湖淤積高液限粘土用作路基填料的物理力學特性研究
發(fā)布時間：2019-06-09 13:31
【摘要】：黃泛區(qū)湖淤積高液限粘土或以湖相沉積層、或以粉土夾層廣泛分布于魯西南-魯西北平原區(qū),其塑性和粘性較高,水穩(wěn)定性差,難以壓實。目前在此類地區(qū)修建道路時,一般按規(guī)范要求,采用換填或改性處理的方法,造成土地資源的浪費,增加工程造價。因此,研究湖淤積高液限粘土的直接利用與經(jīng)濟改性技術(shù),具有重大的理論意義與工程應用價值。本研究選取濟徐高速公路沿線的典型湖淤積高液限粘土,通過室內(nèi)試驗研究其物理、力學特性,以揭示該類土的壓實特性以及在不同含水率與壓實度狀態(tài)下的強度變化規(guī)律。同時,針對路床區(qū)填料強度要求,對該類土進行改性研究。采用FLAC3D軟件分析該類土填筑路基的變形穩(wěn)定性,提出該類土用作路基填料碾壓控制含水率、壓實度的臨界指標。室內(nèi)試驗及數(shù)值模擬結(jié)果表明：(1)黃泛區(qū)湖淤積高液限粘土的顆粒組成以粉粒和粘粒為主,粘土礦物含量高,其塑性指數(shù)高而塑限偏低。因此,該類土兼有粉土與高液限粘土的性質(zhì),表現(xiàn)出高的粘滯力、強的吸濕性和保水性,其壓實過程中對水敏感性強,高于最佳含水率以后4%后飽和度較高,壓實易出現(xiàn)彈簧現(xiàn)象。(2)該類土的CBR值、抗剪強度、回彈模量及壓縮模量等力學性質(zhì)指標表現(xiàn)出相同的規(guī)律性,隨壓實度的增加而增加,隨含水率的增加而降低。該類土的水穩(wěn)定性差,含水率是影響其力學性質(zhì)的主要因素。在含水率不高于最佳含水量4%、壓實度90%以上時,其強度較高,不浸水CBR值滿足規(guī)范對路堤區(qū)填料最低要求。(3)石灰改性和小劑量石灰與粉煤灰的改性效果較好,摻灰拌合后的悶料時間宜為3～4天。改性土的CBR強度在壓實度90%以上時可達10%以上,滿足規(guī)范對路床區(qū)填料的最小承載比要求。(4)黃泛區(qū)湖淤積高液限粘土用作路基填料時,路堤區(qū)的碾壓控制含水率在最佳含水率的基礎上提高4%、壓實度較規(guī)范標準降低3個百分點后,路基的變形與穩(wěn)定性可滿足路用要求。
[Abstract]:The lake siltation of high liquid limit clay or lacustrine sedimentary layer or silt interlayer is widely distributed in the southwest Shandong-northwest Shandong plain in the Yellow River flooding area. The plasticity and viscosity of the lake are high and the water stability is poor, so it is difficult to compaction. At present, when building roads in this kind of area, according to the requirements of the code, the method of replacement and filling or modification is generally adopted, which results in the waste of land resources and increases the cost of the project. Therefore, it is of great theoretical significance and engineering application value to study the direct utilization and economic modification technology of high liquid limit clay in lake siltation. In this study, the typical lake silted high liquid limit clay along Jixu Expressway was selected to study its physical and mechanical properties through laboratory tests in order to reveal the compaction characteristics of this kind of soil and the variation of strength under different water content and compaction conditions. At the same time, according to the requirement of packing strength in road bed area, the modification of this kind of soil was studied. The deformation stability of subgrade filled with this kind of soil is analyzed by FLAC3D software, and it is put forward that this kind of soil can be used as a critical index to control moisture content and compaction degree of subgrade filling. The results of laboratory test and numerical simulation show that: (1) the particle composition of high liquid limit clay in lake siltation in the flood area of the Yellow River is mainly silt and clay, the clay mineral content is high, the plastic index is high and the plastic limit is on the low side. Therefore, this kind of soil has the properties of both silt and high liquid limit clay, showing high viscosity, strong hygroscopicity and water retention, and has strong sensitivity to water in the compaction process, which is higher than that of 4% after the optimum moisture content. Compaction is easy to appear spring phenomenon. (2) the mechanical properties of this kind of soil, such as RR value, shear strength, springback modulus and compression modulus, show the same regularity, increase with the increase of compaction degree, and decrease with the increase of moisture content. The water stability of this kind of soil is poor, and the moisture content is the main factor affecting its mechanical properties. When the moisture content is not higher than the optimum water content 4% and the compaction degree is more than 90%, the strength is higher, and the CBR value of non-immersion meets the minimum requirements of the code for embankment filling. (3) the modification effect of lime modification and low dose lime and fly ash is better. The stuffing time after mixing with ash should be 3 times 4 days. The CBR strength of the modified soil can reach more than 10% when the compaction degree is more than 90%, which meets the requirements of the code for the minimum bearing ratio of the filling in the road bed area. (4) when the lake siltation high liquid limit clay is used as subgrade filling in the flood area of the Yellow River, After the rolling control moisture content of embankment area is increased by 4% on the basis of the optimum moisture content, and the compaction degree is reduced by 3% compared with the standard, the deformation and stability of subgrade can meet the requirements of road use.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U416.1
本文編號：2495587
[Abstract]:The lake siltation of high liquid limit clay or lacustrine sedimentary layer or silt interlayer is widely distributed in the southwest Shandong-northwest Shandong plain in the Yellow River flooding area. The plasticity and viscosity of the lake are high and the water stability is poor, so it is difficult to compaction. At present, when building roads in this kind of area, according to the requirements of the code, the method of replacement and filling or modification is generally adopted, which results in the waste of land resources and increases the cost of the project. Therefore, it is of great theoretical significance and engineering application value to study the direct utilization and economic modification technology of high liquid limit clay in lake siltation. In this study, the typical lake silted high liquid limit clay along Jixu Expressway was selected to study its physical and mechanical properties through laboratory tests in order to reveal the compaction characteristics of this kind of soil and the variation of strength under different water content and compaction conditions. At the same time, according to the requirement of packing strength in road bed area, the modification of this kind of soil was studied. The deformation stability of subgrade filled with this kind of soil is analyzed by FLAC3D software, and it is put forward that this kind of soil can be used as a critical index to control moisture content and compaction degree of subgrade filling. The results of laboratory test and numerical simulation show that: (1) the particle composition of high liquid limit clay in lake siltation in the flood area of the Yellow River is mainly silt and clay, the clay mineral content is high, the plastic index is high and the plastic limit is on the low side. Therefore, this kind of soil has the properties of both silt and high liquid limit clay, showing high viscosity, strong hygroscopicity and water retention, and has strong sensitivity to water in the compaction process, which is higher than that of 4% after the optimum moisture content. Compaction is easy to appear spring phenomenon. (2) the mechanical properties of this kind of soil, such as RR value, shear strength, springback modulus and compression modulus, show the same regularity, increase with the increase of compaction degree, and decrease with the increase of moisture content. The water stability of this kind of soil is poor, and the moisture content is the main factor affecting its mechanical properties. When the moisture content is not higher than the optimum water content 4% and the compaction degree is more than 90%, the strength is higher, and the CBR value of non-immersion meets the minimum requirements of the code for embankment filling. (3) the modification effect of lime modification and low dose lime and fly ash is better. The stuffing time after mixing with ash should be 3 times 4 days. The CBR strength of the modified soil can reach more than 10% when the compaction degree is more than 90%, which meets the requirements of the code for the minimum bearing ratio of the filling in the road bed area. (4) when the lake siltation high liquid limit clay is used as subgrade filling in the flood area of the Yellow River, After the rolling control moisture content of embankment area is increased by 4% on the basis of the optimum moisture content, and the compaction degree is reduced by 3% compared with the standard, the deformation and stability of subgrade can meet the requirements of road use.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U416.1
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