本文選題：螺旋鋼樁 + 凍脹融沉��； 參考：《北京交通大學》2017年碩士論文

【摘要】：建(構(gòu))筑物基礎(chǔ)的凍脹融沉破壞一直是寒區(qū)工程所面臨的主要問題,其嚴重影響著上部結(jié)構(gòu)的穩(wěn)定性。螺旋樁是一種擁有良好抗拔承載力和整體穩(wěn)定性的新型樁基礎(chǔ),在非凍土地區(qū)抗拔工程中已經(jīng)得到驗證。近些年發(fā)展起來的寒區(qū)光伏發(fā)電工程,已經(jīng)開始使用螺旋鋼樁作為光伏電池板的支架基礎(chǔ)。目前國內(nèi)外關(guān)于螺旋樁的凍脹融沉特性研究相對缺乏,研究成果尚不成熟,因而針對光伏支架螺旋鋼樁的凍脹融沉特性加以研究,不但對光伏發(fā)電工程具有重要意義,也對寒區(qū)工程樁基選型具有重要指導意義。本文采用室內(nèi)模型試驗的方法對樁型參數(shù)不同的螺旋鋼樁進行凍脹融沉特性研究,主要研究內(nèi)容包括:1)以傳統(tǒng)樁基凍拔受力分析和非凍土環(huán)境下螺旋鋼樁抗拔承載力分析為基礎(chǔ),提出螺旋鋼樁在樁周土凍脹過程中樁身受力特點,分析了凍深范圍內(nèi)螺旋葉片對于凍拔力大小所產(chǎn)生的影響,并針對半螺旋樁提出一種樁頂凍脹力的簡單計算模型。2)通過基礎(chǔ)試驗測定了填土的各項物理指標,為凍脹融沉試驗提供了基礎(chǔ)。通過試驗結(jié)果可判斷所選土樣為粉土,屬強凍脹土。3)在樁頂無約束的情況下,對不同型號的螺旋鋼樁進行一維凍脹試驗和融沉試驗,分析了試驗過程中箱內(nèi)土體溫度場變化規(guī)律、樁身凍拔位移量發(fā)展規(guī)律以及融化階段樁體沉降規(guī)律,并擬合得到凍拔位移量Δh和凍結(jié)深度Hf的多項式方程。對比試驗結(jié)果可得到,在凍土層內(nèi)布置螺旋葉片會大大增加樁體凍拔位移量,減小未凍土層范圍內(nèi)的螺旋鋼樁螺距并增大螺旋葉片直徑均會提高樁體的凍脹融沉穩(wěn)定性。4)在限制樁頂凍拔位移的情況下,對不同型號的螺旋鋼樁進行一維凍脹試驗和融沉試驗,分析了試驗過程中樁頂凍脹力的發(fā)展規(guī)律,并擬合得到樁頂凍脹力N和凍結(jié)深度Hf的指數(shù)方程。對比試驗結(jié)果可得到,在凍土層內(nèi)布置螺旋葉片會大大增加樁頂凍脹力,減小未凍土層范圍內(nèi)的螺旋鋼樁螺距并增大螺旋葉片直徑對減小樁頂凍脹力有一定作用,但效果不明顯。
[Abstract]:The frost heaving and thawing collapse of the building foundation is always the main problem in the cold region engineering, which seriously affects the stability of the superstructure.Spiral pile is a new type of pile foundation with good uplift bearing capacity and overall stability, which has been verified in non-frozen soil area.In recent years, helical steel piles have been used as the support foundation of photovoltaic panels in cold area photovoltaic power generation projects.At present, the research on frost heaving and thawing settlement characteristics of spiral piles at home and abroad is relatively lacking, and the research results are still immature. Therefore, it is not only of great significance to photovoltaic power generation engineering to study the characteristics of frost heave thawing settlement of helical steel piles with photovoltaic support.It is also of great significance to the selection of pile foundation in cold region.In this paper, the frost heaving and thawing settlement characteristics of helical steel piles with different pile parameters are studied by using indoor model test.The main research contents include: (1) based on the traditional analysis of freezing and drawing force of pile foundation and the analysis of uplift bearing capacity of spiral steel pile under non-frozen soil environment, the characteristics of pile body bearing capacity during frost heaving process of spiral steel pile are put forward.This paper analyzes the influence of helical blade on the freezing drawing force in the range of freezing depth, and puts forward a simple calculation model of frost heave force at the top of the pile for semi-helical pile.It provides a basis for frost heaving and thawing test.Through the test results, it can be judged that the selected soil sample is silt, which belongs to strong frost heaving soil .3) under the condition that the pile top is unconstrained, the one-dimensional frost heave test and thawing test are carried out on different types of spiral steel piles.The variation law of temperature field in box soil mass, the development law of frozen drawing displacement of pile body and the settlement law of pile body in melting stage are analyzed, and the polynomial equations of displacement 螖 h and freezing depth HF are obtained.By comparing the test results, it is found that the placement of helical blades in the frozen soil will greatly increase the displacement of the pile during freezing and drawing.Reducing the pitch of spiral steel pile and increasing the diameter of helical blade in unfrozen soil can improve the stability of frost heave thawing settlement of pile. 4) under the condition of limiting the displacement of pile top freezing and drawing,The one-dimensional frost heave test and thawing test for different types of spiral steel piles are carried out. The development law of the pile top frost heave force is analyzed and the exponential equations of the pile top frost heave force N and freezing depth HF are obtained.By comparing the test results, it is found that the placement of helical blades in frozen soil will greatly increase the frost heaving force of the pile top, reduce the pitch of the spiral steel pile and increase the diameter of the helical blade in the unfrozen soil layer, which will play a certain role in reducing the frost heave force of the pile top.But the effect is not obvious.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU473.1

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