發(fā)布時(shí)間：2018-04-15 07:36

  本文選題：軟土地基 + 復(fù)合地基�。� 參考：《長(zhǎng)安大學(xué)》2015年博士論文

【摘要】：本文依托河北沿海高速公路實(shí)際工程,對(duì)水泥攪拌樁復(fù)合地基和塑料排水板豎向排水體地基設(shè)計(jì)了軟土地基變形試驗(yàn)觀測(cè)方案,采用測(cè)斜導(dǎo)管、沉降板、孔隙水壓力計(jì)和土壓力計(jì)等測(cè)試方法,對(duì)軟土地基填筑期、預(yù)壓期和卸荷再加載三個(gè)階段進(jìn)行了長(zhǎng)達(dá)2年多的全過(guò)程監(jiān)測(cè),通過(guò)現(xiàn)場(chǎng)試驗(yàn)和理論分析,取得了以下主要研究成果:1.分析研究了兩種不同地基處理方式下軟土地基沉降、水平位移及孔隙水壓力變化規(guī)律。填筑期水泥攪拌樁復(fù)合地基沉降僅為塑料排水板地基的7.64%~25.70%,最終沉降預(yù)測(cè)值僅為塑料排水板地基的8.76%~28.9%,不設(shè)預(yù)壓期的水泥攪拌樁工后沉降預(yù)測(cè)值為不設(shè)預(yù)壓期塑料排水板地基的6.78%~25.01%,為設(shè)2個(gè)月預(yù)壓期塑料排水板地基的8.51%~36.46%。填筑期水泥攪拌樁復(fù)合地基最大沉降為最大水平位移的3.7~4.1倍,而塑料排水板地基最大沉降為最大水平位移的8.6~15.3倍。由以上分析可見(jiàn),水泥攪拌樁復(fù)合地基可顯著減小軟基工后沉降和填筑期水平位移,更適合工后沉降要求較高的橋頭路段和快速填筑路段。2.水泥攪拌樁復(fù)合地基填筑期沉降、最終沉降預(yù)測(cè)值和工后沉降預(yù)測(cè)值均隨樁間距的增大而明顯增加,填筑期末樁間距為1.4m的地基沉降分別為樁間距1.2m和1.0m地基沉降的1.79倍和2.91倍,最終沉降預(yù)測(cè)值分別為1.2m和1.0m最終沉降預(yù)測(cè)值的1.67倍和2.79倍,工后沉降預(yù)測(cè)值分別為1.2m和1.0m工后沉降預(yù)測(cè)值的1.58倍和2.63倍。因此通過(guò)對(duì)橋臺(tái)后一定長(zhǎng)度范圍內(nèi)水泥攪拌樁樁間距的調(diào)整形成沉降過(guò)渡段,從而有效地減少“橋臺(tái)跳車(chē)”病害。3.水泥攪拌樁復(fù)合地基樁頂、樁間土壓力和樁土應(yīng)力比均隨所加荷載的增加而逐漸增加,基本為線性關(guān)系,但樁頂壓力的增幅為樁間土壓力增幅的8.65~12.3倍,樁間距為1.4m的樁土應(yīng)力比分別為樁間距1.2m和1.0m樁土應(yīng)力比的1.39倍和2.57倍;建議在樁間距為1.0m~1.4m時(shí)該地區(qū)樁土應(yīng)力比為2~6。4.補(bǔ)充了沉降系數(shù)綜合計(jì)算公式中地基處理類型修正值,經(jīng)分析計(jì)算建議水泥攪拌樁復(fù)合地基修正值為0.85~0.95;沉降系數(shù)綜合計(jì)算公式計(jì)算的沉降系數(shù)與反算系數(shù)非常接近且公式計(jì)算值略大,并建議該地區(qū)沉降系數(shù)為1.05~1.15。5.通過(guò)對(duì)費(fèi)爾哈斯曲線模型的時(shí)間因子進(jìn)行指數(shù)修正,提出了指數(shù)型費(fèi)爾哈斯曲線模型,改進(jìn)后的模型沉降預(yù)測(cè)值與實(shí)測(cè)值保持較高的相關(guān)性,并能得到較滿意的最終沉降預(yù)測(cè)結(jié)果。通過(guò)對(duì)分析計(jì)算,推薦該地區(qū)修正指數(shù)為1.5。6.基于MATLAB建立了水泥攪拌樁復(fù)合地基和塑料排水板地基的BP神經(jīng)網(wǎng)絡(luò)預(yù)測(cè)模型,該模型仿真預(yù)測(cè)結(jié)果與指數(shù)型費(fèi)爾哈斯模型預(yù)測(cè)結(jié)果非常接近,但較雙曲線法和新野法預(yù)測(cè)值增加6.4%~42.87%。因此,BP神經(jīng)網(wǎng)絡(luò)預(yù)測(cè)模型和指數(shù)型費(fèi)爾哈斯曲線模型較好地解決了其它沉降曲線模型最終沉降量預(yù)測(cè)偏小的問(wèn)題。7.對(duì)工后沉降研究表明,塑料排水板地基一般路段可不設(shè)預(yù)壓期,但在等載甚至超載條件下,塑料排水板法用于涵洞或箱形通道時(shí)均應(yīng)設(shè)置不小于2個(gè)月的預(yù)壓期。這一結(jié)果表明該地區(qū)預(yù)壓期可小于現(xiàn)行《公路路基設(shè)計(jì)規(guī)范》中關(guān)于豎向排水體處治法預(yù)壓期不宜小于6個(gè)月的規(guī)定。
[Abstract]:This paper relies on the Hebei coastal highway engineering, the composite foundation of cement mixing pile and plastic drainage plate vertical drains design of soft soil foundation deformation observation scheme, using inclinometer tubes, settlement plate, pore water pressure and soil pressure meter test method for filling soft soil foundation period, the period of preloading and unloading bearing loading in three stages for more than 2 years of monitoring, through field test and theoretical analysis, the main results are as follows: 1. analysis of the two different methods of foundation treatment under the soft soil foundation settlement, lateral displacement and pore water pressure. The composite pile foundation settlement is only plastic drainage the 7.64%~25.70% foundation board of filling cement mixing, the prediction of final settlement value is only the plastic drainage plate foundation 8.76%~28.9%, a cement mixing pile under pre settlement prediction value for the precompression term Plastic drainage plate foundation 6.78%~25.01%, 3.7~4.1 times for a 2 month period of preloading with plastic drainage plate foundation 8.51%~36.46%. filling cement mixing pile composite foundation for the maximum settlement of the maximum horizontal displacement, and the plastic drainage plate foundation maximum settlement is the maximum horizontal displacement 8.6~15.3 times. By the above analysis shows that, can obviously reduce the soft foundation after filling the settlement and horizontal displacement of cement mixing pile composite foundation, the bridge sections requiring high and fast filling sections of.2. cement filling pile composite foundation settlement is more suitable for the industry, the prediction of final settlement value increased significantly with the increase of pile spacing and settlement prediction and after filling the final pile spacing of 1.4m the settlement of the foundation settlement of pile spacing were 1.2m and 1.0m foundation 1.79 times and 2.91 times, the prediction of final settlement value were 1.2m and 1.0m in the prediction of final settlement value of 1.67 times and 2.79 times. Settlement prediction values were 1.2m and 1.0m post construction settlement prediction value of 1.58 times and 2.63 times. So the settlement of transitional section formed by the abutment after a certain length of cement mixing pile spacing adjustment, so as to effectively reduce the pile composite foundation top disease.3. cement abutment jump, pile soil pressure and the pile-soil stress ratio increases with the increasing load and gradually increased linearly, but the pressure on the top of the pile in soil between piles pressure increase 8.65~12.3 times, pile spacing of pile soil stress ratio of 1.4m pile spacing 1.2m and 1.0m pile soil stress ratio of 1.39 times and 2.57 times respectively; in pile spacing of 1.0m~1.4m pile and soil stress ratio in the region added type correction value calculation formula in the treatment of foundation coefficient of settlement for the 2~6.4., the calculated correction value for 0.85~0.95 pile composite foundation of cement mixing coefficient of the comprehensive settlement proposal; The settlement coefficient calculation formula and inverse coefficient is very close to the calculated value and the formula is slightly larger, and suggested that the area sedimentation coefficient of 1.05~1.15.5. by the time factor on Verhulst curve model of exponent, presents exponential Verhulst curve model, the improved model of settlement prediction value to maintain a high correlation with the measured. And can get a satisfactory prediction of final settlement results. Through the analysis, the recommendation of the area correction index for 1.5.6. based on MATLAB BP neural network prediction model is established the composite foundation of cement mixing pile and plastic drainage plate foundation, the model simulation results and forecast index prediction results Verhulst model closely, but compared with the hyperbolic method and Xinye prediction value increased 6.4%~42.87%. therefore, prediction model and exponential Phil Haas curve model can solve the BP neural network The settlement curve of final settlement prediction model of small.7. of settlement after construction of plastic drainage plate foundation general sections not to set the pre pressing period, but in the other load even under overload conditions, plastic drainage method for culvert box or channel shall be not less than 2 months of pre compression period. This result indicates that the area of preloading period can be less than the current "specifications for design of highway subgrades > on vertical drainage body treatment preloading period of not less than 6 months.

【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U416.1

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