本文選題：黃泛區(qū) + 粉土��； 參考：《中國地質大學》2017年博士論文

【摘要】：在黃泛區(qū),粉土粒徑較為均一的粉粒堆積孔隙缺乏細粒填充,即使按照現(xiàn)行規(guī)范的壓實方法也不易形成密實結構體,毛細孔隙發(fā)達,雨季集中降水以及高地下水位有利條件下孔隙內水分運輸致使路基土顯著增濕、誘發(fā)多種工程問題出現(xiàn)。路基土的增濕機制涉及到(非)飽和滲透、水分特征曲線與毛細吸水等水力特征參數(shù),而目前研究人員對黃泛區(qū)粉土的研究大都集中在壓實度、毛細水上升高度及強度與含水量關系等方面,并沒有注意到黃泛區(qū)粉土水力特征參數(shù)與干密度、壓實含水量關系以及經驗估算的方法。從已發(fā)表的研究文獻看,目前還沒有這方面的相關資料,這直接影響到對黃泛區(qū)粉土路基病害機理的認識與分析。鑒于此,本文從黃泛區(qū)粉土的水力特征參數(shù)入手,采用(非)飽和滲透系數(shù)、水分特征曲線、毛細吸水性室內實驗與理論分析方法,研究黃泛區(qū)粉土的(非)飽和滲透性、毛細吸水性、水分特征曲線,獲得了黃泛區(qū)粉土水力特征參數(shù)的變化規(guī)律,建立了土粒堆積填充等效孔隙模型,并將土粒堆積填充等效孔隙模型應用到水分特征曲線的估算方法中,闡明了黃泛區(qū)粉土水力特征參數(shù)隨干密度與壓實含水量的變化機理。本文的主要研究工作如下:1.通過資料搜集闡明了黃泛區(qū)的區(qū)域范圍,涵蓋了河南省鄭州、開封、濮陽等地區(qū),山東省菏澤(東明縣)、濟寧、聊城、濟南、濱州、東營等地區(qū),以及蘇北故黃河泛濫地區(qū)�？傮w來說,該地區(qū)粉土的粉粒含量都在60%以上,粉土的砂粒絕大部分粒徑均小于0.25mm;粘粒含量基本上處于5%~15%之間。Fredlund(F)模型適合描述黃泛區(qū)粉土粒徑分布函數(shù),模型參數(shù)回歸表明:參數(shù)α大體上隨著粉土砂粒含量的增大而增大;參數(shù)n的變化規(guī)律呈現(xiàn)分段性,當粉粒含量小于75%時,參數(shù)n隨著粉粒含量的增大而降低,當粉粒含量大于75%時,參數(shù)n隨著粉粒含量的增大而增大;參數(shù)m隨著參數(shù)n的增大而減小,當參數(shù)n大于5.5以后,參數(shù)m基本穩(wěn)定在0.5~1之間。2.通過簡化堆積填充過程中土粒間互相作用關系與條件,構建了均一土粒堆積模式,推導了孔隙比(半徑)與堆積土粒數(shù),以及毛細管半徑的函數(shù)關系表達式。緊密堆積狀態(tài)下不存在細粒鍥入效應,在此基礎上推導出了依據(jù)粗粒細粒分量比的土粒堆積模式辨別方法,若細粒與粗粒徑比處于0.05~0.5內時,均一堆積壓實度為0.6,緊密堆積時所需細粒分量始終為0.325左右。按總孔隙體積相等的原則構建了兩組份土粒堆積等效孔隙模式,并分別推導了粗粒與細粒骨架模式下孔隙比與等效毛細孔徑的函數(shù)表達式。多組份土粒堆積涉及多種不等粒徑顆粒之間接觸堆積關系,采用了緊密堆積與兩兩組合的簡化原則將多種不等粒徑顆粒之間接觸堆積關系簡化為多種兩組份土粒堆積關系,復雜孔隙構成關系也簡化為骨架土�？紫�、骨架-非骨架土�？紫逗凸羌�-次骨架土�？紫�。在此基礎上,構建了多組份土粒堆積等效孔隙模式。最后,確立了多組份土粒堆積時的匹配原則與次序,等效孔隙參數(shù)的計算步驟與方法。3.在孔隙比位于0.51~0.71范圍內,飽和滲透系數(shù)均值位于10-4cm/s左右,屬于中等滲透性土。飽和滲透系數(shù)與孔隙比成指數(shù)關系,隨孔隙比增大而非線性增大。壓實含水量大于最優(yōu)含水量時隨孔隙比非線性增大最為顯著,最優(yōu)含水量時非線性最不顯著。飽和滲透系數(shù)與壓實含水量關系復雜。在大孔隙比的條件下,飽和滲透系數(shù)與壓實含水量呈非線性關系,當壓實含水量大于最優(yōu)含水量時,飽和滲透系數(shù)隨壓實含水量的增大而增大,當含壓實含水量小于最優(yōu)含水量時,飽和滲透系數(shù)隨含水量的增大而減小,最優(yōu)含水量時,飽和滲透系數(shù)總是最小。在小孔隙比的條件下,試樣的飽和滲透系數(shù)與壓實含水量近似呈線性關系,飽和滲透系數(shù)隨壓實含水量的增大而減小。最優(yōu)含水量條件下壓實土體的飽和滲透系數(shù)對孔隙比的敏感度較低,也就是說,最優(yōu)含水量條件下壓實路基土時,實際控制孔隙比稍有偏差對飽和滲透系數(shù)造成的不利影響相對要小。4.黃泛區(qū)粉土的水分特征曲線具有典型水分特征曲線的形態(tài)特征,包含了邊界效應區(qū)、第一過渡區(qū)和第二過渡區(qū)、非飽和殘余區(qū)。(1)當壓實含水量小于最優(yōu)含水量時,干密度對水分特征曲線形態(tài)的影響在邊界效應區(qū);壓實含水量大于最優(yōu)含水量時,干密度對水分特征曲線形態(tài)的影響在過渡區(qū)。壓實含水量控制著水分特征曲線過渡區(qū)的斜率與寬度。壓實含水量高于最優(yōu)含水量,過渡區(qū)曲線整體平緩,第一過渡區(qū)特征消失;壓實含水量低于最優(yōu)含水量,過渡區(qū)曲線有陡降段與平緩段,即第一過渡區(qū)和第二過渡區(qū)特征明顯。(2)基于基質吸力0~500kPa范圍內實驗數(shù)據(jù)點,采用VG模型的擬合曲線與實驗值比較吻合,且表達出水分特征曲線所具有典型形態(tài)特征。VG模型參數(shù)a、飽和含水率隨干密度、壓實含水量的增大而線性減小;殘余含水率與干密度、壓實含水量成線性關系,隨著干密度增大而減小,隨著壓實含水量增大而增大;模型參數(shù)n由干密度與壓實含水量共同控制。(3)基于AP模型的水分特征曲線預測值僅在0~100kPa的基質吸力范圍內與實驗值吻合度較好,當基質吸力大于100kPa時,預測含水量比實測值小的多。(4)采用基于土粒等效孔隙模型且疊加膜狀水和吸附水后的水分特征曲線在基質吸力為0~500kPa范圍內與實驗數(shù)據(jù)更加吻合,能更準確地表達黃泛區(qū)粉土中、高飽和狀態(tài)下的的水分特征曲線形態(tài)。但綜合預測曲線并不完整,沒有能反映包含高基質吸力段在內的水分特征曲線形態(tài)特征。5.毛細吸水量時程擬合曲線分為兩類,毛細吸水過程有明顯的快速吸水段和勻速吸水段之分,快速段內累計毛細吸水量與時間之間為二次函數(shù)關系,勻速吸水段內為兩者為線性關系。毛細吸水過程吸水速度沒有明顯的陡降,整個毛細吸水過程中累計毛細吸水量與時間為二次函數(shù)關系。壓實含水量控制著土樣毛細吸水率-時間曲線的形態(tài)。壓實含水量小于最優(yōu)含水量時,土樣吸水速率和吸水量均隨著干密度的增大而減小,壓實含水量大于最優(yōu)含水量時,土樣吸水速率和吸水量均隨著干密度的增大而增大,最優(yōu)含水量時,最大干密度土樣的吸水速率和吸水量屬于中等。干密度和壓實含水量共同控制著土毛細吸水速率和吸水量,最優(yōu)含水量和最大干密度狀態(tài)附近毛細吸水現(xiàn)象比較顯著。毛細吸水上升速度隨著吸水時間延長逐漸減小,毛細水上升高度與吸水時間在雙對數(shù)坐標中成二次函數(shù)關系;毛細水上升穩(wěn)定后土的含水量沿吸水高度大致線性減小。6.總體上,非飽和排水量隨著干密度的增大而減小,但是并非隨著干密度的增加而單調減小或增大。干密度較小情況下,壓實含水量為最優(yōu)含水量時自重排水量最大;干密度較大情況下,壓實含水量大于最優(yōu)含水量時,土樣在基質吸力大于25kPa后排水速度較大。壓實含水量對排水時程曲線形態(tài)、排水速率影響較大。采用基于Arya-Paris模型的非飽和滲透系數(shù)計算結果表明,隨著飽和度的降低,非飽和滲透系數(shù)迅速減小,當飽和度由0.9減小到0.1時,非飽和滲透系數(shù)快速從10-5數(shù)量級減小到10-10數(shù)量級,特別地,當基質吸力增加到105kPa時,非飽和滲透系數(shù)降低到10-10數(shù)量級,此時主要受粘�？刂�,當基質吸力繼續(xù)增大時,非飽和滲透系數(shù)的降低速率明顯下降,且減小幅度也大大降低。
[Abstract]:In the yellow area, the fine particle size of silt particles is not filled with fine particles. Even if the compaction method of current standard is not easy to form dense structure, the capillary pores are well developed, the precipitation in the rainy season and the water level in the high ground water lead to the significant wetting of the subgrade soil, which induces a variety of engineering problems. The humidification mechanism of subgrade soil involves the hydraulic characteristic parameters such as (non) saturated permeability, water characteristic curve and capillary water absorption, but most researchers have concentrated on the compaction degree, the height of the capillary water and the relationship between the strength and the water content, and the hydraulic characteristic parameters and dry density of the yellow pan soil are not paid attention to. In view of the hydraulic characteristic parameters of the silty soil in the Yellow pan area, this paper starts with the hydraulic characteristic parameters of the silty soil in the Yellow pan region, and uses the saturated permeability coefficient and the moisture content. The (non) saturated permeability, capillary water absorption and water characteristic curves of the silt in the yellow area are studied, and the variation law of the hydraulic characteristic parameters of the silt is obtained. The equivalent Kong Ximo type of soil accumulation filling and filling is established, and the equivalent pore model is applied to the water to apply to the water. In the estimation of the characteristic curve, the variation mechanism of the hydraulic characteristic parameters of the silt in the Yellow River area with the dry density and the compacted water content is clarified. The main research work of this paper is as follows: 1. through the collection of data, the regional range of the Yellow River area is clarified, covering Zhengzhou, Kaifeng, Puyang, Shandong Province, Heze (Dongming county), Jining, Liaocheng, and other areas in Henan province. In Ji'nan, Binzhou, Dongying and so on, as well as the flooding area of the Yellow River in Northern Jiangsu Province, the silt content of the silt in this area is above 60% and the most of the silt grains are less than 0.25mm, and the.Fredlund (F) model of the clay content is basically between the 5%~15% and the grain size distribution function of the Yellow pan silt, and the regression of the model parameters shows that The parameter n increases with the increase of silt sand content, and the parameter n changes piecewise. When the powder content is less than 75%, the parameter n decreases with the increase of the powder content. When the powder content is more than 75%, the parameter n increases with the increase of the powder content; parameter m decreases with the increase of the parameter n, when the parameter n is greater than 5 After.5, the parameter m is basically stable between 0.5~1 and.2. by simplifying the intergranular interaction and condition of the soil particles in the process of packing and filling. A homogeneous soil accumulation model is constructed. The expression of the function relation between the pore ratio (radius) and the number of accumulated soil particles and the capillary radius is derived. On the basis of this, a method for identifying the soil grain accumulation based on the ratio of coarse grain and fine grain is derived. If the ratio of fine grain to coarse particle size is within 0.05~0.5, the bulk density is 0.6, and the fine grain components are always about 0.325. The equivalent pore pattern of two components is constructed according to the principle of total pore volume. The function expression of the pore ratio and the equivalent capillary pore size under the coarse grain and fine grain framework model is derived. The accumulation of multi component soil particles involves a variety of contact accumulation relations between different particle sizes, and the close accumulation and the 22 combination principle are adopted to simplify the contact accumulation relationship between different particle sizes into a variety of two components. The relationship between the complex pore structure and the complex pore structure is also simplified as the skeleton grain pore, the skeleton non skeleton pore and the skeleton and the skeleton grain pore. On this basis, the equivalent pore model of the multi component soil particle accumulation is constructed. Finally, the matching principle and order of the accumulation of multiple components of the soil are established, and the calculation procedure and method of the equivalent pore parameters,.3 When the pore ratio is located in the range of 0.51~0.71, the mean value of the saturation permeability coefficient is about 10-4cm/s, which belongs to medium permeability soil. The saturated permeability coefficient is exponentially related to the porosity ratio, and the nonlinearity increases with the increase of the pore ratio. When the compacted water content is larger than the optimal water content, it is the most significant with the non linear increase of the pore ratio, and the optimal water content is nonlinear. The saturation permeability coefficient has a complicated relationship with the compacted water content. Under the condition of large pore ratio, the saturated permeability coefficient and the compacted water content have a nonlinear relationship. When the compacted water content is greater than the optimal water content, the saturated permeability coefficient increases with the increase of the compacted water content. The saturation permeability coefficient is always the smallest when the water content is increased. Under the condition of small pore ratio, the saturated permeability coefficient of the sample is approximately linear with the compacted water content, and the saturated permeability coefficient decreases with the increase of the compacted water content. The saturated permeability coefficient of the compacted soil under the optimal water content condition The sensitivity of the pore ratio is low, that is to say, when the soil is compacted under the optimal water content, the actual control pore ratio is slightly deviated from the negative effect on the saturated permeability coefficient. The water characteristic curve of the.4. yellow pan silt has the shape characteristic of the typical water characteristic curve, including the boundary effect area and the first transition zone. And second transition zone, unsaturated residual area. (1) when the compacted water content is less than the optimal water content, the effect of dry density on the shape of water characteristic curve is in the boundary effect area; when the compacted water content is greater than the optimal water content, the influence of dry density on the shape of water characteristic curve is in the transition zone. The slope and width. The compacted water content is higher than the optimal water content, the transition zone curve is slow and the first transition zone is disappearing; the compacted water content is lower than the optimal water content, the curve of the transition region has a steep drop section and the gentle section, that is, the first transition zone and the second transition zone are distinct. (2) based on the experimental data points within the range of matrix suction 0~500kPa, V The fitting curves of the G model are in agreement with the experimental values, and the typical morphological characteristics of the water content curve are expressed as the.VG model parameter a. The saturated water content decreases linearly with the increase of dry density and compacted water content, and the residual water content is linearly related to dry density and compacted water content, and decreases with the increase of dry density, with the compaction water cut. The model parameter n is controlled by the dry density and the compacted water content. (3) the prediction value of the water characteristic curve based on the AP model is only in good agreement with the experimental values in the range of the matrix suction of 0~100kPa. When the matrix suction is greater than 100kPa, the predicted water content is much smaller than the measured value. (4) the equivalent pore model based on the soil particle is used. The water characteristic curve of superimposing membrane water and adsorbing water is more consistent with the experimental data in the range of matrix suction 0~500kPa, which can more accurately express the water characteristic curve in the high saturation state of the Yellow pan silt, but the comprehensive prediction curve is not complete and can not reflect the water characteristics including the high matrix suction section. The curve shape characteristic.5. capillary water absorption time course fitting curve is divided into two types, the capillary water absorption process has obvious quick water absorption section and uniform water absorption section, the accumulated capillary water absorption and time in the fast segment are two function relations, and the uniform water absorption section is linear relationship. The water absorption speed of the capillary water absorption process has no obvious steepness. The cumulative water absorption and time in the whole capillary water absorption are two functions. The compacted water content controls the shape of the soil sample capillary water absorption time curve. When the compacted water content is less than the optimal water content, the water absorption rate and water absorption of the soil sample decreases with the increase of dry density, and the compacted water content is greater than the optimal water content. The water absorption rate and water absorption increase with the increase of dry density. The water absorption rate and water absorption of the maximum dry density soil samples are medium. The dry density and the compacted water content control the soil capillary water absorption rate and water absorption, and the capillary water absorption near the optimal water content and the maximum dry density is remarkable. The rising velocity of capillary water absorbency gradually decreases with the extension of water absorption time, the rising height of capillary water and the time of water absorption are two function relations in the double logarithmic coordinates; the water content of the soil after the rising of capillary water is roughly linearly reduced along the water absorption height of.6., and the unsaturated drainage amount decreases with the increase of dry density, but not with the dry water. When the dry density is smaller, the weight of self weight and drainage is the largest when the compacted water content is the optimal water content. When the dry density is larger than the optimal water content, the soil sample has a larger drainage speed after the matrix suction is more than 25kPa. The results of the unsaturated permeability coefficient calculation based on the Arya-Paris model show that the unsaturated permeability coefficient decreases rapidly with the decrease of saturation, and when the saturation is reduced from 0.9 to 0.1, the unsaturated permeability coefficient decreases rapidly from 10-5 orders of magnitude to 10-10 orders of magnitude, especially when the matrix suction is increased to 105kPa, the unsaturated permeability coefficient is unsaturated. The permeability coefficient is reduced to 10-10 orders of magnitude, which is mainly controlled by the clay particles. When the matrix suction continues to increase, the reduction rate of the unsaturated permeability coefficient decreases obviously, and the decrease is also greatly reduced.

【學位授予單位】：中國地質大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：U416.1

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