Modelling the poroelastoplastic behaviour of soils subjected to internal erosion by suffusion     

Quentin Rousseau  Giulio Sciarra  Rachel Gelet  Didier Marot 《国际地质力学数值与分析法杂志》2020,44(1):117-136

Granular soils subjected to seepage flow may suffer suffusion, ie, a selective internal erosion. Extending the classical approach of poromechanics, we deduce a new form of the Clausius-Duhem inequality accounting for dissipation due to suffusion, and we deduce restrictions on the constitutive laws of the soil. We suggest (a) a possible coupling between the seepage forces and the suffusion kinetics and (b) an extension of an existing elastoplastic model for the skeleton mechanical behaviour. Numerical integrations of the elastoplastic model are carried out under drained axisymmetric triaxial and oedometric conditions. As a result, we prove that the extended model is able to qualitatively reproduce the suffusion induced strains and the strength reduction experimentally observed. Predictions on the oedometric behaviour of suffusive soils are also provided.  相似文献   

A smoothed particle hydrodynamics modelling of soil–water mixing and resulting changes in average strength     

Wangcheng Zhang  Mark F. Randolph 《国际地质力学数值与分析法杂志》2020,44(11):1548-1569

Soil–water interaction is a pivotal process in many underwater geohazards such as underwater landslides where soil sediments gradually evolve into turbidity currents after interactions with ambient water. Due to the large deformations, multiphase interactions and phase changes this involves, investigations from numerical modelling of the transition process have been limited so far. This study explores a simple numerical replication of such soil–water mixing with respect to changes in average strength using smoothed particle hydrodynamics (SPH). A uniform viscoplastic model is used for both the solid-like and fluid-like SPH particles. The proposed numerical solution scheme is verified by single-phase dam break tests and multiphase simple shear tests. SPH combinations of solid-like and fluid-like particles can replicate the clay–water mixture as long as the liquidity index of the solid-like particles is larger than unity. The proposed numerical scheme is shown to capture key features of an underwater landslide such as hydroplaning, water entrainment and wave generation and thus shows promise as a tool to simulate the whole process of subaquatic geohazards involving solid–fluid transition during mass transport.  相似文献   

劲芯水泥土桩承载路堤渐进式失稳破坏机制     

张振  张朝  叶观宝  王萌  肖彦  程义 《岩土力学》2020,41(6):2122-2131

劲芯水泥土桩是一种软土地基处理的新方法，近年来已成功应用于公路、铁路路基处理工程中。然而由于人们对其承载路堤的失稳破坏机制认识不足，无法正确指导设计。采用反映桩体材料破坏后特征的应变软化模型，模拟劲芯水泥土桩承载路堤失稳破坏1g模型试验，通过分析路堤失稳破坏过程中桩体塑性区的开展和桩身受力的变化情况，研究了桩体的破坏顺序及其破坏模式。结果表明：路堤失稳过程中，劲芯水泥土桩并非同时发生破坏，路面正下方桩体首先发生受压破坏，坡面下方桩体自坡脚至坡肩依次发生弯剪破坏；由于桩体的存在，路基中滑动面并非完全穿过桩体破坏位置。基于桩体破坏顺序、破坏模式、受力情况变化，以及荷载传递规律，阐释了劲芯水泥土桩承载路堤渐进式失稳破坏机制。采用现行规范中基于残余强度的柔性桩处理方法，计算的安全系数与试验结果较为接近，但其适用性还需做进一步研究。  相似文献   

断层附近地应力扰动带宽度及其影响因素   总被引：3，自引：3，他引：0  

翁剑桥  曾联波  吕文雅  刘奇  祖克威 《地质力学学报》2020,26(1):39-47

在建立正断层模型的基础上，利用三维有限元数值模拟方法研究了断层附近地层中的地应力变化规律。其结果表明，由于断层活动，在断层附近普遍发育应力扰动带；在应力扰动带范围内，地应力方向和大小发生明显的变化，断层中部附近应力值普遍较低，而断层端部的应力值通常异常增大。应力扰动带的分布范围主要受断层规模的控制，与断裂带的岩石力学性质、断层走向、断层面形态和边界应力条件等因素也密切相关。随断层长度和断距逐步增大，应力扰动带的宽度相应增加。断裂带的岩石越破碎，其岩石弹性模量越低，断层对地应力的影响宽度越大。断层走向与区域最大水平主应力方向越接近垂直、断距与断层长度的比值越大，区域内的差应力越大，则扰动带宽度与断层规模的比值也越大。选择渤海湾盆地BZ-X油田进行验证，在建立油田实际三维地质模型基础上，根据边界应力条件，利用三维有限元方法对沙河街组二段的地应力分布进行了数值模拟计算。根据断层周围的地应力变化，确定了应力扰动带的分布范围，断层附近应力扰动带宽度的分布规律与正断层模型分析结果相一致。   相似文献   

Response to the paper by H. Zia,B. Lecampion “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315)     

Aleksandr Linkov 《国际地质力学数值与分析法杂志》2020,44(16):2254-2259

The response presents three comments, which (i) explain theoretical background for the success of the explicit front advancing scheme by Zia and Lecampion (comment 1), (ii) suggest possible extensions (comment 2), and (iii) pay attention on expected limitations of the scheme to be checked by the authors in numerical experiments (comment 3). The response does not intend to present novel results: it is entirely based on known results published in the references cited.  相似文献   

基于卫星遥感海温数据的南海SST预报误差订正     

张培军  周水华  梁昌霞 《热带海洋学报》2020,39(6):57-65

尝试利用卫星遥感高分辨率海表温度资料GHRSST (Group for High Resolution Sea Surface Temperature) 与海表温度(sea surface temperature, SST)数值预报产品之间的误差, 建立一种南海SST模式预报订正方法。首先, 利用南海的Argo浮标上层海温数据对GHRSST 海温数据进行验证, 结果表明两者之间均方根误差约为0.3℃, 相关系数为0.98, GHRSST 海温数据可用于南海业务化数值预报SST的订正。预报订正后的SST与Argo浮标海温数据相比, 24h、48h和72h的均方根误差均由0.8℃左右下降到0.5℃以内。与GHRSST 海温数据相比, 南海北部海域(110°E—121°E, 13°N—23°N)订正后的24h、48h和72h的SST预报空间误差均显著减小, 在冷空气影响南海期间或中尺度涡存在的过程中, SST预报订正效果也较为显著。因此, 该方法可考虑在南海业务化SST数值预报系统中应用。  相似文献   

基于纵横波保幅分离的粘弹介质弹性波正演模拟     

侯志强  尹文笋  李键  孙永壮  刘云 《中国海洋大学学报(自然科学版)》2020,(1):82-92

地下介质往往表现为粘弹特性,研究基于粘弹假设的数值模拟方法对于正确认识地震波的传播规律和提高地震勘探精度具有重要意义。波动方程正演过程中纵横波的保幅解耦是研究准确的粘弹介质中地震波传播机理的前提,基于散度和旋度算子的纵横波解耦方法会使波场的相位和振幅产生畸变,且解耦后的波场在极性反转位置上无法与分离前混合波场各分量对应。在散度和旋度算子上再做一次梯度和旋度运算的波场分离方法虽然能够克服上述缺陷,但存在保幅性差等问题。本文从粘弹介质中的一阶速度-应力方程出发,推导了矢量纵横波分离的波数域表达式,结合有限差分思路给出了其在空间域的求解方法。本文方法利用纵横波的传播速度对现有的矢量波场分离方法进行振幅校正,并将校正结果分别作为纵波与横波对时间的二阶偏导,实现了粘弹介质中的纵横波分离。模型试算结果表明,本文方法能够克服现有方法的缺陷,获得更具保幅性的波场分离结果。  相似文献   

The effect of storm movement on infiltration,runoff and soil erosion in a semi-arid catchment     

Qihua Ran  Feng Wang  Jihui Gao 《水文研究》2020,34(23):4526-4540

Rainfall characteristics are key factors influencing infiltration and runoff generation in catchment hydrology, particularly for arid and semiarid catchments. Although the effect of storm movement on rainfall-runoff processes has been evaluated and emphasized since the 1960s, the effect on the infiltration process has barely been considered. In this study, a physically based distributed hydrological model (InHM) was applied to a typical semi-arid catchment (Shejiagou, 4.26 km²) located in the Loess Plateau, China, to investigate the effect of storm movement on infiltration, runoff and soil erosion at the catchment scale. Simulations of 84 scenarios of storm movement were conducted, including storms moving across the catchment in both the upstream and downstream directions along the main channel, while in each direction considering four storm moving speeds, three rainfall depths and two storm ranges. The simulation results showed that, on both the hillslopes facing downstream (facing south) and in the main channel, the duration of the overland flow process under the upstream-moving storms was longer than that under the downstream-moving storms. Thus, the duration and volume of infiltration under upstream-moving storms were larger in these areas. For the Shejiagou catchment, as there are more hillslopes facing downstream, more infiltration occurred under the upstream-moving storms than the downstream-moving storms. Therefore, downstream-moving storms generated up to 69% larger total runoff and up to 351% more soil loss in the catchment than upstream-moving storms. The difference in infiltration between the storms moving upstream and downstream decreased as the storm moving speed increased. The relative difference in total runoff and sediment yield between the storms moving upstream and downstream decreased with increasing rainfall depth and storm speed. The results of this study revealed that the infiltration differences under moving storms largely influenced the total runoff and sediment yield at the catchment scale, which is of importance in runoff prediction and flood management. The infiltration differences may be a potential factor leading to different groundwater, vegetation cover and ecology conditions for the different sides of the hillslopes.  相似文献   

How soil texture,channel shape and cross-sectional area affect moisture dynamics and water loss in irrigation channels     

Zhifan Mu  Tianxiao Li  Dong Liu  Qiang Fu  Renjie Hou  Qinglin Li  Yi Ji  Song Cui  Mo Li 《水文研究》2021,35(4):e14155

To enhance the utilization efficiency of farmland irrigation water and reduce the leakage of water conveyance channels, the leakage process of channels was simulated dynamically. The simulated results were compared with data measured in laboratory experiments, and the performance of the model was evaluated. The results indicated that the simulated values of the model were consistent with the observation values, and the R² values varied between 0.91 and 0.99. In addition, based on the laboratory experiments, a water supply system (Mariotte bottles) and soil box were built using plexiglass. Three influencing factors, namely, the channel form, soil texture and channel cross-sectional area, were varied to observe and calculate the resulting cumulative infiltration amount, infiltration rate and wetting front migration distance. HYDRUS-3D software was used to solve the three-dimensional soil water movement equation under different initial conditions. The results demonstrated that the U-shaped channel was more effective than the trapezoidal channel in increasing the utilization efficiency of the water resources. A U-shaped channel with a small channel cross-sectional area should be adopted and the soil particle size should be prioritized in the construction of water conveyance channels for farmlands. The simulation results were in agreement with the observed results, which indicates that HYDRUS-3D is a reliable tool that can accurately simulate the soil moisture movement in water conveyance channels. The research results can provide a reference for the design and operation of farmland irrigation systems.  相似文献   

自然和自然贡献情景模型研究综述     

岳天祥  范泽孟  史文娇  赵娜 《地球信息科学学报》2020,22(4):743-750

本文回顾了自然和自然贡献情景模型发展的背景、历史和内容,概括总结了自然和自然贡献情景模型的发展进程以及联合国生物多样性与生态系统服务政府间科学—政策平台(IPBES)情景模型的概念框架,讨论了自然和自然贡献情景模型存在的问题和发展方向。为了在全球层面解决现有综合集成模型存在的问题,根据地球表层建模基本定理和生态环境曲面建模基本定理,提出了具有中国原创特点的自然与自然贡献情景模型概念框架。  相似文献