Field Test And Theoretical Study Of Pile-plank Wall On Expansive Soil Cutting Slope In Yun-Gui Railway

Expansive soil, which may cause great harm to constructions, is widely distributed in China. Especially in southwest rigion of China, the annual spending on the treatment of expansive soil is tremendous. Currently, the failure mechanism and retaining structure design method of expansive soil slope remains to be further studied.In response to above problems and relying on the technology development project of the Minstry of Railway," Researchs on the key technology of Yun-Gui Railway (NO:2010G016-B)", experiments and theoretical research, including information research, scene monitoring and numerical simulation, are conducted to study the retaining effect of pile-plank wall on expansion soil cutting slope.The main contents and conclusions are as follows.(1) The characteristics of expansion soil and the forms and mechanism of expansion soil slope are analyzed and discussed. The influence factors of the stability factor are also discussed and the stability factor of slope, which considers matric suction, are deduced.(2) A long-term monitoring scheme for the typical section is established.Soil pressure cells, concrete strain gauges and soil moister meter s are set in the pile-plank wall structure. The monitored data shows that the distribution along the depth direction of earth pressure on the pile and plank are respectively "K" and"C" type, which is very different with the distribution type of coulomb earth pressure.This difference can be cause by the expansive force exsited in the soil.(3) The earth pressure on the pile-plank wall is regarded as the sum of coulomb earth pressure and expansive presuure. Based on the traditional design and calculation method of pile-plank retaining wall, the lateral expansive pressure effect on structure is also taken into account in a simplified way. The calculated value and pattern of earth pressure, stress and strain acting on the pile-plank are basically in line with the monitoring data. (4) A finite element simulation of the pile-plank structure on the expansive soil cutting slope is estabalished. Four different working conditiongs, from ignoring expansive soil pressure to considering different magnitudes of expansive soil pressure are considered.Also,the calculated value and pattern are constrasted with the monitoring data and theoretical calculation. In the thesis, there are94figures,26tables and128references.