不同降雨条件对高填方边坡变形的影响研究

发布时间：2018-03-08 16:06

本文选题：高填方　切入点：降雨　出处：《成都理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着西部现代化建设进程的不断加快,受其不良地形地质条件的影响,工程建设势必大规模“深挖高填”,使人工边坡数量日益增多。加之当前全球气候变暖,各地极端天气不断恶化,各类边坡失稳问题屡见不鲜,造成了巨大的人员伤亡和经济损失。通过前人不断的研究分析可知降雨入渗与边坡失稳现象密切相关,降雨入渗不但造成岩土体抗剪强度直接降低,同时会使坡体中非饱和区及地下水水位线的动态变化,导致边坡动、静水压力等发生改变,使边坡朝着不稳定方向发展。因此分析降雨入渗时边坡饱和-非饱和渗流场及受饱和-非饱和渗流影响下的边坡变形及稳定性问题,具有重要的理论和实际意义。针对高填方边坡,本文为了研究降雨对其变形的影响,在降雨入渗饱和-非饱渗流理论基础上,对降雨入渗情况下攀枝花机场12#滑坡的渗流场特性进行了数值计算与理论分析,得出了在不同降雨条件下渗流场变化规律,同时在此基础之上,用数值模拟方法对滑坡体的变形情况进行了分析研究。本文取得的主要研究成果如下:1.查明了攀枝花机场12#滑坡基本的工程地质条件、水文地质条件及滑坡变形特征,总结分析了滑坡的失稳破坏机制。2.利用数值模拟对12#滑坡临滑前的雨季及不同降雨形式下渗流场的变化情况进行了计算分析,得到坡体地下水位在降雨条件不同时的变化规律。(1)天然降雨条件下,由于雨季降雨入渗量不断增加,导致地下水位也持续上升。当降雨量最大时,地下水位增幅相应也达到峰值。若降雨持续进行则导致地下水位始终维持较高值,使岩土体长期浸泡饱水,这对坡体稳定性极为不利。(2)短历时小降雨强度的降雨类型,由于其总的降雨量较小加之排泄及蒸发作用,对地下水位的变化影响不大。但若保持该降雨强度很长时间,使总降雨量达到一定大小,降雨强度小的雨型也可以使地下水位上升一定幅度。反之降雨强度较大时,由于入渗快且入渗量大,则地下水位受降雨影响变化剧烈且发生时间较早。(3)当总降雨量相同时,不同降雨历时对边坡影响程度有差异,其中强降雨短历时相较于弱降雨长历时对边坡地下水影响更显著。(4)地下水位随着降雨的不断进行而逐渐升高,降雨结束后,上层雨水持续入渗加之周边区域地下水汇集使地下水位不降反升直到稳定为止。这一规律可以较好说明降雨型边坡失稳破坏滞后性的特点,同时对边坡的水害治理具有一定的指导意义。(5)当降雨强度不变时,随着降雨历时增加总降雨量则增加,地下水位也逐渐升高。针对间断降雨,由于下次降雨时地下水位已经开始下降,则同一降雨强度相同降雨总时间下,连续降雨较间断降雨地下水位更高。3.应用数值模拟方法分析了12#滑坡在各种降雨工况下的变形特征,得到降雨入渗条件下坡体的变形规律。(1)随着雨季降雨入渗量不断增加,沉降变形量越来越大。当地下水位明显升高时,变形量也增大,但增幅并非最大。由于高水位的持续维持,岩土体受饱水软化效应的影响强度参数明显降低,沉降变形量达到最大值并导致边坡“滞后”破坏。(2)当降雨持续时间相同的情况下,坡体整体变形随着降雨量的增加而加剧。因为随着降雨强度增加,降雨入渗量变大,地下水位逐渐升高,非饱和区不断缩小,后缘饱和土体越来越多,导致强度参数减小,变形增大,坡体稳定性系数下降。(3)雨刚停时,地下水位由于“滞后性”仍然处于上升状态,饱和土体区域仍在扩大,沉降量继续加大。一段时间后,地下水位虽有回落,导致沉降量虽缓慢下降,但由于土体储水及软化效应,其与初始值相比仍较大。(4)随着降雨时间延长,剪应变增量不断增大,逐渐形成连续贯通的潜在滑动带(面)。同等时长的间隔型降雨相对连续降雨,虽然其地下水位相对较低,但土体在地下水位不断的动态变化中,基本处于饱和状态,则产生软化效应,如果每次降雨间隔时间较短且雨强较大则更容易失稳破坏。
[Abstract]:With the process of the construction of western modernization is accelerating, affected by the adverse geological conditions, engineering construction will be large-scale digging and filling, the artificial slope increasing. Combined with the global climate warming, extreme weather around the deteriorating, all kinds of problem of slope instability It is often seen. caused huge casualties, and economic losses. Through the study of predecessors continue the analysis of rainfall infiltration and slope instability is closely related to rainfall infiltration caused not only directly reduce the shear strength of rock and soil, and the dynamic change of unsaturated zone and groundwater level in the slope, the slope, the hydrostatic pressure change, the slope towards the unstable the direction of development. Therefore the analysis of rainfall infiltration slope saturated unsaturated seepage field and slope deformation and stability under saturated unsaturated seepage under the influence, has important The theoretical and practical significance. In view of the high embankment slope, in order to study the effect of rainfall on the deformation, the rainfall infiltration saturated unsaturated seepage theory, the rainfall infiltration seepage field characteristics of Panzhihua Airport 12# landslide are carried out under the condition of numerical calculations and theoretical analysis, obtained in different rainfall conditions of seepage the law field change, and on this basis, were analyzed by the method of numerical simulation for deformation of landslide. The main achievements of this dissertation are as follows: 1. to identify the Panzhihua Airport 12# landslide basic engineering geological conditions, hydrogeological conditions and deformation characteristics of landslide, summarizes and analyzes the failure mechanism of.2. by numerical simulation the changes of 12# landslide before the rainy season and rainfall under the form of seepage field are calculated and analyzed by the slope landslide, groundwater level in different rainfall conditions Change law. (1) under the conditions of natural rainfall, rainy season due to rainfall infiltration increasing, the groundwater level has continued to rise. When the maximum rainfall, groundwater level also increase the corresponding peak. If the rainfall continued is the groundwater level maintained higher values, the long-term immersion of rock and soil water saturation, the the slope stability is extremely unfavorable. (2) the small rainfall intensity of short duration rainfall type, because the total rainfall is small and excretion and evaporation, has little effect on the change of the underground water level. But if you keep the intensity of rainfall for a long time, the total rainfall reached a certain size, rain type rainfall intensity is also small the rise of ground water level to a certain extent. If the rainfall intensity is larger, due to infiltration and infiltration, the underground water level is affected by rainfall and dramatic changes occurred earlier. (3) when the total rainfall is the same, different down The rain lasted there are differences on the influence degree of the slope, rainfall with short duration compared to the weak rainfall of long duration effect on the slope of groundwater is more significant. (4) the underground water level and increased gradually with the continuous rainfall, rainfall after upper continuous rain infiltration with the surrounding regional groundwater collection of the underground water level does not fall until stable so far. This law can better explain the failure characteristics of hysteresis loss of rainfall slope, and has certain guiding significance in the control of water disaster on the slope. (5) when the rainfall intensity is constant, with the increase of total rainfall, rainfall duration increased, underground water level has gradually increased. For continuous rainfall, the rainfall next time the underground water level has started to decline, the same rainfall intensity under the same rainfall time, continuous rainfall is intermittent rainfall higher underground water level numerical simulation method to analyze the application of.3. # landslide in 12 The deformation characteristics of various rainfall condition, get the deformation regularity of rainfall infiltration slope. (1) with the rainy season rainfall infiltration volume increased, the settlement is more and more big. When the groundwater level was significantly increased when the deformation increases, but the increase is not the largest. Due to the high water continued to maintain a rock, the soil strength parameters affected by water saturated softening effect is significantly reduced, settlement amount reaches the maximum slope and lead lag damage. (2) when rainfall duration under the same condition, the slope deformation increases with the increase of rainfall. Because with the increase of rainfall intensity, rainfall infiltration quantity, underground the water level gradually increased, unsaturated zone shrinking, the trailing edge of saturated soil is more and more, resulting in decreased strength parameters, deformation increases, the slope stability coefficient decreases. (3) the rain stopped, the underground water level due to "lag" is still on L state, saturated soil region is still in the expansion, the settlement continued to increase. After a period of time, the underground water level has dropped, leading to the settlement of slow decline, but due to soil water storage and its softening effect, compared with the initial value is still large. (4) with rainfall time, shear strain increment increases and gradually formed the potential sliding continuous belt (surface). The same time interval of rainfall relative to continuous rainfall, while the underground water level is relatively low, but the soil in the constant dynamic change of groundwater level, basically saturated, produce soft effect, if every time interval of rainfall is relatively short and strong rain the larger are more prone to failure.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU43;P642.22

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