灵敏性粉土的压缩及触变特性研究

Study on Compression and Thixotropy Properties of Sensitive Silt

山西汾河一级阶地的饱和粉土大多具有灵敏性,使得其强度和变形性质在扰动前后差别很大。为了研究灵敏性粉土的压缩及触变特性,对探井取样的原状土和重塑土样进行了一维固结压缩试验和无侧限抗压强度试验。试验结果表明,原状土加载到结构屈服应力处,沉降量突增,固结系数突增,主固结比突降,次固结对沉降的贡献开始上升;原状土与重塑土的差异是原状土的结构强度引起的,在高压固结压力下两者压缩曲线约在0.58e;处重合;灵敏土无侧限抗压强度试验的应力应变曲线表现出类似超固结土的应变软化特性,其触变后恢复具有时效性,弹性模量受扰动影响较为敏感,可考虑作为扰动指标的量度。

Most of the saturated silt in the first terrace of Fenhe River in Shanxi Province is sensitive, which makes the strength and deformation properties of the silt change greatly before and after disturbance. The compression and thixotropy characteristics of sensitive silt were studied by one-dimensional consolidation compression tests and unconfined compression strength tests on undisturbed and remolded soil samples taken from exploration wells. Test results show that the settlement and consolidation coefficient of undisturbed soil increase and the ratio of the main consolidation decreases suddenly when the structure yield stress is reached, and the contribution of secondary consolidation to settlement increases;The difference between undisturbed soils and remolded soils is caused by the structural strength of undisturbed soils. Their compression curves coincide at about 0.58e;under the higher consolidation pressure;stress-strain curves of sensitive silt unconfined compressive strength test show strain softening characteristics similar to those of over-consolidated soils, and recovery time after disturbance is time-dependent. Elastic modulus is sensitive to disturbance and can be used as a disturbance index.