冻融循环对固化盐渍土的抗压强度与变形的影响

Influence of freezing-thawing cycles on compressive strength and deformation of solidified saline soil

北方地区冬季结冰与春季融化引起土的冻胀和融沉问题,弱化了土的抗压性能。以研究冻融循环对固化盐渍土抗压性能的影响为目的,完成冻融前后盐渍土、石灰固化盐渍土、石灰+SH固化盐渍土的抗压试验。结果表明:盐渍土、石灰固化土和石灰+SH固化土的抗压强度随冻融次数的增加而减小,石灰+SH固化土的抗压强度均高于另2种土;冻融前后石灰固化土和石灰+SH固化土均为应变软化型,盐渍土则由应变软化型转变为应变硬化型。冻融循环次数相同时,石灰+SH固化土的抗压强度随含水率的增加而减小,其应力–应变曲线逐渐趋于平缓,土的脆性减弱。石灰+SH固化土具有相对较好的抗冻融性能,含水率是影响冻融后土的抗压性能的首要因素。

The frost heave and thaw subsidence of saline soil induced by freezing and thawing weaks the compressive property of saline soil in northern China. In order to study the effect of freezing-thawing cycles on the compressive properties of solidified saline soil,unconfined compressive tests（UCS） were conducted on the original saline soil,the lime-saline soil and the lime-SH agent-saline soil. The results indicate that the UCS values of the original saline soil,lime-saline soil and lime-SH agent-saline soil decrease as the freezing-thawing cycles increasing. The UCS value of lime-SH agent-saline soil is higher than that of other two types of soils after each freezing-thawing cycle. The lime-saline soil and lime-SH agent-saline soil are strain-softening after each cycle of freezing-thawing. The original saline soil without being frozen-thawed is strain-softening and after cycles of freezing-thawing is strain-hardening. Under the condition of same freeze-thaw cycles,the UCS values decrease with the increase of water contents of lime-SH agent-saline soil,meanwhile,the stress-strain curves tend to be flat gradually and the brittle behavior of specimen reduces. According to the results,the lime-SH agent-saline soil has a marked resistance against freezing-thawing,and the water content is the key factor to affect the compressive property of three soils after freeze-thaw cycles.