水位循环升降作用下粉土变形及沉降机理

Deformation Law and Settlement Mechanism of Silt Caused by Cyclic Risefall of Water Table

摘要:

地下水位升降变化是浅层地下水普遍存在现象，常常导致土层结构与土体性质发生变化，从而影响地基土变形与沉降.以洛阳地区粉土为研究对象，通过水位循环升降模拟试验，研究水位循环升降作用下粉土孔隙水压力、土压力周期性变化规律及由此产生的变形沉降特性.试验表明：孔隙水压力周期性变化是导致土体周期性变形的主要原因，两者具有相似的周期性变化规律；孔隙水压力对水位升降表现出瞬时响应，而变形则呈现滞后性.通过机理分析发现，振荡孔隙水压力是土体中饱和非饱和状态转变的根本原因，而残余孔隙水压力的衰减消散是土层产生固结沉降的驱动力.

Abstract:

As a common phenomenon of groundwater in shallow soil layers, the cyclic risefall of water table usually causes the change of soil structure and properties, having impacts on the deformation and subsidence of foundations. In order to solve the above problems, this paper takes the silt in Luoyang area as the research object for the model test, and studies the periodic variation law of pore water pressure and earth pressure in different layers of silt at different stages under the action of cyclic risefall of water table. Based on the above exploration, the arising settlement deformation can be studied. The results show that the periodic change of pore pressure is the main reason of the periodic deformation of silt, and the variation laws have the similarity. The pore water pressure responses instantaneously with the cyclic risefall of water table while the variation of deformation shows the hysteresis. The oscillating pore water pressure is the primary cause of the saturationunsaturated state transition in the silt and the dissipation of the residual pore water pressure is the driving force of the settlement deformation.