Study On Stability And Deformation Of High Fill Foundation With High Stone Content Of Soil-Rock Mixture

With the great development of economy in southwest China, the number of airports construction and extension project is increasing rapidly,the construction is becoming larger and larger in scale. The stability and deformation of foundation are becoming more and more obvious. Soil-rock-mixture is the most common fill material used in construction of the airport runway in mountainous areas, the soil-rock mixture have some profitable engineering properties and have been applied widely and increasingly in the engineering construction. Although soil-rock mixture has some profitable engineering properties,the study of it is still in initial stage. It is valuable to research the engineering strength properties and deformation characteristics of soil-rock-mixture,which is hotspot over current geotechnical engineering researches.This paper is on the background of construction of Chongqing Jiangbei airport. Studied on the shear strength and shear characteristics of the filler under different porosity by laboratory direct shear tests; we analyzed dynamic compaction characteristics in condition of different compaction energy and diierent fill materals of the high filled foundation in experimental region. Build three-dimensional model and numerical analyse fill construction process by Flac-3d, the stability of the foundation, the feature of slope deformation and damage are deeply analyzed. The main results of this study are as follows:(1)With the increased compactness and normal stress, the phenomenon of dilatancy will be more likely to take place when fill material shearing. The stress- strain relationship of soil established from shear tests present hardening type when the fill material under the condition of high compactness and low normal stress, and present post-peak softening type when the fill material under the condition of low compactness and high normal stress. Stress – strain curve always showed three kinds of shape: hardening curve, softening curve and approximate idealelastoplastic curve. The shape of shear curve is closely related to compactness and normal stress of the filler.(2)The cohesive force of significantly increased with the increase of compactness packing, there was no significantly change with the increase of compactness. Cohesive force increased by 118.8% with compactness increased from 92% to 96%, it showed that structural increased significantly with the increase of compactness.(3) The total sedimentation volume of compacted foundation and n+1(n is impacting time) present a logarithmic relation, S=aln(n+1), in which a is Constant.(4) For foundation in Qingshangou area, tamping energy in the range of 2000 kN.m~5000 kN.m,the deformability modulus of ground the growing linearly with the increase of shear wave velocity and dynamic sounding number?Consulted the Design Code for Building Foundation of Chengdu Region, in which the empirical formula between deformability modulus of sand-pebble ground and super dynamic sounding number, we revised the empirical formula to E0=2.7N120+15 for filled foundation with Soil- rock mixture.(5)Although there is a clay layer at the bottom of the Qingshan valley, the filled foundation at the bottom of the valley is stable because of the strong restriction from mountain. The potential landslide volume is located at middle of slope above elevation 330.0m, and the depth of the slip plane is about 30 m. The fill body above elevation 360.0m has a large deformation towards to the Yulin highway under its own gravity and constraint from sides of the mountain. The large deformation of fill body above elevation 360.0m has a significant impact on fill body below 360.0m, deformation of fill body below 360.0m had an accelerative stage when filled to fifth layer(elevation 397.5m), the fill body is judged to be unstable.