基岩冻结凿井冻结孔的泥浆置换充填研究

Drilling mud replacing technology for freezing hole with slow setting cement slurry in freezing sinking in rock strata

通过实验室及现场试验,开展了缓凝水泥浆配方及性能、水泥浆结石体冻融力学特性、冻结管下沉可行性及泥浆置换充填工艺的研究.研究表明：通过掺加常用的稳定剂、降失水剂、缓凝剂获得的3种缓凝水泥浆,在35~45℃条件下稳定性良好,缓凝时间达22~34h,能与常用的钻孔泥浆较好地相容;研究掌握了缓凝水泥浆的表观黏度随温度、时间的变化规律,以及掺加膨胀剂、冻融工况对水泥浆结石体的强度、渗透系数的影响.冻结管下沉的安全性分析表明：除浮力外,管外环形空间的大小及浆液黏滞阻力对冻结管安全下沉也具有重要影响.

Extensive laboratory and field tests were conducted to study the mix proportions of slow setting cement slurry and it ＇s properties, the mechanical properties of the set cement, the sinking feasibility of freezing pipes and mud displacing technology. The results show that three kinds of slow setting cement slurry made from conventional stabilizer, fluid loss agent and re- tarding admixture, have excellent stability and 22--34 h setting time under 35--45 ~C, and have considerable compatibility with drilling mud. The rules of apparent viscosity of the slow setting cement slurry varying with temperature and time were established, the impact of swell- ing agent and freezing and thawing condition on the strength and permeability coefficient of the set cement were understood as well. Analysis on the feasibility of freezing pipes sinking re- vealed that in addition to slurry buoyancy, the size of annular space around freezing pipe and the slurry viscous resistance also have important influence on the safety of pipe sinking.