【作者】 杨智翔；

【导师】 黄润秋； 裴向军；

【作者基本信息】 成都理工大学 ， 土木工程， 2018， 硕士

【摘要】 随着西部交通、经济的高速发展,各类地质灾害威胁着西部交通运营的安全,例如:崩塌、滑坡、泥石流、散粒体斜坡等。散粒体斜坡主要是由碎石、碎屑颗粒聚集在一起形成的边坡,具有结构松散、抗渗性差、粘聚力低的结构特点以及稳定性差的成灾特点,失稳后可对挡墙造成巨大的冲击破坏,对交通安全、行人造成严重威胁。本文以新疆天山公路(G217)沿线的“独山子—库车”段为研究区,对公路沿线发育的散粒体斜坡进行调查统计,分析散粒体斜坡的发育分布特点和失稳机理;在调查研究的基础上,采用物理模拟试验的方法研究挡墙受到散粒体冲击后冲击力变化特征;通过数值模拟的方法分析散粒体冲击挡墙的动力特性;最后对天山公路沿线的35处散粒体斜坡进行挡墙易损性评价。通过以上研究,论文主要取得了以下成果:(1)对研究区发育的散粒体斜坡进行调查统计得出:天山公路的散粒体斜坡主要分布于北天山区域k610~k655段,沿线发育35处典型散粒体斜坡,影响公路长度约8.71公里,散粒体斜坡的分布主要与地形、岩性、地质构造、坡向以及大气气候有关,诱发其失稳的主要因素为地震、风载作用、降雨以及滚石的冲击作用。(2)通过散粒体冲击挡墙的物理模拟试验分析得出:散粒体的不同颗粒级配、启动高度、启动厚度、冲击角度以及挡墙结构对冲击力、堆积高度均有显著的影响:(1)散粒体粒径越大,挡墙受到的冲击力越大,在挡墙处堆积高度越高。(2)散粒体的启动高度增大,冲击挡墙后的堆积高度呈线性增大,同时挡墙受到的冲击力呈幂函数增大。(3)散粒体的启动厚度增大,挡墙受到的冲击力呈幂函数增大,同时在挡墙前堆积高度呈线性增大。(4)散粒体对挡墙的冲击角度增大,挡墙受到的冲击力呈幂函数增大,同时堆积高度呈线性减小。(5)折线型挡墙受到的冲击力明显小于直线型挡墙,说明冲击力的大小与挡墙结构有关。(6)从散粒体冲击挡墙的运动过程发现,冲击过程中既有颗粒的摩擦运动又有碰撞运动,两种运动形式会相互转化,对挡墙造成巨大的冲击,开始运动时颗粒间接触比较紧密,此时运动以颗粒与滑槽之间的摩擦运动为主;随着颗粒继续向下运动,前缘开始撞击挡墙,整个流体逐渐拉长,颗粒间接触变得松散,流动厚度逐渐减小,此时以颗粒间的碰撞运动为主;最后受到挡墙阻挡,颗粒间接触又变得紧凑,碰撞运动转为摩擦运动,最终在挡墙前静止堆积。(3)通过数值模拟研究散粒体冲击挡墙的动力特性发现:散粒体冲击挡墙是一个连续冲击的过程,挡墙不同高度处受到的冲击力随时间均呈非线性变化,高度越大受到的冲击力越小。折线型挡墙能够将颗粒向两端分流,增加颗粒间的碰撞频率,造成能量损失,因此折线型挡墙受到的冲击力比直线型挡墙小。颗粒形状对冲击力有一定影响,当坡度较小时,冲击力随着圆形度的增大而增大;随着坡度增大,颗粒形状对冲击力的影响性减小。研究还发现坡度越大时,散粒体对挡墙造成的冲击力非线性变化越明显,这种变化和土拱作用有关:当斜坡坡度比较小时,颗粒与滑槽之间形成小冲击拱,此时挡墙受到的冲击力比较小;当斜坡坡度比较大时,颗粒与挡墙之间形成大冲击拱,此时挡墙受到的冲击力比较大。(4)通过三维激光扫描仪对天山公路k628+500斜坡进行扫描,通过三期扫描数据计算其年平均产屑率,从该斜坡2015年9月和2016年9月地形线变化可知斜坡后缘的损失厚度可达1.12m;根据年平均产屑率建立该斜坡的数值计算模型,发现边坡上部岩体经过长期的风化产生的碎石会不断滚落冲击挡墙,通过模拟散粒体冲击挡墙的倾覆破坏过程可以看出,散粒体对挡墙的冲击首先是在挡墙后方不断堆积,堆积高度会越来越高,甚至能越过挡墙滚落至公路,此时冲击力对挡墙的倾覆作用非常明显;挡墙倾覆后,散粒体斜坡坡脚开始发生滑动,随后上部颗粒会带动下部颗粒一起向前溃滑,掩埋公路。(5)对新疆天山公路沿线发育的散粒体斜坡进行挡墙易损性评价,首先根据路基规范计算出散粒体对下方挡墙的冲击力:(?),然后计算冲击力对挡墙的倾覆力矩:M_f=Fcosβ×h,再按照挡墙抗倾覆计算原理,计算挡墙的抗倾覆力矩:M_d≤Gx+Fbsinβ,最后按照易损性量化评估方法建立挡墙易损性评价模型:(?),并计算出挡墙易损性量化值,以此区分挡墙易损性高低。从结果中可以看出,新疆天山公路沿线的挡墙处于高易损性以上比较少,大部分处在中等易损状态,且分布在北天山地区的k610~k655段。更多还原

【Abstract】 With the rapid development of traffic and economy in the west,various geological disasters threaten the safety of traffic operation in the west,such as collapse,debris slope,debris flow and landslide.Grain body slope is mainly composed of gravel,clastic particles together to form the slope,with loose structure,poor permeability resistance and low cohesive force by characteristics of the structural characteristics and stability,can be a tremendous impact on the retaining wall after buckling destruction,poses a serious threat to traffic safety,pedestrian.This paper takes the xinjiang tianshan road(G217)along the"dushanzi-kuqa"section as the research area,the road along the development of the grain body slope investigation statistics,the analysis of the distribution of grain body slope characteristics and instability mechanism;On the basis of investigation and research,the characteristics of the impact force of the baffle wall under the impact of granular material are studied by means of physical simulation test.By means of numerical simulation,the dynamic characteristics of the impact baffle wall are analyzed.Finally,the vulnerability of retaining wall was evaluated for 35 granular slope along tianshan highway.Through the above research,the paper mainly achieved the following results:(1)The development of grain in the studied area slope statistical investigation concluded that grain of tianshan road body slope is mainly distributed in the north tianshan area k610~k655 section,35 typically developed along the grain body slope,road length is about 8.71 kilometers,the distribution of grain body slope and topography,lithology,geological structure,slope to the relevant climate and atmosphere,causes the instability of the main factors for the earthquake,wind load,rainfall and the impact of the Rolling Stones.(2)Through the grain body impact retaining wall of physical simulation experiment analysis:different grading of grain body,start height,start thickness,impact Angle and the retaining wall structure has a significant effect on impact,stack height:1)the larger the particle size,the impact of the retaining wall is,the greater the stack height,the higher the retaining wall.The higher the starting height of the granule,the higher the accumulation height after the impact wall,and the increase of the power function of the impact force.The larger the starting thickness of the granule,the greater the power function of the impact force of the retaining wall,and the linear increase of the height of the wall in front of the retaining wall.The impact Angle of the granule on the retaining wall is larger,and the impact force of the retaining wall increases with power function,while the accumulation height is linearly reduced.The impact force of the baffle wall is obviously less than the linear retaining wall,which indicates that the impact force is related to the wall structure.6 from schottky retaining wall impacted by a projectile motion process,found that both the particles in the process of impact,friction and collision motion,mutual transformation between two kind of movement form will cause huge impact to the retaining wall,close contact between particles compared when you start,the movement is given priority to with friction between particles and chute movement;As particles continued downward movement,front started hitting the retaining wall,the whole fluid gradually stretched,loose contact between particles,flow thickness decreases,at this point is given priority to with the collision of particles movement;Finally,it is blocked by the retaining wall,and the contact between particles becomes compact,and the collision movement becomes frictional movement,which eventually accumulates in the front of the wall.(3)The dynamic characteristics of the impact wall are studied by numerical simulation:the impact wall is a continuous impact process,and the impact force at different height of the baffle is nonlinear with time,and the higher the height is,the less the impact force is.The baffle wall can divert the particles to both ends and increase the collision frequency between particles,resulting in energy loss.Therefore,the impact of the broken wall is smaller than that of the linear retaining wall.The particle shape has some influence on the impact force.When the slope is smaller,the impact force increases with the increase of the circle degree.As the slope increases,the effect of particle shape on impact force decreases.The study also found that the greater the slope,spread the impact of the granule on retaining wall due to the nonlinear change,the more obvious,this change related to soil arching effect:when the slope gradient is small,form small impact between particles and chute arch,at this time the impact of the retaining wall is smaller;When the slope of the slope is relatively large,there is a large impact arch between the particles and the retaining wall,and the impact force of the retaining wall is larger.(4)By the three dimensional scanner scan highway k628+500 slope of the tianshan mountains,through the three periods of scan data calculation,its average annual production scrap rate from the slope in September 2015 and September 2016known slope terrain line change the loss of the trailing edge thickness up to 1.12 m;According to the average annual production scrap rate established the numerical calculation model of slope,found that over a long period of time the upper slope rock mass weathering of gravel impact will continue to tumble retaining wall,by simulating the grit body impact overturning failure process of retaining wall can be seen,the grain body on the impact of the retaining wall is behind the retaining wall first piled up,stack height will be more and more high,even over the moving to the retaining wall of highway,the impact effect on the fall of the retaining wall is becoming more and more obvious;After the baffle is overthrown,the slope of the granule slope begins to slide,and then the upper particles will cause the lower particles to collapse along,buried roads.(5)In xinjiang G217 roads,the vulnerability assessment of the wall is carried out.Firstly,the impact force of the loose particle on the lower wall is calculated according to the subgrade specification:(?),then calculate the upsetting moment of the impact force against the wall:M_f=Fcosβ×h,The anti-overturning moment of the retaining wall is calculated according to the anti-overturn calculation principle of the retaining wall:M_d≤Gx+Fbsinβ,Finally,the vulnerability model is established according to the vulnerability quantification evaluation model:(?),The quantization value of the baffle is calculated.To distinguish between high and low.It can be seen from the results that the retaining walls along xinjiang tianshan highway are less than high vulnerability,most of them are in moderate vulnerability,and they are distributed in the k610~k655 sections in the north tianshan area.更多还原