| Wenchuan strong earthquake induced landslides and collapses, resulting in massive the landslide accumulation of body, these accumulation body formed in the earthquake zone to produce the effect of the rainfall, runoff, earthquakes, and other outside power, such as the accumulation of landslides, avalanches, slopeerosion newborn soil erosion and other geological disasters, some even a typical earthquake induced secondary mountain disaster chains. Earth and rock material of the accumulation body produces soil erosion into the river, bound blockage of the river, the elevation of riverbed, planing erosion bank slope, a serious impact on the normal flood safety and downstream residents of life and property; thus accompanied and to secondary geological disasters, destroyed towns, roads, farmland and water conservancy facilities, a direct threat to the lives and property of the masses of the earthquake area and production safety, as well as restricting the quake zone economic development and ecological environment construction. Therefore, through the landslide accumulation of body to carry out the implementation of investigation and research, for the safe recovery and reconstruction of the earthquake zone ecohydrological environment protection infrastructure normal operation, the safety of the people’s production and life, and local conditions to select the effective accumulation of body newborn soil erosion and secondary geological disaster prevention measures to provide scientific guidance and basis.In this study, the typical Wenchuan earthquake zone, the upper reaches of the Minjiang River Valley-the Ridge River Basin in Wenchuan Yingxiu-the Wenchuan Old State Road213along the Minjiang a full investigation on the basis of the survey,12highly representative of typical landslide accumulation body is selected as the research object. Field survey investigation and laboratory simulation analysis method of combining the first survey of the quake zone landslide accumulation body material composition and distribution characteristics; explore analyzed accumulation SUBSTANCE gravel particle size and volume of earth and rock content than accumulation of body angle of repose, indoor pile repose angle reliable and rationality of the simulation method and statistical analysis methods were evaluated; established on the basis of site investigation survey combined with the results of the study, the earthquake zone existing classification for the accumulation of new soil erosion and secondary geological disasters prevention measures and evaluation, and ultimately elected the various types of optimal control measures program. In this study, accumulation of body awareness and simulation studies for further analysis to obtain the characteristics of the pile, to reveal the relationship between the relevant parameters, pile-depth study on erosion process and mechanism to provide reliable basic data and theoretical guidance, but also for the gradual implementation of the post-earthquake disaster prevention and mitigation measures to provide technical support, so as to promote comprehensive and sustainable development of economic and social ecology of the quake zone. The main findings are as follows:(1) Earthquake zone landslide accumulation body in the spatial distribution of the number of distribution along the seismic zone, accumulation slope inclination of the central fault zone near landslide accumulation body is higher than the inclination of the former Mountain thrust fault near the pile; ribbondistribution, due to the low river hillside slope, cutting deep, so the when ramp generator landslide, showing along the main river and its tributaries, the river valley development and distribution of the law; the accumulation body material composition of the sand particle size is mainly concentrated in the2-40mm range. Slope distribution, performance uphill to the small particle size gravel, mostly large particle size of gravel in the middle of the slope in the lower part of the slope to the foot of the slope area mainly to larger particle size gravel; accumulation slope adjacent to erosion Gully along the groove formed parts, large size gravel deposition zone, the small size gravel and sand content of the soil in this area is less erosion on both sides of the ditch the Gouyan parts small size gravel and sand soil, sand particle size distribution is more uniform, the majority concentrated in the2to40mm between the most serious of which is gully erosion area. Erosion channel mainly the distribution of the uneven gravel in the middle of the particle size. Vertical distribution, accumulation of body surface concentration of larger particle size of gravel, sand content of the soil with the increase of depth of60cm below the surface within the slightly increasing trend in the distribution of gravel showing no regularity, gravel in each size range are at different depths.(2) Shock accumulated bodies original natural slope of more than between36-46°the accumulation body angle of repose between39to50", most of which is about45°the accumulation body where the original natural slope of slightly larger than theaccumulation body angle of repose. The composition of the accumulation-like substance particle size greater than40mm gravel minimum volume fraction Score of only0.62%, up20.61%, the average volume content of this size gravel fraction of6.13%. The volume fraction of the particle size is10to40mm gravel fraction higher, up66.27%,14.92%minimum. Particle size of from7to10mm and5to7mm gravel volume fraction Score smaller difference, and the same test sample of two particle size smaller gravel volume fraction Score Change, in which the particle size ranging from7to10mm of Room Shingle content of the average volume fraction of9.52%, the particle size between the average volume content of between7mm Shingle Score7.17%. Between2-5mm small size gravel volume content Score large amplitude, wherein the volume content of this size gravel Score a minimum of7.87%, a maximum of22.95%, the average volume content of fraction of14.46%. The sand soil volume content of each test sample scores are quite different, and some even almost does not contain any sand soil, sand soil volume fraction of the maximum score as high as63.38%, the average volume content of31.85%. The Seismic Area landslide accumulation body consisting, on the whole volume of gravel content to be slightly higher than the volume content of sand soil, particularly in the accumulation of body surface material, the volume of gravel content is significantly higher than the volume content of sand soil.0to30cm of thickness of the landslide accumulation layer stacked sample bulk density of1.50g· cm-3, the average soil bulk density of1.00g· cm-3higher than50%compared to the earthquake zone has not been destroyed. Earthquake zone unaffected average initial moisture content of the soil up to about16.00%, far exceeding the initial moisture content of the accumulation of substances.(3) Under the premise of not consider other factors, the accumulation of pure sand soil sample angle of repose is much larger than the accumulation of a single size gravel-like angle of repose, and the accumulation of a single size gravel-like between the angle of repose of the gravel particle size showed a signiflcantnegative correlation, tend to decrease with the increase in particle size gravel angle of repose, the highest goodness-of-fit of the regression equation of this trend is a quadratic curve fit of0.9823, gravel particle size rangewithin the angle of repose increased gradient is not the same, change the angle of repose in the small particle size larger gradient. The results showed that:the type of debris volume content of more than a single particle size of gravel and sand soil with the angle of repose of stacked sample in2-5mm,5-7mm,7-10mm,10-20mm four particle diameter of gravel and sand soil cooperation, with the the debris volume content ratio increases, the accumulation of body angle of repose have shown a tendency to increase, and debris than the angle of repose was a significant positive correlation, goodness-of-fit of the regression equation are logarithmic curve, four different size gravel and sand soil with the goodness of fit were:0.9351,0.9586,0.9389,0.9388. When the accumulation kind of debris volume content than the angle of repose varied in the range of1:9-1:1gradient, earth and rock ratio exceeds1:1showing progressively smaller trend, indicating that the accumulation samples sand soil gravel smaller difference in the volume of content on the accumulation of sample angle of repose greater role, and piled-like material composed of gravel particle size effect is far less than the angle of repose of the accumulation-like earth and rock volume content ratio. Different size gravel and soil with the difference between the angle of repose of the same the debris volume content than simulated in the numerical size smaller.(4) The same with different particle size the debris volume fraction than the mixing of different size gravel-like angle of repose affect the results of the analysis show that: the particle size is relatively close to the gravel piled kind, the volume fraction of an impact than almost no accumulation kind of angle of repose;compared to a bulk sample of the gravel, gravel and soil with the accumulation kind of angle of repose should be large, and the sample with the accumulation of soil particles content increases, the angle of repose was also significantly increasing trend. Mixed stacked sample the debris volume content than the angle of repose affect the results of the analysis show that:five mixed gravel-like soil particles with the, with the accumulation of sample debris volume content increased accumulation of the kind of angle of repose emerged increases trends; the type of debris volume content ratio within the range of variation, the trend of increase in the angle of repose stacked sample also differ, wherein when the debris volume change of the content ratio within the range of1:9-1:1, this increasing trend, when more than1:1change in trend is clearly much flat, indicating that relatively large when compared to the soil particle volume fraction lower volume fraction of gravel, piled kind of the debris volume fraction than the angle of repose, the typical the landslide accumulation of body for the earthquake zone, when the accumulation SUBSTANCE earth and rock is relatively low, the slope angle of the accumulation body are more likely to maintain a relatively stable state. Debris than the angle of repose of the effect of the accumulation of samples is much larger than the fraction of gravel volume fraction; five types of piled-like repose angle regression equation fitting curve fit a quadratic polynomial equations are curve The fitting:0.9122,0.8717,0.9635,0.8829,0.9047. With relative error, standard deviation, range, standard error of four evaluation indexes for stacking angle of repose of the results of simulation of the sample was evaluated by statistical analysis, the results showed that: the room stacked body used in the present study repose angle simulation test method or reliable simulation to obtain the angle of repose is not the only chance to get, but there is a certain inevitability.(5) Landslide pile of debris material slip and the dynamic factors of qualitative analysis, including gravity, and many other factors, including the role of wind power, the role of river erosion, vegetation effects, and loads.of other things. would Accumulation of debris material slipped move evenaccumulation of slope instability have a major impact, but all power factors affect the role of the principle is not the same, should be targeted comprehensive analysis on the basis of investigation and research in engineering practice. After several rounds of in-depth visit earthquake zone survey essential to find out the quake zone for newborn soil erosion and secondary prevention of geological disasters including the types of measures, and by the collapse of the landslide accumulation body, slip, slope erosion prevention and treatment for all types of measures to implement the comprehensive analysis and evaluation of the effect than elected accumulation disaster features optimal control measures program, including self-healing or planted vegetation as the mainstay of prevention and treatment programs; ecological engineering block stopped protective measures. main body, with the than to accumulation slope drainage, vegetation protection and other auxiliary measures for prevention and treatment programs; directly to the nearest pile of debris material control measures program. |
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