【摘要】：隨著城市化進程的加快,城市地下空間開發(fā)利用不斷發(fā)展。深大基礎(chǔ)工程增多,基坑開挖深度增加,工程規(guī)模增大,工程難度提高,對工程技術(shù)和科研水平提出了新的挑戰(zhàn)。如何有效確定土體抗剪強度,準確進行基礎(chǔ)穩(wěn)定計算是關(guān)鍵問題之一。特別對于飽和軟土地區(qū)的深基坑,難以測定施工期的孔隙水壓力,通常要通過原位或室內(nèi)固結(jié)不排水的剪切試驗,測定破壞時的總抗剪強度進行總應(yīng)力法分析。在眾多原位試驗中,靜力觸探儀是在不擾動土體原位狀態(tài)的情況進行試驗,具有設(shè)備簡單、連續(xù)性好、數(shù)據(jù)可靠高等優(yōu)點,在巖土勘察設(shè)計中應(yīng)用廣泛。建立靜力觸探比貫入阻力與土體抗剪強度相關(guān)關(guān)系,可以有效解決前述關(guān)鍵問題。而國內(nèi)外又缺乏相關(guān)應(yīng)用成果,本文通過理論、回歸和數(shù)值方法研究其相關(guān)關(guān)系,研究內(nèi)容和相關(guān)成果主要包括以下方面： 首先,采用圓柱孔穴擴張理論推導(dǎo)了飽和軟土中比貫入阻力與土體抗剪強度之間的關(guān)系。根據(jù)飽和軟土假定,屈服準則,通過平衡方程,幾何方程,本構(gòu)方程以及邊界條件求解給出了極限孔穴擴張壓力,并得到土體彈塑性區(qū)的應(yīng)力解、位移解及塑性區(qū)范圍,給出圓柱孔穴擴張理論下靜力觸探比貫入阻力與土體抗剪強度相關(guān)關(guān)系式。 其次,通過上海地區(qū)19個工程和武漢地區(qū)33個工程,共694組數(shù)據(jù)分不同土類對比貫入阻力與抗剪強度的相關(guān)關(guān)系進行研究,對兩地區(qū)三種土的物理力學(xué)特性進行了分析總結(jié),并經(jīng)過回歸分析確定分土類下可應(yīng)用于相應(yīng)地區(qū)工程的靜力觸探比貫入阻力與土體抗剪強度相關(guān)關(guān)系式。 然后,基于自適應(yīng)網(wǎng)格技術(shù)有限元大變形分析方法,對靜力觸探貫入過程進行模擬研究,土體位移隨貫入深度增大而增大,貫入影響范圍區(qū)向側(cè)方和下方不斷延伸。當(dāng)錐頭深入一定距離后,位移影響區(qū)趨近于環(huán)包狀分布。阻力隨抗剪強度的增大而增大,并根據(jù)錐頭應(yīng)力值得到比貫入阻力與抗剪強度的相關(guān)關(guān)系式。 最后,結(jié)合上海地區(qū)典型工程世博演藝中心工程,對比分析了三種方法下確定土體抗剪強度的吻合性。認為孔穴擴張理論推導(dǎo)和有限元分析的條件理想化,忽略了土體固結(jié)、各向異性、摩擦性等特性。回歸分析采用了當(dāng)?shù)氐墓こ藤Y料,綜合了土體多方面特性,與實際土體抗剪強度吻合度較好。因此,在未建立多因素下通用表達式之前,根據(jù)工程資料確定靜力觸探比貫入阻力與抗剪強度相關(guān)關(guān)系是必要的,具有工程實用價值。 另外,本文基于52個工程的勘察數(shù)據(jù)建立了靜力觸探相關(guān)資料數(shù)據(jù)庫。結(jié)合目前的IT技術(shù)和軟件對工程勘察資料數(shù)據(jù)庫工作(數(shù)字化,標準化,數(shù)據(jù)庫)做了初步探索研究。
[Abstract]:With the acceleration of urbanization, the development and utilization of urban underground space continues to develop. The increase of deep foundation engineering, the increase of excavation depth, the increase of engineering scale and the increase of engineering difficulty raise new challenges to engineering technology and scientific research level. One of the key problems is how to determine the shear strength of soil and calculate the foundation stability accurately. Especially for deep foundation pit in saturated soft soil area, it is difficult to measure pore water pressure during construction period, usually through in-situ or indoor consolidation undrained shear test, the total shear strength of failure is analyzed by total stress method. In many in-situ tests, the static penetration detector is used in the case of undisturbed soil in situ, which has the advantages of simple equipment, good continuity, high reliability and so on. It is widely used in geotechnical survey and design. The key problems mentioned above can be effectively solved by establishing the relationship between the specific penetration resistance and the shear strength of soil. However, there is a lack of relevant application results at home and abroad. In this paper, the correlation relationship is studied by means of theory, regression and numerical method. The research contents and related results mainly include the following aspects: first, The relationship between specific penetration resistance and shear strength of saturated soft soil is derived by using the theory of cylindrical cavity expansion. According to the assumption of saturated soft soil and yield criterion, the ultimate pore expansion pressure is obtained by solving equilibrium equation, geometric equation, constitutive equation and boundary condition, and the stress solution, displacement solution and plastic zone range of soil elastoplastic zone are obtained. The relationship between the penetration resistance of static penetration and the shear strength of soil under the theory of cylindrical cavity expansion is given. Secondly, through 19 projects in Shanghai and 33 projects in Wuhan, 694 groups of data are used to study the correlation between penetration resistance and shear strength of different soil types, and the physical and mechanical properties of three kinds of soils in two regions are analyzed and summarized. Through regression analysis, the relationship between the specific penetration resistance and the shear strength of soil is determined. Then, based on the finite element large deformation analysis method of adaptive mesh technology, the static penetration process is simulated. The soil displacement increases with the depth of penetration, and the penetration area extends to the side and below. When the cone head goes deep into a certain distance, the displacement-affected area approaches to the annular envelope distribution. The resistance increases with the increase of shear strength. Finally, combined with the typical project in Shanghai area, the consistency of shear strength of soil is compared and analyzed under three methods. It is considered that the theory of pore expansion and the condition of finite element analysis are idealized, and the characteristics of soil consolidation, anisotropy and friction are ignored. The regression analysis adopts the local engineering data and synthesizes the various characteristics of the soil, which is in good agreement with the actual shear strength of the soil. Therefore, it is necessary to determine the relationship between the specific penetration resistance of static penetration and shear strength according to engineering data before the establishment of a general expression under multiple factors, which is of practical value in engineering. In addition, based on the survey data of 52 projects, the database of hydrostatic penetration data is established in this paper. Combined with the current IT technology and software, this paper makes a preliminary exploration and research on the database work of engineering survey data (digitization, standardization, database).
【學(xué)位授予單位】：中國水利水電科學(xué)研究院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU43

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