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Quantification of 3D macropore networks in forest soils in Touzhai valley(Yunnan,China)using X-ray computed tomography and image analysis

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Journal of Mountain Science 2017年第3期14卷 474-491页

作者： ZHANG Jia-ming xu ze-min LI Feng HOU Ru-ji REN Zhe Department of Civil Engineering Kunming University of Science and TechnologyKunming 650500China Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Water Transportation Planning and Design Institute of Yunnan Kunming 650051China

The three dimensional （3D） geometry of soil macropores largely controls preferential flow, which is a significant infiltrating mechanism for rainfall in forest soils and affects slope stability. However, detailed studies on the 3D geometry of macropore networks in forest soils are rare. The intense rainfall-triggered potentially unstable slopes were threatening the villages at the downstream of Touzhai valley （Yunnan, China）. We visualized and quantified the 3D macropore networks in undisturbed soil columns （Histosols） taken from a forest hillslope in Touzhai valley, and compared them with those in agricultural soils （corn and soybean in USA; barley, fodder beet and red fescue in Denmark） and grassland soils in USA. We took two large undisturbed soil columns （250 mm^25o mmxsoo mm）, and scanned the soil columns at in-situ soil water content conditions using X-ray computed tomography at a voxel resolution of 0.945 × 0.945 × 1.500o mm^3. After reconstruction and visualization, we quantified the characteristics of macropore networks. In the studied forest soils, the main types of maeropores were root channels, inter-aggregate voids, maeropores without knowing origin, root-soil interfaee and stone-soil interface. While maeropore networks tend to be more eomplex, larger, deeper and longer. The forest soils have high maeroporosity, total maeropore wall area density, node density, and large maeropore volume, hydraulie radius, mean maeropore length, angle, and low tortuosity. The findings suggest that maeropore networks in the forest soils have high inter- connectivity, vertical continuity, linearity and less vertically oriented.

关键词： Slope stability Touzhai valley Rainfall infiltration Forest soils X-ray computed tomography 3D macropore networks

Dye tracer infiltration technique to investigate macropore flow paths in Maka Mountain, Yunnan Province, China

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Journal of Central South University 2016年第8期23卷 2101-2109页

作者：张家明徐则民 Faculty of Civil Engineering and Mechanics Kunming University of Science and Technology

In order to investigate the differences of macropores vertical distribution under different surface plants, and to assess the influences of root systems, organic matter and texture on macropore flow paths, two dye tracer infiltration experiments were performed in slopes under two different plants(Campylotropis polyantha(Franch.) Schindl vs. Cynodon dactylon(Linn.) Pers). Dye tracer infiltration experiments with field observations and measurements of soil properties were combined. Results show that the discrepancy in macropores distribution between two slopes under different plants is significant. Root systems have significant effects on macropore flow paths distribution and the effect become more pronounced as the diameter of roots become larger. Organic matter and stone are important factors to affect macropores distribution. Root-soil interface, inter-aggregate macropore and stone-soil interface are important macropore flow paths in well vegetated slopes.

关键词： landslides macropores plant root systems organic matter stone

Earthquake dynamic response behavior of Xiangchong valley type tailings impoundment in Yunnan, China

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Journal of Mountain Science 2018年第1期15卷 82-99页

作者： REN Zhe WANG Kun ZHANG Qi-shu xu ze-min TANG Zheng-guang CHEN Ji-pu YANG Ji-qing xu Zong-heng Faculty of Civil Engineering and Mechanics Kunming University of Science and Technology College of Architectural Engineering Yunnan Agricultural University School of Tourism and Geographical Science Yunnan Normal University

Tailings impoundments can potentially collapse due to damage caused by earthquakes,which has frequently occurred around the *** study takes the proposed valley type tailings impoundment in Yunnan as the research object to analyze the dynamic response behavior under earthquake action with both numerical simulation and physical model test(1:300).The results of both tests show that the dynamic response of the valley type tailings impoundment is characterized by"medium stiffness effect",in other words,in a certain range,the"softer"the unsaturated tailings sand is,the more energy it can dissipate,which leads the decrease of the value of the acceleration amplification *** addition,the peak acceleration of the monitoring points increases with the vertical elevation,which indicates that the"elevation amplification effect"exists in the tailings impoundment dynamic *** middle part of the outer side of the raised embankment reacts more sensitive than the crest,which is similar to the slope dynamic *** starter dam reacts sensitively under the earthquake excitation,which should be given more attention during the seismic *** dynamic response rules reflected by the numerical simulation are consistent with the results monitored on the physical model test,although there are some differences between their *** dynamic response rules of the valley type tailings impoundment can provide basis for the design of the similar projects in this region.

关键词： Tailings impoundment Dynamic response Shaking table test Medium stiffness effect

Formation and evolution of Emeishan basalt saprolite in vadose zones of Touzhai landslide source rockmass

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Journal of Mountain Science 2017年第6期14卷 1174-1184页

作者： YANG Ji-qing xu ze-min ZHANG Rui CHEN Ji-pu REN Zhe LUO Rong-zhang ZHANG Xiu-shuo Faculty of Civil Engineering and Mechanics Kunming University of Science and Technology College of Architectural Engineering Yunnan Agricultural University

In order to explain the formation process of slope hazards, and to identify the key factors leading to instability of a slope, Emeishan basalt saprolite in vadose zones of the Touzhai landslide in Zhaotong, Yunnan, was studied. The formation and evolution of Emeishan basalt saprolite was examined using, amongst other techniques, field investigations,thin section analysis, scanning electron microscopy(SEM) observations, chemical analysis, physical and water-physical property tests of rock masses. Field observations revealed that the majority of the weathered rock blocks were presented as a concentric layer structure in which an internal corestone was enveloped with several layers of external saprolized crust. Chemical and mineralogical analysis identified that iron was the most sensitive element and that the weathering progress usually started with the oxidation of Fe2+ to Fe3+ in rock blocks. Alkaline elements such as Si, Ca, Mg, Na and K were also dissolved and Fe and Al were concentrated in saprolized crusts. Results indicated that loss on ignition(LOI) also increased significantly. SEM results showed that the weathering intensity of thebasalt blocks decreased gradually from the outside to the inside, and the mineral morphology significantly differed on both sides of the weathering front. The saprolized crusts presented cellular microstructure features due to the generation of micropore and clay minerals. Thin section analysis showed that plagioclase was relatively more stable than pyroxene and chlorite during weathering. With a centripetal propagation of the weathering front, saprolized crusts became thicker and corestones became smaller; fresh Emeishan basalt blocks gradually turned into saprolized blocks. Due to the loose structure and low strength of saprolite, the quality of the Emeishan basalt mass significantly deteriorated, this being a potentially important factor which caused the Touzhai landslide to occur.

关键词： Vadose zone Emeishan basalt Scanning electron microscopy Saprolite Corestone Touzhai landslide

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水岩化学作用对斜坡水文地质及滑坡的影响

自然灾害学报 2007年第5期16卷 16-23页

作者：徐则民昆明理工大学土木系云南昆明650224

在温湿气候区,水岩化学作用对岩质斜坡的水文地质演化及失稳-夷平进程具有重要的控制作用。从地表到新鲜岩体,随着水岩化学作用程度的逐渐减弱,斜坡剖面可依次划分为土层、腐岩带和风化岩带,各带之间多是渐变过渡的。土层多由枯枝落叶... 详细信息

在温湿气候区,水岩化学作用对岩质斜坡的水文地质演化及失稳-夷平进程具有重要的控制作用。从地表到新鲜岩体,随着水岩化学作用程度的逐渐减弱,斜坡剖面可依次划分为土层、腐岩带和风化岩带,各带之间多是渐变过渡的。土层多由枯枝落叶层和土壤层组成,有时底部含有残坡积物;腐岩是由岩浆岩、沉积岩或变质岩经等容风化形成的风化软岩;风化岩带是腐岩带的前身,其特征是含有较高数量的核心石。斜坡垂向分带主要是地下水引起的,而这种分带反过来又会强烈影响地下水自身的埋藏与分布。土层可贮存上层滞水,风化岩带则可赋存潜水或承压水。上层滞水是浅层滑坡的主要控制因素。由于形成条件宽松,但规模不大,上层滞水控制的滑坡灾害多具群发性特点,同时,由于其含水介质为松散土体,失稳含水层很容易转化为泥石流。降雨期间,风化岩带内潜水水位上升甚至承压,导致岩体抗剪强度降低并诱发深层滑坡。

关键词：斜坡水岩化学作用腐岩水文地质滑坡

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用动光弹方法研究隧道岩爆的爆破扰动机理

爆炸与冲击 2009年第6期29卷 632-636页

作者：黄锋徐则民同济大学地下建筑与工程系岩土及地下工程教育部重点实验室上海200092 昆明理工大学土木工程系云南昆明650224

利用动态光弹性方法,以Lamb模型为依据,研究了不同荷载形式下,模型内应力波的传播、相互作用规律以及刻槽的拦截效应。实验结果与弹性动力学解答基本一致:(1)倾斜冲击荷载作用下,模型内传播的有P波、S波和Rayleigh波,其中P波和Rayleigh... 详细信息

利用动态光弹性方法,以Lamb模型为依据,研究了不同荷载形式下,模型内应力波的传播、相互作用规律以及刻槽的拦截效应。实验结果与弹性动力学解答基本一致:(1)倾斜冲击荷载作用下,模型内传播的有P波、S波和Rayleigh波,其中P波和Rayleigh波对岩爆有突出贡献;(2)等差条纹图的分布规律,可以合理解释岩爆高发区段与开挖面的位置关系;(3)模型表面的刻槽,可以实现对Rayleigh波的大量拦截,说明隧道表面切槽的岩爆控制方法理论上是可行的。

关键词：爆炸力学爆破扰动机理动光弹岩爆 Lamb模型

格子Boltzmann方法在斜坡非饱和带土体大孔隙流研究中的应用

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岩土工程学报 2017年第1期39卷 178-184页

作者：徐宗恒徐则民王志良云南师范大学旅游与地理科学学院云南昆明650500 昆明理工大学建筑工程学院云南昆明650500

大孔隙结构的建立和大孔隙流的渗流模拟能定性和定量的解释大孔隙流的产生机理及其动态变化过程。采用CT扫描获取斜坡非饱和带大孔隙域,基于不考虑外力项的格子Boltzmann方法,通过确定离散速度模型、平衡态分布函数和分布函数的演化方... 详细信息

大孔隙结构的建立和大孔隙流的渗流模拟能定性和定量的解释大孔隙流的产生机理及其动态变化过程。采用CT扫描获取斜坡非饱和带大孔隙域,基于不考虑外力项的格子Boltzmann方法,通过确定离散速度模型、平衡态分布函数和分布函数的演化方程三大组成部分,其中边界条件与计算假设依据染色示踪试验设定,定性定量化研究二维大孔隙流的渗流过程,研究结果表明:该方法能清晰定量化描述大孔隙流湿润前锋的推进过程,大孔隙效应明显,渗流场流速随着时间推移逐渐趋于稳定,大孔隙效应逐渐减弱;在连通性较好、孔径较大的区域流体流速较快,且在大孔隙中心流速最大,往两侧逐级递减;下层深度处的流体流量和流速往往受控于上一层大孔隙的孔径尺度。格子Boltzmann方法的应用能为大孔隙流特别是三维渗流过程的研究提供新手段。

关键词：格子Boltzmann方法非饱和带大孔隙流渗流过程

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成渝线典型路基边坡对降雨过程的响应模拟

西南交通大学学报 2000年第1期35卷 23-27页

作者：徐则民杨立中成都理工学院水文系四川成都610031 西南交通大学土木工程学院四川成都610031

成渝铁路典型路基边坡由砂泥岩互层及其风化带组成,顶部为2～5m的砂粘土层。模拟实验表明,边坡对降雨过程的水力学及力学响应取决于土层的初始渗透性、降雨方式和降雨量;能够对边坡渗流场和应力场产生明显影响的降雨过程一般应同时满足... 详细信息

成渝铁路典型路基边坡由砂泥岩互层及其风化带组成,顶部为2～5m的砂粘土层。模拟实验表明,边坡对降雨过程的水力学及力学响应取决于土层的初始渗透性、降雨方式和降雨量;能够对边坡渗流场和应力场产生明显影响的降雨过程一般应同时满足3个条件:(1)雨前经历过较长时间的炎热天气,土层蒸发强烈、初始渗透性良好;(2)降水过程以中到大雨开始,且持续较长时间;(3)降雨时间长。

关键词：路基边坡稳定降雨过程模拟试验成渝铁路

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差异风化型危岩力学模型及破坏机制研究

岩土力学 2015年第1期36卷 195-204页

作者：陈维徐则民刘文连昆明理工大学建筑工程学院云南昆明650500 云南交通咨询有限公司云南昆明650031 中国有色金属工业昆明勘察设计研究院云南昆明650051

差异风化型危岩多形成于由砂岩和泥岩等软、硬岩性组成的互层陡倾岩质边坡中,其崩塌破坏属地质灾害中的常见形态。以普洱渡危岩高边坡为例,推导出差异风化型危岩岩腔后壁泥岩压应力随岩腔深度增加而增大的计算公式。据普洱渡危岩高边坡... 详细信息

差异风化型危岩多形成于由砂岩和泥岩等软、硬岩性组成的互层陡倾岩质边坡中,其崩塌破坏属地质灾害中的常见形态。以普洱渡危岩高边坡为例,推导出差异风化型危岩岩腔后壁泥岩压应力随岩腔深度增加而增大的计算公式。据普洱渡危岩高边坡地形地貌和地质构造特征建立了两类4种差异风化型危岩力学模型:第1类为主控结构面贯通率等于1时的泥岩基座压裂破坏型和转动破坏型危岩;第2类为主控结构面贯通率小于1时的坠落型和倾倒型危岩。利用岩石强度理论推导出研究区砂岩的二次抛物线型摩尔强度包络方程,以极限平衡理论和摩尔强度理论推导了4种危岩体在自重、地震力和裂隙水压力共同作用下的崩塌破坏判别表达式,并由此反演出危岩体的临界崩塌边界方程,得出危岩体崩塌边界(岩腔深度、危岩体厚度和高度、主控裂隙深度)之间的关系,为现场预测和判别危岩体的稳定性和崩落时序提供简便可靠的依据。

关键词：危岩差异风化岩腔主控结构面破坏机制