Deformation C Haracteristics Of Mudstone Filling Material Based On Dense Layer-Macropore Layer Structure

The transport infrastructure in southwest China has improved rapidly with the development of economic,especially the implementation of the Western Development Strategy.Most of the southwestern regions are mountainous and hilly areas,so that there are many foundation projects with high filling and deep excavation.Due to the topography and terrain conditions,the filling of the soil is often lacking,however mudstone soil-rockfill materials formed by the excavation of the mountain are quite rich.And mudstone soil-rockfill materials become the main filling materials in projects because of its good compressive mechanical properties,such as the construction of mountain airports,highways,housing and industrial construction.The filling body is often layered and filled according to the filling time.During each layer of rolling and filling,the compacting effect is gradually weakened from the upper level to the lower level due to the limitation of the rolling machinery and the stress diffusion of the filling body itself.Thus the filling body of each layer can be regarded as fine-coarse grain structure model with the upper layer as the dense layer and the lower layer as the overhead layer.Based on the previous research,the deformation characteristics of mudstone soil-rockfill materials are researched by theoretical derivation and numerical simulation combined with laboratory tests and field tests.The main research contents and results are as follows:(1)Taking an airport in Chengdu as the engineering background,it is observed that the upper layer of the filling body is a dense layer and the lower layer is the structural feature of the overhead layer.The fine-coarse grain structure of mudstone soil-rockfill materials is proposed,combined with the laboratory test and the field test,the fine-coarse grain structure characteristics of the filling body were investigated under the change of the single layer thickness,the weight of the press and the rolling pass of the press.(2)The theoretical derivation of the deformation and settlement of the filling body is carried out,and the equivalent spherical granular void structure and the fine-coarse grain structure settlement deformation calculation model are established for the fine-coarse grain structure of the filling body.Meanwhile,the derivation of the formula was verified by the discrete element particle flow software PFC2D.(3)Based on the classical one-dimensional consolidation theory of Taishaji,the internal equations of one-dimensional consolidation model considering variable load and the uneven structure of the fine-coarse grain structure is established,and the consolidation equation is solved by the finite difference method which was verified by the software Matlab.(4)Combining the wetting-drying cycle laboratory test of standard rock samples of mud--stone soil-rockfill materials and analyzing the test results,FLAC3D was used to carry out three-dimensional numerical simulation on the deformation of standard rock samples during wetting-drying cycle.In this way,some meaningful conclusions are made.