水泥预加固-人工冻结联合工法加固地层冻胀特性

为研究采用联合工法施工，能够有效控制土体冻胀位移的施工参数，本文以广州地铁十四号线某联络通道冻结工程为背景，通过有限元软件建立联络通道冻胀位移场三维数值模型，研究了盐水温度和水泥掺量对土体冻胀位移的影响，并计算不同冻结壁厚度下地表冻胀位移量以及联络通道开挖土体的塑性区域，在满足施工安全的前提下，进一步对冻结壁设计参数进行优化，以减小土体冻胀位移。结果表明：采用水泥预加固-人工冻结联合工法施工，当水泥掺量设定为12%，盐水温度控制在-25℃~-31 ℃时，积极冻结末期，地表冻胀位移能够满足工程监测要求；水泥掺量设定为12%，冻结壁厚度设定在1.8m，盐水温度控制在-31 ℃。可见相对于原施工方案，采用联合工法施工，积极冻结末期地表冻胀量减小了73%。

Study on frost heave characteristics of ground reinforced by cement pre-reinforcement-artificial freezing combined method

In order to study the construction parameters of the combined construction method that can effectively control the frost heave displacement of the soil, this paper takes the freezing project of a connecting passage of Guangzhou Metro Line 14 as the background, and establishes a three-dimensional numerical model of the frost heave displacement field of the connecting passage through the finite element software. The influence of saline temperature and cement content on the frost heave displacement of the soil was studied, and the frost heave displacement of the surface under different thickness of the frozen wall and the plastic zone of the excavated soil of the connecting passage were calculated. Under the premise of satisfying the construction safety, the design parameters of the frozen wall were further optimized to reduce the frost heave displacement of the soil. The results show that when the cement content is set to 12 % and the saline temperature is controlled at-25 °C ~ -31 °C, the surface frost heave displacement can meet the engineering monitoring requirements at the end of active freezing. The cement content is set to 12 %, the thickness of the frozen wall is set to 1.8m, and the brine temperature is controlled at ?31 °C. It can be seen that compared with the original construction scheme, the surface frost heave at the end of active freezing is reduced by 73 % by using the combined construction method.