【摘要】：碎石樁處理軟土地基在實(shí)際工程中應(yīng)用十分廣泛。在碎石樁處理地基之上填筑填方邊坡,因地基土上覆荷載隨著施工的進(jìn)行不斷變化,并且施工速度不同,地基土中超靜孔隙水壓力的變化情況也不同。分析施工期內(nèi)碎石樁處理地基之上的填方邊坡的穩(wěn)定性,通常只停留在定性的角度。本文從定量的角度出發(fā),分析碎石樁處理地基之上的填方邊坡在施工期內(nèi)的穩(wěn)定性,主要工作與成果如下：(1)基于Barron固結(jié)理論推導(dǎo)考慮上覆荷載變化的情況下的固結(jié)方程,采用疊加原理、齊次化原理等數(shù)學(xué)方法進(jìn)行求解,并基于C#語言編寫超靜孔隙水壓力的計(jì)算程序,通過計(jì)算機(jī)計(jì)算求得施工過程中隨著上覆荷載的增加地基土內(nèi)各時(shí)刻的超靜孔隙水壓力。(2)將施工期間超靜孔隙水壓力的數(shù)值帶入到填方邊坡的穩(wěn)定性分析中,計(jì)算存在超靜孔隙水壓力的情況下邊坡的穩(wěn)定性。(3)建立施工期填方邊坡的穩(wěn)定性分析模型：隨著邊坡的填筑,地基土內(nèi)的超靜孔隙水壓力不斷升高,將此時(shí)刻的超靜孔隙水壓力的計(jì)算結(jié)果代入到此時(shí)刻的邊坡計(jì)算模型,得出此時(shí)刻的邊坡安全系數(shù)；計(jì)算施工期內(nèi)不同時(shí)刻、不同邊坡高度的安全系數(shù)；計(jì)算隨著填筑的完成、超靜孔隙水壓力的消散,邊坡在不同時(shí)刻的安全系數(shù)；建立整個(gè)施工期間邊坡的安全系數(shù)變化圖。(4)通過計(jì)算發(fā)現(xiàn),邊坡的整體安全系數(shù)最小值出現(xiàn)在整個(gè)邊坡填筑完成之時(shí),局部安全系數(shù)最小值出現(xiàn)在臺階邊坡填筑完成之時(shí),并且此時(shí)的安全系數(shù)由于超靜孔隙水壓力的存在小于邊坡的最終安全系數(shù),即超靜孔隙水壓力完全消散時(shí)的安全系數(shù)。在安全系數(shù)最小值出現(xiàn)之前,隨著填筑高度的增加以及超靜孔隙水壓力的增大,安全系數(shù)呈近線性下降,直至整體邊坡或臺階邊坡填筑完成。之后隨著上覆荷載不再增加,超靜孔隙水壓力不斷消散,邊坡的安全系數(shù)不斷上升,但上升的速率遠(yuǎn)小于填筑期間安全系數(shù)下降的速率,并且隨著時(shí)間的增加,安全系數(shù)上升的速率逐漸降低,直至趨向于某一特定值,此值即為不存在超靜孔隙水壓力的情況下的安全系數(shù)。(5)通過計(jì)算在不同施工速度下邊坡的安全系數(shù)的變化情況,發(fā)現(xiàn)施工速度越快,最小安全系數(shù)越低,填筑期間安全系數(shù)下降的速率越大。(6)通過具體的工程實(shí)例,證明了本文提出的分析方法的可操作性,通過結(jié)合施工期間邊坡在不同時(shí)刻的安全系數(shù),對施工組織的制定與實(shí)施、施工期間邊坡的監(jiān)測等級的制定具有指導(dǎo)意義。
[Abstract]:Gravel pile is widely used to treat soft soil foundation in practical engineering. When filling fill slope on the foundation treated by gravel pile, the change of excess pore water pressure in foundation soil is different because of the change of overlying load of foundation soil and construction speed. The main work and achievements of this paper are as follows: (1) Based on Barron's consolidation theory, the consolidation equation considering the change of overlying load is deduced, and the superimposed original is adopted. The calculation program of excess pore water pressure is compiled based on C# language, and the excess pore water pressure at every moment in the foundation soil is calculated by computer during the construction process with the increase of overlying load. (2) The value of excess pore water pressure during construction is brought into the stability of fill slope. (3) Set up the stability analysis model of the filling slope during the construction period: With the filling of the slope, the excess pore water pressure in the foundation soil increases continuously, and the calculation results of the excess pore water pressure at this time are substituted into the slope calculation model at this time. The safety factor of slope at this moment is obtained; the safety factor of different slope heights at different times during construction period is calculated; the safety factor of slope at different times is calculated with the completion of filling, the dissipation of excess pore water pressure, and the safety factor of slope at different times; the change diagram of safety factor of slope during the whole construction period is established. (4) The overall safety of slope is found through calculation. The minimum of safety factor appears when the whole slope filling is completed, the minimum of local safety factor appears when the step slope filling is completed, and the safety factor is smaller than the final safety factor of the slope because of the existence of excess pore water pressure, that is, the safety factor when the excess pore water pressure completely dissipates. The safety factor decreases linearly with the increase of filling height and excess pore water pressure until the whole slope or step slope is filled. Then the excess pore water pressure dissipates and the safety factor increases with the increase of overlying load, but the rate of increase is much smaller than that during the filling period. The rate at which the safety factor decreases, and as time goes on, the rate at which the safety factor rises gradually decreases until it tends to a certain value, which is the safety factor without excess pore water pressure. (5) By calculating the variation of the safety factor at different construction speeds, it is found that the faster the construction speed is. Quick, the lower the minimum safety factor, the greater the rate of decrease of safety factor during filling. (6) Through specific engineering examples, the feasibility of the analysis method proposed in this paper is proved. Combining with the safety factor of slope at different times during construction, the formulation and implementation of construction organization and the formulation of monitoring grade of slope during construction are discussed. It has guiding significance.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU753.3

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