中文摘要：

为了解饱和膨胀土在失水条件下,干缩裂隙发育过程中土体内的应变状态、分布以及变化规律,设计了一个长40cm、宽5cm、深3cm的一维模型槽,将3条FBG传感光栅串埋入饱和膨胀土试样中,对膨胀土不同位置的应变进行了测量,得到了土体失水干缩致裂过程中,各个FBG传感器的应变状态及其变化规律,并分析了首条干缩裂隙及其附近土体的应变分布特征及其时空演化规律。试验结果表明：随着土体含水率的降低,土体首先呈现出整体收缩,之后应变状态发生分异,呈现出拉张区和收缩区交替出现的分布规律;位于最大收缩区的边缘,当FBG传感器的应变由压缩状态转变为拉伸状态,并且拉应变及其变化速率相对较大的区域将产生首条裂隙。可见,本文所采用的高空间分辨率FBG传感技术为分析膨胀土裂隙发育全过程、揭示膨胀土失水致裂机理,以及膨胀土裂隙性特征的研究提供了新的思路和技术手段。

英文摘要：

This paper is to find out the strain property,distribution and its variation of the saturated expansive soil during its shrinking and cracking process under the condition of dehydration.A one-dimensional model tank of 40cm long,5cm wide and 3cm high was designed and used for the purpose.The tank was filled with the saturated expansive soil and three grating sensing fibers with 11 FBG sensors were buried into the soil to measure the strain at different positions.Based on the measured strains and their variation,the paper obtained the characteristics of soil stain distribution and its temporal-spatial evolution process,especially the strain distribution on and around the first fissures.It was found that,the soil shows global shrinkage initially with the reduction of soil moisture content.Afterwards,differentiation of the soil stains occurred,showing alternate distribution of tension and compression.At the edge of the maximal shrinking area,when the state of FBG sensors was changed from compression to tension,the first fissure would appear in the region of higher tensile strain and strain variation rate.Thus,the FBG sensing technology of high spatial resolution can be a new idea and technology used for the analysis of the whole shrinking and cracking process of the expansive soil,revealing the cracking mechanism of expansive soil during the dehydration.