Study On Stability Analysis Method Of Canal Lining Structure In Expansive Soil Area

Expansive soil is water-sensitive,multi-fractured,and wet-swelling and shrinking.It is called "the most difficult soil to deal with",and its particularity has caused great harm to engineering construction.The channel project is a water-carrying building,and the channel lining board is relatively thin.The expansion of the foundation soil of the channel caused by water seepage is very harmful to the lining,and it is an urgent technical problem to be solved.In this paper,the representative expansive soils in the northern and southern parts of China,expansive soils in the Songnen Plain of Heilongjiang and Ankang expansive soils in Shaanxi were selected as the research objects.The high-temperature constant-temperature refrigerated centrifuge method was used to carry out different initial dry density and different dry-wet cycles The soil and water characteristic curve test under the action of the number of times and different freezing and thawing cycles,the expansion rate and the expansion force test were carried out,the expansion deformation law of the expansive soil and the influence law of different factors on the soil water characteristic law of the expansive soil were analyzed,and considerations were put forward.The soil-water characteristic curve fitting model of the expansive soil with body deformation,and the stability of the channel lining structure considering the expansion force is analyzed.The main results obtained are as follows:(1)The influencing factors and changing rules of expansion and expansion force are revealed.The main factors affecting the swelling capacity of the expansive soil were the initial dry density,initial moisture content and overlying load.The swelling amount increased with the increase of dry density and the decrease of water content,and decreased with the increase of the overlying load.The swelling force was affected by the initial dry density load and the initial moisture content.The swelling force had a power function relationship with the initial dry density and a linear relationship with the initial moisture content.The greater the initial dry density and the smaller the initial moisture content,the greater the swelling force.(2)The calculation formula of the expansion of Ankang expansive soil considering three factors of initial dry density,initial moisture content and overburden load is improved.The formula can be used to calculate and predict the expansion caused by saturated soil by initial dry density,initial moisture content and overburden load,which can effectively support the design of canal and foundation in Ankang expansive soil area.(3)It is proved that the volumetric correction is necessary to measure the soil water characteristic curve of expansive soil by the fast centrifuge method.The rapid centrifuge method is simple and time-saving,which can greatly improve the test efficiency.However,in the process of centrifugal rotation,the dewetting shrinkage of expansive soil is large and the test accuracy is poor,and the volume change correction method based on shrinkage test can achieve good correction effect.(4)A series of soil water characteristic curve tests of two kinds of expansive soils were carried out,and the change law of water holding characteristics of expansive soils was revealed.The higher the initial dry density was,the better the water holding capacity of soil sample was;the increase of the number of dry wet cycles and freeze-thaw cycles made the water holding capacity worse,and it tended to be stable after a certain number of times;the water loss rate of soil sample in the low suction area was large,and the curve was steep;the curve in the high matrix suction area was gentle.(5)Based on Gardner model,the characteristic expression of expansive soil water considering both the initial dry density and the number of cycles was proposed,which was in good agreement with the test data.(6)The stability of the lining plate and the fixed foot of the channel were analyzed by using the analytical and finite element methods,and the analytical calculation software of the channel stability was developed.The software can easily check the stability of canal lining structure.