本文選題：充氣錨桿 + 黏土地基�。� 參考：《湖南科技大學(xué)》2017年碩士論文

【摘要】：我國沿海廣泛分布著軟弱地基區(qū),充氣錨桿具有較強(qiáng)的承載性能、可立即提供錨固力、可回收利用等優(yōu)點,在海洋工程及軟弱地基區(qū)有著廣闊的應(yīng)用前景。國內(nèi)外許多學(xué)者對充氣錨桿進(jìn)行了研究,但充氣錨桿在黏土地層中的研究尚未涉及,其承載特性及錨固機(jī)理尚不明確。因此,作為一種新型錨桿,有必要在尚未應(yīng)用過的地層和環(huán)境下對其進(jìn)行研究。本文基于前人的研究基礎(chǔ),采用室內(nèi)模型試驗的方法,對充氣錨桿在黏土地層中不同試驗因素條件下的承載特性與群錨效應(yīng)等方面進(jìn)行了探索性研究,主要研究內(nèi)容與成果如下:(1)根據(jù)試驗需求,在廣泛調(diào)研的基礎(chǔ)上研制了充氣錨桿模型和用于單錨、群錨抗拔試驗的整套模型試驗裝置。(2)開展充氣錨桿擴(kuò)大段變形特性研究,獲得不同壓力下充氣錨桿端頭擴(kuò)大段膨脹體積與等效直徑的變化規(guī)律;開展了不同埋深、充氣壓力、填土含水率條件下的抗拔試驗研究表明:埋深增大,極限承載力隨之增長。由于端頭擴(kuò)大段的影響,使得極限承載力得到了較大的提高,其承載力占比為45%~51.8%;充氣壓力為影響極限承載力的最大因素,在一定氣壓范圍內(nèi),增加充氣壓力能有效地提高充氣錨桿的錨固性能;充氣錨桿在含水率接近液限的黏土地層時仍具有較高的承載力�；诜蔷�性最小二乘法原理對獲得的試驗數(shù)據(jù)進(jìn)行擬合得出充氣錨桿Q-S曲線服從冪函數(shù)分布規(guī)律。(3)充氣錨桿在黏土中Q-S曲線可分為彈性階段、彈塑性階段和塑性階段;通過分析加載-卸載試驗獲得的Q-S_E,Q-S_P關(guān)系曲線,其分界荷載分別為23.5%_、83.5%Q_u。(4)開展了循環(huán)荷載試驗,探討了充氣錨桿在循環(huán)荷載條件下承載及位移演化規(guī)律,得出在一定范圍內(nèi)存在一最小循環(huán)荷載次數(shù),當(dāng)循環(huán)荷載次數(shù)小于該值時,累積沉降位移隨著循環(huán)次數(shù)的遞增而增加,反之,累積沉降位移收斂,在接近極限荷載條件下循環(huán)荷載累積位移不收斂。(5)開展了群錨抗拔試驗,雙錨隨著錨桿間距的增大承載能力先減弱后增強(qiáng),獲得了峰值點間距為_=6.84D。三錨、四錨在間距Ru條件下的對比抗拔試驗表明四錨(矩形)布置形式從承載性能及位移控制均要優(yōu)于三錨(三角形)布置形式。(6)基于極限平衡分析法原理,建立了充氣錨桿承載力計算模型。根據(jù)典型黏土抗拔結(jié)構(gòu)與充氣錨桿抗拔特點進(jìn)行類比分析,引入淺埋充氣錨桿在黏土中喇叭形破裂面的計算方程,并運用數(shù)值分析軟件,推導(dǎo)出充氣錨桿極限承載力Qu的估算公式。
[Abstract]:The soft foundation area is widely distributed along the coast of our country. The aerated anchor rod has strong bearing capacity, can provide anchoring force immediately, can be recycled and so on. It has a broad application prospect in marine engineering and soft foundation area. Many scholars at home and abroad have studied the aerated anchor rod, but the research of the aerated anchor rod in clay stratum has not been involved, and its bearing characteristics and anchoring mechanism are not clear. Therefore, as a new type of anchor, it is necessary to study it in the unapplied strata and environment. Based on the previous research, this paper makes an exploratory study on the bearing characteristics and group anchor effect of aerated anchor rods under different experimental factors in clay strata by using the method of indoor model test. The main research contents and results are as follows: (1) based on the extensive investigation and research, the inflatable anchor model and the complete set of model test equipment for single anchor, group anchor pull-out test are developed to study the deformation characteristics of the expanded section of the aerated anchor. The expansion volume and equivalent diameter of the expanded end of the aerated anchor are obtained under different pressures, and the pull-out tests under the conditions of different burying depth, inflatable pressure and water content of the fill show that the ultimate bearing capacity increases with the increase of the buried depth. Due to the influence of the end expansion section, the ultimate bearing capacity has been greatly improved, and the proportion of the ultimate bearing capacity is 451.8.The inflatable pressure is the biggest factor affecting the ultimate bearing capacity, and within a certain pressure range, The Anchorage performance of the aerated anchor rod can be improved effectively by increasing the inflatable pressure and the bearing capacity of the aerated anchor rod is still high when the water content is close to the liquid limit. Based on the principle of nonlinear least square method, the Q-S curve of inflatable anchor can be divided into three stages: elastic stage, elastic-plastic stage and plastic stage, according to the distribution law of power function. The Q-S curve can be divided into three stages: elastic stage, elastic-plastic stage and plastic stage. By analyzing the Q-SSP relation curve obtained from the load-unloading test, the dividing load of Q-SSP is 23.53.5Qu.Qu.f. respectively) the cyclic load test is carried out, and the law of bearing capacity and displacement evolution of inflatable anchor rod under cyclic load is discussed. It is concluded that there is a minimum number of cyclic loads in a certain range. When the number of cyclic loads is less than this value, the cumulative settlement displacement increases with the increase of cycle times, whereas the cumulative settlement displacement converges. Under the condition of close to the limit load, the cumulative displacement of cyclic load is not convergent. The pull-out test of group anchors is carried out. With the increase of anchor spacing, the bearing capacity of double anchors decreases first and then increases, and the peak-point spacing is 6.84D. The comparative pull-out test of three anchors and four anchors under the condition of spacing Ru shows that the layout of four anchors (rectangular) is superior to that of three anchors (triangle) in loading performance and displacement control based on the principle of limit equilibrium analysis. The calculation model of bearing capacity of aerated anchor rod is established. According to the characteristics of typical clay anti-drawing structure and inflatable anchor rod, this paper introduces the calculation equation of shallow buried aerated anchor rod in clay, and applies the numerical analysis software to calculate the fracturing surface of shallow aerated anchor rod in clay. The formula for estimating the ultimate bearing capacity of aerated anchor rod is derived.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU476

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