本文選題：高填明洞 + 土壓力��； 參考：《蘭州交通大學(xué)》2015年碩士論文

【摘要】：明洞作為采用明挖法修筑的隧道結(jié)構(gòu)的一種,在由山、原、川三大地貌類型構(gòu)成主體的黃土高原被廣泛使用。交通的迅速發(fā)展促進(jìn)了城市化進(jìn)程的加快,也使得城市用地日趨緊張,削山造地、深溝回填成為了創(chuàng)造城市用地的一大主要途徑。因而,針對于明洞回填的工程也逐漸增多,回填高度也逐漸增大,而由于多數(shù)明洞設(shè)計(jì)之初大都未考慮明洞上方高回填情況,不斷增大的明洞回填土壓力成為了影響明洞正常安全使用的重要不利因素之一。高填方明洞土壓力問題屬于高填結(jié)構(gòu)物土壓力問題范疇,而目前對于高填結(jié)構(gòu)物土壓力的研究則主要集中在涵洞(管)方面,對于高填明洞研究較少�；靥钸^程中不斷增大的土壓力將對明洞結(jié)構(gòu)安全產(chǎn)生極其不利的影響,導(dǎo)致明洞結(jié)構(gòu)病害的產(chǎn)生�；谝陨蠁栴}的出現(xiàn),本文圍繞明洞回填過程中采取何種措施達(dá)到減小明洞所受土壓力及確定卸載后明洞頂土壓力兩方面問題開展了研究。首先,根據(jù)不同卸載設(shè)置條件下的的室內(nèi)模型試驗(yàn),得到回填過程中明洞土壓力變化規(guī)律;然后,建立有限元分析模型,對影響卸載作用下明洞土壓力影響因素進(jìn)行了探究;最后,根據(jù)室內(nèi)試驗(yàn)和有限元分析結(jié)果,依據(jù)巖土力學(xué)理論,對加筋卸載作用下的明洞頂土壓力進(jìn)行了理論計(jì)算公式推導(dǎo)。主要結(jié)論如下:(1)通過對不同卸載設(shè)置條件下的高填明洞土壓力模型試驗(yàn)的土壓力、土體沉降實(shí)測得到:無論設(shè)置卸載措施與否,明洞回填過程中,洞頂、洞腳土壓力隨填土高度都呈非線性變化;減小明洞內(nèi)外土柱沉降差絕對值而有利于明洞頂土壓力的減小,且設(shè)置方式不同,卸載效率不同;在設(shè)置低壓實(shí)度孔的條件下,土工格柵的鋪設(shè)有利于進(jìn)一步減小明洞洞頂土壓力,但由于格柵變形空間有限,多層減載效果不明顯;增大明洞兩側(cè)填土壓縮模量對提高低壓實(shí)土和土工格柵組合卸載措施的卸載率有積極作用;填土高度不大時(shí),明洞頂土壓力可近似采用土柱法γH計(jì)算,填土高度增大,土柱法不再適用。(2)建立有限元分析模型,分析結(jié)果表明:明洞回填過程中,明洞頂產(chǎn)生土拱效應(yīng)有利于明洞頂土壓力的減小;各因素分析中,低壓實(shí)度孔的設(shè)置對于減小明洞內(nèi)外土柱沉降差絕對值影響最大,因而對明洞頂土壓力大小影響也最為顯著。(3)參照室內(nèi)模型試驗(yàn)、有限元分析結(jié)果,建立邊坡存在條件下的加筋卸載高填明洞頂土壓力計(jì)算模型,以等沉面高度Hc為界,推導(dǎo)得到了不同填土高度下的明洞頂土壓力計(jì)算公式,為高填土明洞及其減載結(jié)構(gòu)設(shè)計(jì)及施工提供理論參考。
[Abstract]:As one of the tunnel structures constructed by the method of open excavation, the Ming Cave is widely used in the Loess Plateau, which is composed of three main geomorphological types: mountain, original and Sichuan. The rapid development of transportation accelerates the process of urbanization and makes urban land use more and more tense. Cutting mountains and making land, deep ditch backfill has become one of the main ways to create urban land. As a result, the number of backfill projects for the Ming Cave is increasing gradually, and the backfill height is also gradually increasing. However, most of the design of the Ming Cave does not consider the high backfill situation above the Ming Cave at the beginning of the design. The increasing backfill pressure has become one of the important unfavorable factors affecting the safe use of the tunnel. The earth pressure problem of high filling open tunnel belongs to the category of high fill structure soil pressure, but at present, the study of high fill structure earth pressure is mainly focused on culvert (pipe), but the research on high fill open tunnel is less. The increasing earth pressure in the backfill process will have an extremely adverse effect on the structural safety of the open tunnel, resulting in the occurrence of the structural diseases of the open tunnel. Based on the above problems, this paper focuses on two aspects: what measures should be taken to reduce the earth pressure of the open tunnel and how to determine the earth pressure of the roof of the open tunnel after unloading. Firstly, according to the indoor model tests under different unloading conditions, the variation law of soil pressure in the open tunnel during backfilling is obtained, and then, the finite element analysis model is established to explore the influencing factors of the soil pressure in the open tunnel under the action of unloading. Finally, according to the results of laboratory tests and finite element analysis, and based on the theory of geotechnical mechanics, the theoretical calculation formula for the earth pressure of the open roof under the action of reinforcement and unloading is derived. The main conclusions are as follows: (1) through the soil pressure of the model test of the high filling tunnel under different unloading conditions, the settlement of the soil is measured: no matter whether the unloading measures are set up or not, the roof of the tunnel in the course of backfilling is obtained. The soil pressure at the bottom of the tunnel varies nonlinear with the height of the fill, and reducing the absolute value of the settlement difference between the soil column inside and outside the tunnel is beneficial to the reduction of the soil pressure at the top of the tunnel, and the setting way is different, and the unloading efficiency is different. Under the condition of setting the hole with low compaction degree, The laying of geogrid is conducive to further reducing the earth pressure at the top of the tunnel, but the effect of multi-layer load reduction is not obvious because of the limited deformation space of the grid. Increasing the compression modulus of the filling on both sides of the open tunnel has a positive effect on increasing the unloading rate of the combined unloading measures of low-pressure solid soil and geogrid, and when the filling height is small, the earth pressure of the roof of the tunnel can be calculated approximately by using the soil column method 緯 H, and the height of the fill will increase. Soil column method is no longer applicable. (2) the finite element analysis model is established. The results show that the soil arch effect at the top of the open tunnel is beneficial to the reduction of the earth pressure of the open roof in the course of the backfilling of the open tunnel, and in the analysis of various factors, The setting of low compaction hole has the greatest influence on reducing the absolute value of settlement difference of soil column inside and outside the open tunnel, so it also has the most significant effect on the soil pressure of the roof of the open tunnel. (3) referring to the results of indoor model test and finite element analysis, In this paper, a calculation model of the earth pressure at the top of a reinforced and unloading high filling tunnel is established under the condition of slope existence. Taking the equal settlement height HC as the boundary, the formula for calculating the earth pressure of the open top of the tunnel with different filling heights is derived. It provides a theoretical reference for the design and construction of high-fill open tunnel and its load-reducing structure.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU432

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