水工沥青混凝土具有较为特殊的运行条件,为保证水工建筑物的安全运用,水工沥青混凝土必须具有一定的可变形能力和刚度要求.影响沥青混凝土特性的因素有很多,如配合比、施工工艺等,其中配合比对沥青混凝土的强度和刚度有着重要影响,文中通过对沥青混凝土进行正交设计试验和控制变量试验,明确单因素对结果的影响趋势和显著性.结论表明,级配指数对混合料的刚度和强度均不显著.填料用量对拉伸应变显著,且填料含量对沥青混凝土的刚度和强度影响相反;油石比对劈裂强度显著,适当的油石比能改善混合料的强度,但随油石比增加会对材料刚度有所损伤.

在水利工程中,土坝的长期稳定性和结构安全十分重要,所以要对土体的工程特性进行研究.试验结果表明,干湿循环次数越多,不同土类的抗剪强度均在降低,土体的稳定性随着干湿循环的增加而降低,然后在达到一定次数后趋于稳定.通过对微观结构进行研究,从微结构角度解释了干湿循环对土体抗剪强度的影响.在此基础上,对今后的研究提出自己的看法.

水库库岸失稳对水库安全运行有重大影响.采用土工试验和干湿循环试验,结合数值计算及理论分析,研究红土型库岸边坡倾角和库水位升降与库岸稳定性的关系.结果 表明:(1)在一定初始干密度条件下,红土抗剪强度随水位升降循环次数增加而非线性减小,且在水位升降循环约10次时趋于稳定.(2)在一定水位升降速率、升降幅度和升降循环次数条件下,红土型库岸稳定安全系数随库岸边坡倾角的增加总体上呈减小的趋势,且在边坡倾角为50°左右存在稳定安全系数极小值.(3)在一定水位升降循环次数条件下,水位上升到坡高的60％左右为上升阶段的相对危险区域,且水位上升速率对库岸稳定安全系数影响很小;水位下降至坡高的70％左右为库水位下降阶段的相对危险区域,且水位下降速率越大,库岸稳定安全系数越小.(4)针对一定初始干密度,库岸稳定安全系数先随水位升降循环次数的增加而减小,但在水位升降循环次数约10次后逐渐趋于稳定.库岸岩土体性质及库岸边坡倾角、水位变化都会对库岸稳定产生影响.

本文通过直剪试验、干湿循环试验和数理统计分析相结合的方法,研究干湿循环条件下,加砂比例变化对云南红土抗剪强度及微结构特性的影响,为云南红土在实际工程中的应用提供参考.结果表明:(1)当干湿循环次数一定时,随加砂比例的增大,红土内摩擦角非线性增加,黏聚力非线性减小;抗剪强度呈减小-增大-减小的波动变化趋势,且在加砂比例约10％左右存在极大值.(2)当加砂比例分别为0、5％、10％和15％时,随干湿循环次数的增加,红土内摩擦角降幅依次为22.8％、30.9％、19.9％、32.6％;黏聚力降幅依次为26.6％、29.2％、17.3％、37.7％;抗剪强度降幅依次为:23.6％、25.6％、18.7％、28.2％.红土颗粒数量降幅依次为35.7％、28.1％、22.7％、20％;孔隙率增幅依次为40.4％、36.5％、28.9％、23.6％;孔隙面积增幅依次为50.8％、42.9％、35.5％、30.7％.(3)干湿循环与加砂会改变红土微结构,其中定向度与定向分维数两个微结构参数与红土黏聚力的变化关系较为紧密;平均圆形度、孔隙面积、孔隙率等微结构参数对内摩擦角的影响较为显著.这些微结构参数与红土黏聚力和内摩擦角均为负相关,相关系数最高为-0.972,最低为-0.928.干湿循环、加砂比例对红土微结构及抗剪强度有显著影响.

在水利工程中,经常涉及粘性土的起动问题.粘性土的起动问题可用临界起动条件来解决,而确定临界起动条件最关键的是分析临界起动切应力.云南红土分布广泛,属于粘性土,其物理特性有别于其它土体,有必要进行云南红土临界起动切应力的影响研究.本文通过理论分析建立云南红土临界起动切应力的公式,选取干密度和含水率两个因素进行土工试验,基于试验结果,结合理论,进行综合对比分析.

This is of great significance in understanding the instability mechanism of bank slopes composed of different types of rocks and soils. The characteristics of Yunnan laterite soil subjected to dry-wet cycles with its influence on the stability of bank slope were studied by experimental tests. The influence of the immersion and fluctuation level of reservoir water was studied through geotechnical tests. Analytical deduction and numerical simulation were also combined in the study. Results showed that,with a fixed initial dry density,the content of clay particles in laterite first increased with the number of wet-dry cycles and then decreased before reaching to a stable value as the cycles increased. At the same time,the cohesion,internal friction angle and shear strength of laterite all decreased first nonlinearly with the increase of the cycling times,and then became stable after round 10 wetting-drying cycles. The shear strength,cohesion and internal friction angle of laterite presented a significant effect on the stability of laterite bank slope. This research could provide reference for preventing and controlling the slope failure of Yunnan lateritic reservoir bank in engineering practice.

针对不同干密度和初始含水率的红土,分别在不同水温条件下,通过变水头渗透试验和理论分析相结合的方法,分析渗透系数随干密度、初始含水率及水温变化的规律,揭示干密度、初始含水率及水温条件变化时对红土渗透系数造成的影响.结果表明:①当红土干密度为1.1g·cm-3～1.4g·cm-3时,红土渗透系数随干密度增大而减小.随着干密度增大,水温和初始含水率对红土渗透系数的影响越来越小.②当初始含水率小于等于26％时,红土渗透系数随初始含水率增大而减小;当初始含水率大于26％时,红土渗透系数急剧减小.初始含水率为26％时,红土渗透系数取得极大值.③红土渗透系数在降温区(5℃～25℃)随水温升高而增波折大,在升温区(25℃～40℃)随水温升高而波折降低.水温为25℃时,渗透系数出现极大值.说明水温为25℃时,对红土渗透系数的影响最大.

In view of the objective reality of drying and wetting cycles which caused by the rise and fall of the reservoir water of the laterite reservoir in Yunnan,this article examines the change law of shear strength and microstructure of laterite under the action of drying and wetting cycles,and reveals the internal relationship between the shear strength and microstructure of laterite under the action of drying and wetting cycles.The results can provide the basis for studying the instability of the laterite reservoir.Simulation of the effect of drying and wetting cycles of red reservoir caused by reservoir water immersion and reservoir water level rise and fall is conducted by carrying out drying and wetting cycle tests of the clay sample and using geotechnical experiments and related theoretical analyses.The results show that:(1) Under certain initial dry density conditions,the cohesion,internal friction angle and shear strength of the laterite decrease with the increasing number of drying and wetting cycles,and it will keep stable when the number of times of drying and wetting cycles is 10.(2) The microstructure of the laterite is changed by drying and wetting cycles.When the initial dry density is 1.2,1.3 and 1.4 g/cm3,respectively,the number of times of drying and wetting cycles rises to 10,the number of the laterite particles decreases by 45.4％,38.2％ and 35.7％,respectively,the porosity increases by 52.6％,45.9％ and 40.4％,and the pore area increases by 64.4％,58.2％ and 50.8％,respectively.(3) Under the drying and wetting cycles,there is a positive correlation between the cohesion of the laterite and the degree of orientation and average circularity of the laterite,and the correlation coefficients R are 0.985 and 0.923.There is a negative correlation between the internal friction angle and the porosity and pore area,and the correlation coefficients R are-0.936 and-0.912.The change of microstructure of the laterite is caused by drying and wetting cycles,which causes the changes in the macroscopic mechanical properties of the laterite.

[Objective] The relationship between water content,dry density,shear strength and erosion modulus of laterite in Yunnan Privince,was studied under rainfall condition,in order to provide a theoretical basis for further studies on the erosion mechanism of laterite.[Methods] The methods included artificial simulated rainfall and soil trough model experiments,soil test and relative theoretical analysis.[Results] (1) The relation of the cohesion of laterite with water content showed a quadratic curve relation.Near the optimum water content,the maximum cohesion occurred.The internal friction angle was approximate to the linear relationship with the water content change,and the internal friction angle decreased with increasing water content.Under the conditions of initial dry density 1.0,1.1,1.2,1.3,1.4 g/cm3,the correlation coefficient(R2)between cohesion and water content ranged from a minimum of 0.754 to a maximum of 0.934,and the R2 between internal friction angle and water content ranges from the minimum of 0.944 to the maximum of 0.996.(2) The relation between cohesion and internal friction angle were close to linear relationship with the change of dry density.When the water content was constant,the curve of the relationship between cohesion and internal friction angle with the change of dry density had a certain variation,and the cohesion and internal friction angle increase with the increasing of dry density.(3) The shear strength decreased with increasing water content,and the amplitude was especially obvious when the water content was higher than the optimum water content.The shear strength increased with increasing dry density.(4) By the end of the rain,for laterite with different dry densities,the relationship between the slope erosion modulus and the shear strength showed a quadratic curve relation,and the correlation coefficient (R2) can be up to 0.988.[Conclusion] There is good correlation between the shear strength and the slope erosion modulus,and estimating the amoum of the slope erosion with the shear strength of laterite after rain is possible.

In this research,it revealed the relationship between the hydrodynamic characteristics of Yunnan laterite slope runoff,dry density,erosion modulus of slope surface and shear stress of slope runoff during rainfall.This was completed specifically for Yunnan laterite slope with a certain rainfall intensity and slope inclination by our proposed research approach by using artificially-mimic-rainfall-model experiments and soil tests in connection with theoretical analysis.The results showed:(1) the average velocity of runoff on slope increased gradually in the early stage of runoff duration and then tended to be stable later on.The average velocity of slope runoff increased significantly with the increase of dry density of laterite.The relationship between the average velocity and unite discharge of runoff could be expressed as a power function:R2 =0.996.(2) Similarly,the average water depth of runoff increased gradually in the early stage of the runoff duration and then tended to be stable.Furthermore,the average water depth of runoff were expected to greater with a larger dry density.The relationship between the average water depth and the unite discharge of runoff could be also expressed as a power function:R2 =0.996.(3) Runoff stayed in the pattern of rapid laminar flow under experimental conditions.(4) In case of the certain experimental conditions and some of dry densities,the erosion modulus of laterite slope increased with runoff shear stress increment,and a linear relationship could be observed between the erosion modulus and the runoff shear stress.With the value of dry density were given to 1.0,1.1,1.2,1.3,1.4 g/cm3,the R2 ranged from minimum 0.816 to maximum 0.945,and the critical shear stress of laterite slope was 0.482,0.510,0.556,0.586,0.656 Pa respectively.The behaviors of slope runoff was controlled by various factors.The erosion modulus of slope and the relevant critical shear stress of slope runoff was closely related to the characteristics of runoff and soil.

Considering the Yunnan laterite with different proportions of sand under the initial conditions of the optimum moisture content and the maximum dry density,this paper reveals the relationship between drying-wetting cycles and the changes in physical and mechanical properties of sandy laterite.On the basis of combining geotechnical tests with relevant theoretical researches,the method of Excel is used to analyze the test data.The results indicate that under the drying-wetting cycles,the specific gravity of laterite with different proportions of sand shows a trend from rise to decline;the dry density shows an upward tendency;the shear strength and shear strength parameters have an upward tendency.The tendency is eventually stable after 10 times of cycling.Under a certain number of dry and wet cycle conditions,the greater sanding proportion of laterite comes with the smaller decrease in clay particle.The smaller increase of particle and sand,the smaller numbers of cracks,and the soil samples are more compacted.The largest decline in shear strength and shear strength parameters is the laterite with 15％ proportions of sand,and the smallest is the laterite with 10％ proportions of sand.

The influencing factors of laterite starting on slopes under the effects of rainfall were revealed.The starting conditions of laterite starting on slopes under the effects of rainfall were established,in order to provide a reference for further study on slope erosion of laterite in Yunnan.According to the characteristics of laterite and the erosion processes and phenomena on the slope surface,the method of combining the model test and the mechanical model was adopted.The results indicated that:(1) The splash erosion and crust were the two main phenomena in the processes of erosion of laterite on slopes.(2) The cohesive force of laterite could block the starting of laterite particles on slopes.The greater the shear strength,the greater the critical shear stress of the laterite particles.Rainfall and pore water pressure could promote the starting of laterite particles on slopes.The greater the raindrop densityρand the final velocity,the greater the impact of rainfall.When the particle size d was larger and the ratio of raindrop diameter to water depth decreased,the effect of rainfall was smaller.(3) The formulas of the critical starting shear stress of laterite particles in the connection and loose state were established.The critical starting shear stress of laterite particles on slopes was closely related to the particle size,shear strength,rainfall characteristics,and runoff characteristics.Under the effects of rainfall,a small flow shear stress could make the laterite particles under loose state start.

[目的]揭示降雨强度、坡度和坡长与云南红土坡面土壤侵蚀之间的关系,为云南红土地区土壤侵蚀的防治提供依据.[方法]采用室内人工模拟降雨试验及理论分析相结合的方法.[结果](1)红土坡面侵蚀模数与降雨强度、坡度和坡长的相关关系显著(R2＞0.95).(2)在相同坡度、坡长条件下,红土坡面侵蚀模数与降雨强度呈幂函数关系;(3)在相同降雨强度、坡长条件下,红土坡面侵蚀模数与坡度呈二次多项式关系;(4)在相同降雨强度、坡度条件下,红土坡面侵蚀模数与坡长呈二次多项式关系.[结论]云南红土坡面侵蚀模数随降雨强度的增大而增大;当坡度小于临界坡度21.4°时,坡面侵蚀模数随坡度的增大而增大,当坡度大于临界坡度21.4°时,坡面侵蚀模数随坡度的增大而减小;坡面侵蚀模数随坡长的增大而增大.

针对不同初始状态的云南红土,在一定雨强、坡度、坡长条件下,研究红土理化特性对坡面侵蚀的影响.采用人工模拟降雨方法进行试验研究,运用Excel分析试验数据.结果表明:(1)红土颗粒组成中黏粒含量对降雨作用下的红土坡面侵蚀影响显著,当黏粒含量增加8.1％时,其侵蚀模数则减小25.8 g/(m2·h);(2)红土初始含水率偏离最优含水率越远,红土侵蚀模数越大.当红土初始含水率从接近最优含水率的24.6％增加到36.5％时,侵蚀模数从110.4 g/(m2·h)增加到121.3 g/(m2·h);(3)在初始干密度为1.0,1.1,1.2,1.3,1.4 g/cm3条件下,红土侵蚀模数呈先增大后减小的二次曲线变化趋势(R2=0.927).初始干密度在1.1～1.2 g/cm3之间,红土侵蚀模数存在极大值[126 g/(m2·h)];(4)降雨作用使坡面红土铁铝氧化物含量减少,接近坡脚处Fe2O3含量从初始状态的8.591％减小到8.143％,Al2O3含量从初始状态的22.242％减小到20.967％;而坡内红土铁铝氧化物含量则随深度增加,坡体中段坡内的Fe2O3含量增加0.407％,Al2O3含量增加0.861％.降雨作用改变了红土理化特性,而红土理化特性的变化会对红土坡面侵蚀产生显著影响.

以昆明红土为研究对象,考虑含水率和击实功的影响,通过击实试验和直剪试验研究昆明红土的击实特性和抗剪强度特性,结果表明:随击数增大,红土呈现出最大干密度提高、最优含水率减小的击实特征;过分偏干或偏湿状态,击数的增大反而减小了干密度,不利于红土的击实.击实红土的抗剪强度特征表现为,随含水率增大,偏干红土的抗剪强度和黏聚力增大,偏湿红土的抗剪强度和黏聚力减小;随击数增大,红土的抗剪强度增大,偏松状态黏聚力增大,偏密状态黏聚力减小;低于最优含水3％ ～5％和25击左右,红土的抗剪强度和黏聚力能够达到极大值;红土的内摩擦角随含水率的增大而减小,随击数的增大而增大.实际红土回填采用室内轻型击实试验结果时,应注意控制红土的含水和击实功,以保证红土回填的质量.

Through indoor artificial rainfall test on the model slope of the laterite, the soil tests on samples of different parts of the model slope of laterite were carried out in the end of rainfall. According to the test results, the changes of the water content, the grain composition and the shear strength of the laterite in the model slope were analysed. The results showed that the effect of rainfall caused the water content of the laterite in the model slope to increase, and the altitude of the model slope was lower, the water content of the laterite in the model slope was higher. The effect of rainfall led to the density of the laterite in the model slope to decrease gradually when the altitude of the model slope was lower gradually. The grain composition exhibited that the silt content was increased and the clay content was reduced with the decrease of the model slope altitude. Based on analysing the variation of the water content, density and grain composition in the laterite of the model slope under the effect of rainfall, the changes of the shear strength of the laterite in the model slope were studied, further the changes of the cementatory characteristics of the laterite in the model slope were analysed under the effect of rainfall.

A feasibility study of the indoor test of the Yunnan laterite landslide was carried out under simulated rainfall conditions. In the study, the modeling material, the Yunnan laterite, was used to make lateritic slopes, and the effects of the size of the slope, the lateritic properties, the molding method, and the rainfall level were all considered. The tests results show that, the success rate is low if a laterite is directly selected for the indoor test. However, a lateritic slope landslide may occur if the test conditions are well controlled. Under the conditions of indoor rainstorms, the sliding process of the lateritic slopes can be divided into the following stages: the formation of the slope, the implementation of rainfall, the formation and development of the sliding surface, and the overall slide. The sliding characteristics can be expressed as cracking and sinking on the top of the slope first, and then cracking and extension on the sides of the slope. The conditions for sliding include larger values of the height and angle of the slope, a moderate width of the slope top, a lower plasticity index, a lower dry density, a moisture content of approaching the plastic limit, the stacked molding method, and a rainstorm.

With hydrochloric acid as the source of pollution, with laterite as the pollution soil, the shear strength and micro-structural characteristics of acid pollution laterite are studied by direct shear test. The results shown that, the shear strength and microstructure characteristics of acid pollution laterite are affected acid concentration and pollution time. The shear strength and indexes of acid pollution laterite decrease in general with the increase of acid concentration and the extension of the specimen pollution time, the shear strength and indexes exist a minimal value at lower concentration and shorter pollution time, the shear strength and indexes exist a great value at higher concentration and longer pollution time, the corresponding microstructure images present to the characteristics of compactness, roughness, color, texture.

The reservoir bank instability is the outcome combined the action of the external factors with the action of the internal factors. The limit equilibrium analysis, the strength reduction finite element method, the saturated/unsaturated seepage coupling and so on were applied to analyze the reservoir bank stability. The condition analogy graphical solution methods, the mathematical analysis method, the balanced cross-section method and so on were applied to forecast the reservoir bank stability. The reservoir bank instability mechanism depends on the physical action, the chemical action and the mechanical action of the water in the reservoir bank rock and soil. At present, the drainage measure, the cutting slope and reducing load measure, the retaining and supporting measure , the anti-slide piles measure and so on have been widely used to control the reservoir banks instability. Aiming at the research status of the reservoir bank instability, the problems in study and the suggestions for future work are pointed out in this paper.