碎石桩处理场地填方边坡填筑速度研究

发布时间：2018-08-20 12:05

【摘要】：碎石桩处理软土地基在实际工程中应用十分广泛。在碎石桩处理地基之上填筑填方边坡,因地基土上覆荷载随着施工的进行不断变化,并且施工速度不同,地基土中超静孔隙水压力的变化情况也不同。分析施工期内碎石桩处理地基之上的填方边坡的稳定性,通常只停留在定性的角度。本文从定量的角度出发,分析碎石桩处理地基之上的填方边坡在施工期内的稳定性,主要工作与成果如下：(1)基于Barron固结理论推导考虑上覆荷载变化的情况下的固结方程,采用叠加原理、齐次化原理等数学方法进行求解,并基于C#语言编写超静孔隙水压力的计算程序,通过计算机计算求得施工过程中随着上覆荷载的增加地基土内各时刻的超静孔隙水压力。(2)将施工期间超静孔隙水压力的数值带入到填方边坡的稳定性分析中,计算存在超静孔隙水压力的情况下边坡的稳定性。(3)建立施工期填方边坡的稳定性分析模型：随着边坡的填筑,地基土内的超静孔隙水压力不断升高,将此时刻的超静孔隙水压力的计算结果代入到此时刻的边坡计算模型,得出此时刻的边坡安全系数；计算施工期内不同时刻、不同边坡高度的安全系数；计算随着填筑的完成、超静孔隙水压力的消散,边坡在不同时刻的安全系数；建立整个施工期间边坡的安全系数变化图。(4)通过计算发现,边坡的整体安全系数最小值出现在整个边坡填筑完成之时,局部安全系数最小值出现在台阶边坡填筑完成之时,并且此时的安全系数由于超静孔隙水压力的存在小于边坡的最终安全系数,即超静孔隙水压力完全消散时的安全系数。在安全系数最小值出现之前,随着填筑高度的增加以及超静孔隙水压力的增大,安全系数呈近线性下降,直至整体边坡或台阶边坡填筑完成。之后随着上覆荷载不再增加,超静孔隙水压力不断消散,边坡的安全系数不断上升,但上升的速率远小于填筑期间安全系数下降的速率,并且随着时间的增加,安全系数上升的速率逐渐降低,直至趋向于某一特定值,此值即为不存在超静孔隙水压力的情况下的安全系数。(5)通过计算在不同施工速度下边坡的安全系数的变化情况,发现施工速度越快,最小安全系数越低,填筑期间安全系数下降的速率越大。(6)通过具体的工程实例,证明了本文提出的分析方法的可操作性,通过结合施工期间边坡在不同时刻的安全系数,对施工组织的制定与实施、施工期间边坡的监测等级的制定具有指导意义。
[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.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU753.3

【参考文献】