【作者】 孙锋；

【导师】 张顶立； 陈铁林；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 厦门翔安海底隧道穿越海底F1、F2、F3、F4四个风化深槽(囊),风化深槽(囊)为全、强风化花岗岩地层,该地层透水性强、出水量大、水压高、海水补给无限,突水、涌泥的风险很大。安全穿越不良地质体及地层结构界面是海底隧道修建的关键问题,对其准确地探测、预报并采取可靠的注浆加固方案及施工方法是海底隧道安全顺利施工的重要保证。海底隧道复杂的地质条件和特殊的水边界,使单一的注浆方式或注浆材料往往不能达到目的,因而就提出了复合注浆。本论文在对国内外相关文献资料进行广泛调研的基础上,针对厦门海底隧道风化槽的工程特点,利用颗粒流软件对风化槽突水过程进行仿真模拟,分析风化槽突水机理,提出防止隧道突水的控制措施和注浆加固的必要性,通过风化槽注浆圈的渗流计算和流固耦合模拟分析确定其合理参数。同时,对复合注浆技术进行系统研究,包括全、强风化花岗岩地层复合注浆的工艺研究、设备及效果评价、注浆材料选择的试验研究等。在以上研究成果的基础上,提出复合注浆工法的设计方法、加固模式和突水防治措施,通过工程实例形成海底隧道穿越风花槽复合注浆关键技术体系。主要研究成果如下：(1)海底隧道隔水岩层突水通道形成过程的颗粒流数值仿真分析表明,对于不同地质模式,隧道突水的关键位置可能不同,但其形成机制都是在隧道开挖卸载和风化槽水压驱动下,岩层裂纹萌生、扩展、水压跟踪传递,从隔水层变成导水层的复杂演化过程。应用颗粒流仿真手段,可以实现对海底隧道穿越风化槽突水通道的初步预测与定位。注浆圈参数的确定是“堵水限排”设计的关键问题,注浆圈的渗流理论计算和流固耦合模拟分析是确定其合理参数的有效途径。以上研究是海底隧道穿越风化槽注浆堵水设计的前提和基础。(2)基于散体介质理论的颗粒流分析方法,运用其内置的Fish语言定义流体域,建立了流动方程和压力方程。同时,针对具有凝聚力的致密土体,引入颗粒接触粘结模型,建立能反映颗粒体与流体域耦合作用的土体注浆颗粒流模型。在此基础上,通过数值仿真试验,对土体压密—劈裂式复合注浆过程进行细观模拟研究,分别对比了不同注浆压力和不同土体性质下浆体压力扩散及劈裂缝的发生、发展规律。(3)土体复合注浆影响范围是浆液锋面沿着劈裂缝扩散的最远距离。宾汉体浆液劈裂注浆最大扩散半径由注浆压力差,裂隙宽度,流速和浆液的流变参数等因素共同决定。流体时变性对注浆扩散半径计算值影响很大,注浆理论忽略时变性会给工程设计带来不利影响。全、强风化花岗岩地层注浆加固机理以劈裂、挤压土体为主,对于该地层2.5 m的孔距完全能够满足注浆帷幕要求。(4)水泥结石体在海水腐蚀过程中,其内部结构经历了一个先由于腐蚀产物的填充作用而逐渐密实再过渡到由于腐蚀产物继续产生和膨胀,使密实度逐渐降低,最后发展为强度逐渐降低的过程。建议海底隧道风化槽地层,注浆材料以HSC特种注浆材料为首选,其次是普通水泥。马丽散作为一种新型注浆材料,在风化槽富水地层堵水加固效果良好。(5)提出复合注浆技术工法设计方法、加固模式和突水防治措施。复合注浆机制就在于它采用多种注浆方式或注浆材料分步骤地改善工程载荷作用的边界条件、应力传递的连续性和完整性。海底隧道复合注浆设计原则主要是材料复合、方式复合、注浆顺序、参数、设备的选择及效果评价等。采用复合注浆方法对F1风化槽进行了堵水和加固,取得了满意的效果,系统介绍了右线隧道F1风化深槽的地质情况、注浆机理、复合注浆方案、参数、施工工艺及注浆效果的检验、评价情况等,形成了海底隧道穿越风化槽复合注浆关键技术体系。更多还原

【Abstract】 According to the geological exploration data, Xiamen Xiang’an subsea tunnel will pass through the four deep weathered slots of troughs, F1、F2、F3、F4, where the strata are complete or strong weathered weak rocks. These strata have high permeability coefficients, huge water amount, high water pressure, and high risk of water and silt pouring in tunnel with infinite seawater supply. Passing through unfavorable geologic bodies and strata interface is one of the most difficult problems during subsea tunnel construction. So tunnel geological forecast ahead, grouting reinforcement schemes and construction method optimization are important issues to guarantee the safety of subsea tunnel construction. Due to the complicated geological and water conditions, composite grouting technique is introduced, which can take advantage of different grouting technologies and materials.In this paper, based on domestic and foreign documents, integrated Xiamen Xiang’an subsea tunnel passing through the weathered slot F1 project, meso-mechanical simulation of groundwater inrush pathway formation between the weathered slot and the tunnel are discussed by using PFC software, appropriate parameters of grouting circle for tunnels with limiting discharge lining is proposed, which can provide reference for the design and construction of composite grouting in weathered slot Fl. Meanwhile, theoretical study and meso-mechanical simulation on composite grouting in the strong-weathered granite stratum are analyzed, grouting materials is introduced by the seawater corrosion test of strength concrete. Combined with above study and engineering case, the key technique of composite grouting for water blockage in weathered slot of subsea tunnel is presented.The work in the present paper can be summarized in the following:(1) Based on the weathered slot configuration and the spatial relation between the weathered slot and the tunnel, the weathered slot water burst is divided into different geological modes. Combined with above study, numerical tests with PFC under coupling environment are conducted to investigate the initiation of fractures, activation of weathered slot and formation of groundwater inrush pathway during the tunnel passing closely through the weathered slot structures with high water pressure. Keeping the completeness and stability of the rock pillars is of key importance to avoid water burst and to minimize there relevant loss when the tunnel passing closely by the weathered slot structures. To find the appropriate parameters of grouting circle is the key issue to perfectly blocking ground water and limiting discharge. The effects of grouting circle will not share the external water pressure on lining with tunnel lining, but to block ground water and reduce the external water pressure on lining remarkably with low discharge. The study can provide instructional advice for the design and construction of composite grouting in Xiamen Xiang’an subsea tunnel passing through the weathered slot F1 project.(2) Based on the theory of particle flow, the domain of flow is defined by using Fish language implemented in PFC and the formulas for flow and pressure are put forward respectively. Furthermore, the Contact-Bond Model is introduced due to the complicated properties of low permeability soil to build PFC model, which can reflect Fluid-solid coupling between particles flow and flow domain. Combined with above study, the process of fracture grouting in soil is simulated from micro-viewpoint under coupling environment. In addition, the emergence and development of crack and grouting pressure in soil is analyzed under different grouting pressure and soil properties.(3) It shows that grouting diffusion radius of bingham fluid is related to grouting pressure difference, gap width, flow velocity and time-dependent behavior of rheological parameters. So it is unreasonable to miss the time-dependent behavior of grouts in computing diffusion radius.The interval of 2.5m can form complete curtain grouting in strong-weathered granite and the mechanism of grouting is fracture grouting no more than penetrate grouting.(4) Grouting materials test indicates that the use of seawater causes an earlier strength compared to the same with tap water. However, after a long period the use of seawater may results in the formation of deeper corrosion compared to tap water, especially the influence is found to be significant for higher W/C. It is understood that at the early age, the microstructure of concrete improved due to the use of seawater. Then it reduces gradually, because seawater may cause deterioration of concrete strength after a long time. Based on the grouting test, it recommended that High Strength Concrete(HSC) and Portland Cement have an satisfactory effects in the strong-weathered granite stratum. Especially, malisan grouting play a improtant role in water-enriched weathered slot.(5) Characteristics and design principles of composite grouting are achieved. Composite grouting is a economic and effective measure to strengthen the weathered slot to the fullest extent, which means grouting in the ground by using different grouting technologies and materials according to a special time and space sequence. In order to assure that the subsea tunnel can pass the weathered slot F1 successfully, the technique of composite grouting is adopted to reinforce the soil to block up the water and a good result is gained. The geological condition, grouting mechanism, scheme and parameters, and the verification and appraisal of the construction technology and grouting effect are introduced in this paper, and therefore composite grouting key technology is formed.更多还原