本文選題：軟粘土 + 各向異性��； 參考：《江西理工大學》2015年碩士論文

【摘要】：軟粘土地基上修筑的高速公路、機場跑道、跨海大橋等交通工程在循環(huán)交通荷載作用下,往往會產(chǎn)生過大的工后沉降,這是因為在自重荷載和交通荷載作用下軟粘土中的應力路徑十分復雜,主要表現(xiàn)在以下兩個方面,第一,軟粘土具有明顯的各向異性,這種各向異性一方面和K0固結有關,另一方面則由路基中的應力引起。第二,在循環(huán)交通荷載作用下,軟粘土單元體中的主應力軸還會發(fā)生連續(xù)旋轉(zhuǎn)。因此,開展各向異性軟粘土在主應力軸旋轉(zhuǎn)作用下的靜動力特性試驗研究是解決軟土地基工程災變問題的重要手段。本文以溫州軟粘土為研究對象,主要做了以下工作:1.研制出一種制備重塑土的儀器即高壓固結儀,利用該儀器通過一系列的加工工藝流程制備出高質(zhì)量的重塑軟粘土,分別取與土樣沉積方向呈0°、30°、45°、60°、90°的原狀土樣和重塑土樣,對每種角度的原狀和重塑土樣依次分別進行壓縮試驗、滲透試驗、直剪試驗,結果表明:無論是重塑土樣還是原狀土樣,其壓縮模量、滲透系數(shù)、抗剪強度等方面都存在各向異性。2.利用GDS空心扭剪系統(tǒng),對原狀溫州飽和軟粘土開展與大主應力方向分別呈0°,30°,45°,60°,90°的定向剪切試驗,結果表明:不同主應力方向角下的剪切,主應力、主應變、應力-應變關系曲線變化規(guī)律差別較大,偏應力峰值和內(nèi)摩擦角也互不相同,且偏應力峰值在0°剪切時最大,而有效內(nèi)摩擦角最大值出現(xiàn)在45°剪切。3.利用GDS空心扭剪系統(tǒng),通過使用自定義的波形及心臟線形應力路徑的加載,模擬了實際工程中交通荷載作用下土單元體中主應力軸連續(xù)旋轉(zhuǎn)的應力路徑,研究了主應力軸連續(xù)旋轉(zhuǎn)作用下,軟粘土中應變、孔壓、彈性模量的變化規(guī)律,結果還發(fā)現(xiàn),與不考慮主應力方向變化的動三軸試驗結果相比,主應力軸旋轉(zhuǎn)會加快軟粘土應變、孔壓的累積和土體的軟化。最后建立了考慮主應力軸旋轉(zhuǎn)作用的軟粘土累積應變預測方程。
[Abstract]:Highway, airport runway, cross-sea bridge and other traffic projects built on soft clay foundation often produce excessive post-construction settlement under cyclic traffic load. This is because the stress paths in soft clay under gravity and traffic loads are very complex and are mainly manifested in the following two aspects: first, the soft clay has obvious anisotropy, which is related to K _ 0 consolidation on one hand. On the other hand, it is caused by the stress in the roadbed. Secondly, under cyclic traffic load, the principal stress axis in the soft clay element will rotate continuously. Therefore, the static and dynamic behavior of anisotropic soft clay under the rotation of principal stress axis is an important means to solve the problem of engineering disaster in soft soil foundation. In this paper, Wenzhou soft clay as the research object, mainly do the following work: 1. A high pressure consolidation instrument for the preparation of remolded soil was developed. High quality soft clay was prepared by a series of processing processes. The original and remolded soil samples with the direction of 0 擄~ 30 擄~ 45 擄~ 45 擄~ 60 擄~ (90 擄) and remolded soil samples were obtained, respectively, when the soil was deposited in the direction of 0 擄~ 30 擄~ 45 擄~ (45 擄) or 60 擄~ 90 擄. Compression tests, permeation tests, and direct shear tests were carried out on the original and remolded soil samples at each angle, respectively. The results showed that the compression modulus and permeability coefficient of the original soil samples, whether the remolded soil samples or the original soil samples, were tested respectively. The shear strength is anisotropic. Using GDS hollow torsional shear system, the directional shear tests of Wenzhou saturated soft clay were carried out in the direction of 0 擄/ 30 擄/ 45 擄/ 60 擄/ 90 擄respectively with large principal stress direction. The results show that the shear, principal stress and principal strain of Wenzhou saturated soft clay in different principal stress directions are different from each other. The variation law of stress-strain relation curve is quite different, the peak value of deflection stress and the angle of internal friction are also different, and the peak value of deviant stress is maximum at 0 擄shear, and the maximum value of effective internal friction angle appears at 45 擄shear. 3. By using the GDS hollow torsional shear system, by using the self-defined waveform and the loading of the linear stress path of the heart, the stress path of continuous rotation of the principal stress axis in the soil element under the traffic load in the actual engineering is simulated. The variation of strain, pore pressure and modulus of elasticity in soft clay under continuous rotation of principal stress axis is studied. It is also found that the dynamic triaxial test results are compared with those of dynamic triaxial test without considering the direction of principal stress. Rotation of principal stress axis accelerates strain, pore pressure accumulation and softening of soft clay. Finally, the cumulative strain prediction equation of soft clay considering the rotation of principal stress axis is established.
【學位授予單位】：江西理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU41

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