为了准确获取复活蠕滑型黄土滑坡滑带土抗剪强度参数, 需要开展黄土的完全软化强度试验研究。以山西黄 土为研究对象, 采用直接固结法和预压固结法制备饱和重塑试样, 并进行了不同剪切速率下的直剪试验和三轴固结 排水剪切试验。结果表明: 低法向应力下, 制样方法对完全软化强度的影响不大, 而高法向应力下, 预压固结试样的 完全软化强度大于直接固结试样; 预压固结直剪试验的剪切速率对完全软化强度的影响不大; 三轴固结排水剪切试 验中, 预压固结应力相同时, 完全软化强度随围压的增加而增大, 围压相同时, 完全软化强度随预压固结应力的增加 而增大, 且应力应变曲线在一定应变范围内重合; 黄土的完全软化黏聚力近似为0 kPa, 预压固结试样的完全软化 内摩擦角更接近实际状态。研究结论为复活蠕滑型滑坡稳定性分析中进行强度参数测试时重塑饱和土样的制样方 法和试验方法提供了依据。

Experimental study o n fully so ftened strengt h o f lo ess needs to be perfo rmed in or der to accurat ely acquire the shear st reng th parameters o f the slip so il in the r esur gent and creeping loess landslide. In this paper, direct co nsolidatio n method and pr eloading co nso lidatio n method w ere used to prepare the saturated r emolded samples of lo ess in Shanx i Pr ov ince fo r the dir ect shear t ests w ith different shear rates and triax ial consolidation drained shea r tests. Resea rch results show ed that ( 1) the fully so ftened strength is not affected by sampling methods under low normal st ress conditions, but the fully soft ened streng th of pre2 loading consolidation samples is gr eater than that of direct consolidation samples under hig h normal str ess co nditions; ( 2) the fully so ftened str eng th is no t affected by the r ates of the direct shear tests in which samples wer e prepared by prelo ading co nsol2 idation met ho d; ( 3) fo r the triax ia l conso lidation dra ined shear tests, t he fully softened streng th incr eases with the increasing of the co nfining pressur e under the same prelo ading co nso lidatio n str ess and it increases with the increasing of preloading consoli2 datio n str ess under the same confining pressur e, and t he str ess2strain curv es appear to o ver lap within a cer tain range o f strain; and ( 4) the fully softened cohesions o f samples are close to 0 kPa, and the fully soft ened fr ictio n angles of prelo ading co nso lida2 tion samples ae clo ser to the actual conditio n. The r esear ch r esult s pro vide reference fo r the sampling methods and ex perimental met ho ds of str eng th par ameter tests in the st abilit y analy sis o f resurg ent and cr eeping lo ess landslides.

国家自然科学基金项目( 40772181)