Study On The Model Test Of Reinforcing Accumulation Layer Expansive Soil Landslide By Micro Piles

A variety of means have been tried to control the landslides, most of which are using traditional slide piles, concrete frame beams, retaining walls, etc. With the development of disaster prevention technology, micro piles are more and more frequently used in the control of shallow deposit landslides with their economy and good reinforcement effect.Control of special accumulation horizon expansive soil landslides in Southern Shaanxi has drawn attention of engineering and academia after the "5.12" earthquake. Reinforcing accumulation horizon expansive soil landslides by micro piles is more frequently used in the disaster control and has achieved good effects and economic benefits. Now many scholars have made some achievements on accumulation horizon landslides and the reinforcement mechanism of micro piles, which has promoted the development of micro pile technology, but there are few research literatures on the mechanism of reinforcing deposit expansive soil landslides by micro piles and a set of mature reinforcement specification has not yet formed, which restricts the promotion and application of micro pile technology, therefore, it has important theoretical and practical significance to study the mechanism of reinforcing accumulation horizon expansive soil landslides by micro piles and propose corresponding design principles and design system.Model test is an important way to study micro pile reinforcement technology. The test is conducted in a 1200 mm×1200 mm×1000mm frame based on the similarity theory. The model test is conducted with the expansive soil collected from the practical engineering in Maojiagou Village, Mian County, Southern Shaanxi as the material of the model. Homemade spray device and bake device are used to simulate natural rainfall and evaporation and to load uniformly on the top of the slope.Pile spacing, pile row spacing, anchorage depth, connecting beam, etc. are variables during the test and are divided into 6 groups with different research purposes. Over 20000 groups of data of different conditions, different locations and different time phases are obtained through real-time measurement by pre-buried earth pressure cells, strain gauges and displacement sensors. The following main conclusions are drawn after analyzing the experimental data: (8～10)d (d is the pile diameter) is the optimal pile spacing; (5～10)d the optimal row spacing; L/3≤D≤2L/5 (L is the pile length) the optimal anchorage depth D; In order to achieve the best soil arching effect,pile spacing is (8～10)d.A series of studies are conducted through a model test in this paper, the mechanism of reinforcing the accumulation horizon expansive soil landslides by micro piles is analyzed and a number of micro pile design principles are proposed, which has promoted the research and technology applications of reinforcing the accumulation horizon expansive soil landslides by micro piles. There are still shortcomings and defects on material similarity and sensor usage due to the limitations of the working time and the technical means of the thesis, which should be improved in the future researches.