风化软岩地区嵌岩桩承载力自平衡试验研究

为研究风化软岩段桩基侧摩阻力承载特性和桩基安全性,采用自平衡试桩法对某工程水稳性较差的风化软岩段3根试桩进行测试分析。结果表明:自平衡法试桩荷载箱上部桩与传统静载法试桩的桩身受力方向相反,前者比后者端阻力发挥更充分;在2倍设计荷载作用下桩顶等效竖向位移较小,桩身侧摩阻力、端阻力大部分未充分发挥,实测桩侧摩阻力可能比勘察提供的侧摩阻力值大;按照经验法和简化法得到的3根试桩的计算安全系数差别较小,均大于2.2,验证了试桩的安全性和自平衡方法的可靠性。

O-cell Experimental Study on Bearing Capacity of Rock-socketed Piles in Weathered Soft Rock Region

To research the bearing behaviors of pile side friction in weathered soft rock region and the safety of pile foundation,three test piles of a certain project were tested and analyzed by using the O-cell pile testing method at the weathered soft rock region where the water stability is poor. The test results indicate:(a) The stress direction of the pile shaft above the load box by O-cell pile testing method is opposite to that by traditional static load test method; the pile tip resistance by the former method is even more effectively exerted than by the latter method.( b) Under the action of twice the design load,the equivalent vertical displacement at pile head is smaller; most of the pile side friction and tip resistance are not brought into full play; the actually-measured pile side friction may be bigger than that provided by survey department.(c) The safety coefficients of three test piles are all greater than 2. 2; there is little difference between safety coefficients calculated respectively by empirical method and by simplified method; therefore,the safety of test piles and the reliability of O-cell pile testing method are verified.