Model test of the influence of cyclic water level fluctuations on a landslide

Many landslides in reservoir areas continuously deform under cyclic water level fluctuations due to reservoir operations. In this paper,a landslide model, developed for a typical colluvial landslide in the Three Gorges Reservoir area, is used to study the effect of cyclic water level fluctuations on the landslide. Five cyclic water level fluctuations were implemented in the test, and the fluctuation rate in the last two fluctuations doubled over the first three fluctuations. The pore water pressure and lateral landslide profiles were obtained during the test. A measurement of the landslide soil loss was proposed to quantitatively evaluate the influence of water level fluctuations. The test results show that the first water level rising is most negative to the landslide among the five cycles. The fourth drawdown with a higher drawdown rate caused further large landslide deformation. An increase of the water level drawdown rate is much more unfavorable to the landslide than an increase of the water level rising rate. In addition, the landslide was found to have an adaptive ability to resist subsequent water level fluctuations after undergoing large deformation during a water level fluctuation. The landslide deformation and observations in the field were found to support the test results well.

Centrifugal model test on a riverine landslide in the Three Gorges Reservoir induced by rainfall and water level fluctuation

Frequent soil landslide events are recorded in the Three Gorges Reservoir area,China,making it necessary to investigate the failure mode of such riverside landslides.Geotechnical centrifugal test is considered to be the most realistic laboratory model,which can reconstruct the required geo-stress.In this study,the Liangshuijing landslide in the Three Gorgers Reservoir area is selected for a scaled centrifugal model experiment,and a water pump system is employed to retain the rainfall condition.Using the techniques of digital photography and pore water pressure transducers,water level fluctuation is controlled,and multi-physical data are thus obtained,including the pore water pressure,earth pressure,surface displacement and deep displacement.The analysis results indicate that:Three stages were set in the test(waterflooding stage,rainfall stage and drainage stage).Seven transverse cracks with wide of 1–5 mm appeared during the model test,of which 3 cracks at the toe landslide were caused by reservoir water fluctuation,and the cracks at the middle and rear part were caused by rainfall.During rainfall process,the maximum displacement of landslide model reaches 3 cm.And the maximum deformation of the model exceeds 12 cm at the drainage stage.The failure process of the slope model can be divided into four stages:microcracks appearance and propagation stage,thrust-type failure stage,retrogressive failure stage,and holistic failure stage.When the thrust-type zone caused by rainfall was connected or even overlapped with the retrogressive failure zone caused by the drainage,the landslide would start,which displayed a typical composite failure pattern.The failure mode and deformation mechanism under the coupling actions of water level fluctuation and rainfall are revealed in the model test,which could appropriately guide for the analysis and evaluation of riverside landslides.

The Research of the Equation Model on the System-level Fault Diagnosis

In this paper we propose an equation model of system-level fault diagnoses, and construct corresponding theory and algorithms. People can turn any PMC model on ex-test into an equivalent equation (or a system of equations), and find all consistent fault patterns based on the equation model. We can also find all fault patterns, in which the fault node numbers are less than or equal to t without supposing t-diagnosable. It is not impossible for all graphic models.

Using Test Employee Capability Maturity Model for Supporting Gaps Bridging in Software Testing

This study addresses the challenge of assessing gaps among the differences of test people in eight groups by matching them based on four scenarios. The proposed model called Test Employee Capability Maturity Model (TEC-MM) helps find the gaps and measure the capability and maturity levels of each sub-maturity models in four dimensions as technicality, management, business, and personality. We applied TEC-MM to a software company which has instituted test people improvement strategy and plans to be a front runner in software testing industry. The findings reveal that gaps existed and consequently affect software testing process quality.

Failure mechanism of a large-scale composite deposits caused by the water level increases

The failure of slope caused by variations in water levels on both banks of reservoirs is common.Reservoir landslides greatly threaten the safety of reservoir area.Taking large-scale composite deposits located on the Lancang River in Southwest China as a study case,the origin of the deposits was analyzed based on the field investigation and a multi-material model was established in the physical model test.Combined with numerical simulation,the failure mechanism of the composite deposits during reservoir water level variations was studied.The results indicate that the deformation of the large-scale composite deposits is a staged sliding mode during the impoundment process.The first slip deformation is greatly affected by the buoyancy weight-reducing effect,and the permeability of soil and variation in the water level are the factors controlling slope deformation initiation.The high water sensitivity and low permeability of fine grained soil play an important role in the re-deformation of deposits slope.During the impoundment process,the deformation trend of the deposit slope is decreasing,and vertical consolidation of soil and increasing hydrostatic pressure on the slope surface are the main reasons for deformation attenuation.It is considered that the probability of large-scale sliding of the deposits during the impoundment period is low.But the damage caused by local bank collapse of the deposit slope still needs attention.The results of this paper will further improve our understanding of the failure mechanism of composite deposits caused by water level increases and provide guidance for the construction of hydropower stations.

合理确定排涝泵站规模的感潮河道模型试验研究

合理确定泵站规模一直是感潮河道排涝工程设计中的关键问题。通过建立物理模型,在选定的水文边界条件和相应工程运行要求下,对某感潮水系两座涌口泵站规模进行试验研究。试验发现,受限于河涌过流能力,泵站规模存在临界值,超过该值后,即使再进一步增加泵站规模,水位也不会继续下降;泵站抽排对某位置水位的降低效应与泵站和该位置之间的距离密切相关,距离越近,水位降低越明显。基于上述认识,通过试验确定了满足水位管控要求的两座泵站规模的合理组合:距离相对较远的温涌泵站为80 m3/s,较近的金紫涌泵站为130 m~3/s。试验方法和主要成果可为工程方案比选及优化提供重要依据,对类似河涌整治工程也具有一定的借鉴意义。

水位差法模拟波浪荷载作用下大直径圆筒稳定性离心模型试验研究

某人工岛护岸工程采用大直径圆筒结构,结构直径和高度尺寸较大,工程所处位置波浪条件恶劣。采用水位差法等效模拟波浪荷载,开展波浪荷载作用下大圆筒施工期稳定特性离心模型试验研究,结果表明,在25 a一遇波吸力荷载作用下,筒体位移模式近似平移,侧向位移量约353 mm,筒顶沉降约为187 mm,施工阶段钢圆筒整体稳定;筒壁环向拉应力均值约为90 MPa,处于钢圆筒材料允许应力范围内;筒壁海侧土压力值随水位差增大至峰值后趋于稳定,表明筒体与周围邻近土体之间没有新的相对位移趋势,大直径钢圆筒护岸结构在波浪荷载作用下是稳定安全的。

水位下降速率对岩溶土洞塌陷的影响分析

水位升降引起的水气压力变化会导致岩溶土洞塌陷。通过开展物理模型试验与FLAC3D数值模拟相结合的方式,模拟相同供水速率不同排水速率下的水位升降波动对岩溶土洞的致塌过程,分析了水位升降波动过程中不同排水速率对既有土洞内水气压力的变化、覆盖层土压、变形的影响,建立了排水速率,覆盖层变形、塌陷与水气压力的关系,提出了水位波动对土洞塌陷的作用规律。结果表明:(1)排水速率对水气压力变化的影响规律基本一致但变化程度不同。水气压力的变化程度、响应时间与排水速率呈正相关。(2)覆盖层变形量、土压的变化与水气压力变化呈正相关,但影响程度不同,排水速率只是加快了其变化程度。(3)土洞变形、塌陷程度是综合因素所致。排水速率、水位波动次数对既有土洞中水气压力变化、以及土体变形效应均具有不同程度的影响。(4)数值模拟结果与试验室模型试验所得结论基本吻合。这些规律为进一步研究水动力因素对岩溶塌陷的作用规律提供了重要的理论支撑,为合理防治、预测岩溶塌陷提供了依据。

引江补汉工程丹江口下游近坝段枯水期通航水位恢复试验研究

引江补汉工程补水口位于丹江口大坝下游安乐河出口约5 km处,且补水量与调水量基本一致,工程对航道的影响主要体现在减水段,为恢复枯水期通航水位需要开展航道综合治理。利用河工模型试验论证了综合治理方案的效果,并对方案进行了优化及进一步论证。结果表明,减水-补水212 m 3/s方案尾门水位分别为86.47、85.90 m条件下,引航道口—黄家港段水位下降,黄家港以下水位保持不变,其中引航道口水位下降幅度最大,分别下降0.08、0.19 m;综合治理方案1实施后引航道口水位下降均为0.02 m,减水段的水位仍未恢复至调水前的水平,主因是从安乐河口补水的水流并未能进入到左侧主航道内;基于试验研究结果,建议对综合治理方案进行优化,在沧浪洲出水口下沿布置2道护底带;通过试验论证了护底带的4个高程,建议护底带高程为85.5 m,并对护底带高程进一步细化论证;优化后的方案可使引航道口至黄家港段的水位略超过调水前的水平,其中引航道口处最大水位抬高0.06 m。

层冰作用下直立圆柱结构冰载荷研究

层冰是冰区海工结构作业时遭遇的主要冰况之一,直立结构是海工结构的常见构型,因此,开展层冰作用下直立结构冰载荷研究对海工结构抗冰强化设计和安全评估具有重要意义。本文首先对层冰与直立结构作用过程进行概括分析。然后开展直立圆柱结构冰载荷的机理性试验,研究层冰的失效行为以及结构冰载荷的特征。最后基于黏聚单元模型和海冰软化本构开发层冰与结构作用模拟的数值仿真模型,对层冰的裂纹扩展和破碎过程进行模拟,同时利用试验数据对数值仿真模型的正确性进行验证。本研究工作可为结构冰载荷的数值和试验研究奠定重要基础,为冰区海工结构的设计建造提供技术参考。

强夯双向土压力模型试验测试及加固效果分析

【目的】从土体应力分布特征的角度研究不同夯击方式对砂土强夯加固效果的影响。【方法】通过室外场地进行的强夯模型试验对夯击过程中土体内部的竖向与径向土压力以及落锤加速度进行监测,并结合数值模拟的方法对土体内部的位移进行分析。【结果】研究得出:在强夯法施工中竖向土压力存在冲击与震荡衰减两种波形,径向土压力则主要以冲击波形为主;在砂土强夯加固过程中存在两种加固模式,夯击点正下方土体主要以竖向压实为主,而斜下方土体同时兼有显著的径向挤密作用;在同能级强夯施工中,“重锤低落”组合适合对深层土体与径向土体进行加固,“轻锤高落”组合适合对浅层土体进行快速加固。【结论】研究成果对同能级强夯夯击方式的选用具有一定的指导意义。

基于Transformer的DC/DC板级验证状态识别

为满足航天产品的高精度、高可靠性需求,实现元器件自主可控、芯片国产化及应用适应性验证十分必要,设计一种基于FPGA的国产DC/DC板级综合测试平台。在长时间的热学环境适应性板级验证项目中,为实现DC/DC器件应用板卡工作状态的实时监测,提出一种基于Transformer的智能识别算法。分别使用空载、负载电流3 A、负载电流5 A、高输入电压、低输入电压、短路状态下的DC DC输出序列,输入到Transformer模型中并利用注意力机制提取各序列的全局注意力特征,并对深度学习模型进行训练。实验结果表明,对于此6种工作状态数据集,Transformer模型识别的准确率为99.2%,具备良好的分类和监测性能,具有一定的工程应用价值。

土工织物加固土质坝堤加高工程的离心模型试验研究

土工织物是一种广泛用于边坡加固的合成材料,但土工织物在土质坝堤加高工程中尚未得到合理应用。针对水位变动条件下土工织物加固的加高土质坝堤进行了离心模型试验,观测了加高坝堤的变形破坏响应过程。试验结果表明,土工织物加固的加高土质坝堤的破坏呈现出新旧坝堤各异的特点,新旧坝堤呈现出不同的破坏特性,离土工织物较远的旧坝堤先发生破坏,土工织物加固的新坝堤的破坏发生较晚,且呈现从上到下渐进发展的特性;加高坝堤的最终破坏是由变形局部化和局部破坏相互耦合渐进发展导致的;土工织物分为加固段和约束段,在约束段坝堤给土工织物提供约束力,在加固段土工织物限制了坝堤的变形,土工织物的加固机理是将坝堤深部的约束力传递到坝堤表面,从而增强了坝堤浅层的抗滑能力;水位变动引起坝堤的变形增加,土工织物的加固作用也随之增强。

子弹撞击下CL-20基PBX装药响应研究

为了提高战斗部安全性,指导CL-20基PBX炸药在战斗部装药中的应用和设计,开展了基于子弹撞击试验的典型战斗部撞击响应特性研究。进行了子弹撞击试验,通过分析战斗部响应后的超压数据、验证板穿孔、试验影像和试验样品回收等,评估了子弹撞击战斗部的反应等级。结果表明,子弹撞击试验中,子弹速度为836 m/s,战斗部在子弹撞击下发生了爆轰等级的反应。此外,开展了不同撞击条件下战斗部安全性数值模拟,研究了不同撞击速度下战斗部的反应过程。结果表明,子弹以850 m/s和750 m/s撞击时,战斗部分别发生爆轰和燃烧等级的反应。该研究为典型战斗部的撞击响应预测及反应等级评价提供了数据支撑。

库水位下降叠加降雨作用时堆积层滑坡渗流-变形机制

随着水库工程的兴建,库区堆积层滑坡变形失稳的问题日益突出。该类滑坡变形往往发生在库水位下降期,且在降雨作用下更加明显,库水位下降与降雨共同作用下滑坡的渗流-变形机制是其中的关键科学问题。以三峡库区万州石龙门滑坡为原型,通过设计物理模型试验,分析在库水位下降叠加不同强度降雨作用时,坡体的宏观现象及坡内的压力变化,揭示了堆积层滑坡在复杂水文条件下的渗流-变形机制。库水位下降对坡体前缘渗流的控制作用更加明显,而降雨会显著抬升坡体中后部水头,两者联合会增大坡内水力梯度从而诱发坡体变形。此类滑坡在库水位下降时的渗流-变形机制为:无降雨作用时,受坡体内外水头差影响仅出现浅层的坡表冲刷型作用,在联合降雨作用下,则转为动水压力型作用,在百年一遇暴雨条件下,坡体在高水位附近出现裂缝,进而发生整体变形,最大位移量可达58.3 mm。本研究成果可为复杂水文条件下堆积层滑坡风险防控提供理论依据。

考虑人因-环境因素的山区公路警觉水平量化模型

为描述山区公路驾驶者的警觉状态及水平,综合考虑人因-环境因素,提出了一种山区公路警觉水平量化方法。通过分析驾驶者的眼动及行为数据来确定初始观测指标,基于核主成分分析法对多源数据进行降维,对降维后的主成分使用K-means聚类方法划分高低警觉水平;以低警觉水平样本概率为目标变量,通过筛选人因-环境因素得到了警觉水平量化因子;基于评分卡方法建立了山区公路警觉水平量化模型,并对模型进行了实例验证。研究结果表明:基于人因-环境因素的山区公路警觉水平量化模型的AUC值为0.907,KS值为71.86%,模型效果较好,能为山区公路驾驶者警觉水平动态评价及安全配套设施建设提供参考依据。

管道-裂隙型岩溶地下水水位变化特征室内试验研究

岩溶区管道-裂隙的发育特征影响着含水层水位面分布。可视化的物理模型,是研究不同试验条件下含水层的水位面特征,并揭示管道-裂隙发育特征影响规律的有效工具之一。为揭示不同裂隙组合、裂隙开度、裂隙发育程度、管道流量等因素对含水层水位面的影响规律,采用自主设计研发的管道-裂隙型双重导水介质物理模型,开展管道、裂隙发育特征对含水层水位面变化规律的影响研究。研究结果表明:在岩溶管道-裂隙发育地区,横向裂隙的主要导水特征是运输或传输,而竖向裂隙的主要导水特征是排泄;管道流量对含水层水位具有主控作用,而裂隙特征具有调控作用,且影响程度由大到小为横、竖向裂隙差异性、横向裂隙开度、裂隙发育程度、竖向裂隙开度;管道和裂隙发育特征对沿水流方向的水力坡降值产生影响,但裂隙特征的影响程度随管道流量的减小逐渐降低。研究结果能够为岩溶区管道、裂隙发育特征的揭露及区域地下水资源开发与保护提供参考。

洋溪水利枢纽横隔板式鱼道设计

洋溪防洪控制性工程是广西柳江上以防洪为主、兼顾发电和航运的大型综合水利枢纽工程。洋溪鱼道工程最大设计水头30 m,鱼池采用横隔板竖缝式。针对洋溪以防洪为主的功能要求,结合运行水位变幅特点及过鱼时长保证率确定了鱼道运行水位,从而优化了鱼道进、出口数量。通过大比尺局部物理模型试验和鱼道整体物理模型试验,开展了鱼道全程水流流态模拟分析,提出了最终的鱼道设计方案。

基于试纸检测皮肤油脂水平的模型建立

通过机器学习技术建立了一种简便的皮肤油脂水平测量方法。采用一次性的油脂试纸测量皮肤的出油程度,采集了669张油脂试纸图像,并将实验室Sebumeter~?设备测量的数值作为参照,建立基于油脂试纸图像的分析模型,可以自动化计算油脂试纸测量后的皮脂水平,得到了一种简便的皮肤油脂水平判定方式。研究结果表明,油脂试纸方法测量出的皮脂水平与Sebumeter~?测量出的皮脂水平一致性为0.897,测量结果的一致性高。

水位涨落作用下加筋路堤稳定性研究

公路洪水水毁现象愈发频繁,洪水引起的水位涨落对路堤有不可逆的损坏。以加筋路堤边坡为研究对象,考虑不同土工合成材料加筋效果,开展水位涨落模型试验,研究不同类型路堤在水位涨落条件下的水力特征及沉降与破坏模式。试验结果表明:水位涨落过程中,加筋改变了加筋层附近土体的孔隙水压力与土压力变化幅度、体积含水量对水分入渗的响应速度,不同筋材的加筋效果影响规律不同;对比未加筋路堤,孔隙水压力变化幅度在土工格栅加筋路堤中随水位涨、落过程逐步增大,体积含水量在土工布加筋路堤中响应最迅速,两者在土工复合材料加筋路堤中的变化利于路堤稳定,综合考虑,土工复合材料加筋效果最优;水位下落后,未加筋路堤斜坡发生牵引式滑移,加筋路堤均未发生,且加筋有效减小了路堤沉降。研究水位涨落条件下加筋路堤稳定特征对洪水水毁灾害防治具有重要意义。