合肥地區(qū)膨脹土大圍壓下三軸強度特性試驗研究
發(fā)布時間：2019-02-15 01:15
【摘要】：隨著國家經(jīng)濟建設(shè)的發(fā)展,城市化建設(shè)程度的加快,人口向大中城市遷移和集中。合肥市作為安徽省的省會、長江三角洲的副中心城市及國家首個高新創(chuàng)新中心。為滿足這種發(fā)展的需求,合肥市建筑物的高度和密度不斷增大,同時為解決城市交通擁堵的問題,地下交通—地鐵的建設(shè)也在全市全面鋪開。在這些工程中,土體常常處于較大的圍壓作用狀態(tài)。目前,針對這類土體的強度和穩(wěn)定計算,由于受到試驗儀器的限制,仍多采用常規(guī)三軸試驗指標(biāo),這顯然與工程土體所處的應(yīng)力狀態(tài)不符。因而,對合肥市的土體(主要是膨脹土),開展超過常規(guī)圍壓的大圍壓三軸試驗,對土體的抗剪強度指標(biāo)進行試驗研究,獲取強度參數(shù)指標(biāo),對處于大圍壓狀態(tài)的土體強度和穩(wěn)定性計算,提供科學(xué)依據(jù)。(1)按照試驗儀器所能承受的圍壓試驗值,將試驗圍壓分為三個圍壓段進行試驗。即100~300kPa為常規(guī)圍壓段,600~800kPa為中圍壓段,1100~1300kPa為大圍壓段。為保證試驗結(jié)果的一致性,在同一基坑中獲取試驗土樣280個,有效試驗225個。(2)三個圍壓段,分別進行不固結(jié)不排水(UU)、固結(jié)不排水(CU)、固結(jié)排水(CD)三軸試驗。試驗顯示隨著圍壓的增大,土體的強度呈現(xiàn)衰減的趨勢;土樣隨著固結(jié)和排水條件的變化,強度衰減幅度不同,按不固結(jié)不排水(UU)、固結(jié)排水(CD)、固結(jié)不排水(CU)順序衰減逐漸減弱。(3)對三個圍壓段,以相同固結(jié)和排水條件的三軸試驗破壞莫爾圓畫出莫爾包絡(luò)線,并對其進行擬合研究,得出合肥市膨脹土中、大圍壓下莫爾包絡(luò)線的基本線型。不固結(jié)不排水(UU)為拋物線型,固結(jié)不排水(CU)與固結(jié)排水(CD)為二次對數(shù)型,為合肥地區(qū)中、大圍壓土體的強度指標(biāo)的工程選取和應(yīng)用提供借鑒。
[Abstract]:With the development of national economic construction and the acceleration of urbanization, the population migrates and concentrates to large and medium cities. Hefei is the provincial capital of Anhui Province, the sub-center city of the Yangtze River Delta and the country's first high-tech innovation center. In order to meet the demand of this kind of development, the height and density of the buildings in Hefei are increasing, and in order to solve the problem of urban traffic congestion, the construction of underground transports-subway is also spread out in the whole city. In these projects, soil is often in a larger confining pressure state. At present, for the strength and stability calculation of this kind of soil mass, because of the limitation of the test instrument, the conventional triaxial test index is often used, which obviously does not accord with the stress state of the engineering soil mass. Therefore, the large confining pressure triaxial test is carried out on the soil mass (mainly expansive soil) in Hefei, and the shear strength index of the soil is studied, and the strength parameter index is obtained. Scientific basis is provided for the calculation of strength and stability of soil in the state of large confining pressure. (1) according to the experimental value of confining pressure which the test instrument can bear, the test confining pressure is divided into three confining pressure sections. That is, 100~300kPa is the normal confining pressure, 600~800kPa is the middle confining pressure, and 1100~1300kPa is the large confining pressure. In order to ensure the consistency of the test results, 280 test soil samples were obtained in the same foundation pit, and 225 effective tests were conducted. (2) three confining pressure sections were carried out respectively for unconsolidated undrained (UU), consolidation and undrained (CU),. Consolidation drainage (CD) triaxial test. The results show that the strength of soil decreases with the increase of confining pressure. With the change of consolidation and drainage conditions, the intensity attenuation ranges of soil samples are different, and the attenuation of unconsolidated undrained (UU), consolidation and drainage (CD), consolidation and undrained (CU) gradually decreases. (3) for three confining pressure sections, The moire envelope line is drawn by triaxial test with the same consolidation and drainage conditions, and the basic shape of moire envelope line is obtained under large confining pressure in expansive soil of Hefei. The unconsolidated undrained (UU) is a parabolic type, and the consolidation undrained (CU) and consolidated drainage (CD) are quadratic logarithmic, which provides a reference for the engineering selection and application of the strength index of the large confining pressure soil in Hefei area.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU443
本文編號：2422804
[Abstract]:With the development of national economic construction and the acceleration of urbanization, the population migrates and concentrates to large and medium cities. Hefei is the provincial capital of Anhui Province, the sub-center city of the Yangtze River Delta and the country's first high-tech innovation center. In order to meet the demand of this kind of development, the height and density of the buildings in Hefei are increasing, and in order to solve the problem of urban traffic congestion, the construction of underground transports-subway is also spread out in the whole city. In these projects, soil is often in a larger confining pressure state. At present, for the strength and stability calculation of this kind of soil mass, because of the limitation of the test instrument, the conventional triaxial test index is often used, which obviously does not accord with the stress state of the engineering soil mass. Therefore, the large confining pressure triaxial test is carried out on the soil mass (mainly expansive soil) in Hefei, and the shear strength index of the soil is studied, and the strength parameter index is obtained. Scientific basis is provided for the calculation of strength and stability of soil in the state of large confining pressure. (1) according to the experimental value of confining pressure which the test instrument can bear, the test confining pressure is divided into three confining pressure sections. That is, 100~300kPa is the normal confining pressure, 600~800kPa is the middle confining pressure, and 1100~1300kPa is the large confining pressure. In order to ensure the consistency of the test results, 280 test soil samples were obtained in the same foundation pit, and 225 effective tests were conducted. (2) three confining pressure sections were carried out respectively for unconsolidated undrained (UU), consolidation and undrained (CU),. Consolidation drainage (CD) triaxial test. The results show that the strength of soil decreases with the increase of confining pressure. With the change of consolidation and drainage conditions, the intensity attenuation ranges of soil samples are different, and the attenuation of unconsolidated undrained (UU), consolidation and drainage (CD), consolidation and undrained (CU) gradually decreases. (3) for three confining pressure sections, The moire envelope line is drawn by triaxial test with the same consolidation and drainage conditions, and the basic shape of moire envelope line is obtained under large confining pressure in expansive soil of Hefei. The unconsolidated undrained (UU) is a parabolic type, and the consolidation undrained (CU) and consolidated drainage (CD) are quadratic logarithmic, which provides a reference for the engineering selection and application of the strength index of the large confining pressure soil in Hefei area.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU443
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