摘要
坝基覆盖层具有很强的原位结构特性,易被扰动,取原状土样进行室内试验很难实现,重塑土样又难以反映其原位结构,故室内试验很难全面反映覆盖层的原位工程力学特性。采用新型直剪试验法在大渡河干流某水电站坝址进行了表层覆盖层原位直剪试验,该方法用链条张拉剪切框使试样受剪,克服了剪切框内壁摩擦对剪切面正应力的影响,从而能精确地测定出试验抗剪强度。试验测得的覆盖层抗剪强度处在地质报告建议值范围内,且略小于室内试验测得的强度。结果表明,新型直剪试验法能够较好地适用于覆盖层原位强度指标的测定,可为工程设计提供客观、合理的依据。
The overburden has strong in-situ structures that are easily disturbed. Laboratory tests can hardly reflect the overburden＇s in-situ engineering mechanical properties comprehensively since it is quite difficult to obtain undisturbed overburden samples and remould overburden samples with in-situ structures. A new direct shear testing method is applied to test overburden＇s shear strength and the in-situ tests are conducted on the river overburden in a dam site, which is lo- cated on the mainstream of Daduhe River. The feature of this new in-situ direct shear test method is to pull the shearing frame with a flexible chain, which causes the mutual movement of the shearing frame and specimen during shear. Thus, the wall friction of the shearing frame has little impact on the normal stress of the shear plane and the correct measure- ment for shearing stress becomes possible. The shear strength of the overburden obtained by the tests is in the range of the suggested values given in geological report and it is less than the result of laboratory tests. The results show that the new direct shear testing method can be used in the test of overburden＇s in situ strength, which provides objective and rea sonable basis for engineering design.
出处
《水电能源科学》
北大核心
2014年第1期122-124,189,共4页
Water Resources and Power
基金
江苏高校优势学科建设工程(YS11001)
