摘要
The deterioration of soft rocks caused by freeze-thaw(F-T)climatic cycles results in huge structural and financial loss for foundation systems placed on soft rocks prone to F-T actions.In this study,cementtreated sand(CTS)and natural soft shale were subjected to unconfined compression and splitting tensile strength tests for evaluation of unconfined compressive strength(UCS,qu),initial small-strain Young’s modulus(Eo)using linear displacement transducers(LDT)up to a small strain of 0.001%,and secant elastic modulus(E_(50))using linear variable differential transducers(LVDTs)up to a large strain of 6%before and after reproduced laboratory weathering(RLW)cycles(-20℃e-110℃).The results showed that eight F-T cycles caused a reduction in q_(u),E_(50) and E_(o),which was 8.6,15.1,and 14.5 times for the CTS,and 2.2,3.5,and 5.3 times for the natural shale,respectively.The tensile strength of the CTS and natural rock samples exhibited a degradation of 5.4 times(after the 8th RLW cycle)and 2.7 times(after the 15th RLW cycle),respectively.Novel correlations have been developed to predict Eo(response)from the parameters qu and E_(50)(predictors)using MATLAB software's curve fitter.The findings of this study will assist in the design of foundations in soft rocks subjected to freezing and thawing.The analysis of variance(ANOVA)indicated 95%confidence in data health for the design of retaining walls,building foundations,excavation in soft rock,large-diameter borehole stability,and transportation tunnels in rocks for an operational strain range of 0.1%e0.01%(using LVDT)and a reference strain of less than 0.001%(using LDT).
