本文選題：盾構(gòu)隧道 + 開(kāi)挖面穩(wěn)定�。� 參考：《浙江大學(xué)》2017年博士論文

【摘要】：為了提高居民的出行效率,急需加快城市地下道路網(wǎng)絡(luò)的建設(shè)。盾構(gòu)隧道施工技術(shù)目前在地下交通工程中得到了廣泛應(yīng)用,并向著超深、超大直徑方向發(fā)展。大直徑隧道是城市越江通道的首選方案,但是泥水盾構(gòu)在穿越江底時(shí)容易因?yàn)楦咚畨�、淺覆土以及河床高滲透性的砂土引發(fā)失穩(wěn)事故�；趯�(shí)際工程需求,本文對(duì)泥水盾構(gòu)泥膜形成規(guī)律和開(kāi)挖面穩(wěn)定性兩個(gè)問(wèn)題進(jìn)行了系統(tǒng)深入的研究。主要工作和研究成果如下:(1)采用自行研制的滲透柱開(kāi)展了不同泥漿壓力條件下泥漿滲透試驗(yàn),研究了泥膜的滲透性與時(shí)間的關(guān)系,以及泥漿滲透對(duì)地層滲透系數(shù)的影響。試驗(yàn)結(jié)果顯示,膨潤(rùn)土質(zhì)量含量為4.76%的泥漿在71至119 kPa泥漿壓力作用下,滲入飽和長(zhǎng)江河砂地層(滲透系數(shù)為×10-4m/s),滲透開(kāi)始5 s內(nèi),形成微透水的泥膜(35mm等效泥膜滲透系數(shù)為7.6×10-5至1.3×10-6m/s);300秒后,才能形成難透水的泥膜(35mm等效泥膜滲透系數(shù)為4.4×10-9至7.9×10-9m/s)。盾構(gòu)在進(jìn)時(shí),開(kāi)挖面上只能形成微透水的泥膜。當(dāng)泥漿壓力為71至119 kPa時(shí),泥漿的平均距離范圍僅為8.5至21.4 cm。因此,可以認(rèn)為當(dāng)D151d85/4.26時(shí)泥漿滲透不會(huì)改變地層的滲透系數(shù)。(2)通過(guò)介紹濾餅過(guò)濾理論,揭示了泥漿過(guò)濾成膜的機(jī)理。在泥漿壓力10至90 kPa作用下開(kāi)展了一系列濾失試驗(yàn),獲得了膨潤(rùn)土質(zhì)量含量為4.76%的泥漿形成的泥膜的本構(gòu)模型的基本參數(shù)(δ =0.2,e0=1.85,α = 2和k0=-5.513)。試驗(yàn)結(jié)果顯示,泥漿壓力越大,形成的泥膜透水性越差�；跒V餅過(guò)濾理論的解析解推導(dǎo),揭示了開(kāi)挖面上泥膜厚度和滲透系數(shù)的動(dòng)態(tài)分布模式。提出了根據(jù)泥膜前后壓力差計(jì)算泥膜平均厚度的方法,發(fā)現(xiàn)了泥膜平均厚度與刀臂間的夾角和刀盤(pán)轉(zhuǎn)速有關(guān)。(3)采用二維數(shù)值軟件SEEP/W,研究了泥水盾構(gòu)開(kāi)挖面前方地層孔壓的瞬態(tài)分布情況。數(shù)值模擬結(jié)果顯示,有效泥漿壓力等于45kPa時(shí),泥膜(35 mm等效泥膜滲透系數(shù)為1×10-6m/s)上的孔壓迅速下降,長(zhǎng)江河砂地層(滲透系數(shù)為2×10-4m/s)中孔壓緩慢下降,距開(kāi)挖面30m時(shí)達(dá)到靜水壓力�；陂_(kāi)挖面前方土體失穩(wěn)模式以及土體孔壓場(chǎng),提出了泥膜和地層失穩(wěn)區(qū)域內(nèi)滲透力的計(jì)算方法。結(jié)果顯示,作用在泥膜和地層失穩(wěn)區(qū)域內(nèi)的滲透力共同維持開(kāi)挖面穩(wěn)定。有效泥漿壓力越大,用于支護(hù)開(kāi)挖面穩(wěn)定的有效泥漿壓力的比例越小,支護(hù)效率越低。棱柱體和泥膜上的滲透力分別是垂直和水平方向上維持開(kāi)挖面穩(wěn)定的主要因素。(4)采用三維數(shù)值軟件COMSOL,研究了泥水盾構(gòu)開(kāi)挖面前方地層總水頭的瞬態(tài)分布情況。數(shù)值模擬結(jié)果顯示,開(kāi)挖時(shí)間和有效泥漿壓力對(duì)歸一化總水頭的分布影響不大。歸一化總水頭分布顯示,泥膜上的滲透力隨著地層滲透系數(shù)增大而增大,開(kāi)挖面前方地層滲透力隨著地層滲透系數(shù)增加而減小,地層滲透系數(shù)對(duì)開(kāi)挖面上部地層滲透力影響很小。埋深比對(duì)泥膜上總水頭的下降幅度及開(kāi)挖面前方地層中歸一化總水頭分布情況影響很小,隧道埋深較大時(shí)(如C/D2),埋深比對(duì)棱柱體上的歸一化總水頭影響較大。(5)基于極限平衡法建立了極限有效泥漿壓力的計(jì)算方法。通過(guò)比較發(fā)現(xiàn)以往研究計(jì)算方法獲得的有效泥漿壓力偏不安全。計(jì)算結(jié)果顯示,有效摩擦角小于25°的地層,且埋深比小于2.5時(shí),歸一化極限有效泥漿壓力隨埋深比增加而顯著增加。泥膜滲透系數(shù)和地層滲透系數(shù)之比與歸一化極限有效泥漿壓力成正比。有效摩擦角與歸一化極限有效泥漿壓力成反比;歸一化極限有效泥漿壓力隨著有效粘聚力增加,而線性下降。最后繪制了適用于實(shí)際工程的計(jì)算圖表。
[Abstract]:In order to improve the efficiency of the residents, it is urgent to speed up the construction of the urban underground road network. The shield tunnel construction technology is widely used in the underground traffic engineering, and is developing towards the ultra deep and ultra large diameter. The large diameter tunnel is the first choice for the city crossing channel, but the slurry shield is easy to pass through the bottom of the river. High water pressure, shallow overlying soil and high permeability sand in river bed cause instability accidents. Based on actual engineering requirements, this paper makes a systematic and thorough study on two problems of mud shield mud film formation and excavation face stability. The main work and research results are as follows: (1) different mud pressure conditions are carried out by the self developed permeable column. Under the mud penetration test, the relationship between the permeability and time of the mud film and the influence of mud penetration on the permeability coefficient are studied. The test results show that the mud of 4.76% of bentonite, under the action of 71 to 119 kPa mud pressure, infiltrates into the saturated Changjiang River sand stratum (permeability coefficient is x 10-4m/s), and the permeability begins to be within 5 s, forming a micro permeability. The mud membrane of water (the permeability coefficient of 35mm is 7.6 x 10-5 to 1.3 x 10-6m/s); after 300 seconds the permeable mud film can be formed (the permeability coefficient of 35mm is 4.4 x 10-9 to 7.9 x 10-9m/s). When the shield is entering, the mud membrane can only be formed on the excavation surface. When the mud pressure is 71 to 119 kPa, the average distance range of the mud is only 8.5 To 21.4 cm., it can be considered that mud penetration will not change the permeability coefficient of the formation when D151d85/4.26. (2) through introducing filter cake filtration theory, the mechanism of mud filtration was revealed. A series of filtration tests were carried out under the action of mud pressure 10 to 90 kPa, and the mud film formed by mud of bentonite with the mass content of 4.76% was obtained. The basic parameters of the constitutive model (delta =0.2, e0=1.85, alpha = 2 and k0=-5.513). The results show that the greater the mud pressure is, the worse the permeability of the mud film is. Based on the analytical solution of filter cake filtration theory, the dynamic distribution pattern of the thickness and permeability coefficient of the mud film on the excavation surface is revealed. The average mud film is calculated according to the pressure difference before and after the mud membrane. The thickness method has been found that the average thickness of the mud film is related to the angle between the arm and the blade speed. (3) a two-dimensional numerical software SEEP/W is used to study the transient distribution of the pore pressure in the front of the slurry shield. The numerical simulation shows that the mud film (the permeability coefficient of the 35 mm is 1 x 10-6m/s) when the effective mud pressure is equal to 45kPa. The pore pressure drops rapidly, and the pore pressure of the Changjiang River sand stratum (permeability coefficient is 2 * 10-4m/s) decreases slowly and reaches the static water pressure when it is 30m from the excavation surface. Based on the model of soil instability in front of the excavated surface and the pore pressure field of the soil, the calculation method of the permeability in the mud and stratum instability region is put forward. The result shows that the effect is unstable in the mud film and the stratum. The more effective mud pressure is, the greater the effective mud pressure, the smaller the ratio of effective mud pressure to the stability of the supporting surface, the lower the support efficiency. The permeability on the prism and the mud film is the main factor to maintain the stability of the excavation face in the vertical and horizontal direction respectively. (4) the three-dimensional numerical software COMSOL is used. The numerical simulation results show that the excavation time and the effective mud pressure have little influence on the distribution of the normalized total water head. The distribution of the total head distribution shows that the permeability on the mud film increases with the increase of the permeability coefficient, and the permeability ahead of the front of the excavation face is along with the seepage force. The permeability coefficient of the stratum decreases and the permeability coefficient of the stratum has little influence on the permeability of the upper layer of the excavated surface. The depth of the buried depth has little influence on the decrease of the total head on the mud film and the distribution of the normalized total head in the strata in the front of the excavation. The depth of the tunnel is larger (such as C/D2), and the depth of the buried depth has a better effect on the normalized total water head on the prism. (5) the calculation method of limit effective mud pressure is established based on the limit equilibrium method. By comparison, it is found that the effective mud pressure obtained by the previous research method is not safe. The results show that the effective friction angle is less than 25 degrees and the depth ratio is less than 2.5, and the effective mud pressure of the normalization limit is significant with the depth ratio of buried depth. The ratio of the permeability coefficient to the permeability coefficient of the mud film is proportional to the effective mud pressure of the normalized limit. The effective friction angle is inversely proportional to the effective mud pressure of the normalized limit; the normalized limit effective mud pressure increases with the effective cohesive force and decreases linearly. Finally, the calculation chart for practical engineering is drawn.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：U455.43

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