含水量对软土无侧限变形影响的试验研究

he soil near the free face will unload stress in the excavation or tunneling, for which the soil occurs lateral deformation. The deformation of soft soil is always great, which may cause great harm to buildings, if not handled properly. In fact, the deformation of soft soil is the deformation under the unconfined condition. To study the characteristics of soft soil under the unconfined condition, a conventional consolidation test apparatus was modified to a unconfined compression apparatus for soft clays. A series of laboratory tests were conducted to investigate the characteristics of the unconfined compression of undisturbed samples and remodeling samples. The result shows that the sample has a rapid deformation after each level of load applied, and the deformation of the sample increases and the deformation rate decreases gradually as time goes on. The axial and lateral strain rate under unconfined condition is far greater than it under unidirectional compression condition especially in the early stage of loading. We mainly analyze the influence of moisture content and axial stress on the deformation. For the samples with identical axial stress, the ratio of the axial and lateral strain decreases with the increase of the moisture content and fit the exponential function well. The ratio of the axial and lateral strain decreases with the increase of the axial stress when the moisture content is certain. The calculation formula of the strain ratio is obtained according to the test results.