卸载等外界环境变化对支护结构的响应规律。试验结果表明预应力锚索复合土钉支护结构具有开挖效应、时间效应、空间效应、降雨滞后效应;指出土钉拉力并非随基坑开挖深度递增,潜在滑移面并非通过基坑坡脚;揭示了预应力锚索的主要作用不在于分担或改善支护结构受力状态,而在于提高边坡抗滑移稳定性和减小边坡位移,并就设计和施工提出了一些合理建议和应注意的问题。

In-situ test was conducted for the prestressed anchor rope composite soil nailing of a deep foundation pit for the Shenzhen Holiday Plaza to study the characteristics, the mechanism of interaction between soil nailing, prestressed anchor rope and soil, and the response of retaining structure to changes in the external environment, such as foundation pit excavation, anchor rope tension and rainfall. Data were collected on tension of soil nailing, stress of anchor rope, pore water pressure and earth pressure. The test reveals the excavation effect, time effect, three- dimensional effect and rainfall lagging effect of the prestressed anchor rope composite soil nailing. The test also indicates that tension in soil nailing does not increase with the excavation depth, and the potential slip plane does not pass through the base of the slope. The major function of the prestressed anchor rope is not for resisting shear or reducing stress in the retaining structure, but rather for improving the stability of slope.