本文選題：樁基 + 水平承載力��； 參考：《武漢理工大學(xué)》2014年碩士論文

【摘要】：樁基工程中的水流沖刷作用是指在地表水或地下滲流水的沖刷作用下，基礎(chǔ)中土顆粒逐漸被帶走，土體被掏空的過程，是水流、易受侵蝕河床和樁基、墩臺(tái)之間的相互作用。海洋平臺(tái)在采油或作業(yè)過程中，樁腿插入泥中，，同時(shí)受到上部載荷、風(fēng)、浪、流等環(huán)境荷載作用，樁腿很可能因?yàn)槭芰^大而發(fā)生各種形式的破壞，造成樁基邊界條件的變化，從而引起樁體應(yīng)力和位移的重新分布，對(duì)海洋平臺(tái)的安全造成影響。同時(shí)土層覆蓋厚度的降低以及其應(yīng)力歷史的變化對(duì)于樁基礎(chǔ)承載性狀也有著直接的影響，隨著樁基承載力的下降將對(duì)樁腿及上部結(jié)構(gòu)的安全性能產(chǎn)生潛在的威脅。由于對(duì)于沖刷前后樁基基礎(chǔ)的荷載傳遞機(jī)理和承載性狀變化的不了解，往往導(dǎo)致實(shí)際工程設(shè)計(jì)過程計(jì)算的不合理，造成工程上的不安全或不經(jīng)濟(jì)。因此有必要對(duì)沖刷前后樁基基礎(chǔ)的荷載傳遞機(jī)理和承載性狀的變化進(jìn)行較深入系統(tǒng)的研究，以便采取相應(yīng)的工程措施提高海洋平臺(tái)的安全性。 在實(shí)際工程中樁基礎(chǔ)的水平靜載試驗(yàn)是確定樁基礎(chǔ)水平承載力最可靠的方法，本文通過不同沖刷深度下的樁基室內(nèi)模型試驗(yàn)，獲得在不同水平荷載下樁頭水平位移以及沿樁身的應(yīng)變，掌握沖刷作用對(duì)樁基水平承載性能的影響。在此基礎(chǔ)上，采用FLAC3D軟件模擬單樁在水平荷載作用下的承載性能，并將單樁水平靜載試驗(yàn)結(jié)果與數(shù)值模擬結(jié)果以及現(xiàn)有規(guī)范計(jì)算出來的結(jié)果進(jìn)行對(duì)比分析，依據(jù)模型試驗(yàn)結(jié)果修正數(shù)值模型相應(yīng)參數(shù)，獲得能考慮沖刷作用影響的單樁水平承載力計(jì)算模型。同時(shí)，根據(jù)試驗(yàn)結(jié)果探討沖刷作用對(duì)土體抗力的影響，提出相應(yīng)的P-Y曲線用于樁基水平承載力計(jì)算。最后采用已獲得的數(shù)值模型對(duì)沖刷角、樁頂固定方式、和不同沖刷深度下單樁的水平承載力性狀進(jìn)行分析，得出一些對(duì)實(shí)際工程有益的結(jié)論。
[Abstract]:In pile foundation engineering, the water flow scour is the process of soil particles being gradually removed and soil being hollowed under the action of surface water or underground seepage water, which is the interaction between water flow, easily eroded river bed and pile foundation, pier and abutment. In the course of oil production or operation, the pile leg is inserted into the mud and subjected to the environmental loads such as upper load, wind, wave, current and so on. The pile leg may be destroyed in various forms because of the excessive force, resulting in the change of the boundary conditions of the pile foundation. Thus the stress and displacement of the pile are redistributed and the safety of the offshore platform is affected. At the same time, the decrease of soil cover thickness and the change of stress history have a direct effect on the bearing capacity of pile foundation. With the decrease of pile foundation bearing capacity, the safety performance of pile leg and superstructure will be threatened. The failure to understand the load transfer mechanism and load bearing behavior of pile foundation before and after scouring often leads to unreasonable calculation of actual engineering design process, resulting in unsafe or uneconomical engineering. Therefore, it is necessary to study the load transfer mechanism and the change of bearing behavior of pile foundation before and after scouring, so as to take corresponding engineering measures to improve the safety of offshore platform. In practical engineering, the water static load test of pile foundation is the most reliable method to determine the horizontal bearing capacity of pile foundation. In this paper, the indoor model test of pile foundation with different scour depth is carried out. The horizontal displacement of the pile head and the strain along the pile body are obtained under different horizontal loads, and the effect of scour on the horizontal bearing capacity of the pile foundation is grasped. On this basis, FLAC3D software is used to simulate the bearing capacity of single pile under horizontal load, and the results of water static load test of single pile are compared with the results of numerical simulation and the results calculated by existing codes. According to the model test results, the corresponding parameters of the numerical model are modified, and the calculation model of horizontal bearing capacity of single pile considering the effect of scour is obtained. At the same time, according to the test results, the effect of scour on soil resistance is discussed, and the corresponding P-Y curve is put forward to calculate the horizontal bearing capacity of pile foundation. Finally, the numerical model is used to analyze the horizontal bearing capacity of the pile, such as the scour angle, the fixed mode of the top of the pile, and the different scour depth, and some useful conclusions are obtained.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P742;TU473.1

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