季节性冻土隧道衬砌开裂机理及整治措施研究

发布时间：2018-03-19 02:18

  本文选题：季节性冻土　切入点：隧道　出处：《中国铁道科学研究院》2014年硕士论文　论文类型：学位论文

【摘要】：隧道衬砌裂缝在季节性冻土隧道中的大量存在，严重影响了隧道衬砌结构的稳定性、适用性、耐久性，且衬砌裂缝的进一步发展同时会诱发其它隧道病害，影响到隧道的安全性。本文以梁家坪2#隧道工程为依托，从现场的试验监测出发，通过运用大型通用有限元软件ANSYS，对季节性冻土隧道温度场、应力场进行计算和分析。并对季节性冻土隧道衬砌开裂机理进行研究分析，为预防和治理此类病害隧道提供理论参考。主要结论如下： （1）由梁家坪2#隧道室内实验可得：围岩含水量约为10.8%，饱和原状土样的含水量则约为12.3%，围岩饱水自由冻胀率约为1.41%，泥岩自由膨胀率为15%，砂岩自由膨胀率为8%，根据规范围岩属非膨胀土。 （2）在对能够造成衬砌开裂的可能性原因分析的基础上，排除了由高地应力、水压力、膨胀土压力、围岩压力等因素导致该隧道开裂的可能性。通过对梁家坪2#隧道进行现场试验监测分析，发现边墙纵向裂缝的变化规律符合由围岩冻胀导致衬砌开裂的变化规律。因此，初步判断该隧道衬砌开裂的主要原因是由于围岩的季节性冻胀所引起。 （3）通过对该地区的气温、降雨统计分析可知，近几年该地区夏季雨量比较丰富，冬季气温比较低，负温持续时间达4个月左右，最冷月份平均气温在-10℃左右。 （4）隧道温度场数值计算结果表明围岩冻结圈深度为104cm，与实测100cm基本相符合，且最大冻结深度发生的时间均在次年的1月19日前后。 （5）由冻胀力计算结果可知，梁家坪2#隧道在冻胀力作用下隧道边墙处拉应力大于混凝土极限抗拉强度，与实际病害相符。 （6）通过对不同围岩冻结圈下隧道衬砌配筋设计得出，隧道衬砌配筋面积与围岩冻结圈深度呈线性关系。因此对于在季节性冻土区修建隧道应考虑冻胀设防。 （7）通过对三种不同方案的配筋加固方案设计，，建议采用第三种方案即切槽放钢筋笼，并在隧道边墙受拉区范围内上下各打设3根Φ25锚杆，以抵抗季节冻胀力，抑制边墙向隧道内挤出，防止衬砌进一步开裂。同时在隧道衬砌背后进行注浆（其注浆范围为0.6m～0.8m）加固，以减小土体孔隙率，减小围岩存水空隙，降低围岩冻胀率，进而有效减小围岩冻胀。
[Abstract]:The existence of tunnel lining cracks in seasonal permafrost tunnels seriously affects the stability, applicability and durability of tunnel lining structures, and the further development of lining cracks will induce other tunnel diseases at the same time. Based on the Liangjiaping2# tunnel project, the temperature field of the seasonal frozen soil tunnel is studied by using the large-scale finite element software ANSYS. based on the field test and monitoring. The stress field is calculated and analyzed, and the cracking mechanism of tunnel lining in seasonal frozen soil is studied and analyzed, which provides a theoretical reference for the prevention and treatment of this kind of disease tunnel. The main conclusions are as follows:. (1) the indoor experiment of Liangjiaping2# tunnel shows that the water content of surrounding rock is about 10.8, the water content of saturated undisturbed soil is about 12.3, the free frost heaving rate of surrounding rock is about 1.41, the free expansion rate of mudstone is 15, the free expansion rate of sandstone is 8. The range of rock is non-expansive soil. (2) on the basis of the analysis of the possible causes of the cracking of the lining, the high ground stress, water pressure and expansive soil pressure are excluded. The possibility of cracking in the tunnel caused by surrounding rock pressure and other factors. Through field test and analysis of Liangjiaping2# tunnel, it is found that the variation law of longitudinal crack of sidewall conforms to the variation law of lining cracking caused by frost heaving of surrounding rock. The main reason for the tunnel lining cracking is the seasonal frost heaving of surrounding rock. 3) through the statistical analysis of the temperature and rainfall in this area, it can be seen that the summer rainfall in this area is relatively abundant in recent years, the winter temperature is relatively low, the negative temperature lasts for about 4 months, and the average temperature in the coldest month is about -10 鈩

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