發(fā)布時間：2018-09-19 20:18

【摘要】：隨著我國高鐵與公路建設(shè)的實施和普及,工程實際中常遇到各種不良地質(zhì),如軟土、膨脹土、濕陷性黃土等。公路軟基的沉降變形分為垂直沉降產(chǎn)生的變形和側(cè)向擠出引起的沉降變形。側(cè)向擠出不僅對路基總沉降產(chǎn)生影響,甚至?xí)绊懼苓吔ㄖ锏陌踩�(wěn)定性。為了限制軟土在預(yù)壓荷載作用下的側(cè)向擠出,減少堆載預(yù)壓排水固結(jié)對周邊環(huán)境的不利影響,提出側(cè)限堆載預(yù)壓控制技術(shù)。本文以導(dǎo)師的科研項目為依托,結(jié)合相關(guān)文獻(xiàn)的實際工程,通過有限差分分析軟件,對這一技術(shù)展開了研究。并在合理假設(shè)的基礎(chǔ)上,構(gòu)造出了有無側(cè)限條件下地基土沉降的近似解析算式。主要有以下幾方面結(jié)論:1.為限制軟土堆載預(yù)壓及堆載預(yù)壓區(qū)以外的地下水位降低對周邊環(huán)境的不利影響,提出側(cè)限堆載預(yù)壓控制新技術(shù)�；谕亮W(xué)理論提出了側(cè)限水泥土墻的計算內(nèi)容及計算方法。2.基于FLAC~(3D)有限差分分析軟件并結(jié)合實際工程,建立了無側(cè)限條件下的堆載預(yù)壓排水固結(jié)模型。將無側(cè)限堆載預(yù)壓模型的模擬結(jié)果與相關(guān)文獻(xiàn)實測結(jié)果進(jìn)行了對比,驗證了堆載預(yù)壓排水固結(jié)數(shù)值模擬模型的合理性及可行性。3.基于FLAC~(3D)有限差分分析軟件,考慮分級堆載的影響,建立了側(cè)限條件下堆載預(yù)壓排水固結(jié)模型。討論了側(cè)限位置、側(cè)限水泥土墻的埋置深度及寬度對堆載預(yù)壓排水固結(jié)效果的影響。研究結(jié)果表明:堆載預(yù)壓側(cè)限控制技術(shù)能有效降低軟土地基沉降,提高前期固結(jié)速率,固結(jié)度達(dá)80%堆載預(yù)壓時間比無側(cè)限堆載預(yù)壓時間最大可縮短10 d。側(cè)限設(shè)置位置對堆載預(yù)壓沉降量影響顯著。當(dāng)側(cè)限位置位于堆載預(yù)壓區(qū)邊緣時,與無側(cè)限相比,堆載預(yù)壓區(qū)最大沉降可降低58.93%。最佳的側(cè)限位置位于堆載預(yù)壓區(qū)邊緣。4.在合理假設(shè)的基礎(chǔ)上,構(gòu)造了滿足位移邊界條件的位移函數(shù)�；趶椥粤W(xué)中變分法,建立了有無側(cè)限堆載預(yù)壓地基變形的變分方程,推出了有無側(cè)限堆載預(yù)壓地基變形計算的近似解析算式,并利用MATLAB軟件編制程序。將理論結(jié)果與模擬結(jié)果進(jìn)行對比,驗證了計算方法的合理性和可行性。
[Abstract]:With the implementation and popularization of high-speed railway and highway construction in China, various kinds of bad geology are often encountered in engineering practice, such as soft soil, expansive soil, collapsible loess and so on. The settlement deformation of soft foundation is divided into vertical settlement and lateral extrusion. Lateral extrusion not only affects the total settlement of roadbed, but also affects the safety and stability of surrounding buildings. In order to limit the lateral extrusion of soft soil under preloading and to reduce the adverse effect on surrounding environment caused by surcharge preloading and drainage consolidation, a lateral limit preloading control technique is proposed. In this paper, based on the scientific research project of the tutor, combining with the actual engineering of the related literature, the research on this technology is carried out by using the finite difference analysis software. On the basis of reasonable assumptions, an approximate analytical formula for the settlement of foundation soil with or without lateral limit is constructed. The main conclusions are as follows: 1. In order to limit the adverse effects on the surrounding environment caused by the decrease of groundwater level outside the soft soil load preloading and the surcharge preloading area, a new technology of side limit surcharge preloading control is put forward. Based on the theory of soil mechanics, the calculation content and calculation method of side limit cement earth wall are put forward. Based on FLAC~ (3D) finite difference analysis software and practical engineering, the consolidation model of surcharge preloading drainage with no side limit is established. The simulation results of the unconfined surcharge preloading model are compared with the measured results of relevant literatures, and the rationality and feasibility of the numerical simulation model of surcharge preloading drainage consolidation are verified. Based on FLAC~ (3D) finite difference analysis software and considering the influence of graded heaped load, the consolidation model of preloading drainage is established under the condition of side limit. The influence of the side limit position, the depth and width of the side limit cement soil wall on the consolidation effect of the surcharge preloading drainage is discussed. The results show that the lateral limit control technique of surcharge preloading can effectively reduce the settlement of soft soil foundation and increase the consolidation rate in the early stage. The maximum consolidation time of 80% surcharge preloading can be shortened by 10 days compared with the maximum time of unconfined surcharge preloading. The position of side limit has a significant effect on the settlement of surcharge preloading. When the side limit is located at the edge of the surcharge preloading zone, the maximum settlement of the surcharge preloading zone can be reduced by 58.93% compared with the non-side limit. The best side limit is located at the edge of the surcharge preloading zone. A displacement function satisfying the displacement boundary condition is constructed on the basis of reasonable assumptions. Based on the variational method in elastic mechanics, the variational equation of foundation deformation with or without lateral limit surcharge preloading is established, and the approximate analytical formula for calculation of foundation deformation with or without lateral limit surcharge preloading is derived, and the program is compiled by using MATLAB software. The theoretical results are compared with the simulation results to verify the rationality and feasibility of the calculation method.
【學(xué)位授予單位】：湖南工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U416.1

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