降雨条件下黏土边坡冲刷水毁试验研究

对黏土土样进行含水率、液限、塑限、直接剪切试验,获得黏土的物理性质和力学特性。通过室内黏土边坡坡面冲刷试验,分析了在模拟自然降雨条件下黏土路基边坡冲刷的一般成因,总结黏土路基边坡冲刷从形成到导致路基破坏,可分为坡面整体冲刷、冲沟形成发展以及冲沟扩展破坏三个典型阶段,探讨了黏土路基边坡的水毁机理。     

探究降雨条件下路基边坡渗流情况

结合岩土饱和—非饱和渗流理论,并采用有限元软件,模拟分析了不同降雨条件下路基边坡的孔隙水压力变化、渗流场和含水率的分布情况,结果表明:当降雨强于饱和渗透系数时,随时间的增加入渗深度逐渐向下推移,而推移深度也会不断加大;当降雨强度小于土壤入渗能力时,入渗速度慢;裂缝的存在对降雨入渗过程中孔隙水压力和含水率分布有很大的影响。     

降雨条件下土质挖方边坡的稳定性分析

边坡开挖会对原始斜坡体产生卸荷效应,降低了土坡抵抗外界荷载的能力,降雨入渗后易引发灾害,给边坡安全施工造成威胁。本文采用非饱和土抗剪强度理论,结合Morgenstern-Price条分法,对不同放坡角度下边坡的稳定性进行分析,同时采用具有不同降雨峰值的两组72 h实测降雨值,动态分析了边坡安全系数,同时探讨了孔隙水压力的变化规律。结果表明：（1）土体饱和度随基质吸力增加而不断减小;（2）由于粉细砂渗透系数大,同一吸力水平下,饱和度下降最快,其次为淤泥质壤土,而黏土的饱和度下降最慢,储水能力最好;（3）随着坡角增大,边坡的潜在滑动面会逐渐靠近开挖形成的临空面,即滑坡的体积会减小,边坡的安全系数越低;（4）总体上随着降雨时长增大,边坡的安全系数呈逐渐减小的趋势,但局部出现了回升的现象。因此在进行实际切坡工程时,应当尽量降低坡角来保持边坡稳定性,对于需要留取较陡边坡的工程,应采取相应的加固措施来防止边坡出现滑坡等灾害。同时,采用实际降雨数据对边坡稳定性分析能够真实反映边坡安全系数边坡变化,对边坡稳定性设计具有实际意义。     

降雨条件下加筋对土质边坡破坏模式影响试验研究

运用自行研制的人工降雨装置,通过改变降雨强度及筋带数量,对加筋土质边坡开展降雨破坏试验研究。试验结果表明:同一加筋土质边坡,雨水入渗速度随降雨强度的增加而增大,随降雨持时的增加而减小;在相同历时条件下,降雨强度越大,湿润锋变化越明显;其变化速度随历时的增加而逐渐减小。同一降雨强度条件下的加筋土质边坡,雨水入渗速度随筋带层数的增加而减小,随降雨持时的增加而减小;在相同历时条件下,筋带的层数越少,边坡的湿润锋变化越明显;其变化速度随历时的增加而逐渐减小。研究成果可对加筋边坡的防灾减灾工程提供参考。     

强降雨条件下某弃土场边坡稳定性研究

根据某弃土场工程实践,采用Geo-Studio软件模拟极端暴雨情况下该弃土场孔隙水压力及稳定性变化情况。结果表明,暴雨条件下边坡的稳定性不满足要求,应积极采取相关边坡防护措施。     

降雨条件下雅砻江某边坡稳定性研究

以雅砻江某边坡为例,模拟该边坡不同时段随降雨产生的饱和—非饱和渗流问题,得到各个时段边坡的负孔隙水压和体积含水率并且通过云图表示,计算该边坡各个时段安全系数,得出降雨条件下该边坡安全系数随着降雨条件的变化规律。     

Pile reinforcement behavior and mechanism in a soil slope under drawdown conditions

Bulletin of Engineering Geology and the Environment - Piles are an effective measure for landslide protection under various loading conditions. However, the pile reinforcement mechanism of slopes...     

降雨条件下膨胀土边坡稳定性分析

应用湿度应力场理论,采用ANSYS软件的热—力耦合计算方式,模拟了降雨入渗下边坡土体产生的膨胀效应,并建立了边坡稳定性分析方法,分析了降雨条件下膨胀土边坡的变形破坏规律,为膨胀土边坡处治提供了理论依据。     

不同pH值环境下砂浆裂缝的自愈合行为

通过分析砂浆裂缝愈合前后的超声波速变化、毛细吸水量和裂缝宽度检测,研究了不同p H溶液(p H=5、7、12)环境下砂浆裂缝的自愈合性能。结果表明,不同p H环境下修复剂的修复效果并不完全相同,在p H=7和p H=12环境下,掺入1%修复剂的试样修复效果最好,声波恢复率最高可达96.03%。在p H=5环境下,不掺修复剂的空白砂浆试样自身修复效果最好,但恢复率要远低于碱性和中性溶液环境。     

地震和降雨工况下露天边坡排土场稳定性分析

为研究降雨和地震对露天矿边坡变形的影响,本文基于刚体极限平衡法,利用GeoStudio软件进行不同工况条件下的稳定性分析。结果表明：在自重+地下水、自重+降雨、自重+地震三种工况下对排土场边坡进行稳定性计算,排土场最危险滑面是圆弧形,计算结果均满足规范要求,边坡整体稳定性较好。研究成果可为该类边坡的灾害防控提供理论支撑。     

强降雨条件下含软弱夹层粘性土坡稳定性分析

为了分析含软弱夹层粘性土坡在强降雨条件下的稳定性,结合某失稳边坡工程现场实际调研资料,基于饱和非饱和渗流与非饱和抗剪强度理论,提出了一种新的含软弱夹层粘性土坡稳定性分析方法,并利用该方法分析了强降雨条件下边坡的渗流特性及安全系数变化规律。分析结果表明:降雨入渗先在边坡软弱夹层内形成暂态饱和区,且当坡顶入渗的雨水未渗流至软弱夹层时,夹层内暂态饱和区中的雨水会沿夹层上表面向着坡顶方向渗流;降雨入渗过程中,边坡基质吸力与铅直有效应力之间存在严格的正相关变化关系;随着降雨历时的增加,塑性区首先在软弱夹层内部贯通,然后向坡顶扩展,边坡安全系数逐渐降低;降雨停止一段时间后,由于坡顶入渗雨水的补给,软弱夹层内局部将仍存在暂态饱和区,此时,塑性区面积会由坡顶向软弱夹层内部减小,再由夹层内部至坡面逐渐缩减,但边坡安全系数并未明显上升;根据数值计算结果可将粘性土坡失稳过程分为夹层软化、夹层挤压、拉伸裂缝、坡顶沉降和断裂滑移等5个阶段。因此,为了降低强降雨对边坡稳定性的影响,在含软弱夹层粘性土坡支护设计时应着重考虑边坡排水系统的合理布设。     

Prediction of grey-catastrophe destabilization time of a granite residual soil slope under rainfall

The stability of a residual soil slope is a system of grey and white, and gradual change and sudden change. It is difficult to accurately forecast the instability time of a granite residual soil slope, because the factors affecting the instability of granite residual soil slopes are random and uncontrollable. Using the grey prediction method, the accumulation generation of data weakens the influence of random disturbance factors in the original sequence, and enhances the regularity of data. In this paper, we proposed a grey cusp catastrophe prediction model to calculate the instability time of granite residual soil slopes under rainfall. We took one-time cumulative transformation of the remote monitoring data of slope displacement, and then conducted polynomial regression fitting on the processed displacement data and monitoring time. The grey cusp catastrophe instability prediction model of granite residual soil slopes was established using the nonlinear dynamic catastrophic prediction theory. The critical instability time of the slope was predicted using the grey catastrophe instability prediction method presented in this paper. For comparison, we conducted exponential curve fitting on the displacement data and monitoring time, and then established the Saito instability forecasting method of a soil slope to predict the slope instability. Through the engineering application, and using the presented grey catastrophe slope instability prediction method, the slope instability process may be accurately predicted. The calculation results using the grey catastrophe slope instability prediction method presented in this paper are in good agreement with the actual situation. Whether it can be used for other slopes remains to be further studied.

     

降雨条件下土质高边坡稳定性影响因素分析

选取影响土质高边坡稳定性的指标,采用变量控制的方法,在ABAQUS软件中分别计算了各个指标不同数值情况下的稳定系数,并利用改进的灰色关联分析法计算出土质高边坡稳定性对各个因子的敏感性,为以后的边坡工程设计和施工提供一定的参考。     

降雨条件下坡积土边坡暂态饱和区形成机理及分布规律

降雨是引起坡积土边坡失稳的最常见外部因素之一.雨水的入渗在引起土体抗剪强度参数降低的同时,还将导致土体重度的增加、基质吸力的降低,最终造成边坡的失稳.开展雨水在边坡内部的渗流过程研究已成为分析边坡在降雨条件下稳定性的前提.基于有限元数值模拟方法,进行了雨水在土体中渗流过程的模拟,着眼于降雨条件下边坡暂态饱和区的形成、分布及消散特征,描述了该过程中边坡内部含水率、基质吸力、水力梯度的变化规律.结果表明:暂态饱和区形成的主要原因是土体中向湿润锋下方渗出的雨水量小于降雨入渗补给量,从而使得土体中的含水率累积升高;暂态饱和区的形成与降雨强度、降雨时间具有十分密切的关系,暂态饱和区形成时间、雨水入渗深度、土体表面体积含水率大小分别与降雨强度存在函数关系;清晰描述了暂态饱和区形成-发展-消散-地下水位升高的全过程,从该过程看,边坡排水措施的设计值得思考.     

降雨条件下公路边坡稳定性数值分析

基于饱和—非饱和渗流理论和有限元强度折减理论,利用数值仿真方法,模拟了不考虑降雨条件和考虑降雨条件两种情况下边坡稳定状况,计算了降雨条件下边坡的孔隙水压力、位移等的变化情况,分别计算了相应的边坡安全系数,并对其边坡稳定性进行了评价,其分析结果对降雨条件下公路边坡的安全设计具有指导作用。     

Research on the improvement of rainfall infiltration behavior of expansive soil slope by the protection of polymer waterproof coating

The repetitive expansion and contraction cracks, as well as the strength attenuation induced by the precipitation-evaporation cycles, are important factors influencing the instability of expansive soil slopes. In this study, a polymer waterproof coating was proposed to protect the expansive soil slope against slope instability caused by precipitation penetration. The bonding performance of expansive soil blocks (with different soil densities) and polymer waterproof coatings (with different coating thicknesses) were analyzed by performing a laboratory pull-out test. The impacts of different protection methods and protection layer coverage on rainwater infiltration behavior were studied using three groups of slope model tests and numerical simulation approaches. The results showed that the bond strength between the expansive soil test block and the coating increased with the increase in soil compaction density, and the test block strength was an important factor affecting the bond performance. The influence of density of test block on bond strength was greater than that of coating thickness. The calculation formula of bond strength was obtained by fitting the test results. Compared to the unprotected slope, the fluctuation of soil moisture content and rainwater infiltration rate in the slope protected by polymer coating was found to be the least. Protective layer of polymer coating proved to have the most significant role in blocking rainwater infiltration, followed by polymer coating + three-dimensional vegetation net protective layer. When the coverage rate of the protective layer exceeds more than 90%, the effect of blocking rainwater infiltration was remarkable. Simultaneously, the variation range of slope water content, rainwater infiltration depth, and infiltration rate decreased significantly. This research result provides a new solution for expansive soil slope protection and rainwater infiltration control.     

Effect of the characteristics of surface cracks on the transient saturated zones in colluvial soil slopes during rainfall

Bulletin of Engineering Geology and the Environment - The presence of surface cracks has a great influence on the formation of transient saturated zones, which are one of the main factors affecting...     

强降雨条件下考虑饱和渗透系数变异性的基岩型层状边坡可靠度分析

边坡土体因其自身的不均匀性及试验监测的不准确性,饱和渗透系数表现出一定的变异性。为探索强降雨条件下基岩型层状边坡的稳定性及失稳破坏概率,以笔者前期对基岩型层状边坡降雨入渗及其稳定性模型的研究为基础,结合Monte Carlo法,建立了考虑饱和渗透系数变异性的基岩型层状边坡稳定性可靠度计算模型,并基于MATLAB将这一计算过程程序化。最后,利用建立的基岩型层状边坡可靠度计算模型,得到了张家湾滑坡在不同饱和渗透系数变异系数及降雨强度下的失稳破坏概率,分析了饱和渗透系数变异系数及降雨强度对滑坡失稳破坏概率及安全系数均值的影响。计算结果表明在一定降雨条件下,当失稳破坏概率小于50%时,变异系数越大、滑坡发生失稳破坏的概率越大;当失稳破坏概率大于50%时,变异系数越小、滑坡发生失稳破坏的概率越大。     

Time-dependent slope stability during intense rainfall with stratified soil water content

Bulletin of Engineering Geology and the Environment - The Green-Ampt (GA) model is one of the most widely used analytical methods of slope stability under rainfall. However, it may overestimate the...     

基于MARC强度折减法在降雨条件下边坡稳定性分析

通过查阅文献和计算对降雨条件下抗剪系数减小和重度增加两个因素对边坡安全系数影响的比较,得出前者对边坡稳定性的影响更显著,应用MARC程序模拟了在降雨条件下,雨水从上而下入浸对边坡安全的影响,得出随着雨量的增加安全系数减小,并进行了分析,其研究结果可为边坡工程的设计和防治提供一定的参考。