| More and more large engineering project are carried out in the Loess Hilly Areas in China, in order to get enough available area in a limited space, usually requires digging the trench is formed to fill a large number of single-stage height of 40 to 50 m high embankment slope, but fill slope material complex, mechanics property difference is large, the construction compaction degree control is difficult. The slope section of the rolling times number, the speed of rolling, rolling thickness and water content are not consistent, and so that the high fill slope deformation and failure to become one of the most dangerous geological activity in the loess region, which seriously affect economic construction and urbanization of the loess area.This paper takes a high embankment slope as the research object, the maximum height of more than 40 m, the anchor pile wall and reinforced retaining wall joint supporting, combined with survey data and field investigation, understand the geology of the study area and the basic characteristics; according to laboratory tests, master the engineering geological conditions of embankment fill loading, a slope the structure model of high embankment slope of the study area; through the backfill loading retaining structure and deformation monitoring analysis, research on anti slide pile, pile plate deformation mechanism; according to the theory of mechanics and numerical analysis of high fill slope mechanical loading process deformation response characteristics, so as to analyze the deformation and damage evolution and failure mechanism of high embankment slope finally, according to the monitoring data, the deformation characteristics of deformation curve and tangent angle time theory, establish the high embankment slope deformation dynamic prediction system, The main research results are as follows:(1)Through laboratory experimental study of unsaturated soil shear strength parameters obtained cohesion and internal friction angle increases with increasing water content by the curve y = 0.2225x~2- 15.422 x + 270.12 and y =-0.0142x~2 + 0.2673 x + 29.03 Fitting both basic parabolic trend; and within shear strength parameters friction angle and cohesion change with matric suction through the basic fitting showing y = 0.0488 x + 23.04 and y = 0.04775 x + 0.827 linear increments trend, While the ratio of increase of cohesion with the matrix that is the difference between the suction non-saturated soil shear parameters .(2)A new strength formula of unsaturated soil is proposed based on the characteristic curve of soil water measured by the pressure plate instrument the unsaturated soil experimental shear strength and other formulas and the proposed new strength formula of error analysis, error are smaller than those of the other formulas for unsaturated soil strength analysis provides a theoretical basis.(3) Between piles plate mainly developed squeeze tension crack, crack resulting from the lower part, upward extension; slit width reach 3mm(can be directly observed) cracks more than accounted for the total number of proportion with time increasing, and eventually a "broken lines are formed in the middle part of the pile wall. At the same time, each block soil in cracks from the middle to both sides of the expansion;(4) The pile body mainly for bulging crack and Shear Torsion crack began in the outer surface of the central bulge crack supporting area, extending to the right and left sides, width of 0.2~1.04 mm, is almost closed, slightly inclined crack basic level, wavy type, no filling, are basically "pinnate bulge crack the narrow, wide on both sides of lateral and horizontal crack bulging connected basically concentrated in the pile anchor head near the 1.5~2.0m away from the ground, on the left side extending slightly shorter, mainly due to the combined effect of shear and moment of cantilever pile" dangerous section "section to show the form of crack. The cross section deformation, when the force exceeds the concrete elastic deformation, bending deformation or even destruction of pile;(5) Using IBIS-L system monitoring technology to monitor the deformation of the support structure of A1 area in real time. Analysis of monitoring data, generate displacement nephogram of reaction out A1 district supporting structure performance obviously regional characteristics and displacement incremental larger region in support of the central circular region, namely 50~67# anti slide pile segment, followed by 68~78# anti slide pile, displacement increment is relatively small area 20~49# anti slide pile segment.(6) The increment of the displacement of the slope after the rainfall has a great relationship with the initial water content and permeability coefficient of the soil. First large-scale rainfall infiltration, rainfall intensity is often less than slope infiltration rate, so the rain almost all infiltration into the soil, followed by the rain delay effects are less obvious, often in more than a dozen hours after the rainfall began displacement increase, and soon reached the maximum value.(7) According to the high fill slope retaining micro change and damage characteristics analysis, the high fill slope deformation and destruction of the formation and evolution can be summarized as "creep- slipping-collapse sliding";(8) Through long-term monitoring and branch of loess high fill retaining slope creep sliding cracking stage of maximum deformation rate is 0.049mm/h, and in sliding and fracturing stage of deformation rate for 2.01mm/h, and high fill branch block slope creep sliding cracking is transformed for sliding and fracturing of the critical deformation value is 0.89mm/h.(9) According to retaining structures of cumulative deformation monitoring curve of tangential angle changes and accelerated deformation characteristic curves analysis, build high fill slope dynamic damage system. Studies have shown that tangent angle is greater than 75 degrees, acceleration from 0 mm/h~2 surge to the 8.9mm/h~2 as high fill slope instability criterion. |
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