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点荷载试验在岩基强度和承载力评价中的应用

董平1, 曹健1, 纪广强2, 胡德昭1   

  1. 1. 南京大学 地球科学系,江苏 南京 210093;2. 南京大学 基建处,江 苏 南京 210093
  • 收稿日期:2000-12-20 修回日期:2000-12-20 出版日期:2000-12-20 发布日期:2000-12-20

Application of Point Load Test to Evaluation of Strength and Bearing Capacity of Rock Foundation

DONG Ping, CAO Jian, JI Guang-qiang, HU De-zhao   

  1. Department of Earth Science, University, Nanjing 210093
  • Received:2000-12-20 Revised:2000-12-20 Online:2000-12-20 Published:2000-12-20

摘要: 岩石点荷载试验可以求得岩石点荷载强度指数,由点荷载强度可以 计算出岩石的单轴抗压强度,进而可计算出岩基承载力。 利用点荷载试验方法对南京地区的多个人工挖孔桩工地的孔底岩基强 度和承载力进行了评价,具体指导了挖孔桩的挖进工作,取得了良好效果。

Abstract: Point load test can determine the poin t load strengt h indexes of rock. The result then can be used to calculate the rock's uniaxial compressive strength, from which the bearing capacity of rock foundation can be decided. This method can be used to evaluate the strength and bearing capacity of rock foundation in the artificial excavated holes for piles. Compar ed with macroscopic perception method, point load test method is more scientific. It is also more economic, simpler and easier to apply in the d igging process in comparison with static load test. In this article, we will poi nt out that point load test can promptly determine the strength of rock foundation by testi ng irregular rock specimens. Therefore, as far as specimen collection is concerned, point load test is simpler, and more ef fective than uniaxial compressive strength test and it is especially significant for the evaluation of soft rock (e.g. the red clay rock in Nanjing area). When applying point load test method to the evaluation of the strength and be aring capacity of rock foundation in the artificial excavated holes for piles, i t should be noted that the sample's length (L), width (b), and height (h) meet this condition: L≥b≥h, and h is b etween 2.5-10cm. Samples can't be tetrahedroid. For point load strength ind ex Is, the area-strength formula or its modified form ( Is=P/De 2) is the most suitable formula for its expression, where De is the equivalent diameter of the area. Applying the point load test meth od, we evaluated the strength and bearing capacity of rock foundation in many artifi cial excavated holes for piles in Nanjing area and guided the digging process wi th good results.