廈門地區(qū)非飽和殘積土土水特征及強度性狀研究
發(fā)布時間：2018-10-20 07:00
【摘要】：殘積土層約占廈門島土地面積的三分之二,是工程建設巖土層的重要組成部分。在自然或人為地改變環(huán)境條件下,殘積土常經(jīng)受脫濕、增濕及干濕交替作用。此時,殘積土會呈現(xiàn)出與其在飽和狀態(tài)迥異的體積、強度、滲透和固結等性狀。非飽和土的強度在土坡穩(wěn)定、地基承載力及側向土壓力等分析計算中起著重要作用。而土水特征曲線(簡稱SWCC)是基質吸力與含水量或飽和度的關系曲線,它可幫助我們了解含水量對非飽和土強度的影響。因此,研究非飽和殘積土的土水特征曲線及抗剪強度具有重要的工程意義和應用前景。本文針對廈門地區(qū)常見的殘積砂質粘性土和殘積粘土,進行了不同干密度、含水量、豎向應力和干濕循環(huán)作用下SWCC測定、無側限抗壓強度和直接剪切的試驗研究,建立了SWCC模型、無側限抗壓強度及剪切強度模型。主要研究內容如下： 1.采用濾紙法測定基質吸力,分析了干密度、含水量、豎向應力及干濕循環(huán)作用等因素對殘積砂質粘性土和殘積粘土的脫濕曲線、吸濕曲線及滯回環(huán)的影響。試驗結果表明,砂質粘性土的SWCC與粘土的SWCC相比,前者的脫濕速率較大,進氣值較低,持水能力較弱。砂質粘性土的SWCC對干密度和豎向應力的變化較敏感,而粘土SWCC對含水量的變化較敏感；3次干濕循環(huán)中,第1次干濕循環(huán)對兩類殘積土SWCC的影響較大。 2.選擇了6個SWCC模型,剔除殘余飽和度參數(shù),建立修正SWCC模型。設置了考慮參數(shù)個數(shù)的模型權值,根據(jù)已測殘積土的SWCC試驗數(shù)據(jù),綜合考慮擬合精度及模型參數(shù)個數(shù),評估各修正SWCC模型的優(yōu)劣。計算結果表明修正Gardner模型是最適合于廈門地區(qū)的殘積砂質粘性土和粘土的SWCC模型。推導了修正的SWCC模型特征值計算公式,它們可取代作圖法,從而較準確地計算出空氣進氣值、曲線拐點的斜率、殘余基質吸力及殘余飽和度等參數(shù)。 3.設計了殘積砂質粘性土和粘土的無側限抗壓強度試驗,得到了考慮初始干密度和含水量下砂質粘性土的無側限抗壓強度經(jīng)驗模型和不同初始含水量下粘土的無側限抗壓強度經(jīng)驗模型。另外,測定了不同干濕幅度、路徑及次數(shù)下兩類殘積土的無側限抗壓強度,得到了干濕幅度、次數(shù)和路徑對兩類殘積土的無側限抗壓強度的影響規(guī)律。 4.采用普通的直剪儀進行非飽和殘積土的剪切強度試驗,并用濾紙法測定各不同含水量狀態(tài)下的基質吸力,研究剪切強度及強度指標隨初始含水量的變化規(guī)律,建立不同初始含水量下殘積砂質粘性土和粘土的剪切強度模型,能夠較好地預測殘積土的抗剪強度及強度指標。同時,開展了干濕循環(huán)作用對殘積土的試驗研究,得到了不同干濕循環(huán)幅度、路徑及次數(shù)下兩類殘積土的剪切強度和強度指標的變化規(guī)律,為今后干濕循環(huán)作用下殘積土強度模型的研究奠定基礎。
[Abstract]:The residual soil layer accounts for 2/3 of the land area of Xiamen Island and is an important part of the engineering construction of geotechnical strata. Under natural or artificial environmental conditions, residual soils are often subjected to dehumidification, humidification, and alternate drying and wetting. At this time, the residual soil will show different volume, strength, permeability and consolidation from its saturation state. The strength of unsaturated soil plays an important role in the analysis and calculation of slope stability, foundation bearing capacity and lateral earth pressure. The soil-water characteristic curve (SWCC) is the relationship between the matrix suction and water content or saturation, which can help us understand the influence of water content on the strength of unsaturated soil. Therefore, the study of soil water characteristic curve and shear strength of unsaturated residual soil has important engineering significance and application prospect. In this paper, SWCC measurement, unconfined compressive strength and direct shear of residual sandy clay and residual clay, under different dry density, water content, vertical stress and dry-wet cycle, are studied in Xiamen area. SWCC model, unconfined compressive strength and shear strength model are established. The main contents are as follows: 1. The effects of dry density, moisture content, vertical stress and dry wet cycle on the dehumidification curve, hygroscopic curve and hysteresis loop of residual sandy clay and residual clay were analyzed by filter paper method. The experimental results show that the SWCC of sandy clay is higher than that of clay SWCC, the former has higher moisture removal rate, lower inlet air value and weaker water holding capacity. The SWCC of sandy clay is more sensitive to the change of dry density and vertical stress, while the clay SWCC is more sensitive to the change of water content, and the first dry and wet cycle has a great effect on the SWCC of the two types of residual soils in three dry and wet cycles. 2. Six SWCC models were selected and the residual saturation parameters were eliminated. The modified SWCC model was established. The weight value of the model considering the number of parameters is set. According to the SWCC test data of the measured residual soil, the fitting accuracy and the number of model parameters are considered synthetically to evaluate the merits and demerits of each modified SWCC model. The results show that the modified Gardner model is the most suitable SWCC model for residual sandy clay and clay in Xiamen area. The modified formulas for calculating the eigenvalues of SWCC model are derived, which can replace the drawing method, so that the parameters such as air intake value, slope of curve inflection point, residual matrix suction and residual saturation can be calculated more accurately. The unconfined compressive strength tests of residual sandy clay and clay are designed. The empirical model of unconfined compressive strength of sandy clay under initial dry density and water content and the empirical model of unconfined compressive strength of clay with different initial water content are obtained. In addition, the unconfined compressive strength of the two types of residual soils under different dry-wet ranges, paths and times were measured, and the influence of dry and wet amplitude, times and paths on the unconfined compressive strength of the two types of residual soils was obtained. 4. The shear strength of unsaturated residual soil was tested with a direct shear apparatus, and the matrix suction under different water content was measured by filter paper method. The variation of shear strength and strength index with initial water content was studied. The shear strength model of residual sandy clay and clay under different initial water content can be used to predict the shear strength and strength index of residual sandy clay. At the same time, the experimental study of dry and wet cycling on residual soil was carried out, and the change rules of shear strength and strength index of two kinds of residual soil under different dry-wet cycle amplitude, path and times were obtained. It will lay a foundation for the study of strength model of residual soil under dry and wet cycle in the future.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TU41;TU44
本文編號：2282403
[Abstract]:The residual soil layer accounts for 2/3 of the land area of Xiamen Island and is an important part of the engineering construction of geotechnical strata. Under natural or artificial environmental conditions, residual soils are often subjected to dehumidification, humidification, and alternate drying and wetting. At this time, the residual soil will show different volume, strength, permeability and consolidation from its saturation state. The strength of unsaturated soil plays an important role in the analysis and calculation of slope stability, foundation bearing capacity and lateral earth pressure. The soil-water characteristic curve (SWCC) is the relationship between the matrix suction and water content or saturation, which can help us understand the influence of water content on the strength of unsaturated soil. Therefore, the study of soil water characteristic curve and shear strength of unsaturated residual soil has important engineering significance and application prospect. In this paper, SWCC measurement, unconfined compressive strength and direct shear of residual sandy clay and residual clay, under different dry density, water content, vertical stress and dry-wet cycle, are studied in Xiamen area. SWCC model, unconfined compressive strength and shear strength model are established. The main contents are as follows: 1. The effects of dry density, moisture content, vertical stress and dry wet cycle on the dehumidification curve, hygroscopic curve and hysteresis loop of residual sandy clay and residual clay were analyzed by filter paper method. The experimental results show that the SWCC of sandy clay is higher than that of clay SWCC, the former has higher moisture removal rate, lower inlet air value and weaker water holding capacity. The SWCC of sandy clay is more sensitive to the change of dry density and vertical stress, while the clay SWCC is more sensitive to the change of water content, and the first dry and wet cycle has a great effect on the SWCC of the two types of residual soils in three dry and wet cycles. 2. Six SWCC models were selected and the residual saturation parameters were eliminated. The modified SWCC model was established. The weight value of the model considering the number of parameters is set. According to the SWCC test data of the measured residual soil, the fitting accuracy and the number of model parameters are considered synthetically to evaluate the merits and demerits of each modified SWCC model. The results show that the modified Gardner model is the most suitable SWCC model for residual sandy clay and clay in Xiamen area. The modified formulas for calculating the eigenvalues of SWCC model are derived, which can replace the drawing method, so that the parameters such as air intake value, slope of curve inflection point, residual matrix suction and residual saturation can be calculated more accurately. The unconfined compressive strength tests of residual sandy clay and clay are designed. The empirical model of unconfined compressive strength of sandy clay under initial dry density and water content and the empirical model of unconfined compressive strength of clay with different initial water content are obtained. In addition, the unconfined compressive strength of the two types of residual soils under different dry-wet ranges, paths and times were measured, and the influence of dry and wet amplitude, times and paths on the unconfined compressive strength of the two types of residual soils was obtained. 4. The shear strength of unsaturated residual soil was tested with a direct shear apparatus, and the matrix suction under different water content was measured by filter paper method. The variation of shear strength and strength index with initial water content was studied. The shear strength model of residual sandy clay and clay under different initial water content can be used to predict the shear strength and strength index of residual sandy clay. At the same time, the experimental study of dry and wet cycling on residual soil was carried out, and the change rules of shear strength and strength index of two kinds of residual soil under different dry-wet cycle amplitude, path and times were obtained. It will lay a foundation for the study of strength model of residual soil under dry and wet cycle in the future.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TU41;TU44
【參考文獻】
相關期刊論文 前10條
1 李培勇;楊慶;;非飽和土抗剪強度的非線性分析[J];大連交通大學學報;2009年01期
2 張永波,張云,陳戈,殷密英;花崗巖殘積土工程類型劃分體系研究[J];地球學報;1997年02期
3 王清;蔣惠忠;唐大雄;;閩南三角地區(qū)花崗巖殘積土及其工程地質特性的研究[J];福建地質;1990年02期
4 閆亞景;文寶萍;計博勛;;基質吸力對非飽和重塑黃土抗剪強度的貢獻[J];工程地質學報;2011年06期
5 劉艷華,龔壁衛(wèi),蘇鴻;非飽和土的土水特征曲線研究[J];工程勘察;2002年03期
6 關亮;陳正漢;黃雪峰;孫樹國;方祥位;;非飽和重塑黃土的三軸試驗研究[J];工程勘察;2011年11期
7 肖治宇;陳昌富;楊劍祥;;非飽和殘坡積土強度隨含水量變化試驗研究[J];湖南大學學報(自然科學版);2010年10期
8 羅軍;王桂堯;匡波;;含水量對粉土強度影響的試驗研究[J];路基工程;2010年01期
9 胡孝彭;趙仲輝;倪曉雯;;應力狀態(tài)對土-水特征曲線的影響規(guī)律[J];河海大學學報(自然科學版);2013年02期
10 邊加敏;王保田;;含水量對非飽和土抗剪強度影響研究[J];人民黃河;2010年11期
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