基质吸力对非饱和滑带土抗剪强度的影响试验研究

Study on influence of matrice suction on shear strength behavior of unsaturated slip soils

在滑坡地质灾害中遇到的滑带土大多数是非饱和土,研究吸力对非饱和滑带土c、φ值的影响,对于滑坡防治具有十分重要的意义。通过不同基质吸力和剪切速率的条件下的四联直剪试验,探讨了基质吸力与非饱和粘性滑带土抗剪强度的关系。试验结果表明,在同一基质吸力条件下,抗剪强度随轴向荷载的增大而增大,且保持平稳线性增长的趋势;随着吸力值的增大,其总粘聚力与内摩擦角均呈现增大趋势。对于总粘聚力来说,当基质吸力≤100 kPa时,随着吸力的增大,总粘聚力增长曲线斜率较大,增长速率较快;当基质吸力>100 kPa时,随着吸力值的增大,总粘聚力增长曲线斜率放缓,增长速率减慢;但总体处于平稳增长的态势。对于内摩擦角来说,当基质吸力≤50 kPa时,随着吸力的增大,内摩擦角增长曲线斜率较大,增长速率较快;当基质吸力>50 kPa时,随着吸力值的增大,内摩擦角增长曲线斜率放缓,增长速率减慢。

It is very important to study the influence of suction on unsaturated slip soil and shear strength in landslide geological disaster.The relationship between matrix suction and the shear strength of unsaturated viscous slippage is discussed through the quadruplet direct shear tests under the condition of different substrate suction and shear rate.The experimental results show that the shear strength increases with the increase of axial load in the same matrix,and the trend of stable linear growth is maintained.With the increase of suction value,the total cohesion and internal friction angle show an increasing trend.When the matrix suction is less than or equal to 100 kPa,with the increase of suction force,the growth curve of the total cohesive force growth curve is larger and the growth rate is faster.When the matrix suction is great than 100 kPa,the slope of the total cohesion growth curve slows down and the growth rate slows down with the suction value increasing.But the overall situation is on the steady rise.When matrix suction is less than or equal to 50 kPa,with the increase of suction force,the growth curve of internal friction angle is larger and the growth rate is faster.When the matrix suction is greater than50 kPa,with the increase of suction value,the slope of the growth curve of internal friction angle decreases,and the growth rate slows down.