本文選題：斜坡地基 + 地基極限承載力　； 參考：《長(zhǎng)安大學(xué)》2015年博士論文

【摘要】：論文通過(guò)離心模型試驗(yàn)、理論計(jì)算和數(shù)值分析,研究了斜坡地基的變形規(guī)律和破壞特征,分析了地基土參數(shù)、坡面條件、荷載條件以及摩擦條件等對(duì)斜坡地基的極限坡面曲線和坡頂極限荷載的影響,并從斜坡地基中塑性區(qū)開(kāi)展范圍的角度分析其內(nèi)在原因。主要研究成果如下:1、斜坡地基破壞形式呈非對(duì)稱性,較之平地地基,斜坡地基上的基礎(chǔ)更易發(fā)生傾斜,從而導(dǎo)致應(yīng)力向傾斜的一側(cè)集中,臨坡一側(cè)的地基因應(yīng)力集中而先達(dá)到極限平衡狀態(tài),破裂面相交于坡面中下部�；A(chǔ)的位置對(duì)斜坡地基的變形規(guī)律和破壞形式有顯著影響,當(dāng)坡頂距大于4倍基礎(chǔ)寬度時(shí),其變形破壞規(guī)律接近平地地基的情況;基礎(chǔ)的摩擦條件會(huì)影響到地基承載力的大小以及破裂面開(kāi)展的形式。2、利用坡頂荷載條件,編寫斜坡地基滑移線方程的差分計(jì)算程序,可求出斜坡地基中塑性區(qū)各點(diǎn)的x、y、?和?值,并最終確定其極限坡面曲線。計(jì)算結(jié)果表明,極限坡面曲線的斜率隨著y的增加而變小�；啄Σ恋拇嬖�,造成主動(dòng)區(qū)開(kāi)角?AOB降低,塑性區(qū)向土體內(nèi)部移動(dòng),極限坡面曲線明顯降低。坡頂荷載的增大,引起極限坡面坡率變緩,坡腳向外延伸。土體重度的增加引起極限坡面曲線向外移動(dòng)、坡腳向下發(fā)展。土體強(qiáng)度參數(shù)的增大引起過(guò)渡區(qū)開(kāi)角?BOC的降低,坡面曲線降低、坡率增大;黏聚力的增大還會(huì)引起過(guò)渡區(qū)、被動(dòng)區(qū)范圍的縮小。3、建立了考慮基底摩擦條件的斜坡地基極限承載力計(jì)算方法,研究了基底摩擦系數(shù)對(duì)斜坡地基極限承載力的影響�；啄Σ翖l件影響到斜坡地基內(nèi)部的塑性區(qū)分布,摩擦系數(shù)tan?越大,土體中的過(guò)渡區(qū)面積增大,主動(dòng)區(qū)范圍縮小;坡頂極限荷載增長(zhǎng)率隨著tan?的增加而增加。4、坡頂極限荷載值及其增長(zhǎng)率隨著坡率的增加而增加。土體重度的增加引起土體中塑性區(qū)的范圍增大,從而引起坡頂極限荷載的增大。但坡頂O點(diǎn)的極限荷載沒(méi)有變化。黏聚力的增加使得土體中的塑性區(qū)范圍向土體內(nèi)部延伸,引起坡頂荷載的增加,對(duì)坡頂極限荷載的增長(zhǎng)率影響不大。內(nèi)摩擦角的增加使得土體中的塑性區(qū)呈縮小趨勢(shì),但是對(duì)坡頂荷載的增長(zhǎng)率影響較大。5、基于統(tǒng)一強(qiáng)度強(qiáng)度理論,建立了考慮中主應(yīng)力的斜坡地基統(tǒng)一滑移線方程,研究了中主應(yīng)力對(duì)斜坡地基承載力的影響。計(jì)算表明,由于中主應(yīng)力的存在,斜坡地基中塑性區(qū)的范圍減小,隨著b值的增加,斜坡地基的極限坡面曲線斜率增大,坡頂極限荷載增長(zhǎng)。在坡頂O點(diǎn),b=0.4和b=1時(shí),極限承載力比不計(jì)中主應(yīng)力時(shí)提高了25.58%和61.18%。
[Abstract]:Through centrifugal model test, theoretical calculation and numerical analysis, the deformation law and failure characteristics of slope foundation are studied, and the soil parameters and slope conditions are analyzed. The influence of load condition and friction condition on the limit slope curve and the limit load of slope top are analyzed from the angle of the development range of plastic zone in slope foundation. The main research results are as follows: 1. The failure form of the slope foundation is asymmetrical, and the foundation on the slope foundation is more inclined than the flat foundation, which leads to the stress concentration on the inclined side. The stress concentration on the side of the slope leads to the ultimate equilibrium state, and the fracture surface intersects in the middle and lower part of the slope. The position of foundation has a significant influence on the deformation law and failure form of slope foundation. When the slope top distance is more than 4 times the width of foundation, the deformation and failure law of slope foundation is close to that of flat foundation. The friction condition of the foundation will affect the bearing capacity of the foundation and the form of the fracture surface. By using the load condition of the slope top, the difference calculation program of slip line equation of the slope foundation can be compiled, and the XY of each point in the plastic zone of the slope foundation can be obtained. And? Value and finally determine its ultimate slope curve. The results show that the slope of the limit slope curve decreases with the increase of y. The existence of base friction results in the decrease of AOB in the active zone, the movement of the plastic zone to the soil, and the decrease of the limit slope curve. With the increase of the load on the top, the slope rate of the limit slope becomes slower and the foot of the slope extends outwards. The increase of soil weight causes the limit slope curve to move outward and the slope foot to develop downwards. The increase of soil strength parameter leads to the decrease of BOC, the decrease of slope curve and the increase of slope ratio, and the increase of cohesion will cause the transition zone. In this paper, the calculation method of ultimate bearing capacity of slope foundation considering the condition of base friction is established, and the influence of the coefficient of foundation friction on ultimate bearing capacity of slope foundation is studied. The friction condition of the base affects the distribution of the plastic zone in the slope foundation, and the friction coefficient tann? The larger the soil is, the larger the area of transition zone is and the smaller the active zone is. The limit load value and its growth rate increase with the increase of slope ratio. The increase of soil weight increases the range of the plastic zone in the soil, which leads to the increase of the limit load on the top of the slope. However, the limit load at O point at the top of the slope does not change. The increase of cohesion makes the range of plastic zone in soil extend to the inside of soil, which causes the increase of slope top load, and has little effect on the growth rate of limit load on slope top. With the increase of internal friction angle, the plastic zone in soil tends to shrink, but it has a great influence on the growth rate of slope top load. Based on the unified strength strength theory, the unified slip line equation of slope foundation considering medium principal stress is established. The effect of medium principal stress on the bearing capacity of slope foundation is studied. The calculation shows that due to the existence of middle principal stress, the range of plastic zone in the slope foundation decreases. With the increase of b value, the slope of the limit slope curve of the slope foundation increases and the limit load of the slope top increases. The ultimate bearing capacity of the slope is increased by 25.58% and 61.18% than that at O point (0.4 and b = 1).
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU470

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