固化粉土小应变剪切模量与强度增长相关性研究
Relationship between small-strain shear modulus and growth of strength for stabilized silt
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摘要: 小应变剪切模量和无侧限抗压强度是表征固化土刚度和强度特性的两个重要参数。简要介绍了弯曲元测试技术的原理及其在试验中存在的问题,采用压电陶瓷弯曲元测试技术对水泥和木质素固化剂固化粉土试样在不同养护龄期下的小应变剪切模量进行了测试,同时对相应龄期下试样进行了常规无侧限抗压强度试验,通过引入归一化参数G28和UCS28对不同固化土的小应变剪切模量和无侧限抗压强度之间的相关关系进行分析,提出了固化土刚度与强度的相关性模型,可为地基处理中固化土的无损测试与加固效果评价提供新的方法。结果表明,水泥、木质素固化粉土的小应变剪切模量随养护龄期增加而增加,养护龄期28 d内增长显著,28 d后增长趋于平稳;相同类型固化土不论固化剂掺量多少,其小应变剪切模量随养护时间的发展在本质上是相同的;固化土归一化无侧限抗压强度表现出与小应变剪切模量相似的发展趋势;提出的固化土归一化模型可作为一种土体强度无损检测的新方法。Abstract: The small-strain shear modulus and unconfined compressive strength are two important parameters to characterize the stiffness and strength of stabilized soils. The fundamental and the main problems existing in the experiment of bender element technique are briefly reviewed. The small-strain shear modulus of cement and lignin stabilized silt are tested under different curing time by piezoelectric bender element technique. The conventional unconfined compressive strength test is also carried out on stabilized samples under different curing time. The relationships between the small-strain shear modulus and unconfined compressive strength of different stabilized soils are analyzed by introducing the normalized parameters G28 and UCS28. A stabilization model for the stiffness and strength of stabilized soils is proposed to provide a new method for the non-destructive testing and evaluation of stabilized soils in ground improvement. It is found that the small-strain shear modulus of the stabilized silt increases with the increase of curing time. The small-strain shear modulus of the stabilized silt increases dramatically during 28 d curing time and gets steady after 28 d. The results suggest that for a given binder, the small-strain shear modulus development with time is essentially the same regardless of the dosage. The normalized unconfined compressive strength of stabilized silt shows similar characteristics to the normalized small-strain shear modulus. The proposed normalized model for stabilized soils can be used as a new method for non-destructive prediction of soil strength.