兰州市区第三系风化砂岩地基承载力试验研究

Study on tests for subgrade bearing capacity of weathered sandstone in the Tertiary in Lanzhou

兰州市区第三系风化砂岩胶结弱,成岩性差,是一种极软质岩石。目前对于砂岩地基承载力的评价尤其是深度与宽度修正模式研究尚少,本文通过现场静载荷试验对比研究,得出了风化砂岩地基受荷后的变形特征与破坏模式,从理论上分析了其承载力特征值可以进行深度修正;并进一步通过模拟边载条件下的载荷试验进行验证,其结果表明,在边载作用下,砂岩地基承载力特征值会大幅度提高,按密实砂土修正系数进行承载力修正结果偏于安全。本文通过现场试验研究结合理论分析,为评价风化砂岩地基承载力提供了一个可靠实例与解决类似问题的研究思路。

The weathered sandstone in Lanzhou in the Tertiary is extremely soft rock,it is weak bond and poor diagenesis,the degree of rock weathering is divided without quantitative criterion. The bearing capacity of sandstone especially for its depth and width correction mode is no clear basis in the specification. According to load tests,the deformation characteristics and failure modes of the loaded foundation are put forward,and the bearing capacity can theoretically be corrected with depth,and further verified by load tests under simulated load conditions. The results show that the bearing capacity characteristic value of sandstone foundation will be greatly enhanced under the edge loads. The bearing capacity result that corrected by compacting sand coefficient is safe. Based on the field testing study and theoretical analysis,the reliable example and the study thinking for the similar issue are provided for the evaluation of the foundation bearing capacity of wethered sandstone.