胶凝砂砾石层面抗剪参数试验研究

胶凝砂砾石坝由于骨料多,水泥掺量少,本体抗剪强度很低,而且胶凝砂砾石坝采用碾压施工,水平向碾压层面的存在,会导致层间结合力的降低,影响层面的抗滑稳定及抗渗安全,因此研究胶凝砂砾石碾压层面抗剪能力具有重要意义。本文根据胶凝砂砾石碾压层面的处理措施,设计了6种试验方案进行胶凝砂砾石碾压层面的抗剪断试验,采用150mm立方体试件研究了单轴压条件下的胶凝砂砾石碾压层面抗剪断特性。并在守口堡大坝坝基不同高度的碾压层面处,采用50cm立方体试件进行了富浆胶凝砂砾石原位抗剪断试验。通过室内和原位试验研究,得到了胶凝砂砾石层面抗剪断基本参数,并通过分析揭示了胶凝砂砾石层面剪裂机理,对比了室内试验与原位试验结果的差异并揭示了其原因,对比了富浆胶凝砂砾石层面原位抗剪参数与RCC的差异。上述研究,为胶凝砂砾石大坝的结构分析提供了可靠的参数,并为碾压层面的施工提供了有益的建议。

Experimental study of shear parameters of CSGR layers

Due to high aggregate and low cement content, the shear strength of CSGR (cemented sand, gravel, and rock) is very low. Moreover, because of its construction by roller compaction machine, the binding force is weakened by the horizontal rolling layers; hence, adjacent layers are separated by the weak surface of the dam. Therefore, a detailed study of the shear strength of CSGR layers is necessary. In this work,laboratory tests on shear strength,with specimens of CSGR (150 mm cube) under uniaxial pressure, have been carried out based on the six proposed treating methods for the rolling layers. In addition, in-situ shear tests on rich-cement CSGR specimens (50 cm cube) have been performed at compacting layers of the Shoukoubao dam foundation. The shear parameters of CSGR compacting layers have been obtained through laboratory and in-situ tests, and the mechanism of shear failure of CSGR layers has been discussed. Further, the differences between the results from laboratory and in-situ tests have been analyzed,and the possible reasons for their occurrence have been discussed. Finally,the in-situ shear parameters of rich-cement CSGR have been compared with the shear parameters of roller compacted concrete (RCC) dams. This work provides reliable parameters for the structural analysis of CSGR dams, and gives beneficial suggestions for the construction of CSGR layers.