砂土与全风化花岗岩中双线盾构隧道近距离下穿高架桥的影响分析

发布时间：2018-03-15 00:34

本文选题：双线盾构隧道　切入点：数值模拟　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文依托穗莞深城际铁路工程中太平隧道穿越高架桥工程实例,采用理论分析、现场实测数据分析和数值模拟的方法,致力于研究以下几个方面的问题:(1)单线隧道和双线隧道施工对土体、桩基和周边环境的影响规律;(2)地层损失变化对土体变形、隧道衬砌内力的影响规律;(3)隧道埋深和注浆对现有桥梁结构的影响规律。研究的主要成果如下:(1)盾构同时穿越砂土和全风化花岗岩组合的复杂地层,由于两土层间物理力学性质差别大,刀盘削土扰动容易引发砂土液化;同时,上软下硬土层有着不同的切削难易程度,砂土易于切削并迅速进入泥土舱,而岩层难以破碎,这直接影响着开挖面的土压平衡建立。施工中通过控制左右区顶力的平衡来保证轴线精度。同时将下区顶力控制为上区顶力的2.1倍,保证开挖面的稳定。(2)本研究分析了盾构穿越高架桥前后的施工参数变化,研究表明:盾构穿越高架桥时,维持刀盘扭矩不变,分别将顶推力和土舱压力提高3.6%、6.7%,可将桥墩沉降量控制在5mm限制内,确保桥梁结构安全。(3)本研究通过分析工程实测数据研究了双线盾构施工环境的影响规律。实测结果表明:①地面沉降历程与盾构机头位置相关,在盾构机头通过测点后沉降增长较快,增长速率小于0.85mm/天;每个测点的最终沉降量与切口通过该测点时的掘进速度有关,掘进速度快的测点沉降量相对较小,掘进速度慢的测点沉降量相对较大,即使掘进速度降至0(换刀期间),沉降也会持续发展。②土体深层沉降在盾构机头通过测点前后约15天内发展明显,以位于隧道埋深附近9~15m的土体沉降最大,随着深度的增加,沉降量逐渐减小。③土压力在盾构机通过测点前后5~10天内出现波动,以深度9.5m~12.5m深度处土压力变化最大。不同深度处土压力或涨或降,最大涨幅28.5%,最大降幅17.9%。(4)数值分析成果表明,地层损失率对土体变形、衬砌内力有较大的影响。并进一步研究了隧道埋深和注浆对桩基的影响,成果表明:①地层损失对土体变形和隧道内力的影响是非线性的;地层损失率大于2.0%时,土体变形急剧发展;在双线隧道施工中,应尽量减小双线地层损失的差值;同时控制每条隧道的地层损失率不宜大于1.4%。②桩顶沉降随着隧道埋深的增加而减小,随着注浆长度的增大而减小;在广东地区砂土和全风化花岗岩组合的特有地质条件下,隧道最优埋深为12~16m,而注浆长度不宜大于8m。
[Abstract]:Based on the engineering example of Taiping tunnel crossing viaduct Guangzhou Dongguan Shenzhen intercity railway project, using theoretical analysis method, field data analysis and numerical simulation, focuses on the following issues: (1) single tunnel and double line tunnel construction on the influence of soil, pile foundation and surrounding environment; (2) formation the loss of variation of soil deformation, influence of internal force of tunnel lining; (3) the depth of the tunnel and grouting on the influence of the existing bridge structures. The main results of the research are as follows: (1) the complex stratum shield while crossing the sand and wind around the granite combination, since the two soil physical and mechanical properties of the big difference between the cutter cut the soil disturbance prone to liquefaction; at the same time, the hard soft soil have different degree of difficulty of cutting, cutting easy and quickly into the sand soil and rock to cabin, broken, which directly affects the excavation face Earth pressure balance is established. By controlling the construction area of the top about the balance of power to ensure the accuracy of the axis. At the same time will be 2.1 times the area under the load control for the District of jacking force, ensure the excavation stability. (2) this study analyzed the changes of the construction parameters of shield tunneling, the viaduct before and after the study shows that the shield crossing overhead the bridge, maintain the cutter torque constant, respectively the roof thrust and the earth pressure is increased by 3.6%, 6.7%, the amount of control in the 5mm within the limits of the settlement of piers, to ensure bridge structure safety. (3) the influence of the construction environment of double line shield are studied through analysis of engineering test data. The results show: the ground the settlement process associated with the shield head position in the shield machine head through the rapid growth of settlement point, the growth rate is less than 0.85mm/ days; each measuring point of the final settlement and the measured point of the incision through the driving speed, driving speed Settlement of measuring points is relatively small, the slow driving settlement of measuring points is relatively large, even if the driving speed to 0 (ATC period), the settlement will be sustainable development. The deep soil settlement in shield machine head through measuring points before and after the development of about 15 days, taking the soil in depth of tunnel near the settlement of 9~15m the largest, with the increase of depth, the settlement gradually decreases. The earth pressure by measuring points before and after 5~10 days, the fluctuations in the shield machine, the maximum depth at the depth of 9.5m~12.5m. The change of earth pressure at different depth of soil pressure or up or down, or 28.5% of the largest, the biggest drop in 17.9%. (4) numerical analysis results show that the formation the loss rate of soil deformation, affects the lining internal force influence, and further study the tunnel depth and grouting pile on the results show that the influence of the ground loss of soil deformation and internal force of tunnel is non linear; ground loss The rate is greater than 2%, the rapid development of soil deformation; in the construction of double track tunnel, should minimize the difference between double ground loss; at the same time to control each of the tunnel ground loss ratio should not be greater than 1.4%. the pile top settlement decreases with increasing tunnel depth, and decreases with the increasing length of grouting in the special geological condition of Guangdong; area of sand and weathered granite under the optimal tunnel depth is 12~16m, and the grouting length should not be more than 8m.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.43

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