【摘要】：膨脹土是一種吸水膨脹、失水收縮的高塑性粘土,具有超固結(jié)性、多裂隙性等不良工程特性。膨脹土邊坡易受氣候變化的影響,其降雨蒸發(fā)干濕循環(huán)效應(yīng)顯著,大量的膨脹土邊坡失穩(wěn)是發(fā)生在降雨期間或者降雨之后,其治理難度大。在降雨蒸發(fā)過程中,對于遇水極為敏感且滲透性極低的膨脹土邊坡而言,膨脹土的密度和結(jié)構(gòu)在局部范圍內(nèi)發(fā)生變化。而體積含水率的分布變化在降雨蒸發(fā)過程中能被最直接的反映出來,也是反映土體強(qiáng)度的最直接的物理量。本文通過室內(nèi)試驗、理論分析與數(shù)值模擬相結(jié)合的方法,建立了土柱模型、不同坡比的膨脹土邊坡模型,旨在探討降雨蒸發(fā)干濕循環(huán)對土柱和邊坡土體內(nèi)部體積含水率分布的影響。本文主要研究工作及成果概括如下:(1)在蒸發(fā)階段,土柱表層土體水分消散的較快,隨著土體埋深增大,水分消散的越慢,并且呈現(xiàn)一定的規(guī)律性。在降雨階段,不同的降雨強(qiáng)度對土柱內(nèi)部體積含水率分布的影響也不同,在一定范圍內(nèi),降雨強(qiáng)度越大,其影響越明顯;而超過一定范圍,隨著降雨強(qiáng)度增大,其影響是有限的。(2)蒸發(fā)效應(yīng)的敏感性分析,主要考慮氣候條件對蒸發(fā)的影響。結(jié)果表明,凈輻射量、風(fēng)速和最大相對溫度對土體蒸發(fā)的影響較大,尤其以凈輻射量和最大相對溫度對蒸發(fā)的影響最為顯著。(3)在降雨蒸發(fā)干濕循環(huán)條件下,膨脹土邊坡的不同部位的干濕效果不同,坡頂?shù)母蓾裱h(huán)效果最為明顯,其次是坡中和坡腳。用nz wwwe????max0???曲線方程可以很好地描述膨脹土邊坡的水分空間分布特性及變化規(guī)律,在此基礎(chǔ)上提出了考慮降雨蒸發(fā)條件下以土體埋深為變量的膨脹土邊坡土體強(qiáng)度關(guān)系式,即強(qiáng)度~體積含水量~埋深的關(guān)系式。(4)通過不同坡比的膨脹土邊坡滲流分析,發(fā)現(xiàn)坡比不同,降雨對邊坡整個滲流場的影響也不同。坡比的差異性在降雨初期和后期表現(xiàn)的較為明顯,坡比越小,水分分布梯度越大,且具有顯著的降雨滯后效應(yīng)。(5)根據(jù)強(qiáng)度~體積含水率~埋深關(guān)系式,對膨脹土邊坡進(jìn)行了強(qiáng)度分層,強(qiáng)度分層的邊坡穩(wěn)定性要高于不分層的邊坡穩(wěn)定性。邊坡穩(wěn)定性受坡比的影響強(qiáng)烈,對于某特定的氣候環(huán)境和土性參數(shù),在一定范圍內(nèi),存在一個最優(yōu)坡比,邊坡安全系數(shù)取極大值。
[Abstract]:Expansive soil is a kind of high plastic clay with water absorption and expansion and water loss and shrinkage, which has some bad engineering characteristics, such as overconsolidation, multiple cracks and so on. Expansive soil slope is easily affected by climate change, and its dry and wet cycle effect of rainfall evaporation is remarkable. A large number of expansive soil slope instability occurs during or after rainfall, so it is difficult to control it. In the process of rainfall evaporation, the density and structure of expansive soil change in local range for expansive soil slope, which is very sensitive to water and has low permeability. The distribution of volume moisture content can be reflected most directly in the process of rainfall evaporation, and it is also the most direct physical quantity reflecting the strength of soil. In this paper, the soil column model and expansive soil slope model with different slope ratios are established by means of laboratory test, theoretical analysis and numerical simulation. The purpose of this paper is to investigate the effect of rainfall evaporation dry and wet cycle on the distribution of volume moisture content in soil columns and slopes. The main research work and results of this paper are summarized as follows: (1) in the evaporation stage, the water dissipation of the surface soil of the soil column is faster, and with the increase of the buried depth of the soil, the slower the water dissipation, and presents a certain regularity. In the rainfall stage, the influence of different rainfall intensity on the distribution of volume moisture content in soil column is also different. In a certain range, the greater the rainfall intensity is, the more obvious the influence is. Over a certain range, with the increase of rainfall intensity, the influence is limited. (2) the sensitivity analysis of evaporation effect mainly considers the influence of climatic conditions on evaporation. The results show that the net radiation, wind speed and maximum relative temperature have great influence on soil evaporation, especially the net radiation and maximum relative temperature have the most significant effect on evaporation. (3) under the condition of dry and wet cycle of rainfall evaporation, The dry and wet effects of different parts of expansive soil slope are different, and the effect of dry and wet cycle on the top of the slope is the most obvious, followed by the neutralization of the slope and the foot of the slope. Using nz wwwe?max0? The curve equation can well describe the spatial distribution characteristics and variation law of water on expansive soil slope. On this basis, the relationship between soil strength of expansive soil slope considering rainfall evaporation and soil depth as variable is put forward. That is, the relationship between strength, volume water content and buried depth. (4) through the seepage analysis of expansive soil slope with different slope ratio, it is found that the influence of rainfall on the whole seepage field of slope is also different when the slope ratio is different. The difference of slope ratio is obvious in the early and late stages of rainfall. The smaller the slope ratio is, the greater the gradient of water distribution is, and has a significant rainfall lag effect. (5) according to the relationship between intensity, volume moisture content and buried depth, The strength stratification of expansive soil slope is carried out, and the slope stability of strength stratification is higher than that of unlayered slope. Slope stability is strongly affected by slope ratio. For a specific climate environment and soil parameters, there is an optimal slope ratio in a certain range, and the slope safety factor is maximized.
【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU443

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 包承綱;非飽和土的性狀及膨脹土邊坡穩(wěn)定問題[J];巖土工程學(xué)報;2004年01期

2 陳建斌;孔令偉;趙艷林;呂海波;;非飽和土的蒸發(fā)效應(yīng)與影響因素分析[J];巖土力學(xué);2007年01期

3 楊洋;姚海林;盧正;;蒸發(fā)條件下路基對氣候變化的響應(yīng)模型及影響因素分析[J];巖土力學(xué);2009年05期

，

本文編號：2479927