分级连续加载条件下原状膨胀土固结变形研究

由固结系数Cv与有效应力??和孔隙比的关系,推导了考虑固结系数变化的分级连续加载固结控制方程。根据方程的解析解得到了分级连续加载的沉降计算公式。结合云桂高速铁路建设,以高路堤分段堆载方式为研究依据,在GDS三轴试验系统开展原状膨胀土分级连续加载K0固结试验。结果表明:沉降与时间关系在加载期呈折线式发展,稳载期呈双曲线变化;膨胀土的应力-应变关系呈阶梯式变化;当??≤c?时,固结系数随有效应力呈先增大而后减小,当??>c?时,固结系数随有效应力呈波动持续减小。固结度理论计算值与试验结果相比,考虑固结系数变化的固结度计算比固结系数为定值更准确。分级连续加载沉降计算公式可作为分析高速铁路路基沉降-时间关系的参考方法。

Study of consolidation deformation of intact expansive soil under stage continuous loading conditions

Based on the relationship among the coefficient of consolidation Cv, effective stress and void ratio, the equations considering the variation of Cv for consolidation under stage continuous loading are derived. According to analytical solutions of the above equations, a formula for settlement calculation under stage continuous loading is obtained. Combined with the construction of Yun-Gui high-speed railway, taking the stage loading of high embankment as the object of study, stage continuous loading oedometer test of intact expansive soil are carried out on geotechnical digital systems (GDS) triaxial apparatus. It is confirmed that the relationship between settlement and time can be fitted with broken line in loading stage and hyperbola in steady stage. The stress-strain curves of expansive soil can be described with ladder. The coefficient of consolidation increases firstly and then decreases with effective stress when ≤ ; however, it decreases continuously as wave while ＞ The calculated values of degree of consolidation are compared with test results. It is found that the degree of consolidation calculated by considering the variation of Cv is more accurate than constant Cv. The formula for settlement calculation under stage continuous loading can be used as a reference method to analyze the relationship between settlement and time of subgrade for high-speed railway.